Electric Raceway Fire 

Barrier Systems in

U.S. Nuclear Power Plants 

Final Report 

Office of Nuclear Regulatory Research 

NUREG-1924
AVAILABILITY OF REFERENCE MATERIALS 

IN NRC PUBLICATIONS 

NRC Reference Material 

As of November 1999, you may electronically access 

NUREG-series publications and other NRC records at 

NRC=s Public Electronic Reading Room at 

http://www.nrc.gov/reading-rm.html. Publicly 

released records include, to name a few, NUREGseries publications; Federal Register notices; applicant, 

licensee, and vendor documents and correspondence; 

NRC correspondence and internal memoranda; 

bulletins and information notices; inspection and 

investigative reports; licensee event reports; and 

Commission papers and their attachments. 

NRC publications in the NUREG series, NRC 

regulations, and Title 10, Energy, in the Code of 

Federal Regulations may also be purchased from one 

of these two sources. 

1. The Superintendent of Documents 

 U.S. Government Printing Office 

 Mail Stop SSOP 

 Washington, DC 20402B0001 

 Internet: bookstore.gpo.gov 

 Telephone: 202-512-1800 

 Fax: 202-512-2250 

2. The National Technical Information Service 

 Springfield, VA 22161B0002 

 www.ntis.gov 

 1B800B553B6847 or, locally, 703B605B6000 

A single copy of each NRC draft report for comment is 

available free, to the extent of supply, upon written 

request as follows: 

Address: Office of the Chief Information Officer, 

Reproduction and Distribution 

 Services Section 

 U.S. Nuclear Regulatory Commission 

 Washington, DC 20555-0001 

E-mail: DISTRIBUTION@nrc.gov 

Facsimile: 301B415B2289 

Some publications in the NUREG series that are 

posted at NRC=s Web site address 

http://www.nrc.gov/reading-rm/doccollections/nuregs 

are updated periodically and may differ from the last 

printed version. Although references to material found 

on a Web site bear the date the material was accessed, 

the material available on the date cited may 

subsequently be removed from the site. 

Non-NRC Reference Material

Documents available from public and special technical 

libraries include all open literature items, such as 

books, journal articles, and transactions, Federal 

Register notices, Federal and State legislation, and 

congressional reports. Such documents as theses, 

dissertations, foreign reports and translations, and 

non-NRC conference proceedings may be purchased 

from their sponsoring organization. 

Copies of industry codes and standards used in a 

substantive manner in NRC regulatory process are 

maintained atC

NRC Technical Library 

Two White Flint North 

11545 Rockville Pike 

Rockville, MD 20852B2738 

These standards are available in the library for 

reference use by the public. Codes and standards are 

usually copyrighted and may be purchased from the 

originating organization or, if they are American 

National Standards, fromC

American National Standards Institute 

11 West 42nd Street 

New York, NY 10036B8002 

www.ansi.org 

Legally binding regulatory requirements are stated only 

in laws; NRC regulations; licenses, including technical 

specifications; or orders, not in 

NUREG-series publications. The views expressed in 

contractor-prepared publications in this series are not 

necessarily those of NRC. 

The NUREG series comprises (1) technical and 

administrative reports and books prepared by the staff 

(NUREGBXXXX) or agency contractors 

(NUREG/CRBXXXX), (2) proceedings of conferences 

(NUREG/CPBXXXX), (3) reports resulting from 

international agreements (NUREG/IABXXXX), (4) 

brochures (NUREG/BRBXXXX), and (5) compilations of 

legal decisions and orders of the Commission and 

Atomic and Safety Licensing Boards and of Directors=

decisions under Section 2.206 of NRC=s regulations 

(NUREGB0750). 

212B642B4900 

DISCLAIMER: This report was prepared as an account of work sponsored by an agency of the U.S. 

Government. Neither the U.S. Government nor any agency thereof, nor any employee, makes any warranty, 

expressed or implied, or assumes any legal liability or responsibility for any third party=s use, or the results of such 

use, of any information, apparatus, product, or process disclosed in this publication, or represents that its use by 

such third party would not infringe privately owned rights. 
Electric Raceway Fire

Barrier Systems in

U.S. Nuclear Power Plants 

Final Report 

Manuscript Completed: May 2010 

Date Published: May 2010 

Prepared by:

G. Taylor and M.H. Salley 

Office of Nuclear Regulatory Research 

NUREG-1924
This page intentionally left blank. 
iii 

ABSTRACT 

In response to the 1975 Browns Ferry Nuclear Power Plant fire, the U.S. Nuclear Regulatory 

Commission (NRC) issued Appendix R to Title 10 of the Code of Federal Regulations Part 50. 

To support fire protection defense-in-depth 1- or 3-hour electric raceway fire barrier systems 

(ERFBS) were permitted for use as an acceptable method to protect electrical cables essential 

to fire protection safe shutdown capability. However, ERFBS were a new approach to fire 

barrier applications and as the initial installation of the ERFBS began, there was uncertainty 

regarding the ERFBS performance and definitive test standards for ERFBS qualification. 

Following review and research efforts, NRC resolved many concerns with ERFBS, including the 

fire resistance, ampacity derating, and seismic position retention. This report documents the 

history of various ERFBS and how U.S. commercial nuclear power plants use ERFBS for 

compliance. This report also documents the current state of the use of ERFBS and evaluates 

the effectiveness of these barriers in achieving adequate protection for nuclear power plants. 
iv 

This page intentionally left blank.. 
v 

TABLE OF CONTENTS 

Section Page

ABSTRACT .................................................................................................................................. iii

TABLE OF CONTENTS ................................................................................................................ v

LIST OF FIGURES ..................................................................................................................... vii

LIST OF TABLES ........................................................................................................................ viii 

EXECUTIVE SUMMARY ............................................................................................................ xiii

ACKNOWLEDGMENTS ............................................................................................................. xv 

ACRONYMS AND ABBREVIATIONS ........................................................................................ xvii

1. INTRODUCTION ............................................................................................................ 1-1

2. DEFENSE IN DEPTH AND THE ROLE OF ELECTRIC RACEWAY FIRE BARRIER 

 SYSTEMS ...................................................................................................................... 2-1

3. ERFBS AND FIRE PROTECTION REGULATIONS ...................................................... 3-1

4. ERFBS FIRE RESISTANCE TESTING CRITERIA ........................................................ 4-1

4.1 History of Testing Criteria ............................................................................................... 4-1

4.2 Fire Endurance Rating ................................................................................................... 4-2

4.3 Acceptance Criteria & Test Standards ........................................................................... 4-3

5. ELECTRICAL RACEWAY FIRE BARRIER SYSTEMS (ERFBSS) ................................ 5-1

5.1 3M InteramTM E-50 Series & Rigid Panel System .......................................................... 5-3

5.2 Thermo-Lag 330-1 (Ablative Material) ....................................................................... 5-21

5.3 DARMATT KM-1 (Hydrate) ERFBS ........................................................................... 5-44

5.4 Hemyc and MT (Insulative and Insulative/Hydrate ERFBS)....................................... 5-50

5.5 Mecatiss (Insulative ERFBS) ..................................................................................... 5-68

5.6 Kaowool and FP-60 (Insulative ERFBS) .................................................................... 5-76

5.7 Promat (Hydrate) ........................................................................................................ 5-88

5.8 Pyrocrete (Hydrate) .................................................................................................... 5-92

5.9 Versawrap (Hydrate/Insulative/Intumescent) ............................................................. 5-95

5.10 Pabco (Intumescent ERFBS) ................................................................................... 5-100

5.11 Concrete (Insulative ERFBS) ................................................................................... 5-101

6. PLANT SPECIFIC USAGE AND RESOLUTION OF ERFBS ISSUES .......................... 6-1

7. SUMMARY OF FINDINGS ............................................................................................. 7-1

8. CONCLUSION ............................................................................................................... 8-1

9. DEFINITIONS ................................................................................................................ 9-1

10. REFERENCES ............................................................................................................. 10-1
vi 

TABLE OF CONTENTS 

(Continued) 

Section Page

Appendix A The Browns Ferry Fire ....................................................................................... A-1 

Appendix B Ampacity Derating ............................................................................................. B-1 

Appendix C Summaries of NRC Generic Communications on ERFBS ................................ C-1 

Appendix D Supplemental Test Result Summaries .............................................................. D-1 

Appendix E Fire Protection Regulations cited from 10 CFR 50 ............................................ E-1 

Appendix F Summary of GL 06-03 Responses ..................................................................... F-1 

Appendix G Additional Information on ERFBS Acceptance Criteria ..................................... G-1 
vii 

LIST OF FIGURES 

Figure Page

4-1. ERFBS Fire Resistance Testing Acceptance Criteria Logic Diagram ......................... 4-4

5-1. 3M Interam E-54 Series ERFBS ................................................................................. 5-3

5-2. Comparison of Butt and Finger Barrier Jointing Methods ........................................... 5-9

5-3. Thermo-Lag 330-1 ERFBS Conduit Application 1- or 3-hour .................................... 5-23

5-4. Thermo-Lag 330-1 ERFBS Cable Tray Application 1- or 3-hour ............................... 5-23

5-5. SNL Full-Scale Thermo-Lag Test Article Shown in Various States ........................... 5-34

5-6. Photo of Two Layer Darmatt KM-1 System ............................................................... 5-45

5-7. (a) Sketch and (b) Photo of Hemyc Mat .................................................................... 5-50

5-8. Hemyc 1-hour ERFBS Conduit Construction ............................................................ 5-51

5-9. Hemyc 1-hour ERFBS Banding ................................................................................. 5-51

5-10. Sectional View and Photos of Hemyc Joint Techniques ........................................... 5-52

5-11. MT ERFBS Construction ........................................................................................... 5-53

5-12. Post-test Photo of Hemyc ERFBS Showing Shrinkage at Junction .......................... 5-57

5-13. MT Installations Process for NRC Testing ................................................................ 5-65

5-14. Photo of Mecatiss ERFBS ......................................................................................... 5-68

5-15. Test Assembly of 1- and 3-hour Thermo-Lag/Mecatiss Test .................................... 5-70

5-16. Picture of (a) Kaowool and (b) FP-60 Material .......................................................... 5-76

5-17. Sketch of Kaowool / FP-50 Installation ...................................................................... 5-77

5-18. Fire Engulfing Cable Trays Clad with Kaowool. ........................................................ 5-80

5-19. Promat-H Cable Tray Protection ............................................................................... 5-88

5-20. Promat-H Conduit Protection .................................................................................... 5-89

5-21. Sketch of Layers Used in Versawarp ERFBS ........................................................... 5-95

5-22. Cut away of Versawrap ERFBS showing individual Layers ...................................... 5-95

A-1. Photograph of Conduit Damaged from Fire (NUREG/BR-0361) ................................ A-1 

G-1. Effects of Cable Mass on Cable Tray ERFBS Performance ...................................... G-6 

G-2. Cable Tray System Weight vs. Endpoint Temperatures – Test 1 .............................. G-7 

G-3. Cable Tray System Weight vs. Endpoint Temperatures – Test 2 .............................. G-8 

G-4. Conduit System Weight vs. Endpoint Temperatures Measured on the Conduit ........ G-9 

G-5. Conduit System Weight vs. Endpoint Temperatures Measured on the Bare Copper 

 Conductor Inside the Raceway ................................................................................ G-10 

G-6. Post-Fire Exposure – Hose Stream Test .................................................................. G-12 

G-7. Thermo-Lag 90 Degree Test Assembly ................................................................... G-18 

G-8. Isometric View of Typical Base Horizontal Test Assembly Prior to ERFBS 

 Installation ................................................................................................................ G-19 

G-9. 12’ x 18’ Horizontal Furnace (Top View) .................................................................. G-19 

 
viii 

LIST OF TABLES 

Table Page

1-1. ERFBS Currently Used in U.S. NPPs ......................................................................... 1-2

4-1. NFPA 251 and ASTM E-119 Temperature Time Curve Values .................................. 4-6

5-1. 3M Interam Design Comparison Old-to-New .............................................................. 5-4

5-2. 3M Interam E-50 Series Generic Installation Requirements ....................................... 5-7

5-3. Summary of April 20, 1995 Fire Endurance Test ...................................................... 5-11

5-4. Summary of May 17, 1995 Fire Endurance Test ....................................................... 5-12

5-5. Summary of July 7, 1995 Fire Endurance Test ......................................................... 5-12

5-6. Peak Seals Test Results ........................................................................................... 5-14

5-7. Peak Seals Test Results with One Additional Layer ................................................. 5-14

5-8. Peak Seals Test Results 1-Hour ............................................................................... 5-14

5-9. 3M Combustibiltiy Test Results ................................................................................. 5-15

5-10. Components of 3M InteramTM E54A ERFBS ............................................................ 5-17

5-11. 3M InteramTM E54A Fire Endurance Test Results .................................................... 5-17

5-12. Summary of Peak Seals Upgrade Testing of 3-hr 3M Interam Design to GL 86-10 

 Supplement 1 Criteria................................................................................................ 5-18

5-13. 3M Interam Combustibility Test Results Conducted at OPL ..................................... 5-18

5-14. 3M InteramTM E54A Ampacity Results ...................................................................... 5-19

5-15. Thermo-Lag 330-1 Confirmatory Order Documentation ............................................ 5-27

5-16. NIST Results of ASTM E-1354 Thermo-Lag 330-1 Testing ...................................... 5-36

5-17. Ampacity Derating Test Results - Thermo-Lag 330-1 ............................................... 5-42

5-18. Darmatt KM-1 Specifications ..................................................................................... 5-45

5-19. KM-1 1-hr Fire Endurance Results (FTCR/94/0060) ................................................. 5-48

5-20. Ampacity Results Faverdale (Test Report FTCR/96/0077) ....................................... 5-48

5-21. One & four-inch RSC Ampacity Results 3-hour KM-1 ............................................... 5-49

5-22. 600mm Cable Tray Ampacity Results (Test Report FTCR/96/0108) ........................ 5-49

5-23. Hemyc and MT Test Matrix (NRC) ............................................................................ 5-62

5-24. Summary of NRC 1-hour Hemyc ERFBS Tests ........................................................ 5-63

5-25. Summary of NRC 3-hour MT ERFBS Tests .............................................................. 5-66

5-26. 1-hour FPC Mecatiss Testing in France .................................................................... 5-72

5-27. 3-hour Mecatiss Testing in France ............................................................................ 5-72

5-28. Results of UL Mecatiss Testing ................................................................................. 5-74

5-29. Kaowool ERFBS Test Results (10/24/1978) ............................................................. 5-82

5-30. Summary of UL FP-60 Fire Resistance Test Results ................................................ 5-84

5-31. VCSNS Kaowool Testing Results ............................................................................. 5-85

5-32. PROMAT Properties .................................................................................................. 5-88

5-33. List of Promat Test Reports....................................................................................... 5-90

5-34. PROMAT-H Ampacity Derating ................................................................................. 5-90

5-35. Results of Pyrocrete 241 Thermal Transmission ..................................................... 5-94

5-36. Summary of UL Testing of Versawrap ...................................................................... 5-97

5-37. Summary of Omega Point Testing of Versawrap ...................................................... 5-98
ix 

LIST OF TABLES 

(Continued) 

Table Page

D-1. 3M Interam E54A Ampacity Results 1" & 4" Conduits ............................................... D-3

D-2. 3M InteramTM E54A Ampacity Results 12" Wide Cable Tray ..................................... D-3

D-3. 3M Interam E54A Ampacity Results ........................................................................... D-4

D-4. 3M InteramTM E54A Ampacity Results 12” Wide Cable Tray ..................................... D-5

D-5. 3M InteramTM E54A Fire Endurance Testing 1", 3", & 5" RSC (OPL) ........................ D-6

D-6. 3M InteramTM E54A Fire Endurance Testing Steel Cable Trays (OPL) ..................... D-7

D-7. 3M Interam E54A Fire Endurance Test Conduits & Junction Boxes (OPL) ............... D-8

D-8. 3M Interam E54A Test Results (OPL Project No. 8610-102570) ............................... D-9

D-9. 3M Interam E54A Fire Endurance Test Tray & Conduits (OPL) .............................. D-11

D-10. E-50A 1-hr (SwRI 01-7912) ...................................................................................... D-12

D-11. E-50A 1-hr (SwRI 01-7912a(1)) ............................................................................... D-13

D-12. UL Test of 3M E-50D 3-hr (R10125, 86NK2919) ..................................................... D-14

D-13. E-50A 1-hr (SwRI 01-7912(2)) ................................................................................. D-15

D-14. UL Subject 1724 Test Results of E-50A 3-hr (R10125-3, 84NK23288) ................... D-16

D-15. UL Subject 1724 Test Results for E-50D 3-hr (R10125-3, 84NK2919) .................... D-17

D-16. UL Subject 1724 Test Results of E-50A 1-hr (R10125, 82NK21937) ...................... D-17

D-17. UL Testing Results for E-50A 1-hr (R10125, 82NK21937) ...................................... D-18

D-18. E-50A UL Test Results (R10125, 82NK21937) ........................................................ D-18

D-19. E-50A UL Test Results (R10125, 84NK23299) ........................................................ D-19

D-20. E-54A 3M Test Results #86-78 ................................................................................ D-20

D-21. E-54A 3M Test Results #92-115 .............................................................................. D-20

D-22. E-54A 3M Test Results #87-82 ................................................................................ D-21

D-23. E-54A 3M Test Results (July 1992) .......................................................................... D-21

D-24. E-53A 3M Test Results #92-167 .............................................................................. D-22

D-25. E-54A 3M Test Results #92-141 .............................................................................. D-22

D-26. E-54A 3M Test Results #87-40 ................................................................................ D-23

D-27. E-53A & E-54A 3M Test Results #87-57 .................................................................. D-23

D-28. 3M E-53A Test Results (June 1987) ........................................................................ D-24

D-29. Twin Cities Testing 3M E-50D Test Results ............................................................. D-25

D-30. Twin Cities Testing 3M E-50 Series 1-hr Test Results ............................................. D-26

D-31. SwRI Ampacity Testing Results at 20°C .................................................................. D-27

D-32. Ampacity Results SwRI Conduits ............................................................................. D-28

D-33. Ampacity Results SwRI Tray/Conduit ...................................................................... D-28

D-34. Ampacity Results SwRI without Baseline ................................................................. D-29

D-35. 3M Ampacity Results Conduit .................................................................................. D-29

D-36. UL Ampacity Test Results for E-50A Cable Tray Configurations ............................. D-30

D-37. UL Ampacity Test Results for E-54A 1-hour Cable Tray Configurations .................. D-30

D-38. UL Interpretations of Previously Completed Test Results ........................................ D-31

D-39. UL Test Report on M20-A 1-hr Cable Tray .............................................................. D-32

D-40. UL Results for 3M M20-A/CS-195 1-hr Junction Box ............................................... D-32

D-41. UL Report on 3M Testing of 3/4, 2, 3-inch Steel Conduits ....................................... D-33
x 

LIST OF TABLES 

(Continued) 

Table Page

D-42. UL M20-A 1-hour Test Results ................................................................................. D-33

D-43. 3M Test Results of M20-A Conduit 1-hr ................................................................... D-34

D-44. UL 723 Test Results for FS-195 ............................................................................... D-35

D-45. 3M Results of Thermo-Lag upgraded with E-54A 3-hr 2" conduit ............................ D-35

D-46. 3M Results of Thermo-Lag upgraded with E-54A 3-hr 1.5" conduit ......................... D-36

D-47. TVA Ampacity Derating of 3M M20A ........................................................................ D-36

D-48. SwRI Ampacity Test Results for M20-A and CS-195 ............................................... D-37

D-49. NUMARC Thermo-Lag Test 1-1 ............................................................................... D-38

D-50. NUMARC Thermo-Lag Test 1-3 ............................................................................... D-39

D-51. NUMARC Thermo-Lag Test 1-4 ............................................................................... D-40

D-52. NUMARC Thermo-Lag Test 1-5 ............................................................................... D-41

D-53. NUMARC Thermo-Lag Test 1-6 ............................................................................... D-41

D-54. NUMARC Thermo-Lag Test 1-7 ............................................................................... D-42

D-55. NUMARC Thermo-Lag Test 2-1 ............................................................................... D-43

D-56. NUMARC Thermo-Lag Test 2-2 ............................................................................... D-44

D-57. NUMARC Thermo-Lag Test 2-3 ............................................................................... D-45

D-58. NUMARC Thermo-Lag Test 2-7 ............................................................................... D-46

D-59. NUMARC Thermo-Lag Test 2-8 ............................................................................... D-47

D-60. NUMARC Thermo-Lag Test 2-9 ............................................................................... D-48

D-61. NUMARC Thermo-Lag Test 2-10 ............................................................................. D-49

D-62. TU Electric Thermo-Lag Test 9-1 ............................................................................. D-50

D-63. TU Electric Thermo-Lag Test 9-3 ............................................................................. D-51

D-64. TU Electric Thermo-Lag Test 10-1 ........................................................................... D-52

D-65. TU Electric Thermo-Lag Test 10-2 ........................................................................... D-53

D-66. TU Electric Thermo-Lag Test 11-1 ........................................................................... D-54

D-67. TU Electric Thermo-Lag Test 11-2 ........................................................................... D-55

D-68. TU Electric Thermo-Lag Test 11-4 ........................................................................... D-56

D-69. TU Electric Thermo-Lag Test 11-5 ........................................................................... D-57

D-70. TU Electric Thermo-Lag Test 12-1 ........................................................................... D-58

D-71. TU Electric Thermo-Lag Test 12-2 ........................................................................... D-59

D-72. TU Electric Thermo-Lag Test 13-1 ........................................................................... D-60

D-73. TU Electric Thermo-Lag Test 13-2 ........................................................................... D-60

D-74. TU Electric Thermo-Lag Test 13-3 ........................................................................... D-62

D-75. TU Electric Thermo-Lag Test 14-1 ........................................................................... D-63

D-76. TU Electric Thermo-Lag Test 15-1 ........................................................................... D-64

D-77. TU Electric Thermo-Lag Test 15-2 ........................................................................... D-65

D-78. TVA Thermo-Lag Test 6.1.1 ..................................................................................... D-66

D-79. TVA Thermo-Lag Test 6.1.2 ..................................................................................... D-67

D-80. TVA Thermo-Lag Test 6.1.3 ..................................................................................... D-68

D-81. TVA Thermo-Lag Test 6.1.4 ..................................................................................... D-69

D-82. TVA Thermo-Lag Test 6.1.5 ..................................................................................... D-70
xi 

LIST OF TABLES 

(Continued) 

Table Page

D-83. TVA Thermo-Lag Test 6.1.6 ..................................................................................... D-71

D-84. TVA Thermo-Lag Test 6.1.7 ..................................................................................... D-72

D-85. TVA Thermo-Lag Test 6.1.8 ..................................................................................... D-73

D-86. TVA Thermo-Lag Test 6.1.9 ..................................................................................... D-74

D-87. TVA Thermo-Lag Test 6.1.10 ................................................................................... D-75

D-88. TVA Thermo-Lag Test 6.1.11 ................................................................................... D-76

D-89. TVA Thermo-Lag Test 6.1.12 ................................................................................... D-77

D-90. TVA Thermo-Lag Test 6.1.13 ................................................................................... D-78

D-91. TVA Thermo-Lag Test 6.1.14 ................................................................................... D-79

D-92. TVA Thermo-Lag Test 6.1.15 ................................................................................... D-80

D-93. TVA Thermo-Lag Test 6.2.2 ..................................................................................... D-82

F-1. Summary of GL 06-03 Responses .............................................................................. F-1 

G-1. Effects of Cable Mass on ERFBS Thermal Performance ......................................... G-10 

G-2. ERFBS Protected Conduit – External Raceway Surface vs. Internal Area 

 Temperature Differential as a Function of Cable Mass ............................................ G-11 

G-3. Summary of Acceptable Cable Insulation Testing Approach ................................... G-14 

 
xii 

This page intentionally left blank. 
xiii 

EXECUTIVE SUMMARY 

In the United States, commercial nuclear power plants (NPPs) are designed with robust 

redundant safety systems, but the 1975 Brown Ferry Nuclear Plant (BFN) fire demonstrated the 

vulnerability of these redundant systems to fire damage from a single fire. At BFN, the fire 

damaged over 1600 cables, rendered numerous systems unavailable, and caused several 

systems to operate inadvertently. This event resulted in additional regulatory attention to fire 

protection aspects of NPP design. In response to this review, the U.S. Nuclear Regulatory 

Commission (NRC) issued new regulatory requirements backfit onto the licensee and 

developed to reduce the likelihood of a single fire causing damage to reactor safety systems 

required to safely shutdown and maintain the plant in a safe condition. As part of these new 

regulatory requirements, Section III.G.2 of Appendix R to 10 CFR Part 50 provided three 

prescriptive means to ensure redundant trains within a single fire area were protected from the 

effects of a fire. Two of the three approaches required the use of a 1- or 3-hour rated fire 

barrier, to protect equipment required for post-fire safe-shutdown. 

Electrical cables are often the primary component requiring protection within a single fire area 

and the barriers used to protect cables became known as electric raceway fire barrier systems 

(ERFBS). ERFBS are widely used in U.S. commercial NPP applications to protect critical 

components (i.e., electrical cables) from a fire not promptly extinguished by the fire suppression 

activities. Employing ERFBS properly will ensure the safe shutdown of the reactor. Although 

ERFBS are not required where other fire protection features can provide adequate protection, 

there is a large fraction of NPPs that use ERFBS to meet the fire protection regulations as well 

as to provide the third level of protection in the fire protection defense-in-depth philosophy, with 

the first level being fire prevention, and the second level being rapid detection and suppression. 

Numerous ERFBS vendors began developing systems that would provide the protection 

required by NRC fire protection regulations in the late 1970s and early 1980s. However, 

unclear guidance on the acceptable level of protection resulted in barriers from different vendors 

being qualified to different acceptance criteria making it difficult to evaluate the performance of 

the various barrier systems available. Clear acceptance criteria were eventually published and 

it soon became clear to NRC that several designs were not providing the required protection. 

This resulted in extensive time and effort by NRC staff and utilities to evaluate and confirm that 

the barriers used were capable of providing the required protection. 

Beginning with the questionable test reports related to the initial design and testing of 

Thermo-Lag 330-1 in the early 1980’s up until the most recent Generic Letter (GL) 2006-03 

regarding Hemyc in 2006, the NRC has had a large role in the review, development and 

ultimate acceptance of the adequate use of ERFBS in NPPs to assure public health and safety. 

NRC staff review identified numerous deficiencies with several ERFBS designs and 

communicated these findings to the U.S. nuclear operating fleet and stakeholders via generic 

communications in the form of GLs, bulletins, and information notices (INs). However, review of 

ERFBS is not the only role of fire protection staff at NRC and in some instances, closure of 

ERFBS issues may have taken longer than should be expected from both NRC and the publics’ 

perspective. 
xiv 

In the mid-2000’s the U.S. Government Accountability Office (GAO) was asked to examine NRC 

oversight of fire protection at U.S. commercial NPPs. GAO documented its conclusion in a 

GAO report issued in June 2008 titled, “Nuclear Safety – NRC’s Oversight of Fire Protection at 

U.S. Commercial Nuclear Reactor Units Could Be Strengthened, GAO-08-0747.” The 

conclusions of the GAO report found it critical, in the opinion of the GAO, for the need of NRC to 

test and resolve the effectiveness of ERFBS installed at nuclear units. This NUREG presents a 

review of the effectiveness of the various ERFBS used in NPPs, including problems identified 

and methods used to resolve these deficiencies. 

Today ERFBS are used in almost every NPP in the U.S. At this writing ERFBS are found in all 

but 12 of the 104 operational U.S. NPPs, adequately performing their passive fire protection 

function. In many NPPs more than one type of ERFBS is used. The rapid development and 

use of ERFBS resulted in regulatory attention to the proper testing, design, installation, 

maintenance, age management, and ability of the barrier to perform the desired function without 

affecting the operability and reliability of other structure, systems, and components important to 

safety. 

This report attempts to provide the complete history of ERFBS use at the U.S. commercial 

NPPs. The history includes discussion of NRC fire protection defense-in-depth philosophy, 

development of NRC fire protection regulations, qualification testing criteria, information on the 

individual ERFBS products, and a review of ERFBS used at each NPP currently operating in the 

U.S. Its purpose is to provide a single document compiling information on the various ERFBS 

used in the United States. This report provides a description of regulatory requirements and 

ERFBS testing acceptance criteria, a detailed evaluation of each type of ERFBS, and a review 

of individual plants use of ERFBS. It also provides the regulatory footprint as to how the NRC 

achieved closure for various ERFBS issues. The report presents a history of the problems and 

benefits of using ERFBS to protect critical components. In addition to providing a historical 

perspective, each ERFBS is evaluated and an attempt has been made to identify the use and 

acceptance of the ERFBS. An electronic media (DVD) is included in the back cover of this 

NUREG to provide an understanding for both the construction and testing of ERFBS as well as 

informative video recordings to allow the reader to better understand the design construction, 

testing and operation of ERFBS. 

The information presented has been collected from hundreds of publically available documents 

and interviews with staff involved with review of these issues. The vast amount of information 

available makes it evident that NRC and nuclear industry have undertaken a substantial amount 

of effort to ensure that ERFBS are performing their design function to ensure public health and 

safety. This report provides additional verification that there are no outstanding generic safety 

issues related to ERFBS known to NRC and past ERFBS deficiencies have been addressed or 

are in the process of resolution via the risk-informed performance-based approach outlined in 

10 CFR 50.48(c), National Fire Protection Association Standard NFPA 805. 

This report also shows that there is reasonable assurance that the ERFBS currently used in 

NPPs to provide protection for safe shutdown capability are sufficient for adequate protection of 

the public health and safety. In addition, the report shows that there are sufficient controls in 

place for future installations of new materials and industry inspections of the existing materials, 

to provide for safety of NPPs. 
xv 

ACKNOWLEDGEMENTS

The authors offer their thanks and appreciation to the many individuals who provided support 

and comments during the development of this report. First we acknowledge the contributions of 

Daniel Breedlove. Dan’s hard work and diligence ensured that this report was published on 

time and include all available information, including past test report and various aspects of plant 

ERFBS activities. 

We also thank H.W. ‘Roy’ Woods who provided invaluable guidance throughout this project as 

well as sharing his experiences with testing ERFBS. Mr. Stephen P. Nowlen of Sandia National 

Laboratories also provided supplemental discussions on the history of ERFBS testing that 

Sandia had conducted in the past. We must also acknowledge Mr. Patrick Madden of the 

Nuclear Regulatory Commission, although Pat is no longer as heavily involved in the Fire 

Protection arena as he once was, he was undoubtedly the most involved individual at NRC 

during the resolution of the Thermo-Lag issues in the mid- to late 1990’s. Pats down to the 

point discussions provided great insights in translating the written history of ERFBS. 

Finally, we would like to thank the internal and external stakeholders who took the time to 

provide comments and suggestions on the draft of this report when it was published in the 

Federal Register (74 FR 51621) on October 7, 2009. Those stakeholders who commented are 

listed and acknowledged below. 

Daniel Frumkin, Nuclear Regulatory Commission, NRR 

Ray Gallucci, Nuclear Regulatory Commission, NRR 

Steven Nowlen, Sandia National Laboratories 

Frank Wyant, Sandia National Laboratories 

Wayne Harper, Energy Northwest 

Patricia Campbell, GE Hitachi Nuclear Energy 

Fred Madden, Luminant Power 

John Butler, Nuclear Energy Institute 

David Helker, Exelon Nuclear 

Alan Holder, Progress Energy 

Randal Brown, PCI Promatec 

 
xvi 

This page intentionally left blank. 
xvii 

ACRONYMS AND ABBREVIATIONS 

3M Minnesota Mining and Manufacturing 

ADAMS Agencywide Document Access and Management System 

ADF ampacity derating factor 

ANI American Nuclear Insurers 

ANO Arkansas Nuclear One 

APCSB Auxiliary and Power Conversion Systems Branch 

ASTM American Society of Testing and Materials 

AWG American Wire Gauge 

BFN Browns Ferry Nuclear Plant 

BL Bulletin 

BSEP Brunswick Steam Electric Plant 

BTP Branch Technical Position 

BVPS Beaver Valley Power Station 

CPL Carolina Power and Light Company 

CFR Code of Federal Regulations 

CMEB Chemical and Mechanical Engineering Branch 

CO2 carbon dioxide 

CPSES Comanche Peak Steam Electric Station 

CRD control rod drive 

CR-3 Crystal River Unit 3 Nuclear Generating Station 

CSPE chlorosulphonated polyethylene 

CSR control spreading room 

DAEC Duane Arnold Energy Center 

DBNPP Davis Besse Nuclear Power Plant 

DC Cook Donald C. Cook Nuclear Power Plant 

DCNPP Diablo Canyon Nuclear Power Plant 

EQ environmental qualification 

ERFBS electric raceway fire barrier system 

FCS Fort Calhoun Station 

FHA fire hazards analysis 

FNP Joseph M. Farley Nuclear Plant 

FPC Florida Power Corporation 

FSC flame spread classification 

FSSD fire safe shutdown 

FR Federal Register 

 
xviii 

ACRONYMS AND ABBREVIATIONS 

(Continued) 

GAO Government Accountability Office 

GDC generic design criteria 

GGNS Grand Gulf Nuclear Station 

GL Generic Letter 

gpm gallons per minute 

GSU Gulf States Utilities 

HNP Shearon Harris Nuclear Plant 

HRR heat release rate 

IEEE Institute of Electrical and Electronic Engineers 

IN Information Notice 

IP-2, IP-3 Indian Point Nuclear Generating Units 2 and 3 

ITL Industrial Testing Laboratories 

JAFNPP James A. Fitzpatrick Nuclear Power Plant 

LCS LaSalle County Station 

LER licensee event report 

MAERP Mutual Atomic Energy Reinsurance Pool 

NAPS North Anna Power Station 

NEI Nuclear Energy Institute 

NFPA National Fire Protection Association 

NIST National Institute of Standards and Technology 

NMS Nine Mile Point Nuclear Station 

NPP nuclear power plant 

NRC Nuclear Regulatory Commission 

NRR Office of Nuclear Reactor Regulation 

NUMARC Nuclear Management and Resources Council 

OBE operating basis earthquake 

OCGS Oyster Creek Nuclear Generating Station 

OIG Office of Inspector General 

OPL Omega Point Laboratories 

PE polyethylene 

PINGP Prairie Island Nuclear Generating Plant 

PNP Palisades Nuclear Plant 

PRA probabilistic risk assessment 

PVC polyvinyl chloride 

PVNGS Palo Verde Nuclear Generating Station 

QCNPS Quad Cities Nuclear Power Station 

 
xix 

ACRONYMS AND ABBREVIATIONS 

(Continued) 

RBS River Bend Station 

RES radiant energy shield 

RG Regulatory Guide 

RRS required response spectra 

RSC rigid steel conduit 

SCE&G South Carolina Electric and Gas Company 

SER safety evaluation report 

SFPE Society of Fire Protection Engineers 

SNL Sandia National Laboratories 

SONGS San Onofre Nuclear Generating Station 

SQN Sequoyah Nuclear Plant 

SRP standard review plan 

SSE safe shutdown earthquake 

STP South Texas Project 

SwRI Southwest Research Institute 

TET thermal exposure threshold 

TIA Task Interface Agreement 

TMI-1 Three Mile Island Unit 1 

TSI Thermal Science, Inc. 

TU Texas Utilities 

TVA Tennessee Valley Authority 

UL Underwriters Laboratories, Inc. 

URI unresolved item 

U.S. United States 

VCSNS Virgil C. Summer Nuclear Station 

WBN Watts Bar Nuclear Plant 

XLPE cross-linked polyethylene 

 
xx 

This page intentionally left blank. 
1-1 

1. INTRODUCTION 

On March 22, 1975, the Tennessee Valley Authority (TVA) Browns Ferry Nuclear Plant (BFN) 

experienced a serious fire in its cable spreading room (CSR) and Unit 1 reactor building. 

The fire burnt for over 7 hours and damaged over 1,600 electrical cables, rendering all of Unit 1 

and many of Unit 2 Emergency Core Cooling Systems inoperable. This near-miss accident 

illustrated the vulnerability of essential electric cables to fire damage. In response to this fire, 

the U.S. Nuclear Regulatory Commission (NRC) issued Appendix R to Title 10 of the Code of 

Federal Regulations Part 50 (10 CFR 50) as a backfit to operating reactors and similar guidance 

was implemented on reactors under construction. 

For compliance1

 via Appendix R, Section III.G.2, two of the three options for lack of separation 

of cables within a single fire area involve protecting cables and/or equipment that are needed for 

post fire safe shutdown or could cause maloperation of post-fire safe shutdown equipment. The 

authors of Appendix R envisioned classical fire-rated walls being installed to separate or protect 

these cables. In actual application of the regulation, often times, classical fire walls could not be 

installed and the need was to protect just a train / division of equipment located in the electrical 

raceway. This is the origin of the ERFBS. 

An ERFBS is defined as a non-load-bearing partition type envelope system installed around 

electrical components and cabling that are rated by test laboratories in hours of fire resistance 

and are used to maintain safe-shutdown functions free of fire damage (RG 1.189). ERFBSs are 

used in NPPs to provide separation between redundant safety-related components and safe 

shutdown functions. ERFBS come in numerous designs and configurations, however, they all 

encase the component they are protecting to reduce the thermal exposure to the protected 

component during elevated fire conditions. Although the majority of ERFBS are used to protect 

electrical cables, there are some applications that use ERFBS to protect piping and other 

components important to safety. They provide fire resistance protection to one safe shutdown 

train in those fire areas that contain both trains. The objective of the safe-shutdown fire barrier is 

to ensure that a safe-shutdown train is conservatively protected from fire-related thermal insult. 

The necessity for ERFBS has been verified by probabilistic risk assessments (PRAs). These 

PRAs indicated that, even with fire barriers installed, fires are still major contributors to core melt 

probabilities. 

In June 2008, the GAO issued its report titled, “NRC’s Oversight of Fire Protection at U.S. 

Commercial Nuclear Reactor Units Could Be Strengthened, GAO-08-747.” One conclusion 

identified the need for NRC to test and resolve the effectiveness of fire wraps2

 at NPPs. 

This report provides the history, effectiveness, and plant resolution of ERFBS (i.e., fire wraps). 

Fire barriers are one level of protection used in fire protection programs to ensure the safety of 

the public and to protect the environment. Fire barriers are often employed to ensure that the 

plant can safely shut down in the event of a fire. ERFBSs are non-structural fire-rated 

assemblies that protect the electrical cables they enclose. In NPP applications, ERFBS are 

required to have a fire-resistance rating of either 1- or 3-hours, based on the specific 

application. One-hour ERFBSs require detection and automatic suppression to be installed 

within the same fire area. For some areas, licensees have requested exemptions to these 

 

1

 Compliance can also be achieved through III.G.1, III.G.3, or through the exemption process (10 CFR 50.12) 2

 Fire wrap is synonymous with ERFBS
1-2 

requirements based on the specific area configuration and low combustible loading. 

Exemptions are reviewed by the NRC staff under the agency's normal exemption process and 

the staff approves or disapproves the exemptions, as appropriate. ERFBSs in use at NPPs 

include Thermo-Lag 330-1, Darmatt, Hemyc, MT, Versa Wrap, Mecatiss, Pyrocrete, FP-60, 

Pabco, Promat, Cerablanket, Kaowool, and Minnesota Mining and Manufacturing (3M) Interam. 

Table 1-1, provides a summary of the ERFBS use at individual NPP sites. The table is ordered 

by plant name alphabetically in left column and by barrier popularity along the top header row 

with the most popular to least popular barriers arranged from left to right. As is shown in the 

table, many plants use more than one type of ERFBS. Although the choice to use multiple 

ERFBS is site specific, some factors that may have influence the use of multiple barriers are 

costs, ease of installation, new product, technical problems with other barriers, better 

performance, etc. Section 5 provides the specific details and history of each ERFBS. 

Table 1-1. ERFBS Currently Used in U.S. NPPs 

Plant Name 

3M Interam 1

Thermo-Lag 

Darmatt 

Hemyc & MT 

Mecatiss 

Kaowool & 

FP-60 

Promat 

Pyrocrete 

VersaWrap 

Pabco 

Concrete 

Arkansas Nuclear One 

Units, 1 and 2 X X X 

Beaver Valley Power Station, 

Units 1 and 2 X X X 

Braidwood Station, Units, 1 and 2 X 

Browns Ferry Nuclear Plant 

Units, 1, 2, and 3 X 

Brunswick Steam Electric Plant 

Units, 1 and 2 X 

Byron Station, Units, 1 and 2 X 

Callaway Plant, Unit 1 X 

Calvert Cliffs Nuclear Power Plant 

Units, 1 and 2 

Catawba Nuclear Station, 

Units, 1 and 2 X 

Clinton Power Station, Unit 1 X X 

Columbia Generating Station X X 

Comanche Peak Steam Electric 

Station, Units, 1 and 2 X X 

Cooper Nuclear Station 

Crystal River Unit 3 Nuclear 

Generating Plant X X 

Davis Besse Nuclear Power Station, 

Unit 1 X 

1 3M Interam includes CS-195 and FS-195 
1-3 

Table 1-1. ERFBS Currently Used in U.S. NPPs (Continued) 

Plant Name 

3M Interam 1

Thermo-Lag 

Darmatt 

Hemyc & MT 

Mecatiss 

Kaowool & 

FP-60 

Promat 

Pyrocrete 

VersaWrap 

Pabco 

Concrete 

Diablo Canyon Nuclear Power Plant, 

Units, 1 and 2 X X 

Donald C. Cook Nuclear Power 

Plant Units, 1 and 2 X X X X 

Dresden Nuclear Power Station, 

Units, 2 and 3 X 

Duane Arnold Energy Center X 

Edwin I. Hatch Nuclear Plant X 

Fermi-2 X 

Fort Calhoun Station, Unit 1 X X X 

Grand Gulf Nuclear Station X X 

H. B. Robinson Steam Electric Plant, 

Unit 2 X 

Edwin I. Hatch Nuclear Plant X 

Hope Creek Generating Station 

Indian Point Nuclear Generating, 

Units, 2 and 3 X X 

James A. Fitzpatrick Nuclear Power 

Plant X X X 

Joseph M. Farley Nuclear Plant X X 

Kewaunee Power Station X 

LaSalle County Station, 

Units, 1 and 2 X X 

Limerick Generating Station, 

Units, 1 and 2 X X 

McGuire Nuclear Station, 

Units, 1 and 2 X 

Millstone Power Station, 

Units, 2 and 3 

Monticello Nuclear Generating Plant, 

Unit 1 

Nine Mile Point Nuclear Station, 

Units, 1 and 2 X 

North Anna Power Station, 

Units, 1 and 2 X 

Oconee Nuclear Station, 

Units, 1, 2, and 3 

Oyster Creek Nuclear Generating 

Station X X X 

 
1-4 

Table 1-1. ERFBS Currently Used in U.S. NPPs (Continued)

Plant Name 

3M Interam 1

Thermo-Lag 

Darmatt 

Hemyc & MT 

Mecatiss 

Kaowool & 

FP-60 

Promat 

Pyrocrete 

VersaWrap 

Pabco 

Concrete 

Palisades Nuclear Plant X 

Palo Verde Nuclear Generating 

Station, Units, 1, 2, and 3 X 

Peach Bottom Atomic Power Station, 

Units, 2 and 3 X X 

Perry Nuclear Power Plant, Unit 1 X 

Pilgrim Nuclear Power Station X X 

Point Beach Nuclear Plant, 

Units, 1 and 2 X 

Prairie Island Nuclear Generating 

Plant, Units, 1 and 2 X X X 

Quad Cities Nuclear Power Station, 

Units, 1 and 2 X X X 

River Bend Station, Unit 1 X X 

R. E Ginna Nuclear Power Plant X 

Salem Nuclear Generating Station, 

Units, 1 and 2 X 

San Onofre Nuclear Generating 

Station, Units, 2 and 3 X X2 

Seabrook Station, Unit 1 X 

Sequoyah Nuclear Plant, 

Units, 1 and 2 X 

Shearon Harris Nuclear Power Plant, 

Unit 1 X X X 

South Texas Project, Units, 1 and 2 X 

St. Lucie Plant, Units, 1 and 2 X X X 

Surry Power Station, Units, 1 and 2 X X 

Susquehanna Steam Electric Station, 

Units 1 and 2 X X 

Three Mile Island Nuclear Station, 

Unit 1 X X 

Turkey Point Nuclear Generating, 

Units, 3 and 4 X 

Vermont Yankee Nuclear Power 

Station X 

Virgil C. Summer Nuclear Station, 

Unit 1 X X 

2 San Onofre uses Certablanket which is a similar product to Kaowool 
1-5 

Table 1-1. ERFBS Currently Used in U.S. NPPs (Continued) 

Plant Name 

3M Interam 1

Thermo-Lag 

Darmatt 

Hemyc & MT 

Mecatiss 

Kaowool & 

FP-60 

Promat 

Pyrocrete 

VersaWrap 

Pabco 

Concrete 

Vogtle Electric Generating Plant, 

Units, 1 and 2 X 

Waterford Steam Electric Station, 

Unit 3 X X 

Watts Bar Nuclear Plant, Unit 1 X 

Wolf Creek Generating Station, Unit 1 X X 

Some licensees have installed ERFBS identified in this report as non-combustible radiant 

energy shields. A non-combustible radiant energy shield is a heat shield designed to provide 

protection of redundant essential raceways or fire safe shutdown equipment against the radiant 

energy heat transfer from an exposure fire inside containment. GL 86-10, Question 3.7.1 

provides additional information on non-combustible radiant energy shields, as does IN 92-82 

and 95-27. Although ERFBS have been used as non-combustible radiant energy shields, there 

are numerous other non-combustible materials and systems that have been used to construct 

these non-combustible radiant energy shields, many of which are plant and licensee specific. 

Due to these variables, non-combustible radiant energy shields are beyond the scope of this 

report. 

 
1-6 

This page intentionally left blank. 
2-1 

2. DEFENSE IN DEPTH AND THE ROLE OF ELECTRIC 

RACEWAY FIRE BARRIER SYSTEMS 

NPPs licensed to operate by the U.S. NRC use the defense-in-depth concept of echelons of fire 

protection features to achieve a high degree of fire safety. 

Section II, “General Requirements” of Appendix R to 10 CFR Part 50 states that the fire 

protection program shall extend the defense-in-depth concept to fire protection in fire areas 

important to safety, with the following objectives: 

 prevent fires from starting; 

 detect rapidly, control, and extinguish promptly those fires that do occur; and 

 provide protection for structures, systems, and components important to safety so that a 

fire that is not promptly extinguished will not prevent the safe shutdown of the plant. 

The multiple layers of fire protection provided by the defense-in-depth concept provide 

reasonable assurance that weakness or deficiencies in any echelon will not present an undue 

risk to public health and safety. To achieve defense-in-depth, each operating reactor has an 

NRC-approved fire protection program which, when properly designed, implemented, and 

maintained, will satisfy Section 50.48, “Fire protection,” of Title 10 of the Code of Federal 

Regulations, Part 50 (10 CFR 50.48). 

The licensees have designed the fire protection programs by analyses that (1) consider 

potential fire hazards, (2) determined the effects of fires in the plant on the ability to safely 

shutdown the reactor or on the ability to minimize and control the release of radioactivity to the 

environment, and (3) specified measures for fire prevention, fire confinement, fire detection, 

automatic and manual fire suppression, and post-fire safe-shutdown capability. 

To confine a fire and limit fire damage, licensees divide NPP buildings into separate fire areas. 

These are generally rooms or plant areas that have fire-rated walls and fire-rated floor-ceiling 

assemblies (structural fire barriers) having sufficient fire resistance rating to withstand the fire 

hazards located in the fire area and, as necessary, to protect important equipment within the 

area from a fire outside the area. This passive fire protection concept, which is called 

“compartmentation,” is a fundamental fire safety measure at U.S. commercial NPPs. 

The fire barriers, which accomplish their intended design function simply by being in place 

during a fire, are important because they are the first and last lines of defense against a fire. 

That is, during the early stages of a fire, the barriers protect important equipment until the fire 

detection and automatic fire suppression systems operate. In addition, in the unlikely event that 

an automatic fire protection system fails to operate, the barriers continue to provide passive fire 

protection. 

NPP operations rely on electrical cables to power, control, and provide indication of systems 

and components. Licensees must design structures, systems and components important to 

safety to minimize the probability and effects of fire and explosions. To protect cables from the 

adverse effects of fire, licensees have and continue to use ERFBS. 
2-2 

ERFBS are a component specific application of the passive fire protection discussed above. 

The purpose of an ERFBS is to provide thermal protection to cables or other equipment 

important to the safe operation of the NPP. 

Following the design, review, testing (if applicable) and installation of an ERFBS, the licensees 

maintain their ERFBS to identify and prevent barrier degradation. Licensees perform this 

function through their maintenance and surveillance procedures. This continual review of 

ERFBS functionality maintains the defense-in-depth aspect of the ERFBS, thus providing the 

reasonable assurance that the ERFBS provides the protection for safe shutdown capability 

sufficient for adequate protection of the public health and safety. In addition, the NRC staff 

performs numerous fire protection inspections at each of the operating plants in the U.S. to 

confirm the licensees are using and maintaining their fire protection features as documented in 

their fire protection plan or other licensing basis documents. 
3-1 

3. ERFBS AND FIRE PROTECTION REGULATIONS 

During the early stage of NPP construction and operation licensing, fire protection compliance 

was implemented based on the performance objective of General Design Criterion (GDC) 3 in 

Appendix A to Title 10 of the Code of Federal Regulations (10 CFR) Part 50. 

GDC 3 states, 

Structures, systems, and components important to safety shall be designed and located 

to minimize, consistent with other safety requirements, the probability and effect of fires 

and explosions. Noncombustible and heat resistant materials shall be used whenever 

practical throughout the unit, particularly in locations such as the containment and control 

room. Fire detection and fighting systems of appropriate capacity and capability shall be 

provided and designed to minimize the adverse effects of fires on structures, systems, 

and components important to safety. Fire fighting systems shall be designed to assure 

that their rupture or inadvertent operation does not significantly impair the safety 

capability of these structures, systems, and components. (Appendix A to 10 CFR 50) 

GDC 3 set high-level goals for the fire protection program but did not provide specific 

implementation guidance. At the time, fire protection was largely based on compliance with 

local fire codes and with the requirements of insurance underwriters, since there were no 

specific regulatory requirements. As a result, fire protection was based largely on best practices 

as established from other industrial facilities including, in particular, fossil fuel power plants. 

Following the Browns Ferry Nuclear Plant Fire3

 in 1975 and the subsequent inspections, 

fundamental changes in the regulatory approach to NPP fire protection was made. The first 

change was new guidance published in Branch Technical Position, Auxiliary and Power 

Conversion Systems Branch 9.5-1 (BTP APCSB 9.5-1) that established the “defense-in-depth” 

concept for fire protection. This concept involved a layered approach to fire protection. As 

discussed previously, the fire protection defense-in-depth principles are aimed at achieving the 

following objectives: 

 Preventing fires from starting, 

 Promptly detecting, controlling, and extinguishing those fires that do occur, 

 Providing protection of structures, systems, and components important to safety to 

ensure that a fire not promptly extinguished by the fire suppression activities will not 

prevent the safe shutdown of the plant or result in release of radioactive materials to the 

environment. 

It should also be mentioned that this “defense-in-depth” philosophy for fire protection actually 

came out of the Browns Ferry Special Review Group recommendations. (NRC IN 92-46, 

Attachment 1) 

In the years following the Browns Ferry Nuclear Plant Fire, the NRC performed numerous 

inspections and re-evaluated the fire risks at NPPs and, in November 1980, NRC published a 

 

3

 The Browns Ferry fire was the root cause for developing NPP fire protection regulations (10 CFR 50.48, 

and Appendix R). A brief overview of the Browns Ferry Fire is provided in Appendix A of this document. 
3-2 

new set of fire protection requirements as 10 CFR 50.48 and Appendix R to 10 CFR Part 50.4 

The new regulations imposed a minimum set of fire protection program and post-fire safe 

shutdown requirements on plants operating prior to January 1, 1979. The primary focus of the 

requirements establishes fire protection criteria for systems needed to safely shutdown and 

maintain the reactor in a safe condition in the event of a fire. As described in more detail below, 

the new Appendix R requirements were imposed on NPPs operating before January 1, 1979, 

with several sections applicable to newer NPPs. However, Section 50.48 allowed for 

exceptions to meeting the requirements of these three sections of Appendix R, if the licensee 

had already received NRC acceptance of fire protection features meeting Appendix A to BTP 

APCSB 9.5-1 or by a comprehensive fire protection safety evaluation prepared by the NRC 

staff. It is therefore important to understand that a NPPs licensing basis documents the 

requirements for determining individual licensee compliance with regulations. 

BTP APCSB 9.5-1 was applicable to plants that were issued a construction permit after July 1, 

1976, while Appendix A to BTP APCSB 9.5-1 was applicable to plants for which application for 

construction permits were docketed prior to July 1, 1976, and plants that were operating or were 

issued construction permits prior to July 1, 1976. 

All facilities operating prior to January 1, 1979, were backfit to 10 CFR 50.48 Appendix R, 

Sections III.G, III.J, and III.O. In addition, all plants to receive their operating license after 

January 1, 1979, have license condition that satisfy specific requirements of Appendix R, 

including Section III.G for redundant trains located in a fire area. Section III.G.2 of Appendix R, 

which states three prescriptive options for ensuring one redundant trains located in the same 

fire area remain free of fire damage5

, is reproduced here: 

Section III.G.2 Except as provided for in paragraph G.3 of this section, where cables or 

equipment, including associated non-safety circuits that could prevent operation or cause 

maloperation due to hot shorts, open circuits, or shorts to ground, of redundant trains of 

systems necessary to achieve and maintain hot shutdown conditions are located within 

the same fire area outside of primary containment, one of the following means of 

ensuring that one of the redundant trains is free of fire damage shall be provided: 

a. Separation of cables and equipment and associated non-safety circuits of redundant 

trains by a fire barrier having a 3-hour rating. Structural steel forming a part of or 

supporting such fire barriers shall be protected to provide fire resistance equivalent to 

that required of the barrier; 

b. Separation of cables and equipment and associated non-safety circuits of redundant 

trains by a horizontal distance of more than 20 feet with no intervening combustible or fire 

hazards. In addition, fire detectors and an automatic fire suppression system shall be 

installed in the fire area; or 

c. Enclosure of cable and equipment and associated non-safety circuits of one redundant 

train in a fire barrier having a 1-hour rating, In addition, fire detectors and an automatic 

fire suppression system shall be installed in the fire area; 

 

4

 10 CFR 50.48 and Appendix R to Part 50 are reproduced in full in Appendix F and became effective on 

February 19, 1981. 5

 The technical basis for Appendix R states that “(i)f specific plant conditions preclude the installation of a 

3-hour fire barrier to separate the redundant trains, a 1-hour fire barrier and automatic fire suppression 

and detection system for each redundant train will be considered the equivalent of a 3-hour barrier.” 
3-3 

The underlying purpose of Section III.G of Appendix R is to ensure that where redundant trains 

are located in the same fire area at least one means of achieving and maintaining safe 

shutdown conditions will remain available during and after any postulated fire in the plant. 

Section III.G specifies three options for limiting fire damage so that one train of systems 

necessary to achieve and maintain hot shutdown remains free of fire damage. Two of the 

options rely on fire-rated barriers. 

Fire-Rated Cables 

In lieu of ERFBS to protect post-fire safe-shutdown circuits, some licensees have elected to use 

fire-rated cables. Fire rated cables are capable of withstanding high temperature (e.g., 927 °C 

[1700°F]), however such cables do not represent rated fire barriers and do not meet the 

requirements of 10 CFR 50, Appendix R, Section III.G.2, for fire rated barriers. The reason is 

that the cables themselves have the rating, not an external barrier. Use of fire rated cables in 

lieu of fire rated barriers should be in accordance with the applicable rules and the plant's 

approved fire protection program. For instance, pre-1979 plants would require an exemption 

from the requirements of Appendix R Sections III.G.2 or III.G.3, while post-1979 plants would 

require a deviation from the guidelines to allow use of a fire rated cable to meet the safety 

requirements. GL 86-10 provides information on the use of these cables in Question 3.7.1, 

“Radiant Energy Shield Fire Rating” and Question 8.10, “ASTM E-119 Design Basis.” 

On January 19, 2006, the NRC issued IN 2006-02 to inform addresses of a generic safety issue 

related to the use of a fire rated cable namely, Meggitt Si 2400 stainless-steel-jacketed. This IN 

identified a failure mode of the Meggitt cable where the cables exterior jacket contacts 

galvanized support members. The degradation was attributed to liquid metal embrittlement of 

the stainless steel cable jacket directly contacting the galvanized support material at high 

temperatures. This failure mode was not observed when the cable samples were not in direct 

contact with the galvanized material. 

Examples of the use of these fire rated cables in presented in Section 6.11 Columbia 

Generating Station, Section 6.20 Farley Nuclear Plant, and Section 6.33 McGuire Nuclear 

Station. Although, other plants may use these fire rated cables, these cables are not the focus 

of this report, however, due to their close association with ERFBS, this information is provided 

for completeness. Therefore, an extensive survey of fire-rated cable use has not been 

conducted in the development of this report. 

National Fire Protection Association (NFPA) 805 

10 CFR 50.48(c) allows licensees to use the NFPA 805, “Performance-Based Standard for Fire 

Protection for Light Water Reactor Electric Generating Plants,” on a voluntary basis, as a risk 

informed performance-based approach to fire protection at NPPs. As is discussed in this report, 

several plants that have indicated their interest to transition to NFPA 805 have ERFBS that are 

not in compliance with the requirements. 

In general, the majority of plants with Hemyc or MT ERFBS installed have notified NRC of their 

intent to transition to NFPA 805, which they believe will allow for resolution of the Hemyc or MT 

ERFBS issues. For those licensees transitioning to NFPA 805, NRC staff has confirmed that 

appropriate compensatory measures are in place for deficient Hemyc materials during the 

quarterly inspections conducted by the resident inspectors (onsite inspectors). These 

compensatory measures will remain in place pending the completion of the transition. 
3-4 

If any of the NPP units intending to transition to NFPA 805 change their mind and do not 

transition, then they will have to submit exemption requests for approval to the NRC providing 

justification for the specific ERFBS configurations, or modify these configurations to come into 

compliance. 
4-1 

4. ERFBS FIRE RESISTANCE TESTING CRITERIA 

4.1 History of Testing Criteria

When the NRC developed Appendix R to 10 CFR Part 50 and other fire protection guidance, 

there were no rated ERFBS or standardized tests for ERFBS. At that time there was only the 

ANI testing standard, which was intended for insurance purposes only. The NRC would review 

and accept an applicant’s use of the American Nuclear Insurers (ANI) standard for qualification 

on a case-by-case basis. During the implementation phase of Appendix R, licensees became 

unclear as to the acceptance criteria for ERFBS. 

Following issuance of the fire protection rule in 1980, NRC began receiving questions related to 

the implementation of the rule. NRC developed responses to these questions and presented 

them in draft form in 1984 at NRC sponsored regional workshops on implementation of NRC fire 

protection requirements at NPPs. In 1986, NRC issued the final form of these responses in GL 

86-10, “Implementation of Fire Protection Requirements.” Enclosure 2 to GL 86-10 provided the 

staff position on several questions raised by licensees: specifically, Question 3.2.1 asked NRC 

staff to clarify the origin of the 163oC (325°F) temperature rise criterion. Enclosure 2 to GL 86-

10 provided the staff position on fire endurance or resistance test acceptance criteria for fire 

barrier cable-tray wraps (ERFBS), as follows; 

The acceptance criteria contained in Chapter 7, ”Tests of Nonbearing Walls and 

Partitions,” of National Fire Protection Association (NFPA) Standard 251, 

”Standard Methods of Fire Tests of Building Construction,” was applicable to 

cable-tray fire wraps. These criteria stipulate that transmission of heat through 

the barrier “shall not have been such as to raise the temperature on its 

unexposed surface more than 139oC (250°F) above its initial temperature. It is 

generally recognized that 24oC (75°F) represents an acceptable norm. The 

resulting 163oC (325°F) cold side temperature criterion is used for cable tray 

wraps because they perform the fire barrier function to preserve the cables free 

of fire damage. It is clear that cable that begins to degrade at 232oC (450°F) is 

free of fire damage at 163oC (325°F). 

Therefore, the origin of the 163°C (325°F) single point acceptance criteria was based on 

NPFA 251 and the American Society for Testing and Materials (ASTM) E-119, “Standard 

Test Methods for Fire Tests of Building Construction and Materials,” testing standards, 

along with the thermal damage threshold of cables found in use at NPPs. 

It is important to understand that when ERFBS started showing up in NPPs the ANI standard 

was the only available method for testing ERFBS and was developed for insurance purposes 

only. NFPA 251 and ASTM E-119 testing standards are used for qualifying traditional building 

members (walls, floors, beams, columns, etc.) under fire exposure conditions, and licensees 

were unclear as to how to apply those standards to ERFBS. The lack of an understanding and 

guidance on acceptable testing standards resulted in uncertainty as to the method of qualifying 

ERFBS. Most nuclear utilities and ERFBS manufacturers originally tested their ERFBS to the 

ANI Criterion. The ANI standard, as discussed below, has its deficiencies and following 

issuance of GL 86-10 and Supplement 1 to GL 86-10, the NRC no longer considered the ANI 

standard to be an acceptable method to NRC staff for qualifying ERFBS. However, these GLs 
4-2 

were not retroactive staff positions, so licensees with approved ERFBS did not have to reevaluate their barriers. 

Following issuance of IN 91-47 and IN 91-79, the Texas Utilities (TU) Electric Company 

conducted their own fire endurance test program in the summer of 1992 to qualify their ERFBS 

following the guidance and acceptance criteria of ANI as specified in ANI Information Bulletin #5 

(79), “ANI/MAERP Standard Fire Endurance Test Method to Qualify a Protective Envelope for 

Class 1E Electrical Circuits,” July 1979. This ANI standard had been developed for insurance 

purposes only and provided a method that was acceptable to ANI for demonstrating that an 

ERFBS was capable of protecting Redundant Class 1E cables in the same fire area for 

particular qualification fire resistance duration. 

Subsequent to several interactions between NRC and TU staff, NRC concluded that the 

licensees were uncertain as to whether the ANI test method established a level of fire-barrier 

performance equivalent to that established by the GL 86-10 acceptance criteria. In recognizing 

that the 1-hour and 3-hour fire rated ERFBS are unique and additional guidance on the proper 

implementation of GL 86-10 would be helpful, NRC issued Supplement 1 to GL 86-10, “Fire 

Endurance Test Acceptance Criteria for Fire Barrier Systems Used to Separate Redundant Safe 

Shutdown Trains Within the Same Fire Area,” in 1994. This supplement provided acceptance 

criteria that were satisfactory to NRC for qualifying an ERFBS fire rating. Supplement 1 to GL 

86-10, also included performance criteria based on the type of cable, and other factors to 

achieve an acceptable barrier without meeting the prescriptive test limits. This guidance was 

not applied retroactively to already approved plant-specific ERFBS. 

The general approach for licensees to qualify an ERFBS is to evaluate ERFBS testing results 

and related data to ensure it applies to the conditions under which they intend to install the 

barriers. If test results are not available for specific applications, the licensees are encouraged 

to perform independent qualification testing to provide adequate results. If all configurations 

cannot be tested, then an engineering analysis must be performed to demonstrate that cables 

would be protected adequately during and after exposure to fire. Enclosure 2 to GL 86-10 also 

provided guidance for instances where exact replication of plant configurations could not be 

tested. This guidance stated that an exemption would not be required if the following five 

criteria are met: 

1. The continuity of the fire barrier material is maintained. 

2. The thickness of the barrier is maintained. 

3. The nature of the support assembly is unchanged from the tested configuration. 

4. The application or “end use” of the fire barrier is unchanged from the tested configuration. 

5. The configuration has been reviewed by a qualified fire protection engineer and found to 

provide an equivalent level of protection. 

4.2 Fire Endurance Rating

The fire protection features required to satisfy GDC 3 include features to ensure that one train of 

those systems necessary to achieve and maintain shutdown conditions be maintained free of 

fire damage. One means of complying with this requirement is to separate one safe shutdown 

train from its redundant train in a fire area with a fire barrier having a 1- or 3-hour rating. 

But what exactly does this “rating” mean? 

Fire rating is defined as the endurance period of a fire barrier or structure, which relates to the 

period of resistance to a standard fire exposure before the first critical point in behavior is 
4-3 

observed (Regulatory Guide 1.189). The level of fire resistance required of the barrier—1 hour 

or 3 hours—depends on the other fire protection features in the fire area. 

The statement of considerations for Appendix R (45 FR 76602), stipulated the following: 

“Fire Barriers are ‘rated’ for fire resistance by being exposed to a ‘standard test 

fire.’ This standard test fire is defined by the American Society for Testing and 

Materials in ASTM E-119, ‘Standard for Fire Resistance of Building Materials.’ 

Fire barriers are commonly rated as having a fire resistance of from 1 to 8 hours.” 

Fire endurance ratings of building construction and materials are demonstrated by testing fire 

barrier assemblies in accordance with the provisions of the applicable sections of NFPA 251 

and ASTM E-119. Assemblies that pass specified acceptance criteria (e.g., standard timetemperature fire endurance exposure, unexposed side temperature rise, hose stream 

impingement) are considered to have a specific fire-resistance rating. The standard timetemperature curve, which is generally accepted for evaluating and rating the fire resistance of all 

types of building fire barriers, is considered to represent a severe fire exposure. However, the 

fire endurance tests are not intended to model any specific room fire or the conditions under 

which the ERFBS will be exposed during a fire, but rather provides a specific standard fire 

exposure against which similar fire-rated assemblies can be evaluated. 

Documentation required to establish the fire rating of a fire barrier should include the design 

description of the barrier and the test reports that verify its fire rating. 

4.3 Acceptance Criteria & Test Standards

NRC issued the following guidance on acceptable methods of satisfying the regulatory 

requirements of GDC 3: 

 BTP APCSB 9.5-1, “Guidelines for Fire Protection for NPPs,” 

 Appendix A to BTP APCSB 9.5-1, 

 BTP CMEB 9.5-1, “Fire Protection for NPPs,” 

 GL 86-10, which took precedence over previous staff guidance, and 

 Supplement 1 to GL 86-10 

In these guidance documents, NRC staff stated that as a minimum, the design of fire barriers for 

horizontal and vertical cable trays should meet the requirements of the American Standard 

ASTM E-119, "Fire Test of Building Construction and Materials," including the hose stream test. 

NRC also stated in GL 86-10 Supplement 1 that the acceptance criteria contained in NFPA 251, 

"Standard Methods of Fire Tests of Building Construction and Materials," pertaining to 

nonbearing fire barriers was applicable to cable-tray fire barrier wraps. Figure 4-1 on the next 

page, is a logic diagram for the qualification and acceptance criteria for ERFBS that was 

provided in Supplement 1 to GL 86-10. Please note the “NRC Review” box in Figure 4-1. NRC 

review of engineering evaluations of ERFBS functionality is conducted at the request of the 

licensee or during NRC staff inspections. 

ASTM E-119 and NFPA 251 provided acceptance criteria for testing ERFBS. However, prior to 

NRC issuing Supplement 1 to GL 86-10, industry had no clear understanding of the specifics on 

how ERFBS testing was supposed to be conducted to ensure adequate testing to NRC. 

In developing Supplement 1, NRC staff relied on input from industry and public stakeholders 

concerning various methods of testing. In particular, the TVA had developed a detailed and 
4-4 

sturdy engineering position on the proper way to test ERFBS, which is presented in Appendix G 

to this report. This position was presented to NRC in the early 1990s and serves as a basis to 

the guidance of GL 86-10 Supplement 1. Figure 4-1 provides the logic diagram presented in 

GL 86-10 Supplement 1 for qualifying ERFBS. Note that the “NRC Review” is done, either at 

the request of the licenses or during routine NRC staff inspections. 

Figure 4-1. ERFBS Fire Resistance Testing Acceptance Criteria Logic Diagram 

 (GL 86-10 Supplement 1) 

4.3.1 American Nuclear Insurers Fire Test Standard 

The ANI test standard was enclosed in ANI Information Bulletin #5 (79), dated July 1979. 

This test standard was to be used by those NPPs insured by ANI to qualify (for insurance 

purposes only) a Protective Envelope for Redundant Class 1E Cables in NPPs when located in 

the same fire area. The intent of this qualification standard was to establish the ability of an 

ERFBS to maintain circuit integrity when exposed to a fire outside of the cabling system, 

adjacent to the protected cable, or when subjected to the mechanical impact of hose stream or 

other impact test. 

The ANI standard includes a test for exposure fires and subjects the protected cable raceway to 

an ASTM E-119 standard temperature-time curve. Following the exposure, a hose stream test 

would be conducted following specific guidelines on line size, pressure, nozzle angle, and flow 

rate. An energized cable was placed within the ERFBS for monitoring the circuit integrity. 

The only failure criterion was loss of circuit integrity during the fire exposure or hose stream 

period. The intent of the test was to identify the onset of fire damage to the cables within the 

raceway fire barrier test specimen during the fire endurance test period. 

Early on during the qualification of ERFBS the NRC accepted the use of the ANI standard from 

several licensee submittals. However, following review of several test reports, the NRC began 

to question the applicability of the ANI standard. After completing a more detailed review of the 
4-5 

standard and test reports, the NRC determined the ANI monitoring approach to be nonconservative. Specifically, Supplement 1 to GL 86-10 states: 

The use of circuit integrity monitoring during the fire endurance test is not a valid 

method for demonstrating that protected shutdown circuits are capable of 

performing their required function during and after the test fire exposure. 

4.3.2 ASTM E-119 and NFPA 251 

GL 86-10 identifies that NRC staff found Chapter 7 of NFPA 251, “Tests of Nonbearing Walls 

and Partitions” to be an adequate testing acceptance criteria to use for qualifying cable tray fire 

barrier wraps. 

Appendix A to BTP APCSB 9.5-1 Position D.3.(d), states that the design of fire barriers for 

horizontal and vertical cable trays should, as a minimum, meet the requirements of the 

ASTM E-119, “Fire Test of Building Construction and Materials,” including hose stream test. 

The technical basis for Section III.M of Appendix R to 10 CFR 50, stipulates that “Fire barriers 

are ‘rated’ for fire resistance by being exposed to a ‘standard test fire.” This standard test fire is 

defined by the ASTM E-119 test standard. It should also be mentioned that NFPA 251 and 

ASTM E-119 are nearly identical testing standards. 

The following acceptance criteria are found in both the ASTM E-119 and NFPA 251 standards: 

 The wall or partition withstood the fire endurance test without the passage of flame or gases 

hot enough to ignite cotton waste, for a period equal to that for which classification is 

desired. 

 The wall or partition withstood the specified fire and hose stream tests, without the passage 

of flame, gases hot enough to ignite cotton waste, or the hose stream. The assembly failed 

the hose stream test if an opening developed that permits the projection of water from the 

stream beyond the unexposed surface during the hose stream test. 

 Transmission of heat through the wall or partition during the fire endurance test did not raise 

the temperature on the unexposed surfaces more than 139°C (250°F) above their initial 

temperatures. 

These standards specify that the test shall be controlled by the standard temperature-time curve 

presented in the standards. Table 4.1 and Error! Reference source not found. provide 

reference to the temperature-time values required by this standard. The measurement of these 

temperatures is the average of no fewer than nine thermocouples symmetrically disposed and 

distributed near all parts of the sample, at least 6 inches away from the sample. 

 
4-6 

Table 4-1. NFPA 251 and ASTM E-119 Temperature Time Curve Values 

4.4 Time 4.5 Temperature 

°C (oF) 

5 minutes 538 (1000) 

10 minutes 704 (1300) 

30 minutes 843 (1550) 

1 hour 927 (1700) 

2 hours 1010 (1850) 

4 hours 1093 (2000) 

8 hours 1260 (2300) 

NFPA 251 and ASTM E-119 present acceptance criteria that stipulate transmission of heat 

through the barrier “shall not be sufficient to raise the temperature on the assembly’s unexposed 

surface more than 140°C (250°F) above the assembly’s initial temperature.” 

Some NRC documentation has referenced a 162oC (325°F) cold side temperature as the 

acceptance criteria. This 162°C (325°F) criterion is based on the 140°C (250°F) acceptance 

criteria of NFPA 251, with the assumption that the beginning ambient air temperature is 24oC 

(75°F) at the start of the fire exposure. The ambient air temperature at the beginning of a fire 

test is usually between 10oC (50°F) and 32oC (90°F) and is generally recognized that 24oC 

(75°F) represents an acceptable norm. Therefore, the 140oC (250°F) criterion of NFPA 251, 

plus the ambient air temperature assumption of 24oC (75°F) is equivalent to the 162oC (325°F) 

criterion. 

Chapter 5 “Conduct of Fire Tests,” of NFPA 251 provides information on the qualification time 

for the fire endurance test along with the Hose Stream Test application. The Hose Stream 

Tests allows for a duplicate test specimen exposed to half of that indicated as the resistance 

period immediately after which the specimen shall be subjected to the impact, erosion, and 

cooling effects of a hose stream. 

Time-Temperature Curve

0

200

400

600

800

1000

1200

0:00 1:00 2:00 3:00

Time (h:min)

Temperature (C)

0

500

1000

1500

2000
4-7 

Additional information on NRC acceptance criteria related to combustibility, ampacity derating, 

seismic qualification and fire endurance (including test specimen construction, hose stream test, 

and cable functionality) are located in Appendix H. 

4.5.1 Purpose and Brief History of the ERFBS Hose Stream Test 

Originally, ERFBS were exposed to the same solid-stream hose stream test that applied to 

primary structural fire walls. As noted above, some standards did allow for a second identical 

test specimen exposed to only 1⁄2 the fire endurance period to be used for hose stream testing, 

whereas others applied the hose stream to the test article after completion of the full fire 

exposure duration test. 

The solid-stream hose test was derived from very early life safety concerns for firefighting 

personnel. During certain historical fire incidents (early 1900’s), structural walls actually 

collapsed when a fire hose was played against them putting firefighters at risk. The hose 

stream test was added to the fire barrier standard (ASTM E119) to reduce the chances of that 

happening. The standard’s specifications were based on a typical solid-stream hand-held fire 

hose (pressure, line and nozzle characteristics). The ASTM and NFPA standards made no 

exception to the hose stream test for non-bearing partitions and those protocols were also being 

applied to ERFBS. 

Many of the early ERFBS tests resulted in severe damage to the barrier system itself when the 

solid-stream hose test was employed. The ERFBS were not, by and large, designed to 

withstand such impact especially at the end of their fire endurance capacity. Early in industry’s 

Thermo-Lag resolution efforts, industry asserted that the solid-stream hose test was 

inappropriate to the ERFBS. They argued that the structural integrity issues that drove the 

standard for a primary fire wall are not of equivalent concern when it comes to ERFBS because 

structural failure of an ERFBS is unlikely to place firefighters at significant hazard as would 

collapse of a primary structural element such as a wall. The nuclear industry also argued that 

industry practice relied on either fog nozzles or adjustable diffusion-type nozzles for interior fire 

fighting rather than fixed pattern solid-stream type nozzles. The NRC ultimately agreed with this 

position and endorsed the use of an alternate hose stream test using a diffusion nozzle rather 

than a solid-stream nozzle. As a result, most of the ERFBS qualification tests performed since 

the early 1990’s have used the diffusion nozzle hose test rather than a solid-stream hose test. 

The purpose for maintaining the hose stream testing of ERFBS is to evaluate the cooling, 

impact and erosion aspects of the ERFBS. 

 
4-8 

This page intentionally left blank. 
5-1 

5. ELECTRICAL RACEWAY FIRE BARRIER SYSTEMS (ERFBSs) 

The purpose of an ERFBS is to ensure redundant safe shutdown circuits located in the same 

fire area are protected and remain operational (i.e., free of fire damage) during a NPP fire. 

ERFBS can accomplish this in several different methods. The following provides a brief 

description of each. 

 Insulation materials limit the exposure to the heat transfer rate by reducing the conductive 

heat transfer rate to the protected cable/circuits in accordance with Fourier’s Law. 

 Insulative ERFBS include: 

o Hemyc 

o Kaowool & FP-60 

o Concrete 

o Mecatiss 

 Intumescences materials reduce the heat transfer rate to the protected cable/circuits by 

chemically absorbing heat energy. This endothermic reaction causes the material to swell, 

increasing in volume and decreasing in density. 

 Intumescent ERFBS include: 

o Pabco o 3M Rigid Panel 

 Ablation materials reduce the heat transferred to the protected cable/circuits by sublimation.6

When heated, the ablation material is consumed (sacrificed) through sublimation and mass 

loss which provides cooling and forms a thermal shield. 

 Ablative ERFBS include: 

o Thermo-Lag 330-1 

 Hydrate materials contain chemically bound water that is used up during a fire exposure by 

an endothermic reaction, which maintain temperatures near 100°C (212°F) until the hydrate 

(water) is converted into steam. Hydrate ERFBS include: 

 Hydrate materials include: 

o Darmatt KM-1 

o Promat 

o Pyrocrete 

Several barriers use a combination of the heat transfer methods, these ERFBS include: 

o Versawrap (hydrate, insulative, and intumescent) 

o MT (hydrate and insulative) 

o 3M Interam E-50 Series (hydrate and insulative) 

This section provides a detailed description of each ERFBS product used in U.S. NPPs in 

operation at the time this document was written. It provides a description of the barrier, a 

historical perspective, identification of problems associated with individual barriers, qualification 

 

6

 Sublimation is a phase transition from a solid to a gas phase with no intermediate liquid phase 
5-2 

testing, and corrective actions taken to address ERFBS deficiencies. It should be noted that 

dimensions presented are for the readers understanding of the ERFBS design and doesn’t 

signify an NRC approved design unless specifically stated. 

 
5-3 

5.1 3M InteramTM E-50 Series & Rigid Panel System (Hydrate/Insulative & Intumescent)

Interam E-50 Series is a fire barrier system designed and manufactured by Minnesota Mining 

and Manufacturing (3M), and supplied by PCI Promatec. 1- and 3-hour rated 3M InteramTM 

E-54 barrier systems have been designed and tested in accordance with Supplement 1 to 

GL 86-10. 

The 3M InteramTM E-50 Series ERFBS is the most commonly used barrier in operating NPPs. 

This ERFBS consists of multiple layers of flexible mat that is used to provide 1- and 3-hours of 

fire resistance rating protection to electrical raceways. Figure 5-1 provides a cut away 

illustration of a 3M Interam E-54 ERFBS. 

Figure 5-1. 3M Interam E-54 Series ERFBS (PCI Promatec, 2010) 

The E-54A ERFBS is manufactured as a mat with a nominal thickness of 10.2 mm (0.4 in). The 

mat contains aluminosilicate fibers bound in an organic matrix that is sandwiched between a 

metal foil (aluminum or stainless steel) and a synthetic polymer (nylon) laminated scrim. 

The 3M Interam 1- and 3-hour rated ERFBS achieve its fire performance and endurance 

properties by a combination of chemical and physical properties. The thermal protection is 

provided by the absorption of heating during an endothermic reaction (from a chemically-bound 

ingredient that releases chemically bound water), and via the thermal mass (heat sink) of the 

mat. After the endothermic reaction has gone to completion, remaining ceramic fibers act as a 

high-temperature insulator. The metallic foil backing is affixed to the outside of the mat to 

provide a reflective substrate that will reflect radiant energy away from the barrier and reduce 

the thermal transmission of heat through the barrier. 

The manufacture identifies the type of foil backing by the postscript “A” for aluminum backed 

mats and “C” for stainless steel backed mats. These laminates are 0.076 mm (0.003 in) thick 

and attached to the base mat by the use of adhesive. Type “C” backing is an annealed 

Type 304 stainless steel foil and is typically used for inside containment where aluminum is not 
5-4 

allowed. UL Test report R10125, 86NK2919 dated May 30, 1986, was conducted to determine 

any differences in thermal protection among the two barriers. The results indicated that the two 

barrier are very similar in their thermal conductance, however the stainless steel backed mat did 

experience a slightly higher internal temperature at the 1-hour time period (approximately 5.6oC 

(10°F) higher). 

WBN Unit 1 use the rigid panel ERFBS (CS-195), while Salem is the only plant that used the 

FS-195 barrier. Both FS-195 and CS-195 are an intumescent type of material that expands up 

to eight times its initial volume upon heating. This expansion begins around 250°C (482oF) and 

exhibits significant expansion in the 350°C (662oF) temperature range. shows a comparison of 

butt and finger barrier jointing methods. 

5.1.1 History 

When 3M decided to enter into the nuclear fire protection business, they first conducted generic 

type fire tests at nationally recognized fire testing laboratories. After satisfying results, upgrades 

and refinements to the installation methods, techniques and materials were obtained by using 

the 3M internal fire test facility with independent quality assurance procedures and inspections. 

These tests were conducted prior to GL 86-10 Supplement 1 guidance and the acceptance 

criteria chosen by 3M was the cable jacket temperature within the ERFBS exceeding 121oC 

(250°F) above ambient and for structural members a failure criterion of the metal surface 

temperature reaching 538oC (1000°F). 

Originally, 3M manufactured several lines of fire protection products used to protect electrical 

raceways, including CS-195, FS-195, E-20 and E-50 series materials. However, following 

successful GL 86-10 Supplement 1 qualification testing of the E-54 series ERFBS, all other 

series of 3M systems were discontinued. 

Peak Seals, Inc. (now PCI Promatec) became the Master Distributer of 3M InteramTM fire wrap 

system for commercial NPPs on April 24, 1995. Following NRC letter to Peak Seals dated 

September 5, 1997, Peak Seals agreed to conduct qualification testing of their systems prior to 

any new installations. Their testing approach was to qualify existing 3M designs to the 

requirements of Supplement 1 to GL 86-10. When the 3M designs previously qualified to ANI 

criteria did not meet the more stringent acceptance criteria of GL 86-10 Supplement 1, Peak 

Seals modified the 3M Interam designs and successfully qualified a range of raceway types, 

sizes, and configurations for both 1- and 3-hour applications. In their October 3, 1997 letter to 

NRC, Peak Seals provided a comparison of the barrier design for pre-GL 86-10 Supplement 1 

barriers and post GL 86-10 Supplement 1 barriers. This information is reproduced in Table 5-1. 

Table 5-1. 3M Interam Design Comparison Old-to-New 

Electric 

Raceway 

Configuration 

Fire 

Resistance 

Rating 

(hours) 

Pre GL 86-10/Supplement 1 

Configuration 

GL 86-10/Supplement 1 

Configuration 

Conduit 1 0.9” Thick (3 Layers E-53A) 1.2” Thick (4 Layers E-54A) 

Tray 1 0.8” Thick (2 Layers E-54A) 1.2” Thick (4 Layers E-54A) 

Junction Box 1 0.9” Thick (3 Layers E-53A) 1.2” Thick (4 Layers E-54A) 
5-5 

Table 5-1. 3M Interam Design Comparison Old-to-New (Continued) 

Electric 

Raceway 

Configuration 

Fire 

Resistance 

Rating 

(hours) 

Pre GL 86-10/Supplement 1 

Configuration 

GL 86-10/Supplement 1 

Configuration 

Air Drop 1 0.9” Thick (3 Layers E-53A) 1.2” Thick (4 Layers E-54A) 

Conduit 3 2.0” Thick (5 Layers E-53A) 2.8” Thick (5 Layers E-54A 

with two 0.4” Air Gaps 

Tray 3 2.0” Thick (5 Layers E-53A) 2.8” Thick (6 Layers E-54A 

with one 0.4” Air Gap) 

Junction Box 3 2.0” Thick (5 Layers E-53A) 3.2” Thick (6 Layers E-54A 2 

Air Gaps) 

Air Drop 3 2.0” Thick (5 Layers E-53A) 2.0” Thick (5 Layers E-54A) 

5.1.2 Problems 

5.1.2.1 Information Notice 93-41 

IN 93-41 indentifies an NRC inspection of the testing basis for Salem using a 3M FS-195 fire 

barrier test report stated, 

“According to the test report, the metal duct temperature on the unexposed side of the 

fire barrier material exceeded 139°C (250°F) above ambient in about 30 minutes. At 60 

minutes the temperature was 326.5°C (620°F). The test specimen was not subject to a 

hose stream test. The condition of the cables at the end of the test was not reported.” 

IN 93-41 also identified that a test report issued by Twin City Testing Corporation, dated 

September 1986, for an InteramTM E-50 Series fire barrier produced by 3M Company didn’t 

adequately document the justification for qualification for this barrier. For this test, circuit 

integrity acceptance criterion specified by the ANI was used. The temperatures within the fire 

barrier and the conditions of the cables at the end of the test were not reported. In addition, the 

fire barrier construction details and methods of fire barrier application for the test specimens 

were not documented in the test report. 

Many of the early test reports did not fully document all of the pertinent information needed by 

today’s guidance to ensure the acceptable qualification of the ERFBS. In addition, 

Supplement 1 to GL 86-10 did not exist when these early testing was being performed, which 

resulted in a majority of the testing having not conducted hose stream tests, cable fill or 

placement of thermocouples, as specified in current NRC guidance documents. 

 
5-6 

5.1.2.2 Information Notice 95-52 

IN 95-52, “Fire Endurance Test Results for Electrical Raceway Fire Barrier Systems 

Constructed from 3M Company Interam Fire Barrier Materials,” reported results of full-scale fire 

endurance tests for ERFBS constructed from 3M Company Interam fire barrier materials. Two 

1-hour tests were conducted, one using Interam E-53A mat material that failed the temperature 

rise criteria towards the end of the fire exposure, while the other test using Interam E-54A mat 

material resulted in no failures. A 3-hour test was also conducted and resulted in no cable 

raceway passing the temperature rise acceptance criteria as specified in Supplement 1 to GL 

86-10. Section 5.1.3 provides a detailed description of these testing configurations and failures. 

5.1.2.3 Information Notice 95-52, Supplement 1 

IN 95-52, Supplement 1, “Fire Endurance Test Results For Electrical Raceway Fire Barrier 

Systems Constructed From 3M Company InterimTM Fire Barrier Materials,” dated March 17, 

1995, documents additional 3-hour fire endurance testing failures identified in test reports 

forwarded to NRC by the Master Distributer Peak Seals, Inc. In these test reports, only a 

minimal fraction of the test articles met the temperature rise acceptance criteria of GL 86-10 

Supplement 1, with the majority of the articles exceeding the criterion prior to the completion of 

the tests duration. 

5.1.2.4 Qualifying 3M InteramTM to GL 86-10 Supplement 1 

Prior to GL 86-10 Supplement 1, 3M InteramTM configurations available from the vendor had 

only been qualified to the ANI/MEARP criteria. To evaluate the 3M barrier performance, Peak 

Seals (PCI Promatec) performed testing to evaluate their ERFBS design against GL 86-10 

Supplement 1 guidance. As documented in IN 95-52 and IN 95-52 Supplement 1, many of the 

older 3M InteramTM designs did not meet the NRC acceptance criteria. As such the vendor reengineered the 3M InteramTM ERFBS to achieve a 1- and 3-hour qualification via the GL 86-10 

Supplement 1 criteria. In many instances an additional layer of mat was added to the older 

system designs to achieve the desired fire rating. However, with the additional layer(s), the 

vendor also had to reevaluate the ampacity derating, and seismic characteristics of the barrier. 

5.1.3 Testing 

Sections 5.1.3.1 and 5.1.3.2, present information on the testing of 3M Interam designs qualified 

before and after GL 86-10 Supplement 1 guidance, respectively. 

5.1.3.1 3M Interam ERFBS Testing Prior to GL-86-10 Supplement 1 Criteria 

There were numerous 3M Interam ERFBS designs qualified to the ANI/MEARP standard. The 

following provides an overview of these barrier designs. A typical 3M InteramTM E-50 Series 

ERFBS of the early vintage consisted of the following; 

 3M InteramTM E-50 series mats (number of layer dependent on rating), 

 3M FireDam 150 Caulk (used as a smoke and flame sealant), 

 3M InteramTM T-49 Aluminum Foil Tape or T-65 Stainless Steel Foil (used as a vapor 

barrier, radiant heat reflector and installation aid.) 

 3M Scotch® Brand 898 Filament Tape (used as an installation aid) 
5-7 

Older designs may have also used the following two materials finishing the ends of a raceway 

 3M Fire Barrier CS-195 Composite Sheet (used to cover openings and as a collar at the 

termination of fire protection envelopes)7

, and 

 3M Fire Barrier CP 25N/S Caulk (used as a smoke and flame sealant)7

. 

FireDam 150 Caulk was used to seal mat-to-mat assemblies and is a paste version of the E-50 

series mat.8

 3M recommended the use of CP 25N/S Caulk9 as a sealant whenever the 3M fire 

barrier terminates at a wall or floor, and caulking is required along the CS-195 product. These 

two caulks are the only material in the 3M ERFBS which are applied wet. 

The 3M InteramTM CS-195 composite sheet is reddish brown in color, 7 mm (0.28-in) thick, with 

sheet metal on one side and aluminum foil on the other. The sheet metal side faces away from 

the 3M mat, when installed around a 3M mat. It should be noted that the CS-195 is an 

intumescent material that will combust if exposed to a heat source that raises its temperature 

above the materials auto (or pilot with pilot present) ignition temperature. As a result, this 

material CS-195 should not be used inside containment unprotected. 

Although many different methods and configurations existed for installing various 3M 

components, the manufacturer specified the generic installation requirements shown in Table 

5-2 to construct an ERFBS capable of providing the required level of protection. 

Table 5-2. 3M Interam E-50 Series Generic Installation Requirements 

Electrical Raceway Configuration Minimum Layers Required for 1-hr Fire-Resistance 

Cable Trays 

< 25% cable fill 2 layers of E-54A 

≥ 25% cable fill 1 layer of E-54A and 1 layer of E-53A 

Conduits 

Steel 3 layers of E-53A 

Aluminum ≥ 5” diameter 3 layers of E-53A 

Aluminum < 5” diameter 1 layer of E-54A and 2 layers of E-53A 

Air Drops 3 layers of E-54A 

Junction Boxes 3 layers of E-54A 

 

7

 Alternative penetration seal methods have been qualified. 

8

 Fire Dam 150 Caulk is no longer manufactured 

9

 CP-25 is not used in Supplement 1 to GL 86-10 qualified 3M Interam ERFBS. 
5-8 

Table 5-2. 3M Interam E-50 Series Generic Installation Requirements (Continued) 

Electrical Raceway Configuration Minimum Layers Required for 1-hr Fire-Resistance 

Supports and Heat Transfer Items 

Supports underneath cable tray 2 layers of E-54A 

Supports partially protected 1 layers of E-54A for 12” 

 2 layers of E-53A for 9” 

 2 layers of E-54A for 6” 

 2 layers of E-53A and 1 layer of E-54A for 5” 

 3 layers of E-54A for 4” 

Electrical Raceway Configuration Minimum Layers Required for 3-hr Fire-Resistance 

All Raceway Types 5 layers of E-54A 

Other Specifications 

 Weight per unit area: E-53A = 1.42 psf (6.95kg/sq.m) ±12% 

 E-54A = 1.81 psf (8.83kg/sq.m) ±12% 

 Thickness: E-53A = 0.3 inch (7.6mm) ± 10% 

 E-54A = 0.4 inch (10.2mm) ± 10% 

3M also recommended a mat seam overlap of 5.1 cm (2.0 in) minimum or a collar with a 

minimum 10.2 cm (4.0 in) width with butt joint seams caulked with FD-150 caulk, end seams 

must be coved with T-49 aluminum foil, steel bands spaced no more than 30.5 cm (12.0 in) 

apart are placed on the surrounding last layer or stainless steel wire mesh to provide structural 

support during fire conditions. 

The selection of the components used in the 3M InteramTM E-50 Series 1-hour and 3-hour fire 

Protection Systems was varied when the item needing fire protection contained a larger than 

normal thermal mass, or when an obstruction prevents the use of typical installation techniques. 

For example, a large bundle of conduits (which represents a thermal mass much greater than a 

single conduit), can be wrapped inside a single fire protective envelope with one layer less of 

E-54A in the 3-hour system. In addition whenever the 3M fire protection systems protect an 

item near a wall or floor, the wall or floor can be used as one or more sides of the fire protective 

envelope. To accommodate an installation near a wall or floor, half inch by half inch welded 

wire mesh may be used in place of banding. 

Protection of raceway support members is achieved by applying 1-layer of E-54A mat for 1-hour 

or five layers of E-54A mat for 3-hour rating, for a distance of at least 30.5 cm (12.0 in) from the 

electrical raceway in both cases. 

For cable trays wider than 30.5 cm (12.0 in) the manufacture specified that strapping must be 

applied around or across the cable tray at a maximum spacing of 30.5 cm (12.0 in) on center 

and underneath all seams. This strapping is used to minimize sagging of the fire protection mat. 

Any strapping system with a minimum tensile strength of 227 kg (500 lbs) is satisfactory to the 

manufacturer. Some options included: 

i. Two wraps of three-fourths inch or wider 3M filament Tape #898 
5-9 

ii. Most half inch or wider polyester or nylon strapping 

iii. Metal strapping 

iv. Metal, plastic, or wood bridging across the top of the cable tray. 

Figure 5-2. Comparison of Butt and Finger Barrier Jointing Methods 

(SwRI Qualification Test – June 1984) 

5.1.3.1.1 NIST Small Scale Testing (Prior to GL 86-10 Supplement 1) 

The NIST small scale testing program involved several tests of the 3M Interam E-50 Series 

barriers. For a description of the NIST test program, please refer to Section 5.2.3.1. The first 

test (A1-1) consisted of three layers of the Interam E-53A 7.6 mm (0.3 in) thick, green, resilient 

base material with 0.076 mm (0.003 in) aluminum foil laminated on one face (exposed face) and 

a reinforcing scrim laminated on the other (unexposed face). This design is considered to be 

adequate for a 1-hour fire resistance rating. The test assembly was subjected to a 1-hour 

ASTM E-119 fire exposure. The results indicated that the average unexposed surface 

temperature rise criterion was met at 1 hour and 12 minutes, while the maximum unexposed 

single point surface temperature rise was no reached. It was also observed that during removal 

of the test specimen from the furnace apparatus, a large portion of the exposed surface material 

fell into the furnace. 

The second test (B1-1) consisted of two layers of 10.2 mm (0.4 in) thick blue Interam E-54A, 

resilient, base material with 0.076 mm (0.003 in) aluminum foil laminated to one face (exposed 

face) and a reinforcing scrim laminated to the other (unexposed face). This design is 

representative of a 1-hour rated barrier. The test assembly was subjected to a 1-hour 

ASTM E-119 fire exposure. The results indicated that this configuration did not provide the 1-

hour of protection as it failed to meet the average temperature rise criterion at 48 minutes. The 

maximum single point temperature rise criterion was not exceeded for the duration of the test. 

The third test (B3-1) consisted of five layers of Interam E-54A fire-barrier mat. The test 

assembly was subjected to the ASTM E-119 standard fire exposure for 3.5 hours. The results 
5-10 

indicated that the average and maximum single point temperature rise criterion were reached 

during the exposure. 

As discussed in Section 5.2.3, the small scale testing may not be representative of actual 

ERFBS fire endurance ratings. 

5.1.3.1.2 Fire Endurance Testing (Prior to GL 86-10 Supplement 1) 

As part of NRC staffs reverification effort following the problems associated with the ThermoLag ERFBS, NRC staff requested qualification information from the 3M to support their review. 

3M and Peak Seals (PCI Promatec) willingly provided all of the non-proprietary information to 

NRC. This included many fire endurance test reports conducted by 3M, UL, and SwRI, along 

with a hand full of seismic and ampacity derating reports conducted by entities other than 3M. 

Due to the massive amount of information provided in these reports, a summary of each test 

report has been presented in Appendix D of this report. Although these test report provide 

indication of the barriers performance, the majority of them were conducted in the mid- to late1980’s at which time NRC acceptance criteria did not exist. As a result much information 

required to make a determination of the adequacy of the fire barrier is either not reported or the 

testing was conducted in a manner differing from NRC guidance making comparison of the 

results difficult. However, as a matter of completeness, summaries of these test results are 

provided in Appendix D of this report and the complete reports can be found publically available 

in NRC NUDOCS system. Another point to make is that a fraction of these tests were 

completed at 3Ms testing facilities with the observations of staff from nationally recognized 

testing laboratories (UL, SwRI, etc.). The testing summaries you will find in this section are 

related to the failed testing reported in the Information Notices discussed above. 

IN 95-52, “Fire Endurance Test Results for Electrical Raceway Fire Barrier Systems 

Constructed from 3M Company Interam Fire Barrier Materials,” reported results of full-scale fire 

endurance tests for ERFBS constructed from 3M Company Interam fire barrier materials. 

These tests were conducted by OPL and NRC staff members were present to witness the 

testing. All test assemblies were subjected to an ASTM E-119 exposure for the duration that 

the barrier was being qualified for, followed by a hose stream test. 

The first 1-hour test conducted on April 20, 1995 used three layers of Interam E-53A fire barrier 

mat materials resulted in failures to meet the temperature rise acceptance criteria for a 61 cm 

(24.0-in) wide cable tray and three differently sized conduits (7.6 cm, 5.1 cm, and 2.54 cm 

(3.0 in, 2.0 in, and 1.0 in)), along with the air drop configuration. This assembly passed the 

hose stream test. The results are shown in Table 5-3. 

The second 1-hour test was conducted on May 17, 1995, and used three layers of Interam 

E-54A mat material to protect a 61-cm (24.0-in-wide) steel cable tray, (2.54-cm and 12.7-cm 

(1.0-in and 5.0-in, respectively)) diameter steel conduits, and a 5.1-cm (2.0-in) diameter air 

drop. No cables were contained within any of the test specimens. In all cases, these test 

specimens met the acceptance criteria specified in Supplement 1 to GL 86-10. The results are 

shown in Table 5-4. 

The last ERFBS qualification test conducted was to qualify a 3-hour Interam barrier system and 

was conducted on July 7, 1995. This test included a 61.0-cm (24.0-in) wide steel cable tray, 

15.2-cm (6.0-in) wide steel cable tray, 2.54-cm (1.0-in) diameter conduit, 3.0-in diameter 

conduit, 5-in diameter conduit, and 5.1-cm (2.0-in) wide air drop, all arranged in a U-shaped 
5-11 

configuration. In addition, a nominal 30.5-cm by 30.5-cm (12.0-in by 12.0-in) by 20.3-cm (8.0-in) 

steel junction box was included in the test arrangement. The raceways and junction boxes were 

protected with 5 to 6 layers of 10.0 mm (0.4 in) thick Interam E-54A mat material. All test 

specimens exceeded the temperature rise acceptance criteria of Supplement 1 to GL 86-10. 

Table 5-5 summarizes these results. 

Table 5-3. Summary of April 20, 1995 Fire Endurance Test 

Peak Seals – 3M Company 1-hour Interam Fire Barrier 

Allowable single point unexposed-side temperature criterion = 204°C (399°F)

Allowable average unexposed-side temperature criterion = 162°C (324°F) 

(Shading shows temperatures that exceeded, acceptance criteria of GL 86-10 Supplement 1) 

Reproduced from IN 95-52 Table 1 

Test 

Specimen 

Thermocouple 

(TC) Locations 

Average 

TC Temp

°C (°F) 

Maximum 

TC TEMP 

 °C (°F) 

Remarks 

6” Cable Tray 

Front side rail 128 (262) 170 (338) Protected with three layers of 

Interam E-53A. 

Met acceptance criteria. 

Rear side rail 128 (262) 169 (337) 

Copper Conductor 109 (228) 139 (282) 

24” Cable 

Tray 

Front side rail 187 (369) 243 (470) 

Protected with four layers of Interam 

E-53A. 

Exceeded the maximum single point 

temperature criterion at 501⁄2 minutes 

and the average temperature rise 

criterion at 541⁄2 minutes. 

Rear side rail 197 (387) 250 (482) 

Copper conductor 172 (342) 194 (382) 

5” Conduit 

Conduit surface 136 (277) 188 (370) Protected with three layers of 

Interam E-53A. 

Met acceptance criteria. Copper conductor 103 (217) 135 (275) 

3” Conduit 

Conduit surface 186 (366) 206 (402) 

Protected with three layers of 

Interam E-53A. 

Exceeded the maximum single point 

temperature criterion at 591⁄2 minutes 

and the average temperature rise 

criterion at 531⁄2 minutes. Copper conductor 165 (329) 190 (374) 

2” Conduit 

Conduit surface 181 (357) 220 (428) 

Protected with three layers of 

Interam E-54A. 

Exceeded the maximum single point 

temperature criterion at 551⁄2 minutes 

and the average temperature rise 

criterion at 55 minutes. Copper conductor 161 (321) 204 (400) 

1” Conduit 

Conduit surface 183 (361) 214 (417) 

Protected with two layers of Interam 

E-53A and an outer layer of Interam 

E-54A. 

Exceeded maximum single point 

temperature criterion at 491⁄2 minutes 

and the average temperature rise 

criterion at 52 minutes. Copper conductor 167 (332) 203 (397) 

2” Air Drop Copper conductor 163 (326) 201 (393) 

Protected with three layers of 

Interam E-54A. 

Exceeded average temperature rise 

criterion at 59 minutes. 

Junction Box Metal surface 125 (257) 155 (311) Protected with three layers of 

Interam E-54A. Met Acceptance. 
5-12 

Table 5-4. Summary of May 17, 1995 Fire Endurance Test 

Peak Seals – 3M Company 1-hour Interam Fire Barrier 

Allowable single point unexposed-side temperature criterion = 207°C (405°F)1 

Allowable average unexposed-side temperature criterion = 166°C (330°F) 

(Shading shows temperatures that exceeded, acceptance criteria of GL 86-10 Supplement 1) 

Reproduced from IN 95-52 Table 2 

Test 

Specimen 

Thermocouple 

(TC)Locations 

Average 

TC TEMP

°C (°F) 

Maximum 

TC TEMP 

°C (°F) 

Remarks 

24” Cable Tray 

Front side rail 143 (290) 198 (389) Protected with three layers of 

Interam E-54A 

Met acceptance criteria. 

Rear side rail 149 (301) 179 (354) 

Copper conductor 108 (226) 129 (265) 

5” Conduit 

Conduit surface 107 (224) 122 (251) Protected with three layers of E54A. 

Met acceptance criteria. 

Copper conductor 103 (217) 118 (244) 

1” Conduit 

Conduit surface 153 (308) 190 (374) Protected with three layers of E-54A 

Met acceptance criteria. Copper conductor 141 (286) 174 (346) 

2” Air Drop Copper conductor 117 (242) 137 (279) 

Protected with three layers of 

Interam E-54A. 

Met acceptance criteria. 

Table 5-5. Summary of July 7, 1995 Fire Endurance Test 

Peak Seals – 3M Company 3-hour Interam Fire Barrier 

Allowable single point unexposed-side temperature criterion = 208°C (407°F)1 

Allowable average unexposed-side temperature criterion = 167°C (332°F) 

(Shading shows temperatures that exceeded, acceptance criteria of GL 86-10 Supplement 1) 

Reproduced from IN 95-52 Table 3 

Test Specimen Thermocouple 

(TC)Locations 

Average 

TC TEMP

°C (°F) 

Maximum 

TC TEMP 

°C (°F) 

Remarks 

6” Cable Tray 

Front side rail 183 (361) 224 (436) Protected with four layers of Interam 

E-53A. 

Exceeded the maximum single point 

temperature criterion at 158 minutes 

and the average temperature rise 

criterion at 166 minutes. 

Rear side rail 181 (357) 234 (454) 

Copper conductor 149 (301) 173 (343) 

24” Cable Tray 

Front side rail 181 (357) 214 (417) Protected with three layers of Interam 

E-53A. 

Exceeded the maximum single point 

temperature criterion at 176 minutes 

and the average temperature rise 

criterion at 167 minutes. 

Rear side rail 173 (344) 208 (406) 

Copper conductor 117 (243) 168 (334) 

5” Conduit 

Conduit surface 113 (236) 233 (451) 

Protected with five layers of Interam 

E-54A. 

Exceeded the maximum single point 

temperature criterion at 161 minutes 

and the average temperature rise 

criterion at 178 minutes. 

Copper conductor 154 (310) 211 (411) 
5-13 

Table 5-5. Summary of July 7, 1995 Fire Endurance Test (Continued) 

Peak Seals – 3M Company 3-hour Interam Fire Barrier 

Allowable single point unexposed-side temperature criterion = 208°C (407°F)1 

Allowable average unexposed-side temperature criterion = 167°C (332°F) 

Reproduced from IN 95-52 Table 3 

Test Specimen Thermocouple 

(TC)Locations 

Average 

TC TEMP

°C (°F) 

Maximum 

TC TEMP 

°C (°F) 

Remarks 

3” Conduit Conduit surface 204 (399) 252 (485)

Protected with five layers of Interam 

E-54A. 

Exceeded the maximum single point 

temperature criterion at 148 minutes 

and the average temperature rise 

criterion at 152 minutes.

Copper conductor 173 (344) 239 (462) 

1” Conduit Conduit surface 185 (365) 277 (530) 

Protected with three layers of Interam 

E-53A. 

Exceeded the maximum single point 

temperature criterion at 126 minutes 

and the average temperature rise 

criterion at 167 minutes. 

Copper conductor 174 (345) 241 (465) 

2” Air drop Copper conductor 176 (349) 219 (426) 

Protected with five layers of Interam 

E-54A. 

Exceeded the maximum single point 

temperature criterion and the average 

temperature rise criterion at 152 

minutes. 

Junction Box Metal Surface 188 (370) 199 (391) 

Protected with six layers of Interam 

E-54A. 

Exceeded the average temperature rise 

criterion at 165 minutes. 

* Shaded cells indicate temperatures that exceeded acceptance criteria of GL 86-10 Supplement 1 

In 1995, 3M informed its nuclear costumers that, Peak Seals performed two 1-hour fire tests to 

NRC Supplement 1 guidance. The following three tables present these results. Table 5-6 

identifies testing that used the number of layers and thickness of 3M material that was shown in 

3M installation manuals and was conducted on empty (no cable) electrical components, which 

included cable trays, conduits, air drops, junction boxes and supports. 

 
5-14 

Table 5-6. Peak Seals Test Results 

Configuration 

Max. Temp. 

°C (°F) 

Avg. Temp. 

°C (°F) Rating (min.) 

6” wide Cable Tray 170 (338) 128 (262) 60+ 

24” wide Cable Tray 250 (482) 197 (387) 49 

5” diameter Conduit 188 (370) 136 (277) 60+ 

3” diameter Conduit 206 (402) 186 (366) 53 

2” diameter Conduit 220 (428) 181 (357) 54 

1” diameter Conduit 214 (417) 183 (361) 54 

Bold text indicates failure to achieve fire resistance rating. 

Table 5-7 summarizes the results of the second fire test which used one additional layer of 3M 

InteramTM mat to each system. 

Table 5-7. Peak Seals Test Results with One Additional Layer 

Configuration 

Max. Temp. 

°C (°F) 

Avg. Temp. 

°C (°F) Rating (min.) 

Cable Tray 24” x 4” 198 (389) 149 (301) 60+ 

5” diameter conduit 122 (251) 107 (224) 60+ 

1” diameter conduit 190 (374) 154 (309) 60+ 

Air Drop #8 bare 137 (279) 117 (242) 60+ 

Table 5-8 documents the fire endurance testing results conducted at UL for conduits protected 

with three layers of InteramTM E-53A and a junction box protected with three layers of 3M 

InteramTM E-54A ERFBS. 

Table 5-8. Peak Seals Test Results 1-Hour 

Configuration 

Barrier 

Construction 

Max. Temp. 

°C (°F) 

Avg. Temp. 

°C (°F) 

Rating 

(min.) 

3⁄4” diameter conduit 3 layers of E-53A 167 (333) 130 (266) 60+ 

2” diameter conduit 3 layers of E-53A 157 (314) 133 (251) 60+ 

Junction Box24” x 24” x 10” 3 layers of E-54A 166 (330) 106 (222) 60+ 
5-15 

5.1.3.1.3 Combustibility Testing (Prior to GL 86-10 Supplement 1) 

3M documented the combustibility properties of several of its products in its June 9, 1993, 

response letter to NRC, reproduced in Table 5-9. 

Table 5-9. 3M Combustibiltiy Test Results 

Material Flame Spread Fuel Contributed 

Smoke 

Development 

E-53A & E-54A mat 0.7 0 0 

FireDam 150 Caulk 2.2-6.3 0 0 

CS-195 Sheet 17 0 0 

CP 25, CP 25N/S & CP 

25S/L Caulks 6 0 0 

Based on a January 15, 1993, test report on noncombustible InteramTM E-50 Series Mat, the 3M 

InteramTM products are considered a Category No. 2 noncombustible. 

The licensee of Davis Besse Nuclear Power Plant (DBNPP) conducted combustibility testing of 

E-50 series 3M ERFBS material. ASTM E-136, “Behavior of Materials in a Vertical Tube 

Furnace at 750oC (1382oF),” testing requirements for noncombustible materials and 

ASTM E-84, “Surface Burning Characteristics of Building Materials,” were used to test the 

barrier. These tests were conducted at OPL and UL. The 3M Interam E-50 material passed the 

E-136 test and had a flame spread rating of 0.7 according to the ASTM E-84 standard. Based 

on NRC NUREG-0800 Standard Review Plan (SRP) Section 9.5-1 definition of a 

noncombustible material, the Interam E-50 series ERFBS would be classified as a noncombustible material. 

5.1.3.1.4 Ampacity Derating (Prior to GL 86-10 Supplement 1) 

The manufacturer reported the following ampacity derating values of the 3M InteramTM E-50 

Series 1- and 3-hour Fire Protection Systems. 

1-hour System:

Conduit 14-23% 

Cable Tray 37-43% 

3-hour System:

Conduit 20-30% 

Cable Tray 45-52% 

Two procedures were used to determine the ampacity derating values: 

 “Procedure of the Ampacity Derating of Fire Protected Cables – June 10, 1986,” prepared 

by SwRI. 

 UL Subject 1712, “Tests for ampacity of insulated electrical conductors installed in fire 

protective systems.” 

In these tests, a baseline of 90°C (194oF) was used and equilibrium current was measured 

before and after applying the 3M InteramTM E-50 Series 1-hour and 3-hour ERFBS. The 

ampacity derating percentages were calculated by dividing the ampere values of the protected 
5-16 

system by those of the unprotected system, subtracting from one and then multiplying by 100. 

This method is presented in further detail in Appendix B to this report. Additional details on 

numerous 3M ERFBS ampacity testing is found in Appendix D of this report. 

5.1.3.1.5 Seismic Analysis 

SwRI test reports dated July 1985 and July 1986, document the seismic testing performed on 

3M InteramTM E-50 Series Mat ERFBS for generic qualification for use in nuclear and 

conventional power plants. The actual material tested was the InteramTM E-50A mat in the 1985 

test and E-50D 3-hour barrier in the 1986 test. Both seismic testing series were conducted to 

show that the fire protection system would not break away or act as a missile when subjected to 

the specified seismic environment. The testing was also performed to demonstrate the 

effectiveness of the fire protection system would not be impaired as a result of the seismic tests 

performed. 

In 1985, a 1-hour system consisted of five layers of E-50A and the 3-hour system consisted of 

10 layers of E-50A mat. The test item was subjected to five Operating Basic Earthquake (OBE) 

tests and a single Safe Shutdown Earthquake (SSE) test. These were carried out in a five step 

sequence; 1⁄4 level, 1⁄2 level, full level, 1 1⁄2 level and 2x level as specified by the required 

response spectra (RRS). Test item included a 76.2 cm (30.0-in) wide cable tray, two 5.1 cm 

(2.0-in) diameter conduits, a Unistrut support, an air drop and 30.5 cm (12.0-in) cube junction 

box configurations. 

The test results indicated that the 1-hour system showed slight physical damage at the highest 

test levels, confined to the interfaces of the four hangers to cable tray, conduit, and junction box. 

This damage was limited to tearing of the aluminum foil tape (T-49) at the seams, which is not a 

critical member of the fire protection system (vapor barrier). The testing of the 3-hour system 

resulted in physical damage near the joints of the system, where the supports met the raceway. 

This damage was noted at half level and full level and would required repair to ensure that the 

ERFBS fire protection characteristics would not be impaired. Based on the acceptance criteria 

of IEEE 344-1975 “IEEE Recommended Practices for Seismic Qualification of Class 1E 

Equipment for Nuclear Power Generating Stations” and IEEE 323-1974, “Guide for Qualifying 

Class 1E Electrical Equipment,” these test results conclude that no part of the system broke 

loose or acted as a missile and therefore the E-50 Series ERFBS seismic performance was 

acceptable. 

The 1986 test was performed on a conduit, air drop and cable tray configuration using a 3-hour 

E-50D barrier, and conducted in the same manner as the 1985 E-50A seismic tests. The cable 

tray was tested with a 38.0 Newton-m (28.0 lbs per ft) assembly setup and the conduits and 

junction box used a 1.84 Newton-m (1.36 lbs per ft) assembly. The seismic qualification testing 

was performed in successive levels of severity up to twice the SSE level (plus 10-percent 

margin) as specified by the RRS in the test plan. The test report concluded that no portion of 

the electrical raceway protection system broke away or acted as missiles for any of the seismic 

tests performed. Physical damage was observed to the system, mostly confined to the joints of 

the conduit and junction box (air drop) and where the unistruts and cable tray layers were 

joined. The damage was first observed following the tests performed at the half and full SSE 

level tests but was minimal at this point. At successively increasing levels of acceleration, the 

joints and cracks opened further. 

Sargent and Lundy performed a seismic analysis for the 3M Rigid ERFBS, documented in a 

report dated August 26, 1982 (3M submittal, 1993). This report makes the following conclusion: 
5-17 

“The seismic loads are represented by a system of equivalent static loads 

corresponding to an acceleration of 5.0 g (0.2 oz) for the systems 

supported in the middle by the cable tray beams. The systems without a 

middle support are investigated for an equivalent load of 2.3 g (0.1 oz). 

The loads are applied simultaneously in three principal directions. The 

results of this study show that the subject fire barrier system can safely 

resist an acceleration of 5.0 g (0.2 oz) if it is supported in the middle by 

cable tray beams and 2.3 g (0.1 oz) without any support.” 

5.1.3.2 3M Interam ERFBS Design Following GL 86-10 Supplement 1 Criteria 

The 3M InteramTM E-54A ERFBS design the passed the GL 86-10 Supplement 1 acceptance 

criteria, based on Peak Seals Procedure Nos. CTP-2003 and CPT-2005, consisted of the 

materials identified in Table 5-10. 

Table 5-10. Components of 3M InteramTM E54A ERFBS

Component Application 

InteramTM E54A Primary Wrap System 

Dow Corning 732 Adhesive/Sealant Filling gaps and seams and at barrier terminations 

FireDamTM FD-150 Caulk Filling gaps at seams and at supports terminations. 

T-49 Aluminum Foil Tape Securing overlap joints, covering exposed mat and 

caulk at edges and seams. 

1⁄2” Stainless Banding and Clips Securement of final mat layer. 

5.1.3.2.1 Fire Endurance Testing (Post GL 86-10 Supplement 1) 

The vendor (Peak Seals) performed fire endurance testing in accordance with GL 86-10 

Supplemen1 at OPL. Table 5-11 provides a summary of the results and identifies 

configurations capable of providing the 3-hour fire endurance rating. Table 5-12 provides 

information on the qualified design developed by Peak Seals. Additional details of these test 

reports are provided in Appendix D. 

Table 5-11. 3M InteramTM E54A Fire Endurance Test Results 

 (OPL Project Nos. 14540-99416 & 14540-99417) 

Thermocouple 

Location 

Fire Endurance 

Rating (hours) 

Max. Single Pt. 

 Temp. 

(Max Allowable) oC 

Max Average 

Temp. 

(Avg. Allowable) oC 

5” Steel Conduit 3 153 (196) 117 (154) 

3” Steel Conduit 3 153 (196) 153 (154) 

1” Steel Conduit 3 192 (196) 153 (154) 

Steel Junction Box 3 107 (196) 101 (154) 

6” wide Cable Tray 3 167 (214) 129 (172) 

24” wide Cable Tray 3 163 (214) 133 (172) 
5-18 

Table 5-12. Summary of Peak Seals Upgrade Testing of 3-hr 3M Interam Design to 

 GL 86-10 Supplement 1 Criteria

Raceway 

Configuration 

Thermocouple (TC) 

Location 

Average

oC (oF) 

Maximum 

oC (oF) 

Upgraded 

Design 

Previous 

Design1

6” Cable Tray1 Front Side Rail (256) (319) 6 layers E54A 5 layers E54A 

 Rear Side Rail (264) (333) 

 #8 AWG Conductor (247) (303) 

24” Cable Tray1

 Front Side Rail (271) (325) 6 layers E54A 5 layers E54A 

 Rear Side Rail (269) (315) 

 #8 AWG Conductor (231) (287) 

5” Conduit2

 Conduit Surface (243) (307) 5 layers E54A 

with standoff 

5 layers E54A 

 #8 AWG Conductor (227) (269) 

3” Conduit2

 Conduit Surface (237) (307) 5 layers E54A 

with standoff 

5 layers E54A 

 #8 AWG Conductor (220) (270) 

1” Conduit2

 Conduit Surface (307) (377) 5 layers E54A 

with standoff 

6 layers E54A 

 #8 AWG Conductor (299) (346) 

2” Airdrop3

 #8 AWG Conductor (294) (338) 5 layers E54A 

with standoff 

5 layers E54A 

Junction Box2 Metal Surface (213) (224) 6 layers E54A 

with standoff 

6 layers E54A 

1 “Previous Design” refers to configurations presented in Table 5-3, Table 5-4, and Table 5-5. 

2 OPL Project 14540-99417 (allowed Avg. T=342oF & Max. T=417oF) 

3 OPL Project 14540-99416 (allowed Avg. T=310oF & Max. T=385oF) 

4 OPL Project 14540-99123 (allowed Avg. T=315oF & Max. T=338oF) 

5.1.3.2.2 Combustibility Testing (Post GL 86-10 Supplement 1) 

The vendor (Peak Seals) performed ASTM E136, “Standard Method of Test for Behavior of 

Materials in a vertical tube furnce at 750oC,” at OPL on December 14, 1995. The report dated 

January 15, 1996, only identifies the material tested as “3M E-50 INTERAMTM SERIES MAT,” 

and “Flexible Endothermic Fire Wrap.” The report concludes that the specimens met the 

specific criteria of the standard and are shown in Table 5-13. 

Table 5-13. 3M Interam Combustibility Test Results Conducted at OPL 

Specimen 

Number 

Initial 

Wt. (g) 

Final 

Wt. (g) 

Wt. 

Loss 

(%) 

Furnace 

Temp. at Start 

of Test (oC) 

Max 

Surface 

Temp. (oC) 

Max. 

Interior 

Temp. (oC) 

1 60.9 49.1 19.4 750 703 283 

2 59.2 47.8 19.3 750 768 367 

3 63.8 51.3 19.6 750 761 392 

4 64.2 52.0 19.5 750 774 306 
5-19 

5.1.3.2.3 Ampacity Testing (Post GL 86-10 Supplement 1) 

The vendor (Peak Seals) performed ampacity tests on the 3M InteramTM E54 ERFBS design 

qualified to GL 86-10 Supplement 1 criteria at OPL. The results of this testing are shown in 

Table 5-14. Additional information on this testing is provided in Appendix D to this report. 

Table 5-14. 3M InteramTM E54A Ampacity Results 

Test Item 

Fire Resistance Rating 

(hours) 

OPL Report 

No(s). 

Ampacity Derating 

Factor (%) 

1” Conduit 1 14540-99074/75 7.86 

4” Conduit 1 14540-99074/75 8.96 

24” Wide Cable Tray 1 14540-100770 49.88 

1” Conduit 3 8610-102164/65 20.29 

4” Conduit 3 8610-102164/65 34.92 

24” Wide Cable Tray 3 8610-102166 56.62 

5.1.3.2.4 LOCA Testing (Post GL 86-10 Supplement 1) 

In 1998, the vendor (Peak Seals) had loss of coolant accident (LOCA) testing performed on the 

3M InteramTM ERFBS, which consisted of radiation exposure, LOCA simulation, and Post-Test 

Inspection. 

The test specimen consisted of two cable trays (24” wide x 4” deep x 24” long) covered with 

three layers of 3M InteramTM E54C endothermic mat. One specimen was exposed to gamma 

radiation from a Cobalt-60 source, receiving a total dose of 2.042x108

 rads, while the other was 

not exposed to any radiation. Both test specimens were then exposed to elevated 

temperatures, pressures, and chemical sprays. The report documents that there was “no 

disintegration or dislodgement of the mat material or associated components.” 

5.1.4 Resolution and Staff Conclusion 

The physical structure and chemical decomposition of 3M InteramTM ERFBS during fire 

exposures allowed this barrier to perform its specified function. Fire endurance testing has 

shown that early designs (pre-1996) of the 3M InteramTM ERFBS were not capable of providing 

the required 1- or 3-hour fire resistance level of protection required by the regulations; however, 

continued development and refinement of the ERFBS resulted in the development of an 3M 

InteramTM E54A ERFBS that has been shown capable of achieving a fire endurance rating as 

outlined in GL 86-10 Supplement 1 guidance. Unlike other barrier systems, the manufacture 

and later distributer performed numerous fire endurance, seismic, LOCA, and ampacity derating 

testing of which adequately bound the configurations used in NPPs. As a result of these 

attributes, the staff has only identified problems with the early 3M InteramTM designs (as 

identified in IN 95-52 and IN 95-52 Supplement 1). 
5-20 

As a result of this review the staff concluded that Interam 3M InteramTM ERFBS when installed 

to bound as tested configurations will satisfactory perform its intended design function. 
5-21 

5.2 Thermo-Lag 330-1 (Ablative Material)

Thermo-Lag 330-1 is manufactured by Thermal Science, Incorporated (TSI), of St. Louis 

Missouri. TSI manufactures a variety of products used in heat transfer applications and the 

“330-1” class of materials is that typically found in U.S. NPPs. Thermo-Lag can be constructed 

to provide a fire endurance design rating of 1-hour or 3-hours as required by NRC regulations 

and guidance. 

Thermo-Lag 330-1 is an ablative, water-based material that will volatize at fixed temperatures 

and change from solid to vapor state. Physically this is achieved by the materials ability to 

exhibit a volumetric increase through the formation of a multicellular matrix that blocks heat to 

protect the substrate material to which it is applied. In this process, the ablative agent is 

consumed through sublimation and mass loss, which when properly designed provides cooling 

and forms a thermal shield. 

During elevated thermal exposures, the Thermo-Lags’ highly endothermic reaction takes place 

above the sublimation layer, in the layer which has been formed by the combined defects of 

pyrolysis of the binder and other ingredients contained within Thermo-Lag. The Thermo-Lag 

material composition also includes a specified quantity of glass fiber that strengthens the virgin 

material and also enhances the physical retention properties of the char layer when formed. 

The formed char layer has a high emissivity that makes its surface an effective retardant to 

heat. The char layer further serves as an effective mass and heat exchanger as well as a 

transport medium for the volatiles leaving the subliming surface. 

The original use of Thermo-Lag was in spray-on applications to provide fire protection of 

structural steel members. When the need to protect electrical cables presented itself, the TSI 

proposed using the spray-on application of Thermo-Lag as a rated ERFBS. During the initial 

installation of Thermo-Lag on NPPs electrical raceway, the installers found that an excessive 

amount of off spray was being applied to adjacent raceways and other equipment that did not 

require protection. This problem caused TSI to develop a new method of using Thermo-Lag to 

protect the electrical raceways. What they developed was a prefabricated panel and half-round 

conduit system that used the base Thermo-Lag material and some additional structural 

members. This new product is what has come to be known and recognized in the nuclear 

industry as Thermo-Lag 330-1. 

The Thermo-Lag 330-1 material is manufactured in nominal 1.588±0.318 cm (0.625±0.125 in) 

flat panels (for use on cable trays and junction boxes) and in half round prefabricated sections 

(sized for use on conduits). Most utilities use Thermo-Lag 330-1 ERFBS to satisfy NRC’s fire 

protection requirements for safe shutdown capability and in some cases licensees use ThermoLag to achieve physical independence of electrical systems per Regulatory Guide (RG) 1.75. 

Thermo-Lag 330-1 ERFBS is used in NPPs to protect cable trays, conduit, air drops (cable in 

free space), junction boxes and structural supports and hangers. Thermo-Lag 330-1 material 

has also been used as components of penetration seals and fire barrier walls. In addition, 

Thermo-Lag ERFBSs were used by some plants to construct a Radiant Energy Shield (RES) for 

cables located in containment; however, when it was identified that Thermo-Lag is a 

combustible material, the utilization of Thermo-Lag as a RES was typically eliminated or 

modified to eliminate combustible materials within containment. 
5-22 

The Thermo-Lag 330-1 ERFBS exists in several basic designs for use in NPPs, including: 

 Pre-fabricated Panel Design 

 Pre-shaped Conduit Section Design 

 Direct Spray Over Stress Skin Design 

 Direct Spray-on Design. 

The first three consist of the same material components—a Thermo-Lag Stress Skin and a 

Thermo-Lag 330-1 ablative material—the only difference being a prefabricated product versus a 

spray-over application. 

The stress skin is a steel mesh10 used in conjunction with the Thermo-Lag 330-1 ERFBS. It is 

composed of an open-weave, self-stiffened steel mesh and is used to provide an enclosure and 

mechanical base for the Thermo-Lag 330-1 ablative material. The stress skin was originally 

designed to be placed over cable trays, conduits, and other items (i.e., beneath the ERFBS), but 

some licensees have also applied the stress skin around the exterior of a Thermo-Lag ERFBS 

with a top coat of trowel grade material to help reinforce and upgrade the barrier system. 

The trowel grade Thermo-Lag 330-1 material is the same material used to fabricate the 

prefabricated panels and preshaped or preformed conduit section. It can also be supplied by 

the vendor in a sprayable form. The trowel grade material is typically applied to seal the joints 

between adjacent Thermo-Lag panels but, as discussed later, was also used to reinforce and 

upgrade the Thermo-Lag ERFBS. Common terms used in the trade were “pre-butter” or “postbutter” thermo-lag assemblies, meaning the trowel grade Thermo-Lag 330-1 was applied prior 

to assembly (i.e., pre-butter) or applied after assembly to fill joints (i.e., post-butter). The trowel 

grade Thermo-Lag 330-1 requires a minimum of 72 hours to cure or a moisture content of less 

than 100 when using a meter with a scale of 0-100. 

The direct spray method installations are limited to Susquehanna Steam Electric Station Unit 1 

and 2, and limited applications at Washington Nuclear Project, Unit 2 (now Columbia 

Generating Station). Most Thermo-Lag fire barriers installed in the field are constructed of 

prefabricated Thermo-Lag 330-1 panels and preshaped conduit sections that have been cut to 

size and shape and fastened together with either stainless steel wires or bands. When securing 

the half round preshaped conduit pieces to conduit, the manufacture recommends as a 

minimum, an 18 gauge standard stainless steel wire and/or a 0.05 cm (0.02 in) thick by 1.27 cm 

(0.50 in) wide standard stainless steel banding be used. 

In addition to protecting the raceway with the Thermo-Lag system, the vendor also recommends 

that all penetrations into the ERFBS should be fire protected for a distance of at least 45 cm 

(18 in) measured from the outer surface of the fire barriers (to prevent thermal shorts). That is, 

any raceways support members of adjoining raceways also need to be protected by the ERFBS 

for a particular distance. Thermal short members, such as support members, may be covered 

(or protected) for various distances depending on the qualified fire tested configurations. 

Although design and construction of Thermo-Lag 330-1 ERFBS vary by plant, Figure 5-1 and 

Figure 5-2 show a breakdown of the components used to construct a Thermo-Lag conduit and 

cable tray ERFBS, respectively. 

 

10 Stress Skin physical parameters 0.043 mcm (0.017 inch] minimum diam; 56 holes/sq. in. minimum; 

1.75 lbs/sq yd min) 
5-23 

 Figure 5-3. Thermo-Lag 330-1 ERFBS Conduit Application 1- or 3-hour 

 (TSI Technical Note) 

 Figure 5-4. Thermo-Lag 330-1 ERFBS Cable Tray Application 1- or 3-hour 

 (TSI Technical Note) 

 
5-24 

5.2.1 History 

Thermo-Lag 330-1 has had a long and contentious history in the NPP industry. Licensees who 

made the first NPP installations of this material did not fully recognize the physical properties 

and limitations of the material nor did they understand its potential benefits. When Appendix R 

was published as a regulation, nuclear utilities unable to meet the requirement for 6.1 m (20 ft) 

of separation between redundant equipment needed to quickly correct their problem, and TSI’s 

Thermo-Lag 330-1 ERFBS appeared to meet their need. As a result of Thermo-Lag’s being 

readily available and having test reports documenting its performance (which would later be 

questioned), Thermo-Lag became the predominant ERFBS used in the industry for compliance 

with Appendix R. However, as discussed below, when the true nature and performance of this 

material became more widely understood, the licensees had to expend considerable resources 

(i.e., a multimillion dollar fire testing project was conducted) to bring their plants into compliance 

with Appendix R’s requirements. 

Because Thermo-Lag 330-1 had no history of use in NPPs to protect safe shutdown 

cable/circuits, prior to 1980 utilities proposing to install this fire barrier material sought NRC staff 

acceptance. Along with their proposals to use Thermo-Lag 330-1, the utilities submitted test 

reports and other documentation to qualify Thermo-Lag 330-1 as a fire barrier that met NRC’s 

fire protection requirements. NRC began receiving requests from licensees for acceptance of 

Thermo-Lag 330-1 in 1981, but it wasn’t until after they first accepted its use that numerous 

additional proposals to use this material were submitted to NRC. Within a few short years over 

three-fourths of the nation’s commercial NPPs had Thermo-Lag installed for Appendix R 

compliance. 

NRC’s concerns regarding Thermo-Lag 330-1 ERFBS began after receiving several licensee 

event reports (LERs) from Gulf States Utilities (GSU) between 1987 and 1990, citing failed 

qualification fire tests and installation problems. The LERs stated that the ASTM E-119 fire 

endurance testing GSU had performed at Southwest Research Institute (SwRI) showed the 3-

hour Thermo-Lag ERFBS installed on wide aluminum cable trays resulted in a complete failure 

within about 60 minutes (i.e., one-third of the 3-hour requirement). GSU conducted this 

confirmatory testing after identifying that the fire barriers had not been installed at its River Bend 

Station in accordance with the manufacturer’s specifications. NRC issued IN 91-47, “Failure of 

Thermo-Lag Fire Barrier Material to Pass Fire Endurance Test,” dated August 6, 1991, to inform 

NPP licensees of this issue. At the time of issuance, NRC knew of at least 40 plants that had 

used Thermo-Lag to construct fire barrier assemblies with 1-hour and 3-hour ratings to enclose 

electrical raceways and other safe shutdown equipment. The amount of Thermo-Lag used at 

each plant varied from only two conduits at Monticello to over 1858 m2

 (20,000 ft2) at Comanche 

Peak Steam Electric Station, Unit 1 (CPSES). 

On December 6, 1991, NRC issued IN 91-79, “Deficiencies in the Procedures for Installing 

Thermo-Lag Fire Barrier Materials,” which provided information on deficiencies in procedures 

that the manufacturer (TSI) provided for installation Thermo-Lag 330 fire barrier material, along 

with details of the TU Electric test failures. 

In response to GSUs operating experience, NRC established a special review team in June 

1991 to review the safety significance and generic applicability of the technical issues regarding 

the use of Thermo-Lag. As part of the teams’ effort, about 40 fire endurance test reports and 

nine ampacity derating test reports were reviewed. Based on this review, the team determined 

that the fire endurance rating of the Thermo-Lag 330-1 system to be indeterminate and the 

ampacity derating tests indicated conflicting results. In addition, the team found that some 
5-25 

licensees did not adequately review and evaluate the test results, did not adequately review 

their configurations, were not bounded by tested configurations, and used inadequate or 

incomplete installation procedures. Based on these findings, the review team issued IN 91-47, 

“Failure of Thermo-Lag Fire Barrier Material to Pass Fire Endurance Test,” August 5, 1991, and 

IN 91-79, “Deficiencies in the Procedures for Installing Thermo-Lag Fire Barrier Materials,” 

dated December 6, 1991. Following the completion of this effort, NRC issued IN 92-46, 

“Thermo-Lag Fire Barrier Material Special Review Team Final Report Findings, Current Fire 

Endurance Testing and Ampacity Calculations Errors,” on June 23, 1992. This report informed 

the nuclear power utilities of the recent raceway barrier fire endurance testing failures 

completed by TU Electric and identified an ampacity calculation error in a test report published 

by Industrial Testing Laboratories (ITL) Incorporated Test Report ITL-82-5-355C. 

Attachment 1 to IN 92-46 contained the Final Report of an NRC Special Review Teams finding 

on the Review of Thermo-Lag Fire Barrier Performance. The final report concluded that the fire 

resistance ratings and ampacity derating factors for Thermo-Lag 330-1 ERFBS were 

indeterminate11 and that some licensees had not adequately reviewed and evaluated the fire 

endurance and ampacity test results for applicability to the Thermo-Lag ERFBS installed in their 

facilities. In addition, the special review team found that some licensees had used inadequate 

installations procedures to construct their Thermo-Lag fire barriers. 

Following issuance of IN 91-47 and IN 91-79 and due to its wide use, TU Electric conducted a 

series of full-scale fire endurance tests to qualify the Thermo-Lag 330-1 electrical raceway fire 

barrier configurations it had installed at its Comanche Peak Steam Electric Station. These tests 

produced additional fire endurance failure results on wide cable trays and small conduits. 

On the basis of these findings, NRC issued Bulletin 92-01, “Failure of Thermo-Lag 330 Fire 

Barrier Systems to Maintain Cabling in Wide Cable Trays and Small Conduits Free From Fire 

Damage,” and Supplement 1, “Failure of Thermo-Lag 330 Fire Barrier Systems to Perform its 

Specified Fire Endurance Function,” in June and August 1992, respectively. The bulletin 

identified that NRC had made the determination that the 1- and 3-hour Thermo-Lag 330-1 

preformed assemblies installed on conduits smaller than 10 cm (4 in) diameter and cable trays 

wider than 36 cm (14 in) did not provide the level of safety needed to meet NRC requirements. 

Bulletin 92-01 required licensees to identify areas that contained such constructions, implement 

the appropriate compensatory measures, and provide NRC with written notification of its use of 

Thermo-Lag 330-1 fire barrier systems. NRC required the licensees compensatory measures to 

remain in place until the licensee could declare the fire barriers operable on the basis of 

applicable tests that demonstrate successful 1- or 3-hour barrier performance. 

Following receipt of all licensee responses related to NRC Bulletin 92-01, NRC staff determined 

that 83 operating plants had Thermo-Lag installed and 28 operating plants did not (based on 

September 21, 1992, data). The staff also determined that most of the licensees with ThermoLag 330-1 installed did take the proper corrective actions, (i.e., they had declared the barriers 

inoperable and implemented compensatory measures consistent with their Technical 

Specifications or licensing conditions for an inoperable barrier). However, some licensees that 

had declared their barriers inoperable also provided arguments to support a determination of 

operability. In most cases, the arguments were that the low fire loading in the area, control of 

transient combustibles, or other administrative controls provided adequate assurance that the 

 

11 Indeterminate test results meant that the details of the testing were not sufficient for the staff to 

conclude that those tests served as an acceptable regulatory basis for Appendix R compliance.
5-26 

Thermo-Lag would remain operable for the limited amount of time needed to perform its 

functions.12 

The staffs’ positions with regard to Thermo-Lag installations within the scope of Bulletin 92-01 

were; 

1. The staff considers Thermo-Lag barriers inoperable unless the licensee has specific test 

data that would demonstrate otherwise. Operability determinations made on the basis of 

functionality of the protected system are not acceptable. To be operable, the barrier must 

be capable of performing its specified function for 1- or 3-hours as required. 

2. GL 86-10 interpretations regarding fire area boundaries and deviations from tested 

configurations are not applicable since the supporting engineering analysis assumes that a 

qualified tested configuration that has successfully passed the test acceptance criteria is 

being used as a basis for the analysis. 

The bulletin was followed by GL 92-08, “Thermo-Lag 330-1 Fire Barriers,” in December 1992, 

requesting information from licensees on their use of Thermo-Lag 330-1 to verify compliance 

with NRC requirements. GL 92-08 addressed three areas of NRC concern: (1) fire endurance 

capability of Thermo-Lag 330-1 barriers, (2) ampacity derating of cables enclosed in ThermoLag 330-1 barriers, and (3) evaluation and application of the results of the endurance and 

ampacity tests. 

GL 92-08 provided for the mechanism for NRC to evaluate the specific details of each licensee’s 

use of Thermo-Lag ERFBS and to prompt the nuclear industry to resolve issues related to 

deficient barriers. Section 6 provides a brief description on each plants resolution to problems 

associated with various barriers used at that plant. NRC closeout of GL 92-08 was a significant 

effort, involving hundreds of requests of additional information (RAI) and several site verification 

visits. GL 92-08 requested that the licensee provide the following information: 

 Chemical composition. 

 Material thickness. 

 Material weight and density. 

 Presence of voids, cracks, and delimitations. 

 Fire endurance capabilities. 

 Combustibility. 

 Flame spread rating. 

 Ampacity derating. 

 Mechanical properties such as tensile strength, compressive strength, 

 shear strength, and flexural strength. 

Following the numerous response to GL 92-08 and subsequent RAIs, NRC staff met with 

licensees to discuss their plans and schedules for implementing GL 92-08. NRC staff became 

concerned with the licensees completing their commitments when a number of licensees 

reported that they had already passed their completion dates without complete resolution. 

Some licensees informed NRC that their completion dates had slipped by as much as three 

 

12 Plants not initially declaring barrier inoperable following Bulletin 92-01 included: Oyster Creek; Three 

Mile Island1; Beaver Valley 2; Vermont Yankee; St Lucie 1 and 2; Browns Ferry 1, 2 and 3; Sequoyah 

1 and 2; Davis Besse; Zion 1 and 2. 
5-27 

years. In 1998, NRC issued Confirmatory Orders to each plant with outstanding Thermo-Lag 

resolution, modifying their license. These Orders required the plants to complete their ThermoLag modification by the dates previously committed to NRC. Table 5-15 provides a list of those 

plants issued Confirmatory Orders, along with the NRC Agencywide Document Access and 

Management System (ADAMS) Accession Numbers for those documents. 

Table 5-15. Thermo-Lag 330-1 Confirmatory Order Documentation 

Plant Name 

Docket 

No. 

Date (ADAMS Accession No.) 

Confirmation 

Order 

Order 

Completion 

St. Lucie Plant, Unit 1 50-335 07/13/98 

(ML013580124) 

04/07/00 

(ML003703549) 

Three Mile Island Nuclear Station, 

Unit 1 

50-289 05/22/98 

(ML003765653) 

08/11/99 

(ML003766024) 

12/30/99 

(ML003676460) 

03/12/00 

(ML003693928) 

Columbia Generating Station 50-397 03/25/98 

(ML022130143) 

01/19/00 

(ML003678400) 

Peach Bottom Atomic Power 

Station, Units, 2 and 3 

50-277,278 05/19/98 

(ML040990313) 

10/12/99 

(ML040990314) 

Limerick Generating Station, Units, 

1 and 2 

50-352,353 05/19/98 

(ML011560778) 

09/17/99 

(ML040990326) 

Crystal River Unit 3 Nuclear 

Generating Plant 

50-302 05/21/98 

(ML020670496) 

05/25/00 

(ML003722384) 

Sequoyah Nuclear Plant, Units, 1 

and 2 

50-387,388 07/02/98 

(ML010160064) 

04/28/00 

(ML003711917) 

North Anna Power Station, Units, 1 

and 2 

50-338 06/15/98 

(ML013530026) 

02/01/99 

(ML040990189) 

Sequoyah Nuclear Plant, Units, 1 

and 2 

50-327,328 06/18/98 

(ML013320074) 

06/30/99 

(ML040990478) 

Davis Besse Nuclear Power Station, 

Unit 1 

50-346 06/22/98 

(ML021210216) 

01/25/99 

(ML040990274) 

Clinton Power Station, Unit 1 50-461 06/26/98 

(ML020990547) 

04/27/99 

(ML040990340) 

Comanche Peak Steam Electric 

Station, Units, 1 and 2 

50-445,446 07/28/98 

(ML021820291) 

12/22/98 

(ML040990491) 

Turkey Point Nuclear Generating, 

Units, 3 and 4 

50-250,251 07/09/99 

(ML013390600) 

06/18/01 

(ML011770240) 

Oyster Creek Nuclear Generating 

Station 

50-219 05/22/98 

(ML040990167) 

01/30/01 

(ML010370267) 

Edwin I. Hatch Nuclear Plant 50-321,366 06/24/98 

(ML013030297) 

10/16/98 

(ML040990196) 

Surry Power Station, Units, 1 and 2 50-280,281 07/09/98 

(ML012700090) 

02/01/99 

(ML040990189) 

South Texas Project, Units, 1 and 2 50-498,499 10/02/98 

(ML040990301) 

02/08/99 

(ML040990180) 

On May 20, 1994, NRC staff briefed the Commission on the status of Thermo-Lag issues. As a 

result of this meeting the staff was directed to provide details on which plants had achieved 
5-28 

compliance with Appendix R, how much Thermo-Lag material was previously used in these 

plants, and the corrective actions performed. Section 6 of this report, provides plant-specific 

information related to resolution of Thermo-Lag ERFBS issues. 

In addition to providing NRC Information Notices on numerous deficiencies with Thermo-Lag 

ERFBS, NRC special technical review team, the U.S. Attorney’s Office, NRC Office of Inspector 

General (OIG), and NRC Office of investigations conducted an investigation as a result of 

numerous anomalies with the reviewed test report. On March 30, 1994, the testing laboratory 

that certified the original Thermo-Lag fire tests, ITL of St. Louis, Missouri, and Alan M. Siegel, 

the president of the company, pleaded guilty to five counts of making and aiding and abetting 

the making of false statements within the jurisdiction of NRC, in violation of Title 18, US Code, 

Section 1001 and 1002. More than 30 false reports transmitted from TSI to NRC and other 

entities. ITL, Inc. was fined $150,000 and agreed to fully cooperate in the criminal investigation 

and prosecution of organizations and individuals associated with the Thermo-Lag fire barrier 

material. On September 29, 1994, TSI was charged by a federal grand jury in Maryland with 

seven counts of wrongdoing, including conspiracy and fraud. On August 1, 1995, a Federal jury 

found TSI and its president not guilty of making false statements about the role of ITL in the 

qualification testing of Thermo-Lag ERFBS. 

5.2.2 Problems 

NRC Staff Findings

Following issuance of IN 91-47 NRC staff visited several sites to inspect the as installed 

Thermo-Lag ERFBS and associated documentation. During those site visits, NRC staff found a 

number of field installations that were not constructed in accordance with the vendor 

recommended installation procedures. The staff also found that the vendor had revised its 

recommended installation procedures without notifying the licensees, and that the vendors’ 

installation procedures were not complete. These two issues were a major cause of ThermoLag ERFBS variations among plants because the installers would construct the barriers 

following either the old procedures or their own judgment when the procedures didn’t provide 

specific instruction regarding a particular aspect of the installation. As a result, the qualification 

of all barriers so constructed was brought into question. 

Upon further review, the NRC staff identified some configurations that did not appear to be 

qualified by fire endurance testing, and installations that deviated from the tested configurations 

without adequate engineering justification. From these findings, it was clear to the staff that 

further regulatory oversight was needed to ensure that issues identified in the field were brought 

to resolution and all licensees who used ERFBS had qualified and properly installed barriers for 

the configurations in their plants. 

Acceptable Test Report Become Unacceptable

Beginning in 1981, NRC had received numerous reports documenting fire tests of Thermo-Lag 

330-1 that were conducted by TSI and witnessed and documented by ITL. In the early 1990s, 

an NRC review of a number of these reports disclosed that the TSI tests had not been 

performed in accordance with the applicable standards. For example, the test furnace and 

temperature measuring devices used by TSI during the tests did not meet the ASTM E-119 

standard. Also, NRC requirements state that a fire endurance test on barrier materials must be 

conducted by a nationally recognized fire testing laboratory. Although it was later learned that 

neither ITL nor TSI had acceptable fire testing experience, NRC staff (erroneously) accepted the 
5-29 

ITL test reports in the 1980s for the TSI tests13, and those reports were subsequently used 

throughout the industry to qualify Thermo-Lag 330-1 for use in NPPs. 

A later OIG inspection found that although the ITL test reports state the fire tests were 

supervised and controlled entirely by ITL, the ITL representative was present only as a witness 

to verify that a test was conducted. The test reports were actually written by TSI and then 

signed by the President of ITL with no substantive verification that the data in the reports 

reflected the actual tests. In some instances, the ITL President merely signed test report cover 

sheets without seeing the test report. OIG identified about 25 tests of Thermo-Lag 330-1 that 

were conducted by TSI with ITL “acting as a witness.” Since neither TSI nor ITL were qualified 

per NRC requirements to conduct the tests, further discussion of who ran and witnessed the 

tests is important only for legal or administrative issues. 

Installation Errors & Procedure Issues

The most prominent problem involving Thermo-Lag 330-1 ERFBS was the differing and 

changing installation requirements. NRC staff found that although the Thermo-Lag 330-1 

materials performed adequately in laboratory test furnaces, field installations introduced 

uncertainties due to variations in the training and abilities of installation personnel. In several 

instances, NRC staff found that the protection provided did not qualify as a 1- or 3-hour fire 

barrier because the licensee applied the material improperly and in untested configurations. 

When these configurations were tested, results showed that the 1-hour barriers would actually 

only provide a nominal 32-minute to 50-minute fire rating while the 3-hour application might 

provide a 150-minute to 160-minute fire rating. 

While conducting site visits after issuing IN 91-47, NRC staff observed that the vendor had 

revised its recommended installation procedures without notifying the licensees, that the vendor 

installation procedures were incomplete, that a number of field installations were not 

constructed in accordance with the vendor recommended installation procedures, that some 

installations did not appear to be qualified by fire endurance testing, and that some installations 

deviated from the tested configurations without justification. All of these issues resulted in wide 

variation in the barriers’ performance among the plants. 

Simple material parameters, such as, inadequate Thermo-Lag thickness also resulted in fire 

barrier degradation. One of the larger problems associated with installation of the Thermo-Lag 

330-1 fire barrier assemblies resulted from the product’s not coming from the vendor as a 

complete assembly (such as a fire door assembly). Instead, assemblies were often “custom 

built” to meet variations in the actual in-plant installations as compared to the tested 

configurations, these variations commonly resulted in plant-to-plant dissimilarities in the barriers’ 

performance. 

 

13 NRC staff review of the test reports consisted of an audit of the paperwork submitted by the utilities. NRC staff 

considered it to be the responsibility of the utilities to provide accurate information concerning the conduct of the 

qualification tests. The licensees’ submittals were under oath and affirmation per 10 CFR 50.9, “Completeness and 

Accuracy of Information.”
5-30 

Ampacity Derating

When current flows in a conductor, heat is produced because every conductor offers some 

resistance to the flow of current. The current-carrying capacity of a particular conductor is 

dictated by its “ampacity” (that is, how many amperes of current it can handle based on its 

design). ERFBS inhibit electrical cable conductors from dissipating resistive heat energy to the 

environment and thus cables protected by ERFBS must be derated to ensure sufficient capacity 

and capability to perform their intended safety functions. 

The special review team reviewed nine ampacity derating test reports and found conflicting test 

results. For example, the vendor has reported derating factors for cable trays that range from 

7 to 28 percent for 1-hour fire barriers and from 16 to 31 percent for 3-hour barriers. In addition, 

ampacity derating tests of Thermo-Lag materials conducted for 3M found the ampacity derating 

to be 37 percent for a 1-hour barrier, 9 percent higher than what had been previously reported 

by the vendor. There are similar inconsistencies for conduit barriers. In addition, Sandia 

National Laboratories (SNL) conducted Ampacity testing of a Thermo-Lag 330-1 “U”-shaped 

configuration and found Ampacity Derating factors to be even higher than that specified by the 

previous testing. (See Section 5.2.3.1 below for more information on the SNL ampacity testing.) 

The results of an OIG inspection identified the root cause of the inconsistencies, excerpt follows: 

Originally, TSI reported to CPSES that Thermo-Lag 330-1 would require a 10-

percent ampacity derating. In 1982, TSI conducted an ampacity derating test 

with ITL as the witness and produced a derating factor of about 17 percent. 

During this same time period, manufactures of other fire barrier materials 

conducted ampacity derating tests and reported ampacity derating figures far 

higher than those reported by TSI, some as high as 40 percent. 

In 1986, an ampacity derating test on Thermo-Lag 330-1 was conducted at a 

nationally recognized laboratory—Underwriters Laboratories (UL). However, TSI 

refused to follow the UL ampacity derating testing procedure and these nonstandard tests resulted in ampacity derating figures of about 31-percent for the 3-

hour Thermo-Lag 330-1 and about 28-percent for the 1-hour Thermo-Lag 330-1 

ERFBS. These figures were significantly larger than those previously reported 

by TSI. Following TSI representative leaving the UL testing facility, UL 

performed an additional ampacity test on Thermo-Lag 330-1 following UL 

procedures, resulting in ampacity derating factors of nearly 40-percent for the 3-

hour barrier and 36-percent for the 1-hour. 

Unfortunately, these results were not reported to NRC at the time they were discovered 

and were only identified during an OIG inspection six years later, in 1992. 
5-31 

Licensee Review Evaluation

When licensee performed independent testing to verify an installed barriers capability, they 

typically found two physical deficiencies (1) for conduits less then 10.2 cm (4 in) the 

temperatures recorded during testing exceeded the maximum allowable limits, and (2) joints on 

the barriers where two sections of material butted would open during the fire test. 

Initial confirmatory and plant-specific testing raised numerous questions associated with the 

capability of Thermo-Lag 330-1 ERFBS to perform its design function. For example, during 

tests did the Thermo-Lag 330-1 structurally remain intact for the fire exposure? Is there a 

sufficient quantity of Thermo-Lag 330-1 material (i.e., thickness) to protect electrical raceways of 

differing mass and materials? 

Bounding Plant Installations

A few instances were identified where facilities had installed fire barriers without a basis for their 

fire rating such as an UL Listing or testing conducted by a nationally recognized testing 

laboratory for the configurations installed in the plant. Some licensees did not adequately 

reviewed and evaluated the fire endurance test results and ampacity derating test results used 

as the licensing basis for their Thermo-Lag 330-1 barriers to determine the validity of the tests 

and the applicability of the test results to their plant designs. Some licensees did not adequately 

review installed fire barrier configurations to ensure that they either replicate the tested 

configuration or provide an equivalent level of protection. 

Combustibility

The National Institute of Standards and Technology (NIST) testing (Section 5.2.3.1) provided 

results that allowed NRC to conclude that the Thermo-Lag 330-1 ERFBS is a combustible 

material. NRC fire protection requirements (Section III.G, Appendix R to 10 CFR 50) preclude 

the use of combustible material to (1) enclose other combustibles, such as cables, between 

redundant safe shutdown trains to eliminate the combustibles as a fire hazard or (2) provide 

radiant energy heat shield protection form shutdown components inside containments. 

OIG Inspection Report

In August 1992, an OIG investigation determined that NRC staff had accepted manufacturer fire 

qualification test results for Thermo-Lag that were reported to have met required standards but 

were later found to have been falsified. 

The NRC OIG, in its Inspection Report entitled, “Adequacy of NRC Staff’s Acceptance and 

Review of Thermo-Lag 330-1 Fire Barrier Material,” of August 12, 1992, found that NRC staff 

did not conduct an adequate review of fire endurance and ampacity derating information 

concerning the ability of Thermo-Lag fire barrier material. The findings suggest that had NRC 

staff conducted a thorough review, they would have found that the TSI test furnace was not 

adequate along with the inadequacy of the TSI quality assurance procedures. Moreover the 

report shows that had a vendor inspection been conducted, NRC would have determined that 

the tests were not conducted, as required by a nationally recognized testing laboratory and that 

the vendor had falsified the test reports. However, because these review and inspections were 

not conducted, it was not until 1992 when the staff determined that the performance of ThermoLag 330-1 with respect to fire resistance ratings and ampacity derating was indeterminate. The 
5-32 

OIG report concludes that in seven instances between 1982 and 1991, NRC did not pursue 

reports of problems with Thermo-Lag 330-1. 

Former NRC Chairman Ivan Selin responded14 to the OIG report by directing the staff to 

address the following three matters: 

(1) the reasons the initial review process did not identify the problems with Thermo-Lag 

330-1 and the causes of deficiencies in NRC’s response to later indications of problems 

that were brought to the agency’s attention; 

(2) whether the problems identified with respect to the initial review and the lack of follow-up 

to latter indications of problems represented a systematic weakness with our review and 

response programs; and 

(3) what corrective actions are necessary to rectify the deficiencies identified with respect to 

the review and response processes. 

5.2.3 Testing 

Attachment 2 to IN 92-46, “The Final Report of the Special Review Team for the Review of 

Thermo-Lag Fire Barrier Performance,” documented the teams finding on 34 of the available 49 

Thermo-Lag fire test reports. This effort by NRC raised several concerns regarding compliance 

with NRC requirements and guidance, compliance with ASTM E119, and adherence to good 

engineering practices. The team’s specific concerns involved test procedures, test facilities, test 

equipment and personnel, methods of assembly, quality assurance, and acceptance criteria. 

The team also found that the configurations of the test specimens for many of the previously 

performed tests are atypical of the field installations observed during the special review teams 

site visit to the plant. The Final Report concluded that many of the tests did not meet NRC 

requirements and guidance and, therefore, may not provide adequate technical bases for 

establishing fire resistance ratings of Thermo-Lag fire barriers. 

GL 92-08, “Thermo-Lag 330-1 Fire Barriers,” required all licensees to individually confirm that 

Thermo-Lag systems have been qualified by representative fire endurance tests, ampacity 

derating values have been derived from valid tests, and barriers have been installed with 

appropriate procedures and quality controls to ensure that they comply with NRC’s 

requirements. The following discusses the various testing completed by NRC, Nuclear Energy 

Institute (NEI), and licensees. 

5.2.3.1 NRC Fire Endurance Testing 

NRC conducted two testing programs at separate national laboratories to independently 

evaluate the performance of the Thermo-Lag 330-1 ERFBS material. NIST performed the initial 

small-scale testing which resulted in the need for full scale testing, subsequently conducted by 

SNL. The following provides a brief description of these tests and the results. 

 

14 Memorandum dated August 17, 1992 
5-33 

NIST Small-Scale Testing

NIST conducted pilot-scale fire-endurance testing on 1- and 3-hour Thermo-Lag 330-1 panels. 

This type of testing is limited to provide insights on materials performance such as determining 

the thermal-transmission characteristics of fire barriers, often under non-conservative edge-loss 

conditions. The report cautioned the use of the results to assess the potential fire performance 

of full-scale cable-tray fire barriers. In full-scale testing the fire barrier enclosure is exposed to 

elevated temperatures on all sides, which is typically more severe than the pilot scale testing 

that only exposes one planar surface to the ASTM E-119 thermal exposure. 

The results for the small-scale 1-hour and 3-hour fire endurance testing of Thermo-Lag 330-1 

materials, conducted at NIST, indicated that the 1-hour test exceeded the temperature rise 

criteria within 22 minutes, while the 3-hour barrier failed at 2 hours 20 minutes. In addition, one 

thermocouple on the unexposed side recorded a temperature of 935oC (1716oF), exceeding the 

corresponding furnace temperature of 923oC (1694°F). These data indicates that Thermo-Lag 

may be supplying energy to the fire, (i.e., combustible). The small-scale testing at NIST also 

consisted of combustibility testing following ASTM E-136 and ASTM E-1354 test standards. 

The NIST tests revealed that Thermo-Lag 330-1 fire barrier material is combustible. NRC 

viewed the results of the NIST tests as indication of an inability of the Thermo-Lag material itself 

to provide protection according to its specified fire resistive rating. The tests conducted at NIST 

were not considered definitive in that the tests were not full scale and only panels were tested. 

However, the information gained from the NIST tests provided enough evidence to NRC to 

confirm doubts raised during the TU Electric tests, such as the bare stress skin observed 

following the TU 76 cm (30 in) wide cable tray test on August 21, 1992, leading to a conclusion 

that Thermo-Lag 330-1 fire barriers should be treated as inoperable in the absence of 

successful, applicable plant-specific tests. 

SNL Testing

Following the small-scale testing conducted at NIST, NRC contracted with SNL to conduct three 

full-scale 3-hour fire endurance tests and one full-scale ampacity derating test of the ThermoLag 330-1 ERFBS. Of the three fire endurance tests conducted, two used the procedure-based 

TSI installation instructions (as presented in TSI Technical Note 20684, Rev. V) and a third test 

was a full reproduction of one of the original manufacturer’s fire endurance qualification tests 

articles (a configuration typically not found at NPPs). These tests were conducted to evaluate 

the performance of the barrier against the results of tests previously reported by TSI (the 

vendor). The program evaluated performance using both the ANI standard and the 

ASTM E-119 temperature rise limits. All tests consisted of a “U” shaped cable tray raceway 

protected with two layers of half inch thick Thermo-Lag 330-1 preformed panels designed to 

achieve a 3-hour fire endurance rating. Stainless steel 18 gauge wire ties were used to secure 

the panels to the test article, with trowel grade Thermo-Lag 330-1 applied to any gaps and to 

pre-butter all material joints. The fire endurance test assemblies were exposed to the standard 

time-temperature as described in ASTM E-119. As discussed below, all three fire endurance 

tests resulted in prematurely failing both acceptance criteria methods. IN 94-22 documents and 

inform the utilities of these results. In addition, the ampacity derating test results indicated 

larger ampacity derating factors (ADFs) than those specified by the vendor. 

Figure 5-5 shows the test assembly used in the SNL tests. The top middle picture presents the 

base test assembly structure, loaded with a single layer of cables. Bottom left photo shows a 

completely protected testing assembly ready to be tested. The bottom right photo shows the 
5-34 

test assembly immediately after being pulled from the test furnace (note that the Thermo-Lag 

330-1 material is combustible and missing in some areas). 

Figure 5-5. SNL Full-Scale Thermo-Lag Test Article Shown in Various States 

 (SAND94-0146) 

All three fire endurance test assemblies failure prematurely and the failure criteria was 

exceeded for both circuit integrity and temperature rise acceptance criteria. The procedurebased installation articles failed electrically 1:15:39 and 0:58:32 into the fire test, while the 

upgraded reproduction assembly failed at 1:58:52. All were well short of the 3-hour design 

rating. The assemblies exceeded the minimum temperature rise (typically single point first) at 

65, 55, and 110 minutes, respectively, again well short of the 180 minutes design rating. 

Two failure modes were noted for the two procedure-based assemblies; namely, very early in 

the test (several minutes) the seams were observed to open in regions between where the tie 

wires were used, and after heating, the tie wires themselves were noted to stretch, allowing the 

protective panels to sag, eventually the tie wires failed allowing the panels to fall away. During 

testing of the reproduction assembly, the failure modes were quite different. Here the seams 

remained closed; however the panel began to sag and eventually the stress skin tore resulting 

in the panel material falling away to allow direct heat exposure to the protected raceway. 

The last test assembly was used for an ampacity derating test. Both protected and unprotected 

ampacity testing was performed on the “U”-shaped test assembly and the testing was 

conducted at UL using the “High Ambient” environmental test chamber. The final ampacity 

derating factors indicated by the SNL test set were 46.4, 36.6, and 35.3 percent for the 

8 American Wire Gauge (AWG), 4 AWG and 2/0 cables respectively. These factors were 

slightly higher than those determined by TSI at 38.1, 32.4, and 35.6 percent, respectively. 

Pre- barrier 

installation (showing 

cable loading) 

Complete Thermo-Lag Fire 

Barrier Installed 

Test Assembly Post-Fire Exposure 
5-35 

5.2.3.2 NRC Combustibility Testing 

As part of the small-scale testing program of Thermo-Lag 330-1 ERFBS, the NRC staff 

contracted NIST to perform combustibility tests using two industry standards: (1) ASTM E-136, 

“Standard Test Method for Behavior of Material in a Vertical Tube Furnace at 750oC (1382oF),” 

and (2) ASTM E-1354, “Standard Test Method for Heat and Visible Smoke Release Rates for 

Materials and Products using an Oxygen Consumption Calorimeter.” 

Both nominal 1.27 cm (0.50 in) and 2.54 cm (1 in) thick Thermo-Lag 330-1 boards were tested 

with the half-inch thick board having a stainless steel wire mesh on only one side and the 1-inch 

board containing the stress skin on both sides. 

The results of the ASTM E-136 testing indicated that the Thermo-Lag 330-1 material is 

combustible. Under this testing standard the material is considered to be “combustible” if three 

out of four samples tested exceed the following criteria: 

 The recorded temperature of the specimen’s surface and interior thermocouples, during the 

test rise 30oC (54oF) above the initial furnace temperature. 

 There is flaming from the specimen after the first 30 seconds of irradiance. 

 The weight loss of the specimen, due to combustion, during the testing exceeds 50 percent. 

Of the four specimens tested, all experienced weight loss greater than 50 percent and flaming 

continued in excess of 30 seconds. 

ASTM E-136 test standard assesses the material combustibility as either pass or fail 

(noncombustible or combustible). To access the level of combustibility of the Thermo-Lag 330-

1 material (i.e., to provide a quantitative measurement scale), the material was additionally 

tested in accordance with ASTM E-1354. ASTM E-1354 is a heat release rate (HRR) test, 

which provides time-resolved information on the combustion of a specimen. Eight ASTM E1354 tests were conducted on 100 cm x 100 cm (39 in x 39 in) specimens irradiated at 50kW/m2

for four tests and 75kW/m2

 for the remaining four. Table 5-16 shows the results of these tests. 

Comparing the total heat released from Thermo-Lag 330-1 to the heat released from other 

building products, Thermo-Lag contributes more heat than Gypsum Board (12 mm (0.47 in) 

thick / unpainted – 4.2MJ/m2

 Total heat release) and is about equivalent to fire retardant 

plywood (12mm thick – 35.8 MJ/m2

 total heat release). Therefore, from a combustibility stand 

point, protecting cable raceways with one layer of Thermo-Lag material would be equivalent to 

enclosing that same raceway with one layer of fire retardant plywood. NRC staff concluded that 

Thermo-Lag 330-1 fire barrier material has combustible characteristics similar to those of other 

NPP combustible materials, such as fire-retardant plywood and cable jackets. 

 
5-36 

Table 5-16. NIST Results of ASTM E-1354 Thermo-Lag 330-1 Testing 

Test 

No. Test condition 

Irradiance 

kW/m2

Peak 

HRR 

KW/m2

Total heat 

in 600s 

MJ/m2

Total 

heat in 

900s 

MJ/m2

5489 Grid used; wire mesh up 50 74 34.1 

5490 Grid used; wire mesh up 50 83 44.1 

5491 Grid used; wire mesh down 50 74 28.2 

5492 Grid used; wire mesh down 50 76 25.9 

5466 Grid not used; wire mesh up 75 120 28.5 

5486 Grid used; wire mesh up 75 107 46.9 

5487 Grid used; wire mesh down 75 110 38.9 

5467 Grid used; wire mesh down 75 100 35.3 

5.2.3.3 Vendor Testing (TSI) 

UL report dated June 16, 1981 evaluated the surface burning characteristics of Thermo-Lag 

330-1. The testing was conducted in accordance with UL 723, “Surface Burning Characteristics 

of Building Materials.” The UL 723 standard provides a method to classify flame spread by 

determining the area under the flame spread distance versus time curve, ignoring any flame 

front regression, and using one of the calculation methods as described below: 

1. If the total area (AT) is less than or equal to 97.5 min-ft (m-minute x 3.3) the flame spread 

classification (FSC) shall be 0.515 times the total area (FSC = 0.515 x AT). 

2. If the total area (AT) is greater than 97.5 min-ft (m-minute x 3.3) the flame spread 

classification is to be 4900 divided by 195 minus the total area (AT) (FSC=4900/(195-AT). 

These UL tests determined that the FSC for thermo-lag 330-1 to be 2.9 – 3.1. This standard 

provides for the determination of the fuel contribution which was determined to be zero for 

Thermo-Lag 330-1. For the smoke development classification, a photoelectric circuit output 

operating across the furnace flue pike was used. A curve is then developed by plotting values 

of light absorption (decrease in cell output) against time. The classification of the smoke 

development is derived by expressing the net area under the curve for the tested material as a 

percentage of the net area under the curve for untreated red oak. The Thermo-Lag 330-1 tests 

indicated a 20.3 and 12.9 smoke development classification for the two tests conducted. 

It should be noted that the test report is unclear as to how the Thermo-Lag 330-1 material was 

tested and doesn’t appear to have tested actual pre-fabricated board but rather an asbestos 

cement board coated in 6.35 mm (0.25 in) thick trowel grade Thermo-Lag 330-1 material. 
5-37 

5.2.3.4 NUMARC Fire Endurance Testing 

An industry Thermo-Lag fire endurance test program was subsequently established by the 

Nuclear Management and Resources Council (NUMARC), which later became NEI. The 

purpose of the nuclear industry program was to assess material performance and to provide a 

basis for evaluation of installed Thermo-Lag fire barriers. Specifically, the industry program, 

assessed current industry configuration through the use of survey data, conducted a number of 

fire tests to document performance of various baselines and upgraded Thermo-Lag fire barrier 

assemblies, and developed a guideline to assist utilities in evaluating their Thermo-Lag fire 

barrier configurations for compliance with respect to the guidance provided by the series of NRC 

Bulletins and GLs. 

NUMARC testing program aimed to test bounding Thermo-Lag installations related to those 

utilities that supported the testing program. Licensees who had not addressed the issues raised 

in GL 92-08 and didn’t plan to do so on an individual basis, planned to use the results of the 

NUMARC testing to determine any plant specific configuration modifications. A majority of the 

licensees using Thermo-Lag choose to wait for industry testing results prior to taking any 

actions to permanently resolve the issues. This is one of the causes for the delay in closing out 

GL 92-08 and ultimately resulted in NRC issuing more RAIs to confirm the licensees’ closure 

plans. 

In December 1993, NRC staff became concerned that the scope of the NUMARC testing would 

not be sufficient to resolve all Thermo-Lag barrier issues identified in the GL 92-08. 

The principal concern of the staff was that the limited number of tests would not yield enough 

data for extrapolation of the large number of specific configurations needing evaluation. 

In response to NRC concerns, NEI developed an Application Guide to assist utilities evaluation 

of their existing Thermo-Lag installations. The NEI Application Guide was used to evaluate 

Thermo-Lag enclosures. The application guide provided a methodology for evaluating 

equivalency between tested and installed Thermo-Lag configurations and is consistent with the 

process previously established by GL 86-10 Supplement 1. By letter dated October 16, 1995, 

NRC staff notified NEI of its review of this method as unacceptable as replacement to the 

guidance provided in GL 86-10 Supplement 1, and that NRC would not generically endorse the 

use of this guide. Instead, NRC staff would review the application of the guide by individual 

licensees on a plant-specific basis. 

The testing was conducted in three phases. The first phase occurred between September and 

October 1993 and tested articles using a minimum material thickness and other construction 

attributes to provide a conservative baseline representation of the Thermo-Lag barrier. 

The second phase of testing involved constructing upgraded Thermo-Lag 330-1 ERFBS to 

evaluate the effectiveness of various upgrading techniques to meet NRC requirements. The 

final phase assessed the performance of baseline and upgraded Thermo-Lag ERFBS on cable 

and raceway “box” design configurations (e.g., junction boxes, cable tray boxes, etc.) using both 

1-hour and 3-hour prefabricated panels. The following presents an overview of the results with 

a summary of all the NEI testing provided in Appendix D of this report. 
5-38 

Of the phase 1 tests, four configurations passed all NRC acceptance criteria, these included; 

 1-hour conduits and junction box. 

 3-hour straight steel cable tray. 

 3-hour junction box. 

 3-hour small conduit. 

Configurations not meeting all aspects of NRC criteria included: 

 3-hour cable tray with “T” section, 91.4 cm (36.0-in) wide cable tray, 

 3-hour medium and large conduits, 

 3-hour air drop, and 

 a 1-hour 91.4 cm (36.0-in) wide cable tray. 

Temperature rise exceeded the criteria with in 1 hour and 13 minutes of 3-hour test completion. 

Although the temperature limit was exceeded, post-test evaluation of the cables determined that 

no cable damage was visible. These results demonstrate the differences in testing standards 

acceptance criteria, with NRC acceptance criteria being more conservative than that of the ANI 

or UL standard. 

Phase 2 of the NUMARC testing emphasized the need to test upgraded barriers versus the 

baseline configurations which showed poor resistance to thermal heat up within the barrier. 

Appendix D also provides a summary of these test results. 

5.2.3.5 TVA and TU 

In 1981, TU Electric conducted a full-scale fire endurance qualification test of the TSI ThermoLag 330-1 at SwRI. The purpose of the testing was to obtain a 1-hour fire rating for Thermo-Lag 

330-1 in accordance with ANI Bulletin No. 5. Based on the ANI criteria all test specimens 

passed and the NRC accepted the qualification in a letter dated December 1, 1981. 

Following issues surrounding the validity of the ANI standard as an appropriate method to 

qualify ERFBS, TU Electric proposed an alternate, site-specific fire test methodology and 

acceptance criteria that did not rely on the ANI approach. In October 1992, NRC concurred with 

the alternative site-specific fire test methods that TU Electric would utilize for conduct of future 

fire tests. 

TU Electric performed Thermo-Lag testing in 1992 and 1993 to qualify ERFBS configurations for 

CPSES Unit 2 which was undergoing the plant licensing process at that time. Testing performed 

to qualify Unit 1 ERFBS configurations was performed later in 1993 and in 1998. The results of 

the TU Electric test program were consistent with the TVA results (discussed below), in that 

small diameter conduits required an additional layer of material, and joints on cable tray and 

other "box" design enclosures required external stress skin reinforcement. 

In the mid-1990s TVA undertook extensive testing program to design, engineer, test, and qualify 

a series of Thermo-Lag 330-1 ERFBS for use in its NPPs. The enclosed DVD contains a video 

presentation summarizing the types of testing and process TVA used to qualify the use of 

Thermo-Lag 330-1 ERFBS for use in its plants, specifically the near term operating license of 

Watts Bar Nuclear Plant (WBN). TVA presented this video summary of its Thermo-Lag test 

program at a public licensee meeting for WBN Unit 1. Thermo-Lag 1-hour and 3-hour designs 
5-39 

were qualified by TVA testing. The results of the testing confirmed that conduits 10.2 cm (4 in) 

and larger could be successfully protected with a single layer of material. However, smaller 

conduits required an additional layer of Thermo-Lag to pass the ASTM E-119 test. During their 

testing, TVA also found that a simple modification of adding an external layer of stainless steel 

mesh and trowel grade Thermo-Lag 330-1 material could alleviate the joint failure problem. The 

external layer controlled and directed the Thermo-Lag 330-1 subliming reaction to that of a more 

effective ablative shielding process. 

Because of the amount of Thermo-Lag 330-1 materials used at CPSES, its licensee also 

performed an extensive testing and qualification program to ensure any Thermo-Lag 330-1 

barrier used would provide the acceptable endurance rating. The NRC staff witnessed CPSES 

testing conducted at Omega Point Laboratories (OPL) in San Antonio, Texas. 

TVA and TU entered into agreement to share information containing Thermo-Lag ERFBS. TVA 

in an effort to license Watts Bar Unit 1, has researched, developed, and rewritten the installation 

procedures, re-engineered the design, and performed the fire resistance qualifying tests for 

Thermo-Lag 330-1, 1-hour ERFBS. Thermo-Lag has undergone extensive testing by both TU 

and TVA. These tests were developed consistent with the guidance contained in the applicable 

codes, standards and regulatory guidance. 

5.2.3.6 Chemical Testing 

In a letter of November 7, 1992, TSI informed NRC that pre-shaped Thermo-Lag conduit 

sections received by TU for CPSES, Unit 2 showed signs of delaminating and voids. The NRC 

staff concern was that the use of such materials could affect the results of TU fire tests and the 

performance the Thermo-Lag barriers installed in CPSES 2. 

GL 92-08 requested that licensees take actions to fully address the technical issues, 

independent of information and data supplied by TSI, before the staff makes any determination 

regarding whether the use of Thermo-Lag fire barriers complies with NRC regulations. 

To support industries assessment of the Thermo-Lag materials, NEI (NUMARC) initiated a 

Thermo-Lag fire barrier material chemical testing program. NUCON International, Inc. 

performed pyrolosis gas chromatography testing consistent with ASTM D3452 on samples 

collected from 25 plants (169 samples total). Based on the test results of the chemical testing 

program sponsored by NEI, the results showed that all samples were consistent with one 

another in terms of organic and inorganic chemical composition. 

NEI transmitted the results of this Thermo-Lag chemical testing program to NRC. The overall 

NEI test program (including 169 utility provided samples) demonstrated that the composition of 

Thermo-Lag fire barrier materials has remained consistent throughout the production dates of 

1984 – 1995. 

5.2.3.7 Industry Combustibility Evaluation Method 

On October 12, 1993, NEI (NUMARC) submitted its “Thermo-Lag 330-1 Combustibility 

Evaluation Methodology Plant Screening Guide”. In that report, NEI stated that Thermo-Lag 

330-1 may not necessarily be considered a combustible material from a generic standpoint and 

recommended a performance-based approach, using fire modeling techniques, to evaluate the 

combustibility hazards presented by Thermo-Lag 330-1 installations. 
5-40 

The NEI guide provided a screening method that determines those areas where the potential 

ignition and subsequent flame propagation of Thermo-Lag is a concern. This method provides 

guidance on determining where Thermo-Lag is located in the plant, calculating the combustible 

loading attributed to the Thermo-Lag, and determining if this combustible loading will impact the 

fire hazards analysis (FHA)/fire safe-shutdown (FSSD) analysis of the plant. Any areas not 

screened out would be analyzed using fire modeling methods developed with the NEI guide. 

This fire modeling analysis would presumably result in additional screening of fire areas. 

Following an NRC staff review, based on existing NRC requirements and guidance, the staff 

determined that the NEI method was unacceptable to justify the use of Thermo-Lag materials, 

or other materials such as fire retardant plywood or cable jackets, as noncombustible where 

noncombustible materials are specified by NRC fire protection requirements. NRC concluded 

that the NEI method does not provide a level of fire safety equivalent to that specified by 

existing NRC fire protection regulations and guidelines. As an alternative to the NEI guidance, 

NRC staff recommended that licensees re-evaluate their use of Thermo-Lag as radiant energy 

heat shields inside the containment or as an enclosure to create a 6.1 m (20 foot) combustiblefree zone between redundant trains and seek other solutions. Possible solutions include: 

 Reanalyze post-fire safe shutdown circuits inside containment and their separation to 

determine if the Thermo-Lag RES is needed. 

 Replace Thermo-Lag barriers installed inside the containment with noncombustible barrier 

materials. 

 Replace Thermo-Lag barriers used to create combustible-free zones with noncombustible 

barrier materials. 

 Reroute cables or relocated other protected components. 

 Request plant-specific exemptions where technically justified. 

5.2.3.8 Seismic Testing 

TVA performed shake-table testing of some typical cable tray and conduit configurations to 

address the seismic adequacy concern related to the Thermo-Lag material at WNB Unit 1. 

This testing showed that Thermo-Lag ERFBSs will not impact the functionality of cables, cable 

trays, and other components during and following a seismic event, when designed to TVA 

standards. The testing included single and ganged cable trays and conduits along with air drop 

configurations. The DVD included with this report provides a video recording of the seismic 

testing conducted on Thermo-Lag ERFBS. Although TVA made the determination that the 

Thermo-Lag 330-1 ERFBS would not impact functionality, the results did indicated significantly 

lower mechanical properties values than those used by the TSI consultant to evaluate seismic 

adequacy of the Thermo-Lag configurations. 

Following the notification of differences between the vendors analysis and the licensees, NRC 

sent follow-up letter to GL 92-08 (pursuant to 10 CFR 50.54(f)) to the licensees and construction 

permit holders that had used Thermo-Lag 330-1 ERFBS in their plants. The letter included a 

request for additional information and some background information. In particular, item 1(9) 

requested information related to the mechanical properties of the Thermo-Lag material. In 

response, a number of licensees stated that they relied on the vendors analysis performed by 

the TSI consultant. 
5-41 

As a result of their review, NRC issued Information Notice 95-49 that informed the addresses of 

two specific NRC concerns related to the possibility of varying physical composition of the 

Thermo-Lag barrier in use across industry and the actual weights of Thermo-Lag use in plants. 

IN 95-49 was followed up with a supplement in 1997 which documented NRC’s evaluation of the 

Thermo-Lag 330-1 seismic properties. The results of the testing indicated significantly lower 

mechanical properties than those used by the vendor to demonstrate the seismic adequacy of 

Thermo-Lag 330-1 panels. 

In addition to the differences associated with the vendor reported material parameters and 

industry and NRC testing results, a review of the as received weights of the Thermo-Lag 330-1 

panels, prefabricated conduit sections, and 330-660 flexi-blanket fire barriers indicated that 

there could be a variation of as much as 45 percent in the unit weights of the fire barriers when 

calculated as a percentage of the weight associated with the thickest panel (maximum weight). 

The variation is primarily related to the variations in the thickness tolerances. For example, the 

thickness of a 1-hour-rated panel could vary between 1.27 cm (0.50 in) and 1.91 cm (0.75 in), 

thus indicating a variation of 33 percent. The remaining 12 percent variation could result from 

the density variation of the material. The weight of one layer of stress skin, staples, steel bands, 

and trowel-grade material (applied during the installation) can increase the average weight of a 

panel by about 10 percent. Depending on the method used by the licensees to incorporate the 

weight of the Thermo-Lag ERFBS in seismic analysis of the raceways and their supports and 

anchorages, the effects of the variations could be non-conservative when the maximum unit 

weight of the fire barrier and its accessories (wire mesh, staples, bands, etc.) is higher then 

nominal values considered in determining the loads on the raceways and their supports and 

anchorages. 

The seismic adequacy of various configurations of Thermo-Lag panels attached to the raceways 

has been determined by static analyses, subjected to simultaneous horizontal and vertical 

accelerations of up to 7.5 g (0.3 oz) and 5.0 g (0.2 oz), respectively. The TSI consultant 

performed their analysis using the mechanical properties (i.e., tensile strength, shear strength, 

and corresponding moduli) at various temperatures specified by TSI. Based on this analysis the 

TSI consultant concluded that the panels and conduit wraps were seismically adequate. After 

review this analysis, NRC staff determined that properly installed Thermo-Lag panels and 

conduit wraps would not undergo appreciable damage during the postulated seismic events at 

the nuclear reactor sites. 
5-42 

5.2.3.9 Ampacity Derating Test Results 

Table 5-17 lists results from ampacity derating test conducted by TSI and UL. Appendix B 

provides a description of ampacity derating and testing methods. 

Table 5-17. Ampacity Derating Test Results - Thermo-Lag 330-1 

Test Report Description 

TSI 

Derating 

Value 

UL 

Derating 

Value 

ITL No. 82-355-F-1 1-hour Cable Tray Test 12.5% 

ITL No. 84-3-275-A 3-hour Cable Tray Test 20.55% 

Technical Note No. 111781 1-hour Conduit Test 7.2% 

ITL No. 84-10-5 3-hour Conduit Test 9.72% 

UL 86NK23826, File R6802 1-hour Cable Tray Test 28.0% 

UL 86NK23826, File R6802 3-hour Cable tray Test 31.2% 

UL 86NK23826, File R6802 3-hour Conduit Test 9.4% 

5.2.4 Resolution and Staff Conclusion 

As a result of GL 92-08, licensee from 71 operating reactor units indicated that actions 

necessary to restore the operability of these barriers would be based on the results of the 

industry testing program being coordinated by the NUMARC. Based on meetings between NRC 

and NUMARC discussing the scope of the testing, the limited success of Phase 1 testing and a 

description of Phase 2 testing, NRC determined that the scope of this testing program would not 

address all issues associated with Thermo-Lag and informed those licensee affected. As a 

result, NRC based its acceptance on plant specific resolution paths, including those using the 

NUMARC results on plant-specific bases. 

Section 6, “Plant Specific Usage and Resolution of ERFBS Issues,” discusses the specific 

resolution each NPP took. In general plants undertook several tasks in the process to resolving 

compliancy issues. 

These activities included re-analyzing the plants FSSD analysis to take credit for other methods 

of plant post-fire safe shutdown paths that wouldn’t rely on redundant trains located within the 

same fire area. This method would typically eliminate a fraction of instances where the ThermoLag ERFBS was previously used. Those locations that still required protection would be 

resolved by either re-routing the cables through another fire area not containing the other train, 

or the Thermo-Lag ERFBS would be replaced by a qualified barrier or upgraded by applying 

more Thermo-Lag material per qualified configurations or by applying a different ERFBS atop of 

the existing Thermo-Lag ERFBS. 

In addition, where barriers were found to no longer be needed, some licensees conducted 

destructive examinations of those barriers to determine the exact installation methods used 

when the barriers were initially installed. The information collected from this initiative was then 

compared to documented installation procedures to provide the licenses with a level of 
5-43 

confidence that the remaining barriers were constructed to a specific level of performance and 

future work would provide a barrier what can endure a fire for the required duration. 

If deviations from installation manuals were identified during the destructive examinations, then 

the licensee would evaluate the effects of these deficiencies and determine what corrective 

actions would be required for the remaining barriers relied on for protection. These destructive 

examinations reviewed the following information. 

 Material type 

 V-rib orientation 

 Stress skin location and use 

 Joint gap 

 Fastener spacing 

 Joint reinforcement mechanisms 

 Box and conduit interface 

 Material thickness 

 V-rib flattening 

 Joint type 

 Fastener size and material 

 Fastener distance from joints 

 Structural support and 

intervening steel protection 

Methods to upgrade Thermo-Lag 330-1 ERFBS to meet 1-hour fire resistance rating varied 

somewhat based upon the specific testing; however the following example provides a typical 

upgrade that was found acceptable. 

An additional layer of Thermo-Lag 330-1 1.27cm (1⁄2 in) preformed conduit sections 

were pre-buttered and encompassed the baseline 1-hour barrier. Tie wires 

spaced 30.5 cm (12 in) apart were used to secure additional layer and all joints 

were offset and covered with a skim coat of trowel grade material. In addition, a 

layer of stress skin was applied to cover the joints of the barrier and a final skim 

coat of trowel grade material was applied atop of all stress skin and fasteners. 

(TVA 1995) 

Although a number of different methods of upgrading the Thermo-Lag 330-1 ERFBS were 

qualified and used, the example mentioned above could be considered a typical upgrade. 

The specific geometry of the configuration also plays a roll as to the performance of the material 

and how it needs to be constructed to perform the intended design function. Both TU and TVA 

conducted extensive test programs to develop and qualify their unique upgrades. 

From its review of documentation and applications of Thermo-Lag 330-1 as an ERFBS, the staff 

concludes Thermo-Lag 330-1 can be used as an acceptable ERFBS, provided that the proper 

testing and engineering assessments of their plant specific applications for the barrier to 

perform its intended design function. 
5-44 

5.3 DARMATT KM-1 (Hydrate) ERFBS

Darmatt KM-1 is a fire barrier system designed and manufactured by Darchem Engineering Ltd., 

and supplied by Transco Products, Inc. 1- and 3-hour rated Darmatt KM-1 barrier systems have 

been designed and tested in accordance with Supplement 1 to GL 86-10. Darmatt KM-1 

consists of a semi rigid endothermic reactive insulating board, expanding paper gaskets, a 

silicon rubber cloth, and conduit mix. Under fire conditions, the Darmatt panels undergo 

multiple endothermic reactions. At the same time a refractory chain interspersed with pockets 

of carbon dioxide (CO2) are produced. These processes reduce the thermal conductivity of the 

material and absorb the heat (by the endothermic process) transmitted into the barrier. 

The Darmatt KM-1 boards are nominally 16mm (5/8-in) thick with a surface density of 13.0 

kilograms per m2

 (3.1 lbs per ft2) and a thermal conductivity of 0.113 Watts per m Kelvin (0.783 

Btu inches per hour *ft2

 * °F) (at 68.9oC (156°F)). The Darmatt KM-1 layers are manufactured 

from a mix of commercially available raw material and cut into pieces or panels as needed for 

installation. Preformed half-round sections are also available for use in protecting conduits. 

The Darmatt KM-1 barrier consists of a multi-layer system that is placed around cable tray. 

The Darmatt KM-1 panels are secured to the raceway by the use of J-hooks attached to the 

Darmatt KM-1 insulating board. These J-hooks are typically spaced 15.2 cm (6.0-in) apart near 

the edge of a panel and lacing wire (18 gauge stainless steel wire) is used to secure panels 

together. Individual panels butt up to the preceding piece and joints are offset. 

Expanding paper gaskets (nominally 3.2 mm (0.1-in) thick) are installed at panel joints. During 

fire conditions the paper gasket expands to fill any remaining joint gaps that are formed during 

installation. Expanding paper gaskets are used along the joints between adjacent panels and 

between the panels and the concrete. For irregular gaps between panels, a conduit mix, known 

as KM-1 Thermal Filler, is used to fill those gaps. The conduit mix has the same density, 

composition, and reaction under fire conditions as the Darmatt KM-1 panels. The exterior most 

panels are wrapped in a wire mesh reinforced silicon rubber cloth (also known as inconnel 

reinforced silicone fabric) to increase the resistance to abrasion of the system during normal 

conditions and to maintain barrier structural integrity during and after the fire exposure. 

The silicon rubber cloth has no fire resistive properties and will burn off leaving behind the 

inconnel wire mesh. Figure 5-6 shows a sample of the Darmatt KM-1 ERFBS. 

For a 1-hour rated barrier, typically two layers of Darmatt KM-1 panels are placed around cable 

trays and a single layer two-piece (half-round) sections are secured around conduits. 3-hour 

Darmatt KM-1 cable tray barriers consist of four layers with the exterior layer pre-wrapped with 

the silicon rubber coated glass cloth with a double layer of half-round sections for the 3-hour 

conduit protection. Air drops are either two-piece pre-molded conduit type sections, or four 

piece cable tray type panels which may have integral steel angle frame sections. Table 5-18 

provides the nominal weight and thickness for the various KM-1 applications. 

 
5-45 

Table 5-18. Darmatt KM-1 Specifications 

System Type 

Weight 

kg/m2

 (lbs/ft2) Thickness cm (in) 

Cable Tray 

 1-hr replacement 26.02 (5.33) 3.20 (1.26) 

 1-hr upgrade 6.83 (1.40) 0.79 (0.31) 

 3-hr replacement 55.17 (11.3) 6.71 (2.64) 

 3-hr upgrade 13.67 (2.80) 1.57 (0.62) 

Conduit – Replacement only 

 1-hr 3⁄4-inch dia. 21.97 (4.5) 3.20 (1.26) 

 1-hr 2 inch dia. 34.17 (7.0) 3.20 (1.26) 

 1-hr 4 inch dia. 53.70 (11.0) 3.20 (1.26) 

 1-hr 6 inch dia. 73.23 (15.0) 3.20 (1.26) 

 3-hr 3⁄4 inch dia. 86.41 (17.7) 6.40 (2.52) 

 3-hr 2 inch dia. 113.75 (23.3) 6.40 (2.52) 

 3-hr 4 inch dia. 110.82 (22.7) 6.40 (2.52) 

 3-hr 6 inch dia. 203.09 (41.6) 6.40 (2.52) 

Figure 5-6. Photo of Two Layer Darmatt KM-1 System (Author, 2009) 

Unlike other ERFBS where removal of the barrier requires destruction of that material, the 

Darmatt barrier was designed for future removal by the use of J-hooks which allows for a 

disassembly method that will not damage the barrier. This feature would be useful for 

evaluation of as installed barrier construction. 

5.3.1 History 

Darmatt KM-1 material came into use in the U.S. operating commercial NPP applications after 

deficiencies documented in GL 92-08 involving Thermo-Lag 330-1 were identified. Many 

licensees used Darmatt KM-1 ERFBS as a replacement or upgrade to their existing Thermo-Lag 

330-1 installations. 
5-46 

5.3.2 Problems 

No generic problems with the current use of Darmatt KM-1 ERFBS in the U.S. nuclear fleet 

have come to the attention of NRC. Test reports and test observations conducted by NRC staff 

have documented that Darmatt KM-1 is capable of achieving the fire endurance temperature 

rise acceptance criteria and hose steam tests as specified by NRC in Supplement 1 to GL 86-

10. Seismic and ampacity derating reviews by NRC staff have also shown that the licensees 

who use this material are adequately accounting for these ERFBS engineering design aspects. 

5.3.3 Testing 

In its brochure15, the vendor states that, 

“The system has successfully passed 1 and 3 hour fire tests in a wide 

range of boundary and site specific configurations. Boundary conditions 

include zero percent cable fill as well as free fall (air drop) single and 

grouped cables. Fire tests are fully compliant with NRC Generic Letter 86-

10, Supplement 1, and include configurations for both upgrades of existing 

systems as well as new applications.” 

The vendor has tested the Darmatt KM-1 Barrier to the following testing standards at 

independent laboratories with acceptable performance results. They include, 

 ampacity derating per IEEE P848 Draft 16, 

 ageing per ASTM E1027, c 

 combustibility per ASTM E136, 

 corrodibility per US Reg. 1.36, 

 surface spread of flames per ASTM E84 and 

 UV resistance testing. 

Testing Laboratories include, Faverdale Technology Centre (NAMAS accredited), inhouse UKAS approved testing facility, and independent laboratories in the USA, such 

as OPL and Wyle Laboratories. 

In addition to the vendor testing, the following licensees also evaluated performance 

of Darmatt KM-1 ERFBS. 

5.3.3.1 Lasalle County Station 1-hour Fire Resistance Testing 

A 1-hour fire endurance test, including hose stream test following ASTM E-119 and GL 86-10 

Supplement 1 acceptance criteria was carried out on the Darmatt KM-1 ERFBS for Lasalle 

County Station (LCS) Units 1 and 2. The test furnace was 3.7 m (12.0 ft) long by 2.1 m (7.0 ft) 

wide and 2.1 m (7.0 ft) high, fired by 8 gas burners and controlled by a total of 13 

thermocouples. The test protected various electrical raceway assemblies including a 76.2 cm 

by 10.1 cm (30.0 in by 4.0 in) galvanized steel cable tray, four small 1.9 cm (0.75 in) conduits, 

 

15 http://www.esterline.com/Portals/8/Darchem/PDF/DTP_Brochure.pdf 
5-47 

an air drop and a 30.5 cm by 30.5 cm by 7.6 cm (12.0 in by 12.0 in by 3.0 in) galvanized steel 

junction box all protected with two layers of Darmatt KM-1 material representing a composite of 

LCS Unit 1 and 2 conditions. The raceways only contained a single bare copper #8AWG 

conductor instrumented with thermocouples every 6 inches. The raceways were monitored for 

temperature by placement of thermocouples as specified in GL 86-10 Supplement 1. 

In addition, the effects of thermal shorts on conduits were evaluated by attaching 1.9 cm (0.75 

in) long copper pieces to the ends of the 1.9 cm (0.75 in) conduit. 

The tests were conducted on June 16, 1994 at Faverdale Technology Centre in Darlington 

(England – UK). Following the ASTM E-119 exposure and hose stream test, post hose stream 

test visual inspections found no instances of barrier failure. Data provided in the report 

indicated that the highest average temperature rise (∆T) reached in any raceway was 65oC 

(149°F) and a maximum single point temperature rise (∆T) of 84oC (183°F). By safety 

evaluation report (SER) dated November 20, 1995, the NRC notified the licensee that the 

Darmatt KM-1 fire endurance test was conducted in accordance with the methodology and 

acceptance criteria specified in GL 86-10 Supplement 1. NRC staff also acknowledged that the 

1-hour fire-rated Darmatt KM-1 fire barriers installed at LaSalle were bounded by the test data. 

However, this SE didn’t address seismic or ampacity derating acceptance related to Darmatt 

KM-1, but indicated that a follow-up action would address these matters generically. 

5.3.3.2 Carolina Power and Light (CPL) Company 

On December 20, 1995, an NRC staff member witnessed a 3-hour fire endurance test of 

Darmatt KM-1 performed at Faverdale Technology Center, Darlington, England, by CPL and 

IES Utilities, Inc. (IES). The Darmatt KM-1 is used by CPL and IES to replace certain ThermoLag barriers at Brunswick Steam Electric Station and Duane Arnold Energy Center. The test 

plan, installation procedure, and quality control were provided by Transco Products, Inc., 

Chicago, the sole sub vendor of Darmatt KM-1 in the United States. 

The 3-hour test consisted of a large junction box 73.7 cm by 83.8 cm by 135.9 cm (29.0 in by 

33.0 in by 53.5 in), a 61.0 cm (24-in) wide steel ladder back cable tray with air drop, four rigid 

steel conduits (two 1.9 cm (0.75 in), one 10.1 cm (4.0 in), and one 12.7 cm (5.0 in) diameter) 

and two flexible steel conduits (1.9 cm (0.75 in) and 10.1 cm (4.0 in) diameter). The test 

assembly was subjected to the ASTM E-119 standard fire endurance test for three hours. 

The maximum average temperature for any raceway was 142oC (287°F) (on the 1.9 cm (0.75 

in) conduit) while the maximum single point temperature was also observed on the same 

conduit as being 184oC (363°F). The ambient conditions at the start of the test were 20oC 

(68°F), resulting in acceptance criteria of 159oC (318°F) and 201oC (393°F), respectively. The 

test specimens all met, with margin, the thermal and hose stream acceptance criteria specified 

in GL 86-10, Supplement 1. 

5.3.3.3 Prairie Island Nuclear Generating Plant, Units 1 and 2 

Fire endurance testing of Darmatt KM-1 was performed for Commonwealth Edison by Faverdale 

Technology Centre on March 29, 1994, in accordance with NRC GL 86-10 Supplement 1. 

The testing involved a 91.4 cm (36.0-in) and 15.2 cm (6.0-in) wide cable trays, along with a 1.9 

cm (0.75-in) conduit protected with a 1-hour rated KM-1 Darmatt barrier. The raceways were 

empty except for the instrumented bare copper conductor. Table 5-19 provides the results this 

testing. A hose stream test was conducted separate from the fire endurance test. The hose 

stream testing followed the guidance from NFPA 251, thus using an assembly identical to the 
5-48 

fire endurance assembly subjected to one-half of the fire endurance duration and then a hose 

stream was applied for 5 minutes. 

Table 5-19. KM-1 1-hr Fire Endurance Results (FTCR/94/0060) 

Raceway 

Failure Time

(minutes) Failure Criteria 

36 x 6 inch cable tray 79 Avg. Temp. Rise 

12 x 3.5 inch cable tray 81 Avg. Temp. Rise 

3⁄4 inch RSC 70 Single Point Temp. Rise 

5.3.3.4 Callaway Plant Ampacity Derating 

Union Electric (the licensee of Callaway Plant) submitted a Darchem Engineering Limited. 

Ampacity derating report conducted at the Faverdale Technology Centre. The testing was in 

accordance with IEEE P848 and carried out between August 29 and September 12, 1996. Test 

Report S-1064-00011-00 evaluated 2.54 cm and 10.1 cm (1.0-in and 4.0-in) diameter conduits 

each insulated with one layer of pre-formed half-round conduit sections (i.e., 1-hour barrier). 

The results are presented in Table 5-20. 

Table 5-20. Ampacity Results Faverdale (Test Report FTCR/96/0077) 

Test 

Average 

Room 

Temperature 

°C (°F) 

Conductor 

Temperature 

°C (°F) 

Normalized 

Current 

(Amps) 

Ampacity 

Derating Factor 

% 

1” diameter conduit 

baseline 39.96 (103.9) 89.8 (193.6) 38.88 - - - 

1” diameter conduit 

insulation 39.82 (103.7) 90.26 (194.5) 35.56 8.54 

4” diameter conduit 

baseline 39.86 (103.7) 89.99 (193.9) 18.03 - - - 

4” diameter conduit 

insulation 40.31 (104.6) 89.83 (193.7) 15.84 12.15 

Test Report S-1064-00012-00 documents the ampacity derating factors for 2.54 cm (1.0 in) and 

10.1 cm (4.0 in) diameter rigid steel conduits encapsulated with two layers of KM-1 Darmatt 

material to provide a 3-hour barrier. The tests were conducted at Faverdale Technology Centre 

on September 3, 9, 11, and 20, 1996. The results are presented in Table 5-21. 

 
5-49 

 Table 5-21. One & four-inch RSC Ampacity Results 3-hour KM-1 

 (Test Report FTCR/96/0099) 

Test 

Average Room 

Temperature 

°C (°F) 

Conductor 

Temperature 

°C (°F) 

Normalized 

Current 

(amps) 

Ampacity 

Derating Factor %

1” diameter conduit 

baseline 39.96 (103.9) 89.80 (193.6) 38.88 - - - 

1” diameter conduit 

insulation 39.91 (103.8) 89.74 (193.5) 32.00 17.7 

4” diameter conduit 

baseline 39.863 (103.8) 89.99 (193.9) 18.03 - - - 

4” diameter conduit 

insulation 40.11 (104.2) 90.03 (194.1) 14.46 19.8

Test Report S-1064-00014-00 provided ampacity derating factors for 600 mm by 101mm by 

3650 mm (24-in by 4-in by 144-in) long cable tray protected with four layers of KM-1 Darmatt 3-

hour replacement material. The testing was performed on August 4 and December 6, 1996 at 

Faverdale Technology Centre. The results are presented in Table 5-22. 

Table 5-22. 600mm Cable Tray Ampacity Results (Test Report FTCR/96/0108) 

Test 

Average Room 

Temperature 

°C (°F) 

Conductor 

Temperature °C 

(°F) 

Normalized 

Current 

(amps) 

Ampacity 

Derating Factor % 

600mm tray 

baseline 39.58 (103.2) 90.45 (194.8) 13.63 - - - 

600mm tray 

insulation 40.40 (104.7) 90.39 (194.7) 6.74 50.55

5.3.4 Resolution and Staff Conclusion 

No generic issues or deficiencies have been identified and associated with this ERFBS; there 

has been no need for generic resolution related to Darmatt KM-1 ERFBS. Darmatt KM-1 has 

been used as replacement materials to other deficient ERFBS. 

As a result of its late entry into NPP applications and testing in accordance with GL 86-10 

Supplement 1, the staff concluded that Darmatt KM-1 when installed to bound as tested 

configurations will satisfactory perform its intended design function. 
5-50 

5.4 Hemyc and MT (Insulative and Insulative/Hydrate ERFBS)

The Hemyc and MT ERFBS were initially products fabricated by B&B Insulation, Inc. an 

affiliated company of INSULCO Inc., but subsequently manufactured and typically installed by 

PCI Promatec, Inc. This transition happened sometime in the early 1980’s. These ERFBS 

have been installed at NPPs to protect circuits in accordance with regulatory requirements and 

plant-specific commitments. Hemyc ERFBS is utilized in 1-hour fire barrier applications and as 

radiant energy shields, while MT can be used as a 1-hour or 3-hour barrier depending on how it 

is constructed. Both ERFBS are basically an assembly of common industrial materials. The 

enclosed DVD contains video footage of NRC testing of Hemyc and MT ERFBS. 

Hemyc is a simple thermal insulator consisting of ceramic blankets constructed of 38.0 mm 

(1.5 in) or 50.0 mm (2.0 in) thick, 128.0 kg per m3

 (8.0 lbs per ft3) or (6.0 lbs per ft3) ceramic 

blanket manufactured by any of the following: 

 Kaowool® blanket manufactured by Thermal Ceramics (formally Babcock and 

Wilcox), 

 Cerablanket® blanket manufactured by Thermal Ceramics (formally JM Manville), or 

 Durablanket manufactured by Carborundum Fiberfrax. 

The ceramic fiber blanket is covered with a Siltemp®16 mesh fabric to produce what is called the 

Hemyc mat. The primary purpose of the cover materials is to protect the ceramic fiber core 

from physical damage. The materials are sewn together with “Astroquartz” thread (high 

temperature thread ~3300°C (5972oF)). The fireproof mats are pre-manufactured to fit the 

specific cable tray or conduit where it is to be installed. 

(a) (b) 

Figure 5-7. (a) Sketch and (b) Photo of Hemyc Mat (Installation Procedure 1985; 

 Author, 2009) 

Hemyc can be applied directly onto a raceway using 50.0 mm (2.0-in) thick wraps (i.e., direct 

attachment) or an air gap construction can be used (i.e., air gap attachment). The Hemyc air 

gap attachment consisted of two basic components; a light weight metal framework attached to 

the raceway and the Hemyc mat that surrounds the framework. The metal framework supports 

the Hemyc mat and provides the required off-set from the raceway to allow a dead air space. 

For air gap attachment, a 38.0-mm (1.5 in) thick Hemyc mat is used. 

 

16 The Promatec vendor manual references either Siltemp®

, Refrasil®, or Alpha 600 as equivalent 

materials for the outer fabric mesh covering on all surfaces exposed to the fire. 
5-51 

Originally, the attachment of the Hemyc blanket is accomplished using threaded studs 

connected to the metal framework for cable trays or with finger straps (as shown in 

 Figure 5-8) for conduit. The blanket is impaled onto the threaded studs or strap fingers 

using nuts and washers, or clips. Experience with this method of assembly showed signs of rips 

occurring at the point of impalement and latter installations used stainless steel banding 

wrapped and compressed around the circumference of the barrier. 

 Figure 5-8. Hemyc 1-hour ERFBS Conduit Construction 

 (Installation Procedure 1985) 

 Figure 5-8 shows the construction of a typical Hemyc ERFBS used on 

conduit. However, instead of the finger straps shown, licensee tended to use stainless steel 

banding to secure the Hemyc wrap to the raceways. This method of attachment is shown in 

Figure 5-9. 

Figure 5-9. Hemyc 1-hour ERFBS Banding(Installation Procedure 1985) 

Hemyc mats were manufactured in sections which needed to be joined together to maintain the 

overall barrier integrity. Two methods predominantly used in the industry were the overlap and 

collar type joints. The two predominant joint techniques are shown in Figure 5-12. 

In the overlap joint, an end of an installed Hemyc mat section is overlapped by a minimum 5.1 

cm (2-in) overlap of the next section of Hemyc to be installed. Typically, at the overlap joint, 

several steel bands are used to secure the joint. In collar type joints, two individual Hemyc mats 

are butt jointed against each other and then a minimum 15.2 cm (6 in) collar made out of Hemyc 

mat is secured around the butt joint seam. As will be discussed later, the joints of the Hemyc 
5-52 

ERFBS tend to be the weakest link in maintaining the barriers integrity during elevated fire 

conditions. 

Overlap Joint Collar Joint

Figure 5-10. Sectional View and Photos of Hemyc Joint Techniques (Author, 2009; NRC 

 Hemyc Testing, 2005) 

The MT ERFBS is an upgraded version of the Hemyc ERFBS and is installed as a 3-hour fire 

barrier. MT consists of four layers, with one of the layers being a heat activated compound: 

 Closest to Raceway 

 Layer 1: 2.54 cm (1.0 in) of Kaowool® ceramic fiber blanket wrapped in a fiberglass 

fabric 

 Layer 2: 2 mm (0.08 in) sheet of stainless steel (moisture barrier) 

 Layer 3: hydrate packet made by stitching together packets of aluminum trihydrate 

 in a fiberglass-coated fabric 

 Layer 4: 3.8 cm (1.5 in) Kaowool® blanket wrapped in a fiberglass fabric 

 Farthest from Raceway 

Exceptions include air drops which consist of a 7.6 cm (3.0 in) thick blanket of Kaowool® as the 

inner layer and structural supports which do not have the hydrating packet layer or the stainless 

steel sheet (Layers 2 and 3). Some licensees may use MT as a 1-hour ERFBS. 

Installation of the MT barriers included the use of lacing hooks, lacing washers and tie wire to 

securely hold the barrier together. 
5-53 

 

Figure 5-11. MT ERFBS Construction (Installation Procedure 1985) 

5.4.1 History 

Hemyc ERFBS was tested and qualified in the early 1980’s using the protocols outlined by 

ANI/MAERP Bulletin No. 5. Supplement 1 to GL 86-10 did not exist at this time, but NRC staff 

in several instances approved the use of Hemyc as a qualified ERFBS based on these ANI test 

results. These acceptances documented in the plants licensing basis provides the applicability 

of Hemyc as a 1-hour fire barrier for specific applications in the plants. 

Following the issuance and licensee responses to GL 92-08, NRC staff believed that some 

technical concerns identified in the GL remained unanswered. However, the staff believed that 

since Hemyc was a 1-hour rated ERFBS only used in application where protection is provided 

by the levels of defense-in-depth, the indeterminate fire resistance rating of Hemyc was not 

seen to be an area of significant risk. At the time 1993 through 1998 the staff was consumed 

with addressing the performance deficiencies of Thermo-Lag 330-1, Kaowool, and FP-60 

ERFBS. In 1994, NRC conducted a series of small-scale, two dimensional fire tests on fire 

barrier materials. The tests were performed as scoping tests to evaluate the generic fireendurance characteristics of available materials. Barriers tested, included 3M Interam E-53A, 

E-54A, FP-60, Promat-H, Thermo-Lag, and Hemyc. Unfortunately these tests couldn’t be used 

to qualify the barriers but provided qualitative insights on the performance of each barrier. 

In the late 1990’s, NRC inspection staff raised concerns with the adequacy of Hemyc ERFBS. 

At the turn of the century, NRC inspections issued several plant-specific findings related to the 

performance of the Hemyc and MT fire barriers. The inspections revealed that the licensee’s 

fire testing and acceptance criteria used to determine the fire resistance of Hemyc required 

further NRC review to determine their acceptability. This review was documented in TIA 99-028 

which concluded that Hemyc was not qualified for use as a fire barrier in NPPs.
5-54 

As a result of these findings, NRC recommended that the industry conduct testing to qualify the 

barrier in accordance with NRC guidance and that NEI coordinate this effort. In NEI’s review of 

the matter and as stated in its April 25, 2001 letter, their positions was, 

“Licensees using the Hemyc materials have stated to NEI their belief that they 

are complying with their licensing bases as supported by prior NRC acceptance 

of the test protocol and use of these fire wrap applications, and that their 

licensing bases demonstrate adequate protection.” 

As a result of industry reluctance to address the safety and technical issues related to the 

acceptability of Hemyc to provide the 1-hour of protection, in 2001 the NRR within NRC planned 

to conduct a series of full scale confirmatory fire endurance tests on both Hemyc and MT 

ERFBS. NRR later transferred the testing program to RES. NRC contracted SNL to conduct 

two full scale Hemyc and one full scale MT ERFBS test. 

 

Throughout the planning phases of NRC Hemyc/MT testing program, NEI provided comments 

and information to NRC to improve and bound the actual plant configurations. In addition, NRC 

held a public meeting on October 31, 2002 with several licensees and NEI to discuss the 

proposed testing plan and acquire additional feedback from the licensees on the proposed 

testing to assure that the testing contained a representative sample of configurations found in 

plants. It should be noted that NRC tests were not conducted to qualify the Hemyc or MT 

ERFBS for use in any NPP, but were undertaken to provide confirmatory evidence of the 

barriers ability or lack thereof to provide the required protection. 

NEI provided formal comment on the testing plan by letter dated December 6, 2002, 

commenting on the licensing basis, program plan additions, including bounding conditions for 

non-tested configurations and a mathematical calculation, information and representation during 

the construction of the barrier materials, along with suggested guidance on the reporting and 

interpretation of results. A detailed discussion of NRC testing program is provided in 

Section 5.4.3. 

The results of NRC Hemyc ERFBS testing were communicated via IN 2005-07, “Results of 

Hemyc Electrical Raceway Fire Barrier System Full Scale Fire Testing,” dated April 1, 2005. 

The Information Notice indicated that the Hemyc ERFBS didn’t perform for the 1-hour period as 

designed because shrinkage of the external cloth covering and thermal shorts. The IN 

concluded that, “... the Hemyc ERFBS does not provide the level of protection expected for a 

rated 1-hour fire barrier.” 

The results of NRC MT ERFBS testing were made publically available on May 23, 2005. 

The test report documented that no raceways protected with a 3-hour MT ERFBS meet the 

acceptance criteria to be rated a 3-hour barrier. More information on these results is provided in 

Section 5.4.3.3 NRC Testing below. 

As a follow-up to IN 2005-07, NRC issued GL 2006-03, “Potentially Nonconforming Hemyc and 

MT Fire Barrier Configurations,” dated April 10, 2006, requesting the addresses to determine 

whether or not Hemyc or MT fire barrier material is installed and relied upon for separation 

and/or safe shutdown purposes to satisfy applicable regulatory requirements. GL 2006-03 also 

requested a description of the controls used to ensure other fire barrier types are capable of 

providing the necessary level of protection. The responses were compiled into a list of ERFBS 

used for each operating NPP as presented in Memorandum to Alex Klein dated December 21, 

2007 and reproduced in Appendix F. 
5-55 

The GL 06-03 guidance further stated, “If licensees identify nonconforming conditions, they 

have several options. (1) replace existing ERFBS with a qualified one, (2) upgrade existing 

barrier to fire rated one, (3) reroute cables or instrumentation lines through another fire area, or 

(4) voluntarily transition to the risk-informed approach to fire protection (NFPA 805).” Although 

other solutions may be acceptable, these are the most popular methods that NRC believes the 

industry would take to resolve the issues identified by the confirmatory testing results. 

5.4.2 Problems 

As noted above, NRC concern with Hemyc ERFBS was brought to light after several inspection 

findings were identified in the 1999 and 2000 time frame.

During a fire protection inspection at Shearon Harris NPP, NRC inspectors identified that the 

licensee’s fire testing and acceptance criteria used to determine the fire resistive performance of 

the Hemyc/MT ERFBS installed to separate safe shutdown functions within the same fire area 

required further NRC review to determine its acceptability. Shearon Harris Nuclear Plant (HNP) 

based their acceptance criteria for the use of Hemyc/MT ERFBS on that reflected by the ANI 

Information Bulletin 5(79) standard, which NRC considers a non-conservative qualification 

approach in that cable damage can occur without indication of excessive temperature on the 

cables. The inspectors identified that the licensee was unable to provide the inspectors with 

engineering evaluation documentation which demonstrated that the shutdown capability is 

protected. Additionally, the inspectors were unable to confirm that the licensee had established 

an acceptable design basis for the Hemyc/MT ERFBS used to separate safe shutdown 

functions within the same fire area. The inspectors concluded that the actual fire resistive 

performance of the Hemyc/MT ERFBS installed to separate safe shutdown functions within the 

same fire area was indeterminate. This issue was documented as an unresolved item (URI) 50-

400/99-13-03 in NRC Inspection Report No. 50-400/99-13, dated February 3, 2000. 

An inspection at Waterford Steam Electric Station, Unit 3, identified that equipment required for 

safe shutdown of the plant following a fire were not separated by 1-hour fire barriers. 

Specifically, several cables from the redundant Train A/B of the chilled water system had either 

missing or damaged 1-hour fire wrap. This Green safety significance non-cited violation was 

documented in NRC Inspection Report No. 50-328/00-07, dated November 29, 2000. 

A triennial fire protection inspection at McGuire Nuclear Station, Units 1 and 2 resulted in the 

inspection team finding that the licensee was unable to provide documentation to demonstrate 

that an adequate design basis had been established for the Hemyc ERFBS in use to protect the 

Train B service water control cable, which was located within the same fire area as Train A. 

This finding was identified as an unresolved issue in the inspection report dated December 15, 

2000. 

These three inspection findings revealed that the licensee’s fire testing and acceptance criteria 

used to determine the fire resistive performance of the Hemyc fire barrier systems installed to 

separate safe shutdown functions within the same fire area required further NRC review to 

determine their acceptability. NRC was concerned that the Hemyc ERFBS may not fulfill the 

requirement of a 1-hour rated fire barrier as required by Appendix R to 10 CFR Part 50 in all 

applications. 
5-56 

On November 23, 1999, NRC Region II offices requested assistance from NRR in Task 

Interface Agreement (TIA) 99-028. A TIA is a process used to address questions or concerns 

raised within NRC regarding nuclear reactor safety and the related regulatory and oversight 

programs.

NRR provided its response to TIA 99-028 on August 1, 2000. In its response, the NRR staff 

evaluated the three fire endurance tests used by HNP to qualify the Hemyc and MT barriers 

used at the plant. 

1-hour Hemyc Barrier Final Report CTP 1026

The staff determined that information documented in Final Report CTP 1026 is 

insufficient to qualify the Hemyc fire barrier as a 1-hour-rated ERFBS. 

Its determination was based on the staffs concern with the size of the furnace, its 

accuracy, and the type, location and number of thermocouples used both in the 

furnace and on the testing assembly to provide this data, along with the fact that 

the assemblies were not bounding (due to heavy and unrealistic cable loading). 

3-hour MT Barrier Report No. 1100A

NRC staff determined that, although the acceptance criteria used (ANI continuity 

criteria and thermocouples attached to cables) deviated from the acceptable 

method identified by NRC guidance, the test may be used to qualify cable 

configurations protected with the “MT” ERFBS, provided that they met the 

conditions identified in the TIA response. 

3-hour MT Barrier Report No. 1071

The staff determined that information documented in Final Report CTP 1071 is 

insufficient to qualify the “MT” fire barrier as a 3-hour-rated conduit fire barrier 

system. While the thermocouple may appear to meet qualifying temperatures, 

there is a concern as to the type, location, and number of these thermocouples 

used on the test assembly to provide the data. In addition, these results were not 

bounding in the fact that the 10.1 cm (4.0 in) conduits were heavily loaded in 

some cases with a non-realistic arrangement of cable. 

TIA 99-028 concluded that CTP 1026 results were “inconclusive to qualify” Hemyc as a 1-hour 

rated fire barrier; CTP 1071 results were “inconclusive to qualify” MT/Hemyc as a 3-hour rated 

fire barrier; and CTP 1100A results could be used to qualify MT/Hemyc as a 3-hour rated fire 

barrier only if the specific configuration of MT/Hemyc installed in NPPs met the criteria (i.e., 

cable tray sizes and cable masses) in CTP 1100A. The TIA response also identified the series 

of NRC small-scale Hemyc tests conducted at NIST, which resulted in failure to meet the coldside temperature rise criteria within 25 minutes. 

Subsequent to the August 2000 TIA determination that Hemyc was not qualified for use as a fire 

barrier in NPPs, NRC staff requested that licensees address the Hemyc concerns as a voluntary 

initiative and that NEI assist with the coordination of this initiative. Industry later decided not to 

pursue voluntary testing to resolve Hemyc issues. NEI stated to NRC that there was insufficient 

evidence to indicate a safety concern that would warrant an industry initiative and in the opinion 

of NEI it believed that the nuclear industry was in compliance with NRC requirements based on 

the fact that NRC had previously accepted the original Hemyc manufacturer fire qualification 

tests. Therefore, NRC through its Office of Research preformed confirmatory testing to identify 

potential safety problems with the Hemyc and MT ERFBS. As discussed below, these NRC 

tests resulted in failure of Hemyc and MT to meet their respective fire endurance rating. 
5-57 

NRC informed licensees that, notwithstanding that the Hemyc material may be part of a plant’s 

licensing basis, the test results that were cited do not fully address the contemporary technical 

concerns regarding the adequacy of this material in satisfying the intent of Commission’s 

regulations. Specifically, technical concerns which were identified in GL 92-08 remain 

unresolved. These issues involve testing adequacy, for example, minimum and maximum fill 

were not performed for all configurations, cable damage occurred in some configurations, and 

energized cables were not included in all tests. Application and bounding questions concerned 

the staff, such as, which sizes and configurations bound what other sizes and configurations. 

 Figure 5-12. Post-test Photo of Hemyc ERFBS Showing Shrinkage at Junction 

 (NRC Hemyc testing, 2005) 

5.4.2.1 NRC Office of Inspector General Special Inquiry 

The Office of Inspector General (OIG), NRC, initiated a special inquiry in response to concerns 

pertaining to Hemyc fire barriers. This inquiry intended to evaluate the failure of Hemyc during 

NRC 2005 tests and whether NRC staff acted appropriately to address the problem. 

In the OIG report, “NRC’s Oversight of Hemyc Fire Barriers,” dated January 22, 2008, the 

following findings were identified: 

 NRC did not communicate the results of the failed 1994 NIST testing of Hemyc to 

the licensees, nor did NRC conduct any follow-up to the NIST small-scale testing. 

 Via its response to TIA 99-028, NRC determined that qualification tests used 

previously to supporting licensing of Waterford were subsequently determined 

inadequate to qualify; however, NRC did not require licensees to take corrective 

action. 

 NRC confirmatory testing of Hemyc and MT resulted in failures of the barrier. 

NRC informed the industry of the results through an information notice, but 

required no follow-up (take action or written response) by the industry. 

 GL 2006-03 required licensees to resolve Hemyc / MT issues by December 1, 

2007, however NRC did not schedule or budget for any inspections to review 

licensees’ resolution of the Hemyc fire barrier issues. 

 In 1993 the former NRC Chairman provided testimony to the House of 

Representatives Subcommittee on Oversight and Investigations. This testimony 

included a commitment to conduct assessments of all fire barriers used to protect 
5-58 

electrical cables in NPPs to identify what improvements were needed to have 

these fire barriers meet NRC requirements. 

Letter dated July 15, 2008 from NRC Chairman Dale E. Klein, addressed the finding of the OIG 

report. Chairman Klein agreed with most of the OIG findings and provided clarification to the 

findings related to budgeting of inspections and purpose of the issued information notice and 

generic letter. 

5.4.2.2 U.S. Government Accountability Office Report to Congressional Requesters 

The GAO was asked to examine NRC oversight of fire protection at U.S. commercial NPPs and 

documented their conclusion in a GAO report issued in June 2008 titled, “Nuclear Safety – 

NRC’s Oversight of Fire Protection at U.S. Commercial Nuclear Reactor Units Could Be 

Strengthened, GAO-08-0747.” The conclusions of this report found it critical, in the opinion of 

the GAO, for the need of NRC to test and resolve the effectiveness of ERFBS at nuclear units. 

5.4.3 Testing 

The Hemyc fire barrier system was tested and qualified in the early 1980’s using the protocol 

outlined by ANI/MAERP bulletin No. 5, “Standard Fire Endurance Test Method to Qualify a 

Protective Envelope for Class 1E Electrical Circuits.” NRC performed follow-on confirmatory 

testing of Hemyc ERFBS in the spring of 2005. This full-scale testing was performed on typical 

NPP conduit, cable tray, junction box and support configurations protected with the Hemyc 

ERFBS. During this testing NRC discovered a previously unidentified failure mode; the outer 

layer of high temperature cloth covering experienced thermal shrinkage resulting in the opening 

of joints in the ERFBS and exposing the protected raceway. Subsequent testing was pursued 

by an informal Hemyc users group, consisting of several utilities, with results consistent with 

those documented in NRC testing. The following provides a detailed review of the testing of 

Hemyc and MT ERFBS 

5.4.3.1 Vendor Testing 

Final Report CTP 1026, “HEMYC Cable Wrap System – One Hour Test,” dated June 1, 1982, 

records the results of a 1-hour Hemyc tested conducted by Central Nuclear de Asco in 

Tarragona, Spain. The purpose of the test was to qualify the barrier for acceptance by ANI and 

as such, the ANI test standard was used, including the ASTM E-119 standard time/temperature 

curve. Three individual tests were conducted, involving a variation of 30.5 cm (12 in) wide cable 

trays, 10.2 cm (4 in) diameter conduits, and air drop configurations. Test acceptance criteria 

included maintaining circuit integrity and having no pass through during the hose stream test. 

Cable tray fill varied from 100 percent visual fill to a single layer, while all conduits were tested 

with 100% visual fill and the air drops consisted of 10 cables bundled together. Water hose test 

consisted of 6.4 cm (2 1⁄2 in) hose provided with 2.86 cm (1 1/8 in) nozzle, from a distance of 

6.1m (20.0 ft) at 206842 Pascal (30 lbs per in2

) pressure for 2 minutes and 30 seconds, while 

maintaining power to monitored cables. The results of the Test 1 indicated no cable damage 

was observed but following the hose stream test, a portion of material was damaged in some of 

the areas of direct impact, having lost 10 to 15 percent of the fiber material. Test 2 also 

indicated that portions of the barrier were slightly torn by the hose stream and again no cable 

damage was observed during post test examinations. Test 3 showed that some of the cable 

located in the cable tray lost continuity and insulation, portions for the barrier mesh fabric were 
5-59 

torn and some permanent deformation of the barrier covers was observed. Although these 

three tests passed the ANI criteria, they do not pass NRCs GL 86-10 Supplement 1 criteria. 

In response to TIA 99-028, NRC staff concluded that information documented in Final Report 

CTP 1026 is insufficient to qualify the Hemyc fire barrier as a 1-hour-rated ERFBS. 

Final Report CTP 1071, “Three Hour fire Qualification Test of PROMATEC ‘MT’ Barrier Wrap 

System Electrical Conduit Circuits,” dated January 6, 1986 documents a qualification test 

conducted by SwRI in San Antonio, Texas on July 30, 1985 (SwRI Project No. 01-8305-049). 

The test assembly consisted of several 10.1 cm (4.0 in) diameter conduits, a 25.4 cm by 25.4 

cm by 61.0 cm (10.0 in by 10.0 in by 24.0 in) junction box, 10.1 cm (4.0 in) diameter pull boxes, 

and a 10.1 cm (4.0-in) diameter conduit tee. Cable loading ranged from 40 percent actual (100 

percent visual) to a single layer of polyethylene (PE) insulated, polyvinyl chloride (PVC) jacketed 

cables in 1/3 power, 1/3 control, and 1/3 instrumentation mix. All raceways were protected by a 

three layered system consisting of (1) an inner blanket assembly (7.6 cm (3-in) thickness of 

alumina silica blanket enveloped with fiberglass cloth, (2) stainless steel foil moisture barrier, 

and (3) a multi-layered outer blanket assembly consisting of a 3.8 cm (1.5-in) alumina silica 

blanket and a fiberglass assembly containing a powdered ingredient enveloped with a fire 

resistant outer fabric. The MT ERFBS was installed by the vendor in accordance with 

procedure number CTP-1071. Test acceptance criteria were based on the ANI/MAERP test 

standard and based on these criteria the MT barriers all passed, with the exception of one 

conduit, which failed at 177 minutes into the 180 minute test. NRC staff reviewed this test 

report for its response to TIA 99-28 and determined that, “Final Report CTP 1071 is insufficient 

to qualify the “MT” fire barrier as a 3-hour-rated conduit fire barrier system.” 

Report CTP 1077, “HEMYC Cable Wrap System – One Hour,” dated October 29, 1984, 

was performed by SwRI in San Antonio, Texas. The testing was for engineering 

purposes only and not intended to qualify the barrier. The test placed 100 percent 

visually filled 7.6 cm (3.0-in) conduits straight through a furnace controlled to the 

standard ASTM E-119 time/temperature curve. At the center of the conduit the Hemyc 

ERFBS was butt jointed with a collar surrounding the joint. The results indicated that the 

barrier failed at the joint, as the thermocouple nearest the joint location exceeded the 

163oC (325°F) temperature rise approximately 55 minutes into the test. 

Final Report CTP 1100A, “Three Hour Fire Qualification Test of PROMATAC ‘MT’ Barrier Wrap 

System Electrical Cable Tray Circuits,” dated June 4, 1986, documents a qualification test 

conducted by SwRI on February 19, 1986 (SwRI Project No. 01-8821-016). The test assembly 

consisted of four raceways, two 45.7 cm (18.0 inch) wide and two 61.0 cm (24.0 in) wide by 

10.1 cm (4.0 in) high cable trays. Each raceway configuration consisted of one-half the length 

ladder back type construction and the remaining half solid back construction. Single layer cable 

tray fill and 100 percent visual (50 percent actual) tray fill were used in this testing. The MT 

ERFBS was constructed with the same three layer system used in CTP 1071. The test 

assembly was exposed to the standard ASTM E-119 standard time temperature curve for three 

hour duration. Based on the acceptance criteria of ANI/MAERP, no test assembly exceeded the 

temperature rise or lost circuit integrity during or after the test. However, the test report does 

state, 

“Post-test examination immediately after the hose stream tests showed 

that some of the PROMATEC, Incorporated, protective envelope was 

dislodged... but none of the seals were penetrated by the hose stream.” 
5-60 

NRC staff reviewed this test report for its review of TIA 99-028 and determined that, although 

the acceptance criteria used (ANI continuity criteria and thermocouples attached to cables) 

deviated from the acceptable method identified by NRC guidance, the test may be used to 

qualify cable configurations protected with the “MT” ERFBS, provided that they met the 

conditions identified in the TIA response. 

5.4.3.1.1 Vendor Ampacity Derating Tests 

For the materials and configurations tested, the vendor supplied the following ampacity derating 

values: 

 MT 3-hour Cable Tray 73.57% 

 MT 3-hour Conduit 42.08% 

 Hemyc 1-hour Cable Tray 54.06% 

 Hemyc 1-hour Conduit 39.58% 

These values were derived from conducting tests in accordance with the original IEEE 848 draft 

standard. 

5.4.3.1.2 Vendor Surface Burning Characteristics 

The vendor performed testing for flame spread, fuel contribution and smoke development for 

both one and three hour systems. Testing was conducted in accordance with ASTM E-84. 

The values were the same for both barriers and were reported as follows: 

 Flame Spread Index 5 

 Fuel Contribution 0 

 Smoke Developed 0 

5.4.3.2 NIST Testing 

In 1994, NRC conducted a series of small-scale, two dimensional fire tests on numerous fire 

barrier materials used in NPPs at the time. The testing used a small scale furnace with one side 

of the sample exposed to the furnace environment; the other side was exposed to the open 

laboratory environment (unexposed side of the barrier). Five thermocouples were placed on the 

unexposed side of the barrier, covered with 7.6 cm (3.0 in) square insulation material and the 

exposed side was subjected to the ASTM E119 standard time/temperature curve. The tests 

were performed as scoping tests to evaluate the generic fire-endurance characteristics of 

available materials. Materials tested included, Hemyc 1-hour and MT 3-hour, among others. 

The 1-hour Hemyc test results indicated that the average temperature rise criterion was 

exceeded at 23.2 minutes into the test, while the maximum temperature rise criterion was 

exceeded at 24.8 minutes. NIST determined that the maximum uncertainty for this test was 

+30/-24 seconds (+0.5/-0.4 minutes). 

The MT 3-hour test assembly consisted of multiple layers: a fire-blanket, a sheet of stainless 

steel foil, a layer of encapsulated hydrated powder material, a fire-barrier blanket encapsulated 

within a glass cloth (e.g., Siltemp). The assembly was subjected to 3.5 hours of the ASTM 

E-119 standard time/temperature exposure. At no point during the test did the unexposed 
5-61 

surface temperature exceed NRC 325°C (250oF) criteria. At the end of the 3.5 hour exposure 

the peak temperature recorded on the unexposed side was 77°C (171°F). 

Although the NIST tests provided insights into the performance of several different barrier 

systems, the NIST report emphasized that this type of testing is limited to assessing the 

thermal-transmission characteristics of fire-barrier materials, often under non-conservative 

edge-loss conditions. As such, NRC believed that the NIST tests were not sufficient to make a 

final determination regarding the capability of fire barrier. Although the Hemyc tests indicated a 

less robust material among other 1-hour barriers, NRC staff didn’t use these results to 

determine whether additional testing or review was necessary. NRC also didn’t communicate 

the results of the failures identified in the NIST testing to the industry through its typical means 

(e.g., Information Notices, Generic Letter), as these small-scale tests were not qualification tests 

and industries use of such information was indeterminate. 

5.4.3.3 NRC Testing 

As a result of Industries reluctance to undertake the responsibility of performing testing of 

Hemyc and MT, NRC performed three ASTM E-119 furnace tests on a number of cable 

raceway types protected by the Hemyc ERFBS (with and without air gaps) and MT ERFBS at 

the OPL in San Antonio, Texas. The Hemyc and MT ERFBS were manufactured and installed 

by qualified Promatec employees to the manufactures vendor manual and procedures. A bare 

No. 8 stranded copper conductor, instrumented with thermocouples every 15.2 cm (6.0 in) along 

its length, was routed through each of the conduit and cable tray test specimens. To expand on 

the testing methodology and understand how various aspects of raceway configurations affect 

the heat transfer characteristics of this particular barrier, NRC testing included both empty and 

fully loaded conduits and it also tested supports independently. The Hemyc ERFBS tests were 

performed for a period of 60-mintutes each and 180-minutes for the MT testing, followed by a 

hose stream test and post-test visual inspection of the ERFBS. In other words, this testing was 

performed in accordance with Supplement 1 to GL 86-10 guidance. An average temperature 

rise of ≤121oC (250°F), maximum single point temperature rise of ≤162oC (325°F) and hose 

stream testing were the acceptable criteria for qualification. Ampacity derating and seismic 

position retention testing was beyond the scope of this testing program. Table 5-23 provides a 

summary of the raceway configurations tested. 

 
5-62 

Table 5-23. Hemyc and MT Test Matrix (NRC) 

Raceway Type 

Hemyc 

(1-hour, Direct 

Attachment) 

Test #1 

Hemyc 

(1-hour, Framed For 

Air Gap And Direct 

Attachment) 

Test #2 

M.T. 

(3-hour, Direct 

Attachment) 

Test #3 

27-mm (1 in) Conduit17 X X 

63-mm (2.5 in) Conduit9 X X 

103-mm (4 in) Conduit9

 X X 

305-mm (12 in) Tray X 

914-mm (12 in) Tray X 

Junction Box X X X 

Cable Drop X 

Unistrut Support X X 

Tube Steel Support X X 

During the development of the test plan, the NRC interfaced with industry to better understand 

what was installed in NPPs, however, no test articles were constructed to conform to a specific 

site installation. Although NRC Hemyc and MT tests were not intended to address all issues 

with the limited number of tests, NEI did provide, in its letter dated December 28, 2001, a list of 

typical installation practices used at commercial NPPs. This letter provided NRC with 

information to help develop the test plan that was representative of configurations found in 

NPPs. However, it should be emphasized that NRC test program was to evaluate the 

conformance of the Hemyc and MT barriers to perform their intended function and not to qualify 

any particular barrier configuration. 

Test 1 consisted of 2.5, 6.4, and 10.1 cm (1.0, 2.5 and 4.0 in) conduits empty and with 

significant cable fill, junction box, and structural steel supports, with all Hemyc material directly 

attached to the raceways (no air gap). Test 2 consisted of 30.5 and 91.4 cm (12.0 and 36.0 in) 

cable trays and cable airdrop configurations with direct attachment and 5.1 cm (2.0 in) air gap 

Hemyc attached over special frames, and a junction box with direct attachment. Test 3 was 

identical to Test 1 with the use of MT ERFBS instead of Hemyc. The DVD enclosed, contains 

video footage of the NRC Hemyc and MT testing. 

Hemyc Tests

The Hemyc mats were constructed of 5.1 cm (2.0 in) Kaowool insulation inside an outer 

covering of Refrasil® high temperature fabric. The mats are custom sized for the particular 

application and machine stitched at the factory. Where the 5.1 cm (2.0 in) air gap configuration 

was used, 3.8 cm (1.5 in) Kaowool mat was used instead of 5.1 cm (2.0 in) material. Refrasil®

was used for the outer covering of the Hemyc ERFBS mats (the vendor manual referenced 

Siltemp, Refrasil or Alpha 600 as equivalent materials for the outer covering of the Hemyc 

 

17 Conduit test specimens were tested under both “empty” and “loaded-with-cable” conditions. 
5-63 

EFRBS mats). At the time of NRC testing Siltemp was not available for purchase and the only 

remaining quantities of this material were new-old-stock remaining in some licensees 

warehouses. 

After construction of the Hemyc ERFBS, the test assembly was lowered into the test furnace 

and exposed to the standard fire endurance test for 1-hour as specified in ASTM E-119. The 

results of the testing indicated gross Hemyc ERFBS shrinkage and opening of joints which 

resulted in none of the protected raceways passing the 1-hour test. Thermal shorting of the 

raceway support members was also identified as a root cause of the barrier failure. During the 

testing, the Refrasil mesh consistently experience a phenomenon of thermal shrinkage and 

change of color from tan to white. This shrinkage led to the mats contracting and opening gaps 

in the ERFBS. The temperature rise acceptance criteria was exceed in all raceways between 

15 and 57 minutes, with the average failure time of approximately 30 minutes. 

NRC testing demonstrated that when the Hemyc ERFBS is constructed per vendor procedures 

and evaluated against NRC acceptance criteria, it is unable to meet the required fire endurance 

rating of 1-hour. Table 5-24 provides a list of the Hemyc configurations tested and the final fire 

endurance rating. 

Table 5-24. Summary of NRC 1-hour Hemyc ERFBS Tests 

Raceway ID 

Raceway 

Time to 

∆Tavg≥250°F 

(min) 

Time to 

∆Tind≥325°F 

(min) 

Max. 

Temp 

Bare #8 

@1h (°C)

BurnThrough/ 

Structural 

Failure 

Yes/No 

Pass 

Hose 

Stream 

Yes/No 

Final Fire 

Endurance 

(min) 

1E 1” Conduit (Empty) 46 42 545 Yes Yes 42 

1F 

1” Conduit 

(1.02 lb./lin.ft. Cable 

Fill) 

44 34 636 Yes Yes 34 

1C 2 1⁄2” Conduit 

(Empty) 48 41 376 Yes Yes 41 

1D 2 1⁄2” Conduit (5.85 

lb./lin.ft. Cable Fill) 51 38 230 Yes Yes 38 

1A 4” Conduit (Empty) 49 33 463 Yes Yes 33 

1B 4” Conduit (14.84 

lb./lin.ft. Cable Fill) 57 43 93 Yes Yes 43 

1I 

Junction Box 

18” x 24” x 8” 

(Empty) 

17 15 N/A Yes Yes 15 

1G Unistrut N/A 22 – 32 N/A N/A Yes 22 – 32 

1H 2” Tube Steel 

Support N/A 13 – 25 N/A N/A Yes 13 – 25 

2A 

12” Cable Tray 

(Empty, Direct 

Attach) 

27 18 682 Yes Yes 18 

 
5-64 

Table 5-24. Summary of NRC 1-hour Hemyc ERFBS Tests (Continued) 

Raceway ID 

Raceway 

Time to 

∆Tavg≥250°F 

(min) 

Time to 

∆Tind≥325°F 

(min) 

Max. 

Temp 

Bare #8 

@1h (°C)

BurnThrough/ 

Structural 

Failure 

Yes/No 

Pass 

Hose 

Stream 

Yes/No 

Final Fire 

Endurance 

(min) 

2B 12” Cable Tray 

(Empty, 2” air gap) 33 35 539 Yes Yes 35 

2C 

36” Cable Tray 

(Empty, Direct 

Attach) 

34 33 721 Yes Yes 33 

2D 36” Cable Tray 

(Empty, 2” air gap) 28 31 603 Yes Yes 31 

2E Air Drop (Direct 

Attach) 35 32 933 Yes Yes 32 

2F Air Drop (2” air gap) 32 28 766 Yes Yes 28 

2G 

Junction Box 

18” x 24” x 8” (Direct 

Attach, with Bands) 

31 28 N/A Yes Yes 31 

Failures are usually manifested by the opening of a gap in the outer covering material at its 

weakest point. The weakest point is most often at a seam between two pieces of the material, or 

at a fastening where the material is connected to the underlying electric raceway. If there are 

no seams, or the existing seams are exceptionally strong and connections to the raceway are 

made so forces generated by the thermal shrinkage are distributed over a large area, the outer 

covering material itself will rip. Shrinkage also causes extreme compression of the Kaowool 

insulation material under the outer covering, which decreased the ERFBS heat transfer 

resistance sufficient to exceed acceptance criteria.

NRC testing also examined the four most common methods of joining the Hemyc material into a 

complete ERFBS, namely stitched joints, minimum 15.25 cm (6 in) collars over a joint, minimum 

5.1 cm (2.0 in) overlapping of the mats, and through bolts/fender washers for cable trays and 

junction boxes using the 5.08 cm (2 in) air gap space frames. The shrinkage led to failure of 

each of the joint systems. At the time, NRC was uncertain if this shrinkage effect was solely a 

result of using the Refrasil or if the other Hemyc outer coverings experienced the same 

shrinkage phenomena. 

As a result of the shrinkage experienced during NRC testing of Hemyc, which used Refrasil® as 

the fabric mesh covering, NRC contracted with SNL who performed testing on both Siltemp®

and Refrasil® to determine any differences between the two materials thermal properties. 

The testing was conducted by SNL on March 24, 2005. The Refrasil sample was taken from the 

actual bolt on material used to construct insulating pads for the SNL/NRC fire endurance 

testing, while the Siltemp® was provided as new-old-stock from licensees own on hand stock. 

Siltemp® is no longer manufactured and can no longer be purchased on open market. 

The two materials were placed on a thin insulating board, and placed inside a cylindrical radiant 

heating chamber. The radiant chamber shroud temperature began at 300°C (572oF) and was 
5-65 

increased in 50°C (122oF) increments to a maximum temperature of 800°C (1472oF). Total test 

duration was 90 minutes. 

The test results indicated that the two materials behaved in a virtually identical manner with 

shrinkage on the order of 5% and the physical aspects of the two materials are similar enough 

to be considered essentially the same. The first visible signs of shrinkage were noted at a 

shroud temperature of 450°C (842oF), where the shrinkage was visually estimated at 0.16 cm to 

0.32 cm (1/16 in to 1/8 in) total (or about 2%). At 600°C (1112oF) the total shrinkage looked to 

be roughly 3% and at 800°C (1472oF) the material turned stark white in appearance. Post test 

measurements revealed that both materials experienced a total shrinkage of about 5% with 

uniform shrinkage in both directions. These results indicate that no substantial differences in 

either the timing or extent of the material shrinkage behavior between Refrasil and Siltemp 

should be expected. It should be noted that, Siltemp and Refrasil were both available from the 

manufacture in standard (as tested) and pre-shrunk versions. The typical installation in the 

nuclear industry is with the standard (not pre-shrunk) version of the outer covering. Pre-shrunk 

can be identified by its stark white appearance, while the standard (non pre-shrunk) version is 

tan in color. 

MT TESTS

As stated above, Test #3 was identical to Test #1, with the exception of a 3-hour MT ERFBS 

being used instead of the 1-hour Hemyc wrap. Qualified Promatec workers installed the MT 

ERFBS in accordance with the vendor installation manual. Figure 5-13 provides pictures and 

annotation of the four layers used to construct the MT barrier. 

Figure 5-13. MT Installations Process for NRC Testing (NRC MT testing, 2005) 

Aluminum 

trihydrate 

wrap is 

installed on 

top of foil 

wrap and 

secured 

with duck 

tape. 

Base Hemyc wrap is 

installed and secured 

with duck tape. Foil 

wrap is shown being 

installed. 

Outer Hemyc 

wrap is being 

installed at 

conduit elbow 

location. (Note 

lacing hooks 

and wire used 

to secure 

elbow) 
5-66 

After the raceway barrier had been installed on all raceways, the entire test assembly was 

hoisted into the test furnace and subjected to the standard time/temperature curve exposure as 

specified in ASTM E-119. Thermocouples were located on the exterior of the raceways with 

15.2 cm (6.0 in) spacing and on a bare # 8 AWG conductor located within the raceway. 

Acceptance criteria were based on GL 86-10 Supplement 1 guidance. Table 5-25, provides the 

results of the 3-hour test for each raceway. For the 3M tests, all raceways systems failed to 

meet the 3-hour fire endurance period. 

Table 5-25. Summary of NRC 3-hour MT ERFBS Tests 

Raceway ID 

Raceway 

Time to 

∆Tavg≥250°F 

(min) 

Time to 

∆Tind≥325°F 

(min) 

Max. 

Temp 

Bare #8 

@3h (°C)

TurnThrough/ 

Structural 

Failure 

Yes/No 

Pass 

Hose 

Stream 

Yes/No 

Final Fire 

Endurance 

(min) 

3A 4” Conduit (empty) 121 110 516 No Yes 110 

3B 4” Conduit (loaded: 

fill=30%, 14.48 lb/ft 143 113 190 No Yes 113 

3C 2 1⁄2” Conduit 

(Empty) 119 103 604 No Yes 103 

3D 

2 1⁄2” Conduit 

(loaded: fill=29.8%, 

5.85 lb/ft) 

126 112 303 No Yes 112 

3E 1” Conduit (empty) 98 87 712 No Yes 87 

3F 1” Conduit (loaded: 

fill=29.7%, 1.02 lb/ft) 108 96 584 No Yes 96 

3I Junction Box (empty) 122 134 n/a No Yes 122 

3J 

Cable Air Drop 

(seven pcs of bare 

#8) 

169 159 319 No Yes 159 

Conclusions from NRC/SNL Testing

Shrinkage: A major defect in the performance of both Hemyc and MT ERFBS is the physical 

properties of the exterior covering which exhibits severe shrinkage effects when exposed to a 

thermal insult. This shrinkage results in junctions to open exposing the protected raceway to 

direct heat exposure and thus causing unacceptable abrupt temperature rise within the barrier. 

Supports: Where Unistrut and steel supports were protected with Hemyc material, the 

temperature at a location 45.7 cm (18.0 in) from the edge of the protected member achieved a 

fire endurance rating of 58 and 56 minutes respectively. The steel member had a higher crosssectional area of metal and as would be expected conducted heat better. The testing indicated 

that, with only the 7.62 cm (3 in) protection on supports as required by the vendor manual, 

thermal shorts could be introduced into the ERFBS in the range of 13 to 32 minutes. These 

findings would also apply to intervening metallic items that penetrate the completed Hemyc 

ERFBS as is common in NPP installations.
5-67 

Raceway Loading: Although both loaded and empty raceways were tested, it is believed that the 

barriers failure by shrinkage altered the effects associated with cable fill and therefore effects of 

cable fill could not be obtained from the MT tests. 

5.4.3.4 Industry Testing 

Most utilities using Hemyc and MT relied on qualification testing conducted and supplied by the 

vendor (Promatec). As a result of the failures identified through NRC testing, an informal 

Hemyc users group conducted testing of the Hemyc ERFBS on August 23, 2005, in 

configuration similar to Test 1 conducted by NRC. The objective of the industry testing was to 

identify performance differences between new-old-stock Siltemp fabric mesh and the Refrasil 

fabric used in NRC testing. The industry test program also used more robust barrier 

construction design, some of which were considered to be more representative of what is used 

in NPPs. The Siltemp® used for the testing was taken from two different licensees stock and 

used for comparison purposes to NRC test results. The industry results are proprietary to the 

licensees involved with the testing and cannot be discussed in this report. However, what can 

be said is that with the design changes and use of Siltemp fabric, the Hemyc barrier failure 

times were consistent with what was observed during NRC testing, as were the modes of 

failure. 

5.4.4 Resolution and Staff Conclusion 

The specific resolution each NPP took is discussed in detail in Section 6. 

Out of the 17 units that use Hemyc, 12 have informed NRC of their intent to transition to the 

risk-informed method per 10 CFR 50.48(c). A discussion of NFPA 805 is provided above in 

Section 3, “ERFBS Regulations.” 

NRC staff has confirmed through inspection that licensees not transitioning to NFPA 805, where 

their fire protection program includes Hemyc and MT fire barrier materials, have resolved issues 

with the Hemyc and MT materials by completing plant modifications and/or requesting and 

receiving NRC staff approval for changes to their licensing bases. 

Based on its review of Hemyc, the staff believes that the licensees are taking the adequate 

actions to bring their plants into compliance. The NRC reactor oversight process allows for 

periodic review of licensee fire protection programs, which can identify future deficiencies. 

The NRC staff review of each NFPA 805 application will ensure that the performance-based 

methods using Hemyc as part of it fire protection plan will adequately protect plant safe 

shutdown capability in the event of a fire. 
5-68 

5.5 Mecatiss (Insulative ERFBS)

Mecatiss ERFBS is manufactured by Mecatiss of Morestal, France. According to the Mecatiss 

website (www.mecatiss.com), Mecatiss specializes in passive fire barrier systems, watertight, 

airtight, and biological protections, but can also provide private laboratory and testing facilities. 

The Mecatiss ERFBS used in US NPPs consists of several layers, including a silicon fabric, a 

mineral wool insulation, a silicon based mastic, and an adhesive. The silicon fabric, called Silco 

cloth is a nominal 0.05 cm (0.02 in) thick woven glass silicon fabric. This material is claimed to 

be gas and water tight at normal pressures and chemically inert. It is applied around the cable 

raceway and again around the exterior of the completed barrier and held together by the use of 

an adhesive identified as Silicone Glue Mastic Type 75A. The 75A adhesive is cold application 

silicon-based mastic used in thin layers for filling, coating, insulating, bonding, and joining work. 

It is used to seal the SILCO fabric and bounds Silco to itself, concrete, metal, etc. The MPF-A 

and MPF-B refractory mineral wool insulation provided that actual thermal insulation of the 

system. The type and number of layers used depend on the design of the ERFBS, but all 

mineral wool mats are held together with Mecatiss refractory glue Type F-active adhesive. 

This adhesive is an air-hardening adhesive component and exhibits adhesive characteristics up 

to 1302oC (2375°F). Figure 5-14 shows a conduit test assembly protected with Mecatiss prior to 

testing. 

Figure 5-14. Photo of Mecatiss ERFBS (NRC Photograph) 

5.5.1 History 

Mecatiss found its application as an ERFBS upgrade and standalone product approximately 14 

years following the issuance of the fire regulation (Appendix R). When it was introduced in the 

late 1990’s the ERFBS testing criteria specified in NRC guidance documents had been used 

and understood for several years. As a result, the Mecatiss ERFBS was designed and tested to 

pass the GL 86-10 Supplement 1 testing criteria. In addition, licensee who elected to use 

Mecatiss learned from previous failure to install a barrier system per the tested configurations 

and were more vigilant to install Mecatiss ERFBS in plant applications that were bounded by 

tested configurations. 

 
5-69 

5.5.2 Problems 

As of the date this report is being written, there have been no generic problems or issues 

identified related to the plants use of Mecatiss as an ERFBS. As with all ERFBS, NRC 

inspection staff inspects numerous ERFBS systems during plants triennial fire protection 

inspections and during routine resident inspector inspections. 

5.5.3 Testing 

Florida Power Corporation (FPC), the licensee of Crystal River 3, notified NRC during a 

February 28, 1995 meeting of its intent to use Mecatiss as an upgrade and replacement ERFBS 

for resolution of the extensive amount of Thermo-Lag used in the plant. At that time, this 

licensee noted 2,345m (7,700 linear feet) of Thermo-Lag protecting conduits and cable trays 

and another 4,732m (15,526 feet) of Thermo-Lag protecting raceway supports, were used at 

CR-3. FPC also informed NRC of the recently completed fire barrier testing conducted in 

France and their planned follow-up testing of the replacement barriers at a US testing 

laboratory. These two testing programs are described below. The French test was conducted 

at the Mecatiss vendors’ site as a viability test, while the UL test provided the qualification of the 

barrier. 

5.5.3.1 Mecatiss over Thermo-Lag Testing (Morestel, France) 

Test report file No. NE0016 documents 1- and 3-hour fire endurance and hose stream tests 

conducted on a combination of Thermo-Lag and Mecatiss barriers, tested in Morestel, France. 

The raceway test assemblies were identical and included, eight “U” shaped aluminum conduits 

consisting of a single group of six conduits (two 1.9 cm (0.75 in) and four 2.54 cm (1.0 in) 

aluminum conduits all oriented side-by-side) and two singular conduits (1.9 cm (0.75 in) 

diameter). The six conduit group was enclosed in a single ERFBS, while the singular conduits 

were protected by individual ERFBS. Figure 5-15, shows the configurations of the test 

assemblies. Note that the individually enclosed conduits had condulets on one bend while the 

group of six used radial bends exclusively. All conduits were supported by Unistrut and Unistrut 

pipe hanger hardware. The two test articles (1- and 3-hour) were designed and constructed to 

represent CR-3 existing thermo-lag barrier system. 

Temperature measurements were taken using Type K, No. 24 AWG thermocouples installed on 

surface of fire conduits at FPC, and on a single bare #8 AWG stranded copper conductor, all 

spaced approximately 15.2 cm (6.0 in) on center. 
5-70 

Figure 5-15. Test Assembly of 1- and 3-hour Thermo-Lag/Mecatiss Test (Author, 2009) 

The ERFBS configurations used for these tests varied, as documented in Table 5-26 and Table 

5-27, a Thermo-Lag stand alone barrier and a Thermo-Lag with Mecatiss overlay barrier were 

tested. For the 1-hour test, all conduits were protected with a base Thermo-Lag ERFBS 

consisting of pre-shaped conduit sections with the stress skin on the interior face. For the group 

of six conduits, pre-shaped conduit sections were secured to the outside of the two exterior 

conduits while the standard nominal 1.3 cm (0.5 in) Thermo-Lag panels (with ribs and stress 

skin) were fit to the top and bottom of the conduit group and butt jointed to the exterior preshaped conduit sections. Stainless steel band straps and 18 gauge stainless steel tie wire were 

used to secure the panels to the raceway, with trowel grade Thermo-Lag 330-1 used to prebutter and post-butter the joints during construction. For the 3-hour test assembly, the ThermoLag base layer was the same as above, with the exceptions that the prefabricated panels and 

conduit sections being 2.858 cm to 3.175 cm (1.125 to 1.250 in) thick with a 0.858 cm (0.125 in) 

square coated mesh stress skin on the inside and outside of each section. 

The Thermo-Lag materials were obtained from storage at FPC, except for the material placed 

on the single 1.9 cm (0.75 in) conduit, which was removed from an actual plant installation. 

Installation of the Thermo-Lag was installed by certified installers at FPC, witnessed by UL 

laboratory staff and FPC’s Quality Control organization. 

The test articles were then shipped to France where the Mecatiss overlay was installed. The 1-

hour Mecatiss system consisted of (in order from conduit to exterior): 

 A woven glass cloth coated on one surface with a silicone sealant. The coated glass 

cloth was identified as Silco. 

 An adhesive identified as No. 75A 

 A nominal 2.54 cm (1.0-in) thick refractory mineral wool insulation identified as MPF60 

 Nylon Twine 

 An adhesive identified as F-active 

For the 1-hour test assembly, the Mecatiss barrier was installed on top of the Thermo-Lag base 

layer by performing the following: 

 applying approximately 0.64 cm (0.25 in) diameter beads of Type 75A adhesive to the 
5-71 

coated side of the Silco 

 wrapping the Silco (inner layer) around the Thermo-Lag with the coated side of the Silco 

in contact with the Thermo-Lag 

 applying type F active adhesive to the uncoated side of the Silco and on one side of the 

MPF60 insulation 

 applying the MPF60 insulation to the silco and securing the insulation in place with nylon 

twine 

 applying the Type F active adhesive to the exposed surface of the MPF60 insulation and 

on an uncoated side of Silco 

 wrapping the MPF60 insulation with a layer of Silco (outer layer) with the uncoated side 

of the Silco being in contact with the MPF60 insulation 

 applying bead of type 75A adhesive to the exposed Silco joints. 

The installation of the Mecatiss barrier was performed by employees of Mecatiss and witnessed 

by a member of UL engineering staff and representative of FPC and Babcock and Wilcox 

(B&W) Nuclear technologies. 

For the 3-hour test, the Mecatiss overlay was as described above with the exception of the 

mineral wool being different, namely a nominal 2.54 cm (1.0 in) thick refractory mineral wool 

insulation identified as MPF180A and another 2.54 cm (1.0 in) thick refractory mineral wool 

identified as MPF180B was used instead of MPF60. Again, installations of the Mecatiss barriers 

were witnessed by UL staff and FPC staff. 

Furnace thermocouples included four (4) used by Mecatiss to control furnace, four (4) were 

used as input to the data acquisition system and four (4) used by UL as long time constant 

thermocouples (ASTM E-199). Furnace dimensions were 2.6m by 1.1m by 1.4m(8.5 feet by 3.5 

feet by 4.7 feet) and a pressure differential throughout this test was slightly negative at - 40 

Pascal (-0.8 pounds per square foot). 

Following each tests, a water hose spray test was administered. The hose spray test consisted 

of the following parameters: 

 3.8 cm (1.5 in) fog nozzle, 

 30o discharge angle, 

 pump pressure between 596397 and 695681 Pascal (86.5 and 100.9 lbs per in2

), and 

 minimum discharge of 423 liters per minute (93 gallons per minute (gpm)) 

The hose spray was applied to all exposed surfaces for 5.5 minutes for a nominal distance of 

1.5 m (5.0 ft) from test article that was rotated at approximately 6 revolutions per minute. Hose 

stream testing began approximately 4 minutes after the completion of the thermal endurance 

test, and no conduits were identified as being exposed at the end of the hose stream test. 

Post test observations identified the following: Mecatiss appeared homogenous, without 

distortion, but with several blow holes seen, as the result of the off gassing of the inner TL layer. 

There was complete burn-through of the aluminum conduit on the 90o bend of conduit A 

(Thermo-Lag only article). Molten aluminum had formed pools at the bottom of the test furnace. 

In addition, to the bend having melted, it was also observed that the horizontal portion of 

Conduit A had completely melted, leaving only the vertical portion. Table 5-26 and Table 5-27 

provide descriptions of each test article along with the actual endurance rating achieved during 

the test. 

 
5-72 

Table 5-26. 1-hour FPC Mecatiss Testing in France 

Article Barrier 

Failure time when 

ΔTavg = 131oC 

(250oF) 

Failure time when 

ΔTmax = 181oC (325oF) 

Group of Six 

Conduits Thermo-Lag 44 minutes 45 minutes 

3⁄4” Conduit Thermo-Lag 26 minutes 29 minutes 

3⁄4” Conduit Thermo-Lag & 

Mecatiss Overlay Did not exceed Did not exceed 

Table 5-27. 3-hour Mecatiss Testing in France 

Article Barrier 

Failure time 

ΔTavg= 139oC 

(250oF) 

Failure time 

ΔTmax = 181oC 

(325oF) 

Max. Avg. 

Temp. (oC)* 

Max. Single 

Temp. (oC)* 

Group of 

Six 

Conduits 3⁄4” 

Thermo-Lag & 

Mecatiss 

Overlay 

N/A N/A 270 238 

3⁄4” Conduit Thermo-Lag 1 hr. 9 min 1 hr. 13 min. 598 1148 

3⁄4” Conduit Thermo-Lag & 

Mecatiss 

Overlay 

2 hr. 56 min 3 hr. 1 min. 146 239 

* Temperature measurement at 3 hours and 11 minutes 

These results clearly demonstrate that the use of Mecatiss as an overlay to existing ThermoLag 330-1 ERFBS provides additional fire endurance rating to the barrier system. For instance, 

the test results indicate that the Thermo-Lag only conduit covering exceeds the temperature rise 

criteria at approximately 73 minutes, while the additional Mecatiss overlay provided 

approximately 108 additional minutes of protection. 

NRC review of French Mecatiss Tests

By letter dated April 7, 1995, NRC provided FPC with comments on the tests conducted in 

Morestel, France on the Thermo-Lag and Mecatiss ERFBS. The intent of this letter was to 

provide comment for the licensees’ consideration when developing a plan for future testing. 

NRC comments pointed out the following concerns with the French Mecatiss Testing: 

 Ambient temperature at start of test was outside the range identified in ASTM E-119 and 

not representative of conditions expected at CR-3. This deviation is expected to affect 

the test results for assemblies that meet the temperature criteria with little to no margin. 

 The negative furnace pressure in the 1-hour test deviated from the 3-hour test by 16.00 

Pascal (0.06 in of water). 

 Furnace and burner specifics were not reported 

 Only 4 thermocouples were used to record the furnace temperature, while ASTM E-119 

requires a minimum of nine thermocouples symmetrically distributed. 

 The furnace temperature, as measured by the UL thermocouples, was below the E-119 
5-73 

temperature and the area under the actual temperature curve was not within the 10% as 

required by E-119 for several exposure periods in both tests. 

 The 1.90 cm (0.75 in) conduit protected with Thermo-Lag and Mecatiss failed to meet the 

3-hour rating. (If these results are to be used, the licensee was directed to request a 

deviation from the acceptance criteria based on an engineering evaluation acceptable to 

the staff, such as demonstration of cable functionality.) 

The licensee responded to NRC comments in its letter dated May 17, 1995. As explained in 

that letter, much of the deviations were a result of the test furnace size and instrumentation 

available to conduct the testing. As discussed previously, the licensee conducted the French 

Mecatiss testing to identify the viability of this barrier system to resolve Thermo-Lag issues and 

planned to conduct qualification testing in the USA, if favorable results were obtained. 

5.5.3.2 UL Testing of Mecatiss for Florida Power Corporation 

Following FPCs viability testing of Mecatiss at Morestal, France, the Mecatiss qualification tests 

were conducted at UL. Five fire tests were conducted at UL to qualify a 1- and 3-hour 

standalone Mecatiss barrier (MTS-1 & MTS-3), along with a 1- and 3-hour upgraded overlay 

Mecatiss barrier system (MPF-60 & MPF-180). The test plan was provided to NRC staff for 

comment. 

The proprietary UL fire endurance test reports were submitted to NRC on March 30, 1996, while 

the non-proprietary versions were submitted on July 31, 1996. NRC staff reviewed these test 

reports and concluded in an SE dated January 29, 1997, that the Mecatiss fire barrier system, 

when designed and installed in accordance with the techniques utilized for the test specimens, 

meets the acceptance criteria specified in Supplement 1 to GL 86-10, and is, therefore, 

acceptable for use as a fire barrier systems relied upon by the licensee to meet NRC fire 

protection requirements. The following description of the test and results are based on public 

information, including NRC staff trip reports, NRC safety evaluations and a public FPC test 

results summery letter. A summary table of the results and details of this testing is presented in 

Table 5-28. 

Test Deck No. 1 was subjected to a 1-hr test while test decks 2 and 6 were subjected to a 3-

hour test, all in the UL column furnace, as specified by GL 86-10 Supplement 1. Test Deck No. 

3 and 4 were tested in the UL “Floor Furnace,” while Test Deck No. 5 contained three test 

articles were tested in the UL “wall furnace.” 

 
5-74 

Table 5-28. Results of UL Mecatiss Testing 

Test 

Deck No. 

Article 

No. Raceway ERFBS Fire Test Rating (minutes) 

1 1 3⁄4” conduit MTS-1 60 

 2 24” cable tray 1⁄2 length TL1 + MPF-60 

1⁄2 length MTS-1 

60 

 3 3⁄4” conduit 1-hr TL + MPF-60 60 

2 4 3⁄4” conduit MTS-3 180 

 5 24” tray 3-hr TL + MPF-180 180 

 6 3⁄4” conduit 3-hr TL + MPF-180 180 

3 7 24” cable tray MTS-1 60 

 8 3⁄4 & 4” conduit 1-hr TL + MPF-60 60 

 9 two 3⁄4” conduit 1-hr TL + MPF-60 60 

 10 24” cable tray tee 

with four conduit 

stubs 

3-hr TL + MPF-180 60 

4 11 24” cable tray MTS-3 80 

 12 3⁄4” & 4” conduit 3-hr TL + MPF-180 80 

 13 two 3⁄4” conduit 3-hr TL + MPF-180 80 

 14 24” cable tray tee 

with four conduit 

stubs 

3-hr TL + MPF-180 80 

5 15 24” cable tray 1-hr TL + MPF-60 60 

 16 3⁄4” conduit & 

12”x14”x6” junction 

box 

1-hr TL + MPF-60 60 

 17 3⁄4” & 4” conduit 1-hr TL + MPF-60 60 

6 18 6” cable tray 1-hr TL + MPF-60 93 

 19 6” cable tray MTS-1 102 

 20 6” cable tray 3-hr TL + MPF-180 115 

 21 6” cable tray MTS-3 180 

 22 6”x6” cable wire way 1⁄2 length TL1

 + MPF-60 

1⁄2 length MTS-1 

110 

1

TL is an abbreviation for Thermo-Lag 330 

It should be noted that for the results reported for Test 6 in Table 5-28, are the times when the 

barrier first exceeded the temperature rise criteria of GL 86-10 Supplement 1. All test articles of 

test deck No. 6 were subjected to a 3-hour E-119 fire endurance test, although not all were 

designed to be 3-hour barriers. 
5-75 

5.5.3.3 Ampacity Derating Tests 

UL also performed several ampacity derating tests for FPC for the Mecatiss and ThermoLag/Mecatiss ERFBS used at CR-3. The testing was performed in accordance with IEEE 

P848/D15 “Procedure for the Determination of the Ampacity Derating of Fire Protected Cables,” 

dated January 1, 1995. The results of this testing were submitted to NRC for review, but were 

determined to be proprietary to FPC and will not be presented in this repot. However, it can be 

said that the ampacity derating values of the Mecatiss ERFBS were consistent with derating 

values of other barrier types. 

5.5.4 Resolution and Staff Conclusion 

The Mecatiss ERFBS was used as a replacement barrier to Thermo-Lag or other ERFBS that 

were found incapable of performing there design function. There have been no generic 

problems identified with the use of Mecatiss to provide the required 1- or 3-hour protection of 

equipment important to safe shutdown. Therefore, the staff concluded that the use of Mecatiss 

as an ERFBS in accordance with applicable testing results will provide adequate assurance that 

the structures, systems, and components will be protected by the use of Mecatiss in 

configurations bounded by test results. 

 
5-76 

5.6 Kaowool and FP-60 (Insulative ERFBS)

Kaowool is manufactured by Thermal Ceramics. The Kaowool blanket material is produced 

from kaolin, a naturally occurring alumina-silica fire clay. It is a noncombustible, flexible, 

ceramic-fiber blanket, composed primarily of silica and alumina compounds (SiO2 and Al2O3) 

and has a melting point of 1760°C (3200°F). FP-60 is basically an upgraded version of 

Kaowool with a 2.00 mm (0.08-in) aluminum foil skin laminated to both sides of a ceramic-fiber 

blanket. Kaowool and FP-60 are used to construct barriers intended to have a 1-hour fire 

resistance rating, but neither are rated for 3-hour use. In addition to their use as a fire barrier, 

some licensees used these barriers for separation of certain electrical systems in accordance 

with the guidance of RG 1.75, “Physical Independence of Electrical Systems,” or to limit 

combustible sources within a fire area by wrapping it with either of these materials. San Onofre 

Nuclear Generating Station, Units 2 and 3 uses a product called Cerablanket which is a flexible, 

ceramic-fiber blanket similar to Kaowool and is shown in . 

(a) (b) 

Figure 5-16. Picture of (a) Kaowool and (b) FP-60 Material (Author, 2009) 

The installation of the Kaowool and FP-60 ERFBS are similar. For cable trays, the trays are first 

prepped with steel banding wrapped around the tray and spaced approximately 35.6 cm 

(14.0 in) on center (OC), then a wire mesh cut to the width to the cable tray is secured to the top 

of the tray with filament tape. The cable trays are then wrapped with two to six layers of the 

ceramic fiber blanket. Each wrap consists of a nominal width blanket 61.0 to 122 cm (24 to 

48 in) overlapping on the top side of the raceway. During installation, each layer is held in place 

with filament tape. The adjacent wrap overlaps the preceding wrap by a minimum of 2.54 cm 

(1.0 in). Successive layer of the ceramic wrap are installed in the same manner with the overlap 

locations for succeeding layer offset a minimum of 30.5 cm (12 in) from the overlap of the 

preceding layer. As a final step, a nominal 1.9 cm (0.75 in) wide by 0.038 cm (0.015 in) thick 

steel band straps are wrapped around the cable tray system and secured with 2.54 cm (1.0 in) 

long channel-shaped crimp clips. The steel bandings are spaced at a maximum of 35.6 cm 

(14 in) on center and a maximum of 10.1 cm (4 in) from any joint on the outer blanket. After the 

installation of the ceramic fiber blanket is completed, an optional silica or glass fiber cloth can be 

wrapped around the outer layer. This will help protect the base Kaowool material but is not 

required. At wall and floor interfaces loose ceramic fiber is firmly packed round the periphery of 

the cable raceway. 
5-77 

Kaowool and FP-60 ERFBS can be installed on conduits and air drop configurations in the 

same manner as done with cable trays. , provides a diagram showing the various layer and 

configurations used to construct a Kaowool or FP-60 ERFBS. 

Figure 5-17. Sketch of Kaowool / FP-50 Installation (Fire Test, 1978) 

Kaowool is available in numerous thicknesses and licensees used various configurations 

(number of layers versus thickness of material) to construct their ERFBS. When the FP-60 

material came into use, the 1.3 cm (0.5-in) thick material provided somewhat better fire 

resistance rating. This is a result of multiple layers of thinner material will outperform the fewer 

layers of thicker material, because trapped air in space between the layers acts as an insulator. 

The consequences of a joint failure are also lessened because of the multiple joints and 

staggering of the joints. 

5.6.1 History 

Kaowool was originally developed by Babcock and Wilcox to be an asbestos replacement 

material and is commonly used to insulate high temperature furnaces, forges, and kilns. Its low 

density of 64.1, 96.1, or 128.1 kg per m3

 (4.0, 6.0, or 8.0 lbs per ft3), very low thermal 

conductivity and ease of handling and cutting resulted in Kaowool being used in numerous 

commercial applications and configurations. 

As a result of its successful use in other industrial applications, Kaowool insulation was one of 

the first materials to be used in protecting electrical raceways containing FSSD circuits. This is 

primarily due to the fact that, during the late 1970’s and early 1980’s there were concerns that 

there were no material commercially available that clearly met a 1-hour fire barrier requirement 

and because some licensees had experience with Kaowool installation to meet BTP APCSB 
5-78 

9.5.1 guidance, Kaowool was chosen as a viable solution to Appendix R fire barrier applications. 

Although the use of Kaowool and FP-60 material in the nuclear industry was a result of 

Appendix R requirements, the material was in existence well before the need for its employment 

as an ERFBS. 

Subsequent to the issuance of GL 92-08, “Thermo-Lag 330-1 Fire Barriers,” NRC began 

evaluation other known fire barrier materials and systems that are used by licensees to fulfill 

NRC fire protection requirements. Following NRC staffs review of the Kaowool and FP-60 test 

reports provided by Thermal Ceramic (manufacture) and a reverification inspection at Salem 

Nuclear Generating Station in 1993, NRC issued two IN regarding potential problems with 

Kaowool and FP-60 ERFBS. IN 93-40, “Fire Endurance Test Results for Thermal Ceramics 

FP-60 Fire Barrier Material,” and IN 93-41, “One Hour Fire Endurance Test Results for Thermal 

Ceramics Kaowool, 3M Company FS-195 and 3M Company Interam E-50 Fire Barrier 

Systems.” Both Information Notices informed the nuclear industry of deficiencies found in the 

test reports concerning qualification the barriers and that NRC would continue its review of the 

barriers ability to perform its fire resistive function and will issue further generic communications, 

if needed. Although no other generic communications were issued, NRC continued to interface 

with industry to determine its use and compliance with regulations. 

During an NRC inspection of Joseph M. Farley Nuclear Plant (FNP) in 1996, the NRC 

inspectors identified technical issues associated with the design, installation, and fire-resistive 

performance of Kaowool raceway fire barriers installed at FNP. In the later part of 1996, NRC 

Region II offices requested Office of Nuclear Reactor Regulation (NRR) support in reviewing the 

identified issues through a Task Interface Agreement (TIA) 96-023. Following a detailed review 

of the performance and licensing basis of the use of Kaowool at FNP, NRC staff determined that 

the fire rating of the Kaowool installed at FNP was indeterminate, but less than the 1-hour 

needed to meet the Appendix R requirements. A response to TIA 96-023 was provided to the 

Region II offices on June 18, 1999. The response concluded that the licensee FNP did not have 

a sound technical basis for concluding that the Kaowool ERFBS installed at FNP meet the 

regulatory requirements or provided an adequate level of fire protection for the post-fire safeshutdown capability. In SECY-99-204, NRC staff informed the Commission of its review of this 

matter and provided its TIA 96-023 response as an attachment. 

When SECY 99-204 was issued on August 4, 1999, there were 15 unites (9 plants) that used 

Kaowool or FP-60 to meet the Appendix R regulatory requirements, they were: 

 Farley 1 & 2 

 Grand Gulf 

 Prairie Island 1 & 2 

 Sequoyah 1 & 2 

 Susquehanna 1 & 2 

 Fitzpatrick 

 Hatch 1 & 2 

 Salem 1 & 2 

 Summer 

Of the 15 units identified, all licensees except FNP, James A. Fitzpatrick Nuclear Power Plant, 

Grand Gulf Nuclear Station, and Virgil C. Summer Nuclear Station elected to voluntarily 

eliminate the use of Kaowool to meet the regulatory requirements. Farley Nuclear Plant used 

the largest quantity of Kaowool approximately 1,920 m (6,300 linear feet), Summer used 304.8 

m (1,000 linear feet) (3 layers, each 2.54 cm (1-in) thick), Fitzpatrick used 18 m (60 linear feet) 

(six layers, each layer 1.3 cm (0.5 in) thick) and Grand Gulf used nearly 457 m (1,500 linear 

feet) (two layers, each 2.54 cm (1-in) thick). 
5-79 

5.6.2 Problems 

As presented in the testing section that followings, the pure insulation properties of the ceramic 

fiber was not capable of reducing the heat transfer from the extreme heat of the test furnace 

(ASTM E-119 curve) to the protected cable raceways. In fact, there were only two test 

specimens (see Virgil C Summer Nuclear Station testing) which provide the rated 1-hour 

protection as specified in Supplement 1. All other testing of Kaowool and FP-60 ERFBS failed 

the Supplement 1 criteria or the test report was not sufficient in detail to determine if the test 

specimen would pass the GL 86-10 Supplement 1 guidance. 

The construction of Kaowool resulted in a major problem with maintaining the barrier, namely 

any physical contact with the ERFBS had the potential to damage the barrier. Unlike other 

barriers that were a rigid or semi-rigid system, the loose Kaowool ceramic fiber could easily be 

pulled away with little to no effort. As a result, anytime a barrier was bumped into, had a tool 

dropped on, or was improperly used as a step or human support during maintenance activities, 

the barrier would typically become damaged and likely have a reduction in its thermal insulation 

capacity. As a result, several inspection findings and violations have been issued for damaged 

or missing Kaowool barriers. This is one of the reasons some licensees replaced or upgrade 

the Kaowool ERFBS with the FP-60 material which has the 2-mil aluminum foil skin on the 

exterior layer to protect the internal Kaowool fiber. As discussed in the Section 5.4, Hemyc and 

MT ERFBS were another solution which provided protection to the base Kaowool fiber. 

A phenomena referred to as “wicking,” also had the potential to degrade the barrier and cause 

additional fire hazards within the plant. Wicking is when a flammable liquid, like diesel fuel or 

flammable solvents (liquid hydrocarbon), are spilled or leak onto the noncombustible Kaowool 

fabric, causing the barrier to aid combustion if a fire were to occur. Think of an old kerosene 

lantern, same idea. Not only will wicking aid a fire, but when the Kaowool fabric becomes wet, 

the moisture and added weight has been known to cause layers of the material to fall away, 

thus reducing the quality of the barrier. 

As discussed above, plants licensed to operate prior to incorporating Appendix R in the 

regulations, are required to satisfy Appendix R requirements. However, GL 86-10 states that 

licensees need not replace Kaowool materials that were installed before Appendix R became 

effective and that were accepted by NRC as 1-hour fire-rated barriers. According to SECY 

99-204, NRC staff and the licensees have interpreted the GL 86-10 guidance to mean that 

Kaowool raceway fire barriers installed before Appendix R became effective and that were 

accepted by NRC as a 1-hour fire-rated barriers are “grandfathered” and that exemptions are 

not needed even though the barriers may not meet the technical requirements of Appendix R. 

However, GL 86-10 guidance does not relieve the licensee from establishing and maintaining 

the design bases for the fire barriers it has installed to satisfy NRC’s fire-protection 

requirements. NRC staff review of FNP, determined that the licensee did not establish an 

acceptable design basis for the Kaowool ERFBS installed to satisfy Appendix R. 

5.6.3 Testing 

During NRC review and response to TIA 96-023, the licensee of FNP submitted 16 Kaowool fire 

test reports. In reviewing the testing documentation submitted by the licensee, fundamental 

generic testing deficiencies were discovered in most of the tests reviewed. These generic 

deficiencies included (1) non-standard full-scale test furnaces, (2) non-standard furnace 

instrumentation, (3) non-standard fire exposures, and (4) no hose stream testing. 
5-80 

The following test summaries are those applicable to testing ERFBS, although only one was 

performed in accordance with Supplement 1, these results do indicate the inability of Kaowool to 

provide the required fire protection of safe shutdown equipment. 

5.6.3.1 Sandia National Laboratories (SNL) Testing 

On September 15, 1978, a full-scale fire test was conducted at UL to demonstrate the 

effectiveness of a ceramic fiber blanket and automatic fire suppression system to protect cables 

in a vertical cable tray configuration. An open pool fire fueled by liquid hydrocarbon was used in 

the test. 

The test was carried out in a corner-ceiling assembly approximately 6.1 m long by 6.1 m wide 

by 4.6 m high (20 ft x 20 ft x 15 ft). The walls of the assembly consisted of steel framing and 1.3 

cm (0.5 in) thick Marinite boards covering the steel. Five open ladder cable trays were installed 

in the test assembly 45.7 cm (18 in) wide with rungs installed at 22.9 cm (9 in) intervals. Three 

conductor cables were run through the cable trays. The cables were 1.2 cm (0.468 in) diameter 

with 600 V rating made of #12 AWG stranded copper. A conductor insulation of 0.7 mm (0.027 

in) covered the 9.4 m (31 ft) long cables which were bundled in groups of eight. 

Kaowool fire barrier was installed along the entire length of each cable tray with a thickness of 

2.54 cm (1 in) and fastened to the cable trays with 1.9 cm (0.75 in) thick steel bands and band 

clips. Additional pieces of Kaowool covered 1) the entire front surface of the cable bundle along 

the vertical overlapping joint of the outer layer, 2) the back surface of the cable bundle and tray 

at horizontal butt joints of the outer layer, 3) the horizontal butt joints of the outer layer, and 4) 

the ceiling and floor butt joints. 

Seven Type K thermocouples were located in each tray and additionally between cable trays 

over the fire pan and near each open head sprinkler. The test began by pouring two gallons of 

n-heptane into a pan below the test assembly and igniting by torch. Within ten seconds of 

ignition, the flames had reached a maximum of 1.2 m (4 ft) and covered the entire fuel pool. 

All flaming ceased after 40 minutes. Cable trays clad with flame-engulfed Kaowool are shown 

in . 

. 

Figure 5-18. Fire Engulfing Cable Trays Clad with Kaowool. (NUREG/CR-0596) 
5-81 

Post test observations indicated that the Kaowool was blackened on the base of each tray 

upward about 0.3 m (1 ft) but remained largely unaffected on the inner surface except for light 

brown areas in the bases of trays 1, 2, 3, and 4. Thermal damage of cables was noted in all 

trays except for tray five, approximately 3 to 6 inches above the fire pan. Cable material in all 

four trays were melted and charred with the greatest damage occurring in cable tray 3. 

Maximum temperatures recorded for cable trays one through five were 56.9oC, 58.8oC, 60.6oC, 

54.7oC, and 35.2oC (134.5oF, 137.9oF, 141.1oF, 130.4oF, and 95.3oF) respectively. 

During testing, cables were energized with low voltage and conductors with the same color code 

in each tray were connected in parallel to provide three circuits per tray. Each circuit had low 

current flow during the test and was monitored continuously for shorts between conductors or 

between conductors and trays. A short circuit between conductors 1 and 3 in cable tray 3 was 

indicated at 3 minutes 13 seconds into the test. Three minutes 55 seconds into the testing, 

erratic measurements were recorded in tray 1 indicating intermittent short circuits. The 

complete detail of this testing can be found in NUREG/CR-0596, “A Preliminary Report on Fire 

Protection Research Program Fire Barriers and Suppression (September 15, 1978, Test).” 

5.6.3.2 NIST Small Scale Testing 

NIST performed small-scale testing of a 1-hour FP-60 barrier system consisting of four layers of 

a ceramic fiber blanket nominally 12.7 mm (0.5-in) thick with 0.051 mm (0.002-in) aluminum foil 

laminated on both surfaces. The test assembly was subjected to a 1-hour ASTM E-119 fire 

exposure. The results indicated that the average and maximum single point temperature rise 

criterion were reached during the 3.5 hour exposure. 

5.6.3.3 Vendor Testing 

5.6.3.3.1 Babcock and Wilcox Testing 

This test series evaluated that protection provided by varying layers of Kaowool insulation 

installed on cable trays and conduits. The cable trays and conduits tested were loaded with 

IEEE-383 “Qualifying Class 1E Electric Cables and Field Splices for Nuclear Power Generating 

Stations,” qualified and non-qualified cables with 5 to10 thermocouples placed on the exterior of 

the cables, within the cable tray. The natural gas fired 91.4 cm by 91.4 cm (36.0-in by 36.0-in) 

furnace was controlled to the ASTM E-119 time-temperature curve for all tests. For each test, 

the tray raceway was located such that the flames from the burners would be along the side and 

bottom of the cable tray. The conduit raceway was suspended above the cable tray assembly. 

The cables were connected to an incandescent display board capable of monitoring 20 circuits 

and powered by either 440 or 110 Volts AC power through a circuit breaker. This circuit 

configuration allowed for the detection of cable-to-cable and cable-to-raceway shorts, as well as 

open circuit faults. 

Test 1 evaluated the performance of cables when no Kaowool protection, which resulted in 

circuit failure of the non-qualified cable within eight minutes. The configurations and results of 

all tests are shown in . 

 
5-82 

Table 5-29. Kaowool ERFBS Test Results (10/24/1978) 

Test 

# Raceway Configuration Barrier Configuration 

Min. Cable 

Failure 

Time 

(minutes) 

1 Tray: Solid bottom, Steel 

Galvanized 

Conduit: Steel 

Tray: None 

Conduit: None 8a

2 Same as Test #1 Tray: 1” Kaowool on top of cables, 2 la

 with 3” overlaps 

Conduit: 2 layers of 1” Kaowool 

51 

65 

3A Tray: Aluminum open ladder back 

Conduit: Aluminum Same as Test #2 11a

3B Same as Test #3A Same as Test #3A except brackets 

used to hold exterior of blanket near 

butt joints were relocated to 3” on 

each side of butt joint, instead of 2” 

as done in Test #3A. 

61a

4 Same as Test #2 Tray: 1” Kaowool on top of cables, 1 

layer of 1” Kaowool wrapped with 3” 

overlaps. 

Conduit: 1 layer of 1” Kaowool 

For both raceways, a 4” wide strip of 

Kaowool was wrapped around the 

butt joints and held in place by steel 

banding. 

40a

a Report did not specify failure location (tray or conduit)

Post test evaluation of the barrier with comparison of the thermocouple data indicated that butt 

joint failed resulting in the direct heat exposure to the cables and early failure times. Test 3B 

incorporated design changes to make the butt joints more thermally robust by adding a Kaowool 

collar surrounding all exterior butt joints. As shown in , the collar design change significantly 

improved the performance of the Kaowool barrier. The test report concluded with the following 

insights. 

 Unprotected cables fail early (eight minutes) in complete engulfment fires 

 Wrapping solid bottom and open ladder trays and conduit with 5.1 cm (2.0-in) of Kaowool 

blanket (with all butt joints tight) provides approximately 50 minutes of protection in complete 

engulfment fires. 

 Wrapping solid bottom trays with 2.54 cm (1.0 inch) of Kaowool blanket (10.1 cm (4.0-in) 

collar over butt joints) provides approximately 40 minutes of protection in complete 

engulfment fires. 

 Loose and open butt joints in insulation may lead to early cable failure in engulfment fires. 
5-83 

5.6.3.3.2 Underwriters Laboratories Testing 

UL performed fire endurance and hose stream testing on a FP-60 floor protected assembly (File 

R11044-1 Project 84NK9356). The testing followed UL Subject 1724 (dated May 1984) and 

was performed by UL on September 26, 1984. The materials used in the test assembly were 

readily installed by qualified workers with tools and methods commonly used for construction 

work of this nature. 

The ERFBS was installed, with four layers of ceramic fiber used on cable trays and the cable air 

drop configuration was protected with six layer of ceramic fiber. All steel supports were 

protected with the ceramic blanket wrapped with approximately 21⁄2 layers; however, the test 

report does not specify the distance from the raceway which the supports are protected. 

Every conductor was energized and monitored for circuit integrity throughout the fire endurance 

and hose stream testing. The test assembly consisted of eight configurations, four 91.4 cm 

(36.0 in) wide cable trays (half open ladder back and half solid back), two nominally 12.7 cm 

(5.0 in) diameter rigid steel conduit, one 30.5 cm by 30.5 cm by 15.2 cm (12.0-in by 12.0-in by 

6.0 in) junction box, and one air drop cable. Cable tray cable fill used 1/C 300MCM power, 7/C 

# 12 AWG control, and 2/C # 16 AWG instrumentation cables. Actual percent cable fill varied 

from 18.5 percent to 87.6 percent for the cable trays and from 6.9 to 100 percent fill for the 

conduits raceways. 

Ten days following assembly of the ERFBS, the endurance test was conducted in accordance 

with UL Subject 1724 and terminated at 61 minutes; the assembly was raised and subjected to 

a 206.8 Pascal (30 lbs per sq. in), 2.604 cm (1.025 in) diameter nozzle hose stream 525.8 cm 

(17.0 ft 3 in) away, for duration of 2.5 minutes. It was noted at 20 minutes into the fire test that 

the blanket wrap on the bottom surface of System No. 2 had slipped from beneath the steel 

banding strap and was bowing downward such that a maximum 1.3 cm (0.5-in) wide vertical 

opening was present at the center of the sheet edge. At the completion of the test, this opening 

had grown to be approximately 8.9 cm (3.5-in). The test report concluded that, “the 1-hour fire 

rating of the FP-60 ERFBS was established by evaluating the performance of the system with 

respect to maintaining the integrity of the electrical circuits under fire exposure conditions and 

during a hose stream test following the fire exposure.” Based on this rating criterion UL 

determined that the FP-60 barrier tested provided the 1-hour rated protection. 

Although the FP-60 barrier passed the test, per the UL Subject 1724 testing criteria, it was 

noted in the test report the following visual damage, as summarized in . As you can see from 

the results, although the circuit integrity was never lost during the fire endurance and hose 

stream portions of the test, the cable jackets and FP-60 ERFBS did experience a finite amount 

of damage. 

 
5-84 

Table 5-30. Summary of UL FP-60 Fire Resistance Test Results 

Test Article Description 

#1 : 36” tray ...approximately 50 percent of the two conductor No. 16 AWG located on 

the north bend of the tray were fused together. 

#2 : 36” tray ...approximately 1⁄2 of the blanket was eroded by the water hose stream 

such that the bottom surface of the cable tray was exposed. It was also 

noted that cables were fused together at numerous points. 

#3 : 36” tray ...approximately 1⁄2 of the insulation on the bottom surface was (missing 

following hose stream test). ...cable jacket of the seven conductor cables 

were fused together. 

#4 : 36” tray ...approximately 3⁄4 of the fiberglass cloth was consumed. Steel banding 

straps were missing. Bottom of cable wrap was eroded. Blistering was 

present on the cable jacket, ranging in size from 1⁄4” to 1⁄2” in diameter. 

#5 : 5” Conduit ...1/2 of blanket on bottom of conduit was consumed. At one point, all three 

cables fused together. 

#6 : 5” Conduit Side outer two layers were consumed. Outer three layers of bottom were 

consumed. All three cable types were undamaged. 

#7 : Junction 

Box 

All four Layers were consumed. Jackets of cables within junction box were 

fused together. 

#8 : Air Drop No information was provided on the air drop configuration. 

If you were to use these test results and the Supplement 1 acceptance criteria, it is easy to see 

that all configurations would not have been found acceptable (with maybe the exception of #8) 

to use this barrier as a qualified 1-hour ERFBS. 

5.6.3.3.3 Southwest Research Institute Testing 

SwRI performed testing of the FP-60 ERFBS (Project No. 01-8305-053). The testing was 

performed in accordance with the ANI/MAERP standard. The test assembly slab was 2.1 m by 

2.1 m (7.0 ft by 7.0 ft) square and 3 configurations were installed, namely a 2.54 cm (1.0 in) 

diameter rigid conduit adjacent to concrete slab (less than 1.3 cm (0.5 inches) from concrete 

slab) containing one control and one instrument cable, a cable air drop consisting of one power, 

one control, and one instrument cable, and a 3.7 m by 3.7 m by 15.2 cm (12.0 ft by 12.0 ft by 

6.0 in) junction boxed mounted in a pendulum configuration using a 5.1 cm (2 in) diameter rigid 

conduit. The junction box contained the three types of cables, all instrumented with 

thermocouples (thermocouple spacing was not specified). The testing used a small scale 

horizontal exposure furnace with an expansion collar to fit the test deck assembly. The test 

furnace followed the standard time/temperature curve and at 60 minutes it was 5.2 percent 

above the corresponding area under the standard curve (ASTM E-119 allows for ± 10%). 

All cables were monitored for circuit integrity before the start of the test, at 50 minutes into the 

test, and after the hose stream test. No circuit integrity was lost during these periodic checks. 

The hose stream test consisted of a 6.4 cm (2.5-in) National Standard playpipe equipped with a 

2.858 cm (1.125 in) tip, at a nozzle pressure of 206842.7 Pascal (30 lbs per sq. in) from a 

distance of 6.1 m (20.0 ft) for 2-1/2 minutes. 
5-85 

5.6.3.3.4 Southwest Research Institute Ampacity Derating Tests 

SwRI performed ampacity derating testing of the FP-60 ERFBS. The test derived ampacity 

derating values for cable trays and conduits, both filled with 100 percent visual fill of a 3/C 

# 6 AWG XLPE insulated and CSPE (Hypalon) jacketed power cable. The cables were 

approximately 3.7 m (12.0 feet) in length with 0.3 to 0.6 m (1 to 2 ft) extending outside of each 

wrap. Type K (Chromel-Alumel) thermocouples were used to measure the temperature of the 

copper conductor within the cable. In the cable tray test, 39 thermocouples were used, while 15 

were used when testing conduits. All cables were connected in series and supplies with 60Hz 

single phase AC power sufficient to reach a steady-state temperature of 90°C (194oF) at the 

hottest single point monitored. The test was conducted in the summer of 1986 and resulted in 

an ampacity derating factor of 62.2 percent for cable trays and 38.75 percent for conduits 

protected with the FP-60 ERFBS. 

5.6.3.4 Industry Testing 

5.6.3.4.1 Virgil C. Summer Nuclear Station, Unit 1 Testing 

On December 28, 1999, NRC staff witnessed testing conducted by the licensee of Virgil C. 

Summer Nuclear Station (VCSNS) for several Summer-specific Kaowool configurations. 

LER 1999-014 informed NRC that engineering personnel determined that some as installed 

applications may not meet the current regulatory requirements for one train free of fire damage 

for one hour. 

NRC staff review the test results provided by the licensee and concluded that the fire endurance 

rating of the Kaowool ERFBS is highly configuration dependent. As shown in , the rating varies 

depending on the particular configuration tested. NRC staff also noted that the testing did not 

perform continuous megger testing, as suggested in Supplement 1 to GL 86-10 for evaluation of 

cable performance. 

Table 5-31. VCSNS Kaowool Testing Results 

Item 

No. Size Configuration 

Cable 

Weight 

(lb/ft) 

Raceway 

Weight 

(lb/ft) 

Fire 

Resistance 

Rating 

(minutes) 

Rigid Steel Conduit 

4 1-inch Free Air 0.4 1.5 43 

7 1-inch Free Air 0.4 1.5 44 

2 1-1/4 & 4-inch Wall/Ceiling Mount 5.1 9.8 56 

1 4-inch Free Air 6.7 9.8 60 

6 1-1/4-inch Wall/Ceiling Mount 0.3 2.0 60 
5-86 

Table 5-31. VCSNS Kaowool Testing Results (Continued) 

Item 

No. Size Configuration 

Cable 

Weight 

(lb/ft) 

Raceway 

Weight 

(lb/ft) 

Fire 

Resistance 

Rating 

(minutes) 

Steel Ladder Back Cable Tray 

3 6x6-inch Free Air 5.3 8.0 46 

5 6x36-inch Free Air 18.5 15.0 58 

Air Drop

10 Air Drop Free Air 0.34 0 31 

5.6.4 Resolution and Staff Conclusion 

Plant specific resolution of Kaowool is provided in Section 6. Currently, the only plant that uses 

the Kaowool as an ERFBS is VCSNS, and the only plant using FP-60 ERFBS is James A. 

Fitzpatrick (JAF). 

In some instances VCSNS uses Kaowool to meet the RG 1.75 criteria for safety related cable 

separation not related to Appendix R separation and/or safe shutdown. Where Kaowool is 

relied upon for Appendix R separation and/or safe shutdown, the licensee South Carolina 

Electric and Gas Company (SCE&G) informed NRC that, 

“In some applications Kaowool was found to be acceptable, after modification, in 

configurations determined by station supported testing of the product. The fire 

endurance testing for Kaowool was conducted in accordance with GL 86-10, 

Supplement 1.” 

Kaowool barriers that did not meet the fire endurance rating for the configurations that they are 

installed at VCSNS are being replaced with 3M product. 

Initially the licensee of JFP determined that the FP-60 barrier used is operable and as such did 

not initiate compensatory measures. It also believed that its barrier is of a different construction 

than at other plants and did not join any industry initiative to resolve the issue. However, 

following issuance of SECY-99-204 questioning the ability of the FP-60 to withstand a 1-hour 

fire rating, FitzPatrick applied for and received an exemption from the requirement of Appendix 

R for its use of the FP-60 ERFBS, on May 29, 2001. Based on fire barrier testing, the licensee 

determined that the FP-60 ERFBS exceeded test acceptance criteria at 30 minutes. NRC staffs 

safety review concluded that an adequate level of fire safety such that there is reasonable 

assurance that at least one means of achieving and maintaining safe shutdown conditions will 

remain available during and after any postulated fire in the plant, and therefore, the underlying 

purpose of the rule is met. 

Prairie Island Nuclear Generating Plant, Units, 1 and 2, Sequoyah Nuclear Plant, Units, 1 and 2, 

Susquehanna Steam Electric Station, Units 1 and 2, Edwin I. Hatch Units 1 and 2, and Salem 

Nuclear Generating Station, Units 1 and 2 all removed Kaowool from their plants as a method of 

meeting Section III.G of Appendix R. In addition, Farley Unit 1 and 2 have removed the use of 
5-87 

Kaowool from protection of safe-shutdown components, and Grand Gulf Nuclear Station has 

replaced Kaowool with a qualified 3M product. 

In limited cases, Kaowool and FP-60 have been determined to adequately perform its design 

function for a specific time frame in combination with other fire protection features. However, in 

general, the staff concluded that Kaowool and FP-60 are unacceptable ERFBS as rated 1-hr 

and 3-hr ERFBS without proper testing to show otherwise. 

 
5-88 

5.7 Promat (Hydrate)

Promat Fire Protection is a division of Eternit Inc. which manufactures PROMAT-H rigid calcium 

silicate cement boards. Typically, 2.54 cm (1.0 in) thick boards are used for construction of 

cable tray and conduits ERFBS. The properties of these two boards are shown in Table 5-32. 

Table 5-32. PROMAT Properties 

Property PROMAT-H PROMAT-L 

Density 870 kg/m3 430 kg/m3

Thermal Conductivity 0.175 W/mK 0.083 W/mK 

Flame Spread 0 0 

Smoke Development 0 0 

Combustibility Non Combustible Non Combustible 

Installation of Promat-H involves cutting support strips 7.6 cm (3.0 in) wide and as long as the 

cable tray width or conduit outside diameter. These support strips are attached to the top and 

bottom of the raceway with 1.90 cm (0.750 in) by 0.025 gauge steel banding, spaced 30.5 to 

61.0 cm (12.0 to 24.0 in) apart, along the entire length of raceway to be protected. These 

support strips provide a base to attach the Promat panels to surround the raceway. Individual 

layers of Promat are placed around the raceway to form a box and secured to each other by 

self-drilling screws. The first layer is also secured to the support strips. A 1-hour barrier 

typically has 2 layers of 2.54 cm (1.0 inch) thick Promat-H, while a 3-hour barrier has 4 layers of 

2.54 cm (1.0 in) thick Promat-H cement board. Any gaps and joints are filled with an approved 

fire resistant caulk. An installation diagram for cable tray and conduit applications are shown 

below in Figure 5-19 and Figure 5-20 respectively. 

Figure 5-19. Promat-H Cable Tray Protection (Author, 2009) 

 
5-89 

Figure 5-20. Promat-H Conduit Protection (Author, 2009) 

5.7.1 History 

Promat fire protection products have a long history in providing passive fire protection products 

for various structural members (steel I-beams, walls, grease ducts, concrete, membrane 

ceilings, and roof decks). However, the use of Promat in the commercial U.S. NPP fleet is 

limited to Farley Nuclear Plant and Hatch Nuclear Plant. 

5.7.2 Problems 

No generic problems have been identified with the use of Promat-H or Promat-L rigid boards for 

ERFBS installations. 

5.7.3 Testing 

5.7.3.1 NIST Testing 

Several samples of PROMAT-H were tested in the NIST small scale testing program. For a 

description of the NIST test program, please refer to Section 5.2.3.1. The first test (D1-1) 

consisted of two layers of 25 mm (0.98 in) thick ceramic board (i.e., a 1-hour barrier). The test 

assembly was subjected to an ASTM E-119 fire exposure. The results indicated that the 

average unexposed surface temperature rise criterion was met at 1 hour and 18 minutes, while 

the maximum unexposed single point surface temperature rise was no reached. 

The second test (E3-1) consisted of two layers of 50 mm (1.97 in) thick ceramic board (i.e., a 

3-hour barrier). The test assembly was subjected to the ASTM E-119 fire exposure. The results 

indicated that the average unexposed surface temperature rise criterion was met at 3 hours and 

46 minutes, while the maximum unexposed single point surface temperature rise was no 

reached during the 3.92 hr test. 

These small scale tests prove that homogeneous layers of Promat-H can provide the 

acceptable level of protection. However joints and bends are typically encountered in actual 

NPP ERFBS installations and workmanship of the installed barrier may affect its fire resistance. 

For this and other reasons discussed above, the applicability of these tests is limited. 

By comparison to other barriers tested in the NIST small scale program, the Promat-H 

performed well. 

 
5-90 

5.7.3.2 Fire Endurance Testing 

Although no fire endurance test reports have been submitted on the plant docket for either plant 

that use these barriers, an NRC Inspection of the Promat-H barriers installed at Hatch Nuclear 

Plant resulted in no findings. NRC Inspection team reviewed the installed fire barriers in detail 

to verify that the as-built configurations met design requirements, licensee commitments, and 

standard industry practice and had been either properly evaluated or qualified by appropriate 

fire endurance tests. This review also included confirmation that the ERFBS were installed on 

the required circuits, fire barrier was of appropriate fire rating, and the barrier installations were 

consistent with the tested configurations. 

Farley identified in its response to GL 06-03, that Promat was tested and qualified to ASTM 

E119-88 standard by Performance Contracting Inc. and conducted at OPL under Project No. 

8806-90254 (Promat Report SR90-005). In addition to this report, the vendor identifies the 

following test reports related to Promat. 

Table 5-33. List of Promat Test Reports 

Test Lab. Description Report 

Number 

SwRIa 1 Hr Cable Tray 0% Fill 01-2299-001 

SwRI 1 Hr Conduit 01-2299-001 

SwRI 1 Hr Cable Drop 01-2299-001 

OPLb

 3 Hr Cable 80% Visual Fill 8806-89017a 

OPL 3 Hr Cable Tray 0% Visual Fill 8806-89006 

OPL 3 Hr Conduit Against Concrete 8806-89004 

OPL 3 Hr Conduit Free Standing 8806-89017b 

OPL 3 Hr Cable Drop 8806-88053 a SwRI – Southwest Research Institute b

 OPL – Omega Point Laboratories 

5.7.3.3 Ampacity Derating 

The PROMAT vendor manual provides the following ampacity derating values for a PROMAT-H 

ERFBS. 

Table 5-34. PROMAT-H Ampacity Derating 

Configuration 1 – Hour 3 – Hour 

Solid Bottom Tray 8.7% 27.2% 

Ladder Bottom Tray 31.8% 45.3% 

Conduit 15.9% 36.7% 

 
5-91 

5.7.4 Resolution and Staff Conclusion 

No generic issues or deficiencies have been identified and associated with this ERFBS, there 

has been no need for generic resolution related to Promat ERFBS. Therefore, the staff 

concluded that Promat when installed to bound as tested configurations will satisfactory perform 

its intended design function. 

 
5-92 

5.8 Pyrocrete (Hydrate)

Pyrocrete is a cementitious inorganic fireproofing material. It is supplied as a single powder 

component that is mixed with water before application. Typical installation includes mounting a 

galvanized metal lath around the structure to be protected. This lath will support the pyrocrete 

and help adhere it to the raceway until the pyrocrete cures. The pyrocrete powder is mixed with 

water and sprayed onto the area to be protected with special equipment. The pyrocrete mix can 

also be toweled onto the raceway. A trowel, roller or brush can typically be used to smooth the 

top of the pyrocrete applications to ensure a smooth and consistent thickness. Vendor testing 

of Pyrocrete 241 produced by Carboline® using ASTM E-84 resulted in zero (0) flame spread 

and zero (0) smoke development. 

5.8.1 History 

Pyrocrete is not widely used in the commercial NPP industry as an ERFBS. It is more 

commonly used to provide fire proofing to structural steel beams or ceiling members. As of this 

writing, there are only three sites that use Pyrocrete as an ERFBS, Surry Power Station, Units 1 

and 2, Diablo Canyon Nuclear Power Plant Units 1 and 2, and Fort Calhoun Station, Unit 1. 

5.8.2 Problems 

No generic problems have been identified with the use of Pyrocrete as an ERFBS at US NPPs. 

However, Licensee Event Report 95-003-01 reports the licensee of Diablo Canyon Nuclear 

Power Plant identified untested configuration of Pyrocrete Fire Barriers. NRC staff inspections 

conducted in 1997 provided closure to the problems identified in the event report. 

5.8.3 Testing 

No fire endurance test reports were found to have been submitted to NRC for review; however 

the following summarizes NRC inspections of the Pyrocrete ERFBS installation in use at the 

three plants mentioned above. During these inspections, NRC staff reviewed fire tests and 

visually inspected the installed barriers. 

NRC Inspection Reports 50-275/97-17 and 50-323/97-17, documents NRC inspection staffs 

review of the application of Pyrocrete as an ERFBS at Diablo Canyon Nuclear Power Plant 

Units 1 and 2. The report concludes that the barriers installed in the plant were acceptable. 

The inspectors based their conclusions on their review of pyrocrete fire tests completed to test 

the installed barriers and visually inspected pyrocrete fire barriers installed in the plant. The 

inspectors observed that the fire test for the pyrocrete passed the 3-hour test required by NRC 

and also observed that the configurations installed in the plant were in accordance with the 

configurations tested. 

NRC Triennial Fire Protection Inspection Report 05000280/2006009 and 05000281/200609, 

dated April 11, 2006 documents NRC inspection staffs review of the Pyrocrete ERFBS used at 

Surry Power Station, Units 1 and 2. That report stated, 

The team inspected the material condition of accessible passive fire barriers 

surrounding and within the fire areas selected for review. Barriers in use included 

walls, ceilings, floors, mechanical and electrical penetration seals, doors, 
5-93 

dampers and cementitious fire resistive coatings. Construction details and fire 

endurance test data which established the ratings of fire barriers and fire resistive 

material were reviewed by the team. Engineering evaluations and relevant 

exemptions described in NRC safety evaluations related to fire barriers were 

reviewed. Where applicable, the team examined installed barriers to compare the 

configuration of the barrier to the rated configuration. 

The report concludes that “no findings of significance were identified” related to the review of 

passive fire protection features. 

According to a Surry Power Station Response to GL 06-03, Pyrocrete 241 has been qualified by 

Thermal Transmission Test (ref. Tech. Report EP-001 1) that uses the ASTM E-119 fire 

exposure and the failure criteria of an average temperature of 121oC (250°F) or single point 

temperature 162oC (325°F) above ambient backside temperature. The barrier was installed prior 

to the issuance of GL 86-10 Supplement 1. 

The Fort Calhoun Station triennial fire protection inspection performed in 2008 concluded that 

no findings of significance were identified. The team observed the material condition and 

configuration of the installed barriers, seals, doors and cables. The team compared the installed 

configurations to the approved construction details and supporting fire tests. The team reviewed 

licensee documentation, such as NRC safety evaluation reports, exemptions from NRC 

regulations and deviations from the National Fire Protection Association codes, to verify that fire 

protection features met license commitments. 

Niagra Mohawk, the licensee of Nine Mile Point Unit 1 submitted a fire endurance test reported 

completed by Industrial Testing Laboratories (ITL)18 of St. Louis Missouri, dated September 6, 

1979. In that test report, a planar 5.1 cm (2.0 in) thick pyrocrete barrier was exposed to that 

standard time-temperature curve exposure of E-119 and five thermocouples on the unexposed 

side of the barrier measured temperature rise. This testing was similar to the NIST small-scale 

testing. The ITL report indicated that the average temperature rise of ∆Tavg≥121oC (250°F) 

occurred at approximately 257 minutes and the maximum temperature rise (∆Tmax≥121oC 

(250°F)) did not occur prior to the shutdown of the furnace. 

In addition to this testing, Niagra Mohawk also provided NRC staff with a report entitled, 

“Thermal Transmission of Pyrocrete 241 at Varying Thicknesses,” completed by Johns-Manville. 

The purpose of this report was to experimentally determine the time the back side temperature 

of Pyrocrete 241 coated steel panels reached 121oC (250°F) above ambient, when applied at 

varying thicknesses and exposed to the ASTM E-119 time-temperature curve. The report 

documented the results, reproduced in : 

 

 

18 This is the same laboratory that plead guilty to falsifying records for Thermo-Lag testing. 
5-94 

Table 5-35. Results of Pyrocrete 241 Thermal Transmission 

Pyrocrete Thickness Time to Reach 

∆T≥250°F (minutes) 

0.635 cm (1⁄4 in.) 6 

1.27 cm (1⁄2 in.) 10 

2.54 cm (1 in.) 31 

3.81 cm (1.5 in.) 73 

5.08 cm (2 in.) 257 (ITL testing) 

These results indicate that the thickness of the Pyrocrete applied will affect the fire endurance 

rating. Although these results are not representative of a full-scale fire endurance test raceway 

assembly, the 257 minutes to reach the failure criteria indicates that relative to other materials 

tested in this manner, the 5.1 cm (2.0 in) Pyrocrete barrier can exhibit greater thermal 

resistance to the standard time-temperature curve exposures than most ERFBS. 

5.8.4 Resolution and Staff Conclusion 

No generic issues or deficiencies have been identified and associated with this ERFBS, there 

has been no need for generic resolution related to Pyrocrete ERFBS. Staff inspections have 

found the use of Pyrocrete adequately perform its intended design function. As such, the staff 

concluded that when installed to bound as tested configurations Pyrocrete will satisfactory 

perform its intended design function. 

 
5-95 

5.9 Versawrap (Hydrate/Insulative/Intumescent)

Versawrap was developed by Transco Products, Inc., as a stand-alone fire barrier and as a 

potential upgrade for existing raceway fire barriers, such as Thermo-Lag 330-1. Versawrap fire 

barriers are installed as individual layers of foil, water filled Mylar tubes, fiber blankets, foil and 

intumescent-coated fiberglass cloth. The numbers and arrangements of the specific barrier 

components are dependent on the type of items to be protected (raceway, cable, support, etc.) 

and the desired fire rating. and provide a graphical view of the barrier construction for a typical 

1-hour barrier. 

Figure 5-21. Sketch of Layers Used in Versawarp ERFBS (NRC Trip Report 1997) 

Figure 5-22. Cut away of Versawrap ERFBS showing individual Layers 

 (NRC Trip Report, 1997) 
5-96 

5.9.1 History 

In 1997, NRC staff met with Entergy Operations, Inc., the licensee of Arkansas Nuclear One 

(ANO), to discuss the use of Versawrap as an upgrade to its Thermo-Lag 330-1 ERFBS and to 

observe full scale fire endurance testing of the product for 1- and 3-hour rating periods. 

Following the testing, NRC issued IN 97-59, “Fire Endurance Test Results of Versawrap Fire 

Barriers,” to alert licensees of the preliminary results of the testing and the potential for 

Versawrap to not perform its design function for the rated period of time. 

5.9.2 Problems 

IN 97-59, “Fire Endurance Test Results of Versawrap Fire Barriers,” dated August 1, 1997, 

identified several test assemblies that didn’t pass NRC acceptance criteria, as specified in GL 

86-10, Supplement 1. Section Error! Reference source not found. below discuss the results 

of this testing. 

5.9.3 Testing 

5.9.3.1 UL Testing of Versawrap for Arkansas Nuclear One and Prairie Island 

Transco Products, Inc. performed testing of its Versawrap ERFBS at UL on April 10, 1997. 

The purpose of this testing was to qualify barriers that are planned to be installed at Arkansas 

Nuclear One Unit 1 (1-hour and 3-hour) and at Prairie Island Nuclear Power Station (1-hour). 

This single 3-hour fire exposure test followed by a solid-stream hose stream test that was 

intended to demonstrate the ability of both 1- and 3-hour Versawrap fire barrier systems (in the 

same test) to meet the acceptance criteria of GL 86-10 Supplement 1. The overall tests 

assembly consisted of a steel and concrete horizontal test deck from which 18 individual 1- and 

3-hour test articles were suspended into UL’s large floor furnace. The Versawrap ERFBS were 

installed on all articles in accordance with Transco instruction and procedures. The test articles 

were instrumented in accordance with GL 86-10 Supplement 1, with UL and Transco quality 

assurance personnel witnessing and documenting the test specimen construction. All testing 

used a single bare #8 AWG conductor to measure temperature within the raceway. The fire 

endurance hose stream tests were administered in accordance with GL 86-10 Supplement 1 

guidance. , provides the results of the 1-hour and 3-hour test results for each raceway. 

 
5-97 

Table 5-36. Summary of UL Testing of Versawrap 

Article 

No. Raceway Description 

Desired 

Rating 

Pass/Fail1

A 2”x2” Aluminum Solid-Back Cable Tray/Tube Track 1-hr Pass 

B 30”x4” Steel Ladder-Back Cable Tray 1-hr Pass 

C 3⁄4” diameter Rigid Steel Conduit 1-hr Pass 

D 4” diameter Rigid Steel Conduit 1-hr Pass 

E 3⁄4” diameter Rigid Steel Conduit Near Concrete Barrier 1-hr Fail 

F Multiple intersecting Unistrut Hangers and 3⁄4” dia. Rigid 

Steel Conduit 

3-hr Pass 

G 2”x2” Aluminum Solid-Back Cable Tray/Tube Track 3-hr Pass 

H 30”x4” Steel Ladder-Back Cable Tray 3-hr Pass 

I 3⁄4” diameter Rigid Steel Conduit 3-hr Pass 

J 4” diameter Rigid Steel Conduit 3-hr Fail 

K 3⁄4” diameter Rigid Steel Conduit Near Concrete Barrier 3-hr Fail 

L Multiple intersecting Unistrut Hangers and 3⁄4” dia. Rigid 

Steel Conduit 

1-hr Pass 

M 1-1⁄2” diameter Steel Conduit Covered with Modified 

Versawrap (modified meaning that an unprotected 

Unistrut support will be used to support the horizontal 

section of the raceway. 

3-hr Fail 

N 12”x12”x12”(16 gauge) Steel Box attached to 3⁄4” dia. 

Steel Conduit 

3-hr Fail 

O Two 6”x6”x6” (16 gauge) Steel Boxes attached to a 3⁄4” 

diameter steel Conduit 

1-hr Pass 

P Two 6”x6”x6” (16 gauge) Steel Boxes attached to a 3⁄4” 

diameter Steel Conduit 

3-hr Fail 

Q Air Drop - 3/C 500MCM Aluminum Armored Cable (this 

test was conducted to bound plant specific application) 

1-hr Fail 

1 The Pass/Fail results are based on NRC staff observation of preliminary data collected during observation of test. 

5.9.3.2 Omega Point Laboratories Testing of Versawrap for Transco Products, Inc. 

Transco Products, Inc. preformed testing of its Versawrap ERFBS at OPL on November 21, 

1997. OPL Test Report Product No. 12000-101105 documents the test setup and procedure, 

along with the results. Seventeen test articles were tested in the single fire test. Conduit sizes 

from 1.9 cm (0.75 in) up to 12.7 cm (5.0 in) diameter were tested along with 61.0 cm (24.0 in) 

and 76.2 inches (30.0 in) cable trays and several junction boxes. A single #8 AWG bare copper 
5-98 

conductor instrumented with thermocouples every 15.2 cm (6.0 in), along with thermocouples 

attached to the raceways (every six inches) were used to monitor the unexposed side 

temperature rise. GL 86-10, Supplement 1 acceptance criteria was used to evaluate the 

performance of the test articles. Although both 1-hour and 3-hour assemblies were contained in 

this one test, all articles were exposed to a 3-hour ASTM E 119 standard fire exposure, after 

which the entire assembly was subjected to the hose stream test (as stipulated in NRC 

guidance). Of the 17 test items, three failed to meet the temperature rise acceptance criteria. 

Item 1, a 1.9 cm (0.75 in) diameter rigid steel conduit failed at 170 minutes into a 180 minute 

test, post test examination revealed that a collar had slipped down, exposing the bare conduit. 

Item 15 a horizontal solid bottom steel cable tray 76.2 cm (30.0 in) wide by 10.1 cm (4.0 in) 

deep) failed at 28 minutes of a 1-hour rating, post test examination was not documented for any 

1-hour test specimen. Item 15 was protected with a Thermo-lag upgrade (i.e. thermo-lag base 

layer enclosed by a 1-hour layer of Versa-Wrap). Item 17a was a 5.1 cm (2.0 in) diameter rigid 

steel conduit protected by a 3-hour Versa-Wrap design failed at 84 minutes of a 180 minute test. 

Post test examination of item 17a indicated that the Mylar tubes had melted and no water 

remained inside, discoloration was also noted on the cloth, foil, and blanket. provides a 

description of each test article along with the actual endurance rating achieved during the test. 

Table 5-37. Summary of Omega Point Testing of Versawrap 

Article 

No. Raceway Description 

Desired 

Rating 

Actual 

Rating 

(min) 

1 3⁄4” diameter rigid steel conduit 3-hr 170 Fail 

1a Mock Box Assembly protected with a 3-hr Darmatt 

ERFBS with two 3⁄4” steel conduits protected with a 

3-hr Versawrap ERFBS 

3-hr 180 

2a 3” diameter rigid steel conduit 1-hr 60 

2b 3” diameter rigid steel conduit 1-hr 60 

3 “L” shaped 4” diameter rigid steel conduit with cast 

iron LB fitting 

3-hr 180 

4 two vertical 2” diameter rigid steel conduits 

connected to common horizontal Unistrut support 

1-hr 60 

5 same as article 4 3-hr 180 

6 6” high x 40” wide x 18” deep sheet steel junction 

box bolted in direct contact with concrete slab 

1-hr 60 

7 Pair of RSC (3/4” and 4”) transitioning from vertical 

to horizontal thought large radius bend 

1-hr 60 

8a 6”x6”x6” sheet steel junction box 1-hr 60 

8b 3⁄4” diameter vertically oriented rigid steel conduit 1-hr 60 

8c 6”x6”x6” sheet steel junction box in direct contact 

with concrete test slab 

1-hr 60 

9 4” diameter horizontally oriented rigid steel conduit 1-hr 60 

10 3” diameter vertically oriented rigid steel conduit 1-hr 60 
5-99 

Table 5-37. Summary of Omega Point Testing of Versawrap (Continued) 

Article 

No. Raceway Description 

Desired 

Rating 

Actual 

Rating 

(min) 

11 2”x2” aluminum wire way 1-hr 60 

12 24” wide by 4” deep solid bottom steel cable tray 3-hr 180 

13 12” diameter schedule 80 steel pipe penetration 

(Darmatt ERFBS) 

3-hr 180 

14 “L” shaped solid bottom steel cable tray (30”x4”) 1-hr 60 

15 30”x4” solid bottom steel cable tray in horizontal 

orientation 

1-hr Thermo-Lag base layer with Upgrade 

Versawrap 

1-hr 28 Fail 

16 24”x4” solid bottom steel cable tray in horizontal 

orientation 

1-hr 3M-CS195 CT upgraded with Versawrap 

1-hr 60 

17a 2” diameter rigid steel conduit 3-hr 84 Fail 

17b 2” diameter rigid steel conduit 1-hr 60 

17c 2” diameter rigid steel conduit 1-hr 60 

17d 6”x6” sheet steel wire way horizontally oriented 1-hr 60 

5.9.3.3 Omega Point Laboratories Testing of Versawrap for PP&L 

On April 16, 1998, a staff member from NRC witnessed fire endurance testing conducted at 

OPL for Pennsylvania Power and Light. The test assemblies consisted of 20 Thermo-Lag 

configurations, some of which were upgraded with a Versawrap overlay system. The testing 

followed the guidance specified in Supplement 1 to GL 86-10. Although the results are 

proprietary, approximately 2/3 of the test assemblies failed to meet the temperature rise 

acceptance criteria for 1-hour qualification. 

5.9.4 Resolution and Staff Conclusion 

No generic issues or deficiencies have been identified and associated with this ERFBS; there 

has been no need for generic resolution related to Versawrap ERFBS. Versawrap has been 

used as replacement materials to other deficient ERFBS. 

As a result of its late entry into NPP applications and testing in accordance with GL 86-10 

Supplement 1, the staff concluded that Versawrap when installed to bound as tested 

configurations will satisfactory perform its intended design function. 

 
5-100 

5.10 Pabco (Intumescent ERFBS)

5.10.1 History 

Pabco was sold to Johns Manville in 1998, and the material was renamed “Thermo-12 Gold”. 

Pabco Super Caltemp Gold Insulation contains about 1⁄2 to 3⁄4 percent by weight of rayon fiber, 1⁄2 

percent pulp, < 1⁄2 percent alkali resistant fiber glass, < 1⁄2 percent yellow iron oxide for color and 

the remainder is Tobermorite calcium silicate. In initial heat up, the rayon and pulp will 

decompose and give off water vapor and CO2. Tobermorite is a crystalline calcium silicate 

mineral that is stable up to 677oC (1250°F). 

Fort Calhoun Station (FCS) is the only US NPP which uses Pabco material as fire barrier 

protection for redundant trains of safe shutdown equipment located in the same fire area to 

satisfy 10 CFR 50, Appendix R Section III.G requirements. Licensee installation and inspection 

procedures have verified that these fire barrier materials were installed in a manner consistent 

with tested configurations. Deviations from tested and analyzed configurations were evaluated 

in accordance with GL 86-10, Supplement 1. These evaluations provide the necessary 

assurance that the installed fire barrier systems would possess the commensurate level of fire 

protection. OPPD inspects fire barrier configurations outside of containment on an 18 month 

frequency and inside containment on a refueling outage frequency. 

5.10.2 Problems 

No problems with the use of Pabco ERFBS as a redundant train fire separation found. 

5.10.3 Testing 

No public test reports for Pabco ERFBS found. 

5.10.4 Resolution and Staff Conclusion 

To date no generic issues related to Pabco ERFBS found. NRC staff inspections at Fort 

Calhoun Station have and will continue to allow for opportunities to evaluate this type of barrier. 

 
5-101 

5.11 Concrete (Insulative ERFBS)

5.11.1 History 

Concrete is only used at one plant (Palisades Nuclear Plant) to provide a 1-hour barrier to 

separate redundant trains within the same fire area. The use of this concrete barrier was a 

result of resolving Thermo-Lag deficiencies in the plant. Palisades initially used approximately 

44 m (144 linear ft) of 1-hour Thermo-Lag 330-1 and 9 m (30 linear ft) of a 3-hour Thermo-Lag 

330-1 ERFBS. The concrete barrier was constructed by enclosing approximately a 1.22 m (4 ft) 

section of a 7.6 cm (3.0 in) diameter galvanized steel rigid conduit and pullbox within concrete. 

Resolution of all other applications of Thermo-Lag 330-1 was resolved by using a 1-hour fire 

rated cable or rerouting cables. 

5.11.2 Problems 

No problems with the use of Concete as an ERFBS for protection a redundant train fire 

separation have been identified. 

5.11.3 Testing 

No public records available to determine acceptable use of concrete as a rated 1-hour ERFBS. 

However, extensive experimental research has been done in the past to determine the required 

thickness of various types of structural concrete members to provide a specific fire rating. The 

Society of Fire Protection Engineering (SFPE) Handbook of Fire Protection Engineering has a 

section dedicated to analysis methods for determining fire resistance of concrete members. In 

addition, several experts knowledgeable with the effects of heat on concrete have developed 

models to determine the internal temperatures of concrete. Thus, there are several methods for 

licensees to determine the fire resistance rating of a concrete ERFBS with a specified minimum 

thickness. 

5.11.4 Resolution and Staff Conclusion 

Due to the limited use of concrete as an ERFBS material and its well understood heat transfer 

properties, there have not been any issues identified with the use of concrete as an ERFBS. 

Past and future NRC fire protection inspections will continue to provide the opportunities to 

evaluate this type of barrier. 

 
5-102 

This page intentionally left blank.. 
6-1 

6. Plant Specific Usage and Resolution of ERFBS Issues 

This section provides information as to how each operating NPP resolved their compliance 

issues related to the respective ERFBS that they installed. It should be noted, that only 

operating plants are documented in this section. Plants in the decommissioning phase are not 

discussed; however, it is likely that these plants may have some type of ERFBS installed. 

The information provided in this section is for reference purposes only and was obtained from 

numerous official communications between the NRC and its licensees. Although the intent of 

this section is to provide the most accurate information on plant usage of ERFBS, there may be 

instances where the documented application of ERFBS does not accurately represent what is 

actually used in plants. This information is also time sensitive, i.e., the information is current at 

the writing of the report. Licensees may, in the future, perform plant/licensing basis changes 

which will make this information obsolete. The reader is cautioned to verify the latest plant 

specific information. Each plants licensing basis documents the usage of ERFBS and 

exemptions from requirements or guidance. Therefore, the information provided is NOT 

intended to represent official NRC approval of fire barrier configurations. Only the plant specific 

licensing information can be relied upon for licensing basis judgments. 

6.1 Arkansas Nuclear One, Units 1 and 2

Arkansas Nuclear One (ANO) initially used approximately 30 feet of a 3-hour rated Thermo-Lag 

330-1 ERFBS in Arkansas Nuclear One Unit 2 to protect conduit raceway in the service water 

pump pits. The water pump pits are located in the intake structure and are pre-formed conduit 

shapes and panels on two 10.16 cm (4 in) conduits. The conduits contain power cables for two 

service water pumps. In a letter dated April 16, 1993, ANO stated that appropriate 

compensatory measures would be taken to fix the questionable Thermo-Lag installations. 

Following re-analysis the licensee determined that the barrier was no longer needed to meet 

10CFR50.48 or Appendix R to Part 50, achieve physical independence of electrical systems, or 

meet a condition of the plant operating license. 

By letter dated June 21, 1994, NRC concluded that the issues addressed in GL 92-08 were 

resolved and NRC review of the matter as tracked by TAC No. 85515 was complete. 

Currently ANO uses Versawrap and Hemyc to meet the Appendix R requirements. In its 

response letter to GL 2006-03, the licensee stated that it uses Versawrap ERFBS to meet 

Appendix R separation requirements and all Versawrap applications have been qualified by 

various fire tests conducted by independent laboratories consistent with the guidance provided 

in GL 86-10 Supplement 1. In addition, the response stated that for this category of fire barrier, 

bases documentation will be maintained on site, and will be subjected to inspection during the 

normal NRC inspection process. 

Approximately 1000 linear feet of Hemyc is use between the two units (802 linear feet Unit 1; 

197 linear feet Unit 2). After reviewing NRC Hemyc test reports, the licensee determined that 

the Hemyc installed at ANO does not conform to the licensing basis and has been declared 

inoperable. Hourly or continuous fire watches have been established (depending on area fire 

detection operability) as a compensatory measure until the operability of Hemyc can be 
6-2 

established. ANO has informed NRC of its plan to transition both units to NFPA 805, and plans 

to address the Hemyc issues during the implementation of NFPA 805. In the case that ANO 

does not transition to NFPA 805, then they will have to submit exemption requests to the NRC 

providing justification for the specific Hemyc configurations, or modify these configurations to 

come into compliance. A discussion of NFPA 805 is provided above in Section 3, “ERFBS 

Regulations.” 

6.2 Beaver Valley Power Station, Units 1 and 2

Beaver Valley Power Station (BVPS) uses Thermo-Lag, 3M Interam E-50 Series, and Darmatt 

KM-1 ERFBSs to provide separation of redundant trains locate in a single fire area. Following 

issuance of GL 92-08 and IN 93-41 all barriers were evaluated and found to be acceptable for 

the configurations that they are installed. In addition, tests and evaluations were preformed for 

Beaver Valley to determine that the Thermo-Lag material properties and attributes conform to 

NRC regulations. Tests and evaluations were also preformed on the 3M Interam E-50 Series 

and Darmatt KM-1 ERFBS which concluded that these barriers conform to NRC requirements. 

BVPS Unit 1 initially used approximately 3 feet of a 1.5-hour rated Thermo-Lag 330-1 ERFBS to 

protect conduit penetration seals. In this application, the Thermo-Lag material is not used to 

protect the electrical cables, but to maintain the integrity of the fire area boundary of the cable 

mezzanine floor. Following re-analysis the licensee determined that the barrier was no longer 

needed. 

BVPS Unit 1 used Hemyc ERFBS to protect electrical raceways associated with charging pump 

feeder cable CH-P-1B. The Hemyc fire barrier was replaced with Darmatt KM-1 material. 

Regional staff verified the Darmatt KM-1 fire barrier installation and configuration during site 

inspection and documented this review in NRC Inspection Report (IR) 50-344/02-04 and IR 50-

412/02-04. 

BVPS Unit 2 uses approximately 2900 linear feet of 1-hour and 1500 linear feet of a 3-hour 

Thermo-Lag barrier system to protected electrical raceway conduits. In addition, 1370 ft.2

 of 1-

hour and 1770 ft.2

 of 3-hour Thermo-Lag barriers are used to protected supports, junction 

boxes, removable floor plugs, seismic gap seals, conduit sleeve extensions, and structural steel 

support plates for oversized penetration seals. 

The actions required for review of GL 92-08 were communicated to be closed by NRC in letters 

dated September 23, 1994 and April 6, 1998 for Units 1 and 2, respectively. NRC letter dated 

October 1, 1998, identifies the completion and acceptance of its review of the ampacity derating 

methodology used at Beaver Valley. 

6.3 Braidwood Station, Units 1 and 2

Braidwood Station Unit 1 initially relied on Thermo-Lag 330-1 barriers to meet 10 CFR 50.48 

regulations and to provide separation between redundant electrical systems. Following 

issuance of GL 92-08 and the results from the NUMARC testing program, the licensee decided 

to abandon the Thermo-Lag barriers in place. The licensee then reduced the number of cables 

requiring protection by re-evaluating its safe shutdown analysis, re-routing cables and began 

installing a rated Darmatt KM-1 barrier. However, initial attempts to install the Darmatt KM-1 

barrier identified that cable rerouting of all required cables would be more efficient and cost 

effective and therefore the use of Darmatt as a solution was abandoned. NRC closed out its 

review of Thermo-Lag actions for Braidwood station in its letter dated May 13, 1997. 
6-3 

Braidwood Station Unit 2 uses 3M Interam ERFBS in two locations (i.e., Unit 2 Cable Tunnel 

and Unit 2 Lower Cable Spreading Room) to ensure separation of redundant trains in the same 

fire zone. The 3M Interam ERFBS were installed during the original plant construction in 

accordance with Braidwood specifications. Following IN 95-52 and IN 95-52 Supplement 1, the 

licensee evaluated the 3M Interam installed configurations and determined that the barriers 

were capable of providing the necessary level of protection. Specifically, these evaluations 

determined that those ERFBS are considered to have at least a 49 minute fire rating when 

exposed to ASTM E-119 fire test and following the acceptance criteria of GL 86-10, Supplement 

1. The licensee based the acceptance of the 49 minute fire rating on the basis that fire loads 

normally present in these two rooms are only capable of producing fire duration of 30 minutes if 

an ASTM E-119 type fire was postulated to occur. 

By letter and SE dated November 2, 1999 NRC determined that all ampacity related concerns 

have been resolved and the licensee has provided adequate technical basis to ensure that all of 

ERFBS enclosed cables are operating within acceptable ampacity limits. 

6.4 Browns Ferry Nuclear Plant, Units 1, 2 and 3, Sequoyah Nuclear Plant, Units 1 &2

TVA relies upon Thermo-Lag fire barrier material to protect fire safe shutdown circuits at BFN 

Units 1, 2 and 3, Sequoyah Nuclear Plant (SQN) Units 1 and 2, and WBN Unit 1 as approved by 

NRC Staff. Configurations installed at TVA facilities are in accordance with the tested 

configurations or have been evaluated by persons knowledgeable in fire barrier design and 

installation. The results of both the testing and engineering evaluations have been documented 

consistent with accepted engineering and industry standards. These configurations, both those 

specifically tested and unique configurations, are documented in facility design basis 

documentation that are controlled and maintained in accordance with TVA's Design Control and 

Quality Assurance Programs. 

Initially Browns Ferry Unit 2 was the only unit to originally use Thermo-Lag 330-1. 

Approximately 200 linear feet of conduit barrier was used in Unit 2, which was subsequently 

upgraded per TVA tested configurations. TVA has Thermo-Lag installed in the BFN1 Intake 

Pumping Station to provide a 1-hour fire barrier. Most of the Thermo-Lag material in Browns 

Ferry Unit 1 was found to be unnecessary to comply with 10CFR50 and abandoned in place. 

Instead of costly amounts of fire barrier material, the plant chose to reroute electrical cables 

essential to the plant’s safe shutdown. Abandoned Thermo-Lag which was accessible and cost 

effective to remove was discarded completely by June 20, 1996. 

Ampacity derating issues at Browns Ferry Nuclear Plant Units 1-3 with regards to GL 92-08 

were considered complete by NRC in a letter dated July 16, 1999. 

6.5 Brunswick Steam Electric Plant, Units 1 and 2

Brunswick Steam Electric Plant (BSEP) has used Thermo-Lag 330-1 to satisfy 10 CFR 50.48 

separation requirements, licensing commitments, and conditions associated with its Fire 

Protection Program. Only 12m (40 linear feet) of a 1-hour rated Thermo-Lag 330-1 barrier were 

used to protect two 6 m (20 foot) sections of cable trays. The majority of Thermo-Lag used was 

applied to conduits, which included 320m (1050 linear feet) of a 1-hour barrier and 430m (1410 

linear feet) of a 3-hour barrier. In addition, 113 m2

 (1220 ft2) of a 3-hour and 12 m2 (130 ft2) of a 

1-hour barrier were used to protect junction boxes, equipment enclosures, door transoms, and 

penetration seals. 
6-4 

BSEP uses Kaowool as part of an approved Appendix A Fire Protection Program and Appendix 

R exemption. Kaowool provides additional protection defense-in-depth, but it is not credited as 

a 1-hour or 3-hour barrier as required by Appendix R. 

BSEP uses 3M Interam E50A and E54A ERFBS materials for Appendix R purposes. 

The materials used in the 3M barriers have been installed to manufacturer’s instructions and 

has been independently tested in accordance with national standards. 

6.6 Byron Station, Units 1 and 2

Byron Station used about 954 m (3129 linear feet) of Thermo-Lag 330-1 ERFBS to protect 

redundant cable trains within the same fire area. Both 1- and 3-hour Thermo-Lag configurations 

were used in both units. By letter dated January 17, 1997, three methods of resolution were 

utilized, which included; 1) re-analysis of Safe Shutdown Analyses to eliminate the need for the 

fire barrier, 2) re-routing of cables such that redundant safe shutdown trains are not located in 

the same fire zone, or 3) replacement of the Thermo-Lag 330-1 with a qualified fire barrier (see 

Section 5.3 above on Darmatt KM-1). The licensee informed NRC that all planned modifications 

had been completed, as a result of GL 92-08. These modifications included, removing ThermoLag 330-1 ERFBS from several safe shutdown cables located in Unit 1 and protecting them with 

Darmatt KM-1 ERFBS, rerouting the remaining cables and their redundant counterparts and 

associated support equipment cables such that they are not located in the same zone. Circuits 

that no longer required protection have the Thermo-Lag 330-1 ERFBS abandoned in place. 

Byron Station currently uses Darmatt KM-1 fire barrier on all electrical raceways where a fire 

barrier is required to ensure separation of redundant trains in the same fire zone. Darmatt KM-1 

material was installed as a qualified replacement of the Thermo-Lag 330-1 fire barrier as part of 

Byron Station’s corrective actions in response to GL 92-08. 

By letter and SE dated November 2, 1999 NRC determined that all ampacity related concerns 

have been resolved and the licensee has provided adequate technical basis to ensure that all of 

ERFBS enclosed cables are operating within acceptable ampacity limits. 

6.7 Callaway Plant, Unit 1

The Callaway Plant initially used limited quantities of Thermo-Lag 330-1 for raceway protection. 

The plant utilized approximately 31 linear feet of 3-hour cable tray barriers, 132 linear feet of 1-

hour conduit barriers, and 614 linear feet of 3-hour conduit barriers. In order to satisfy the 

requirements of 10 CFR 50, Appendix R, the licensee made several modifications to the use of 

Thermo-Lag ERFBS. An Appendix R, Section III.G.2 reanalysis was performed which 

documented the technical basis for removal of Thermo-Lag from cables that were not needed 

for safe shutdown. A conduit was re-routed to meet the 20 foot separation criteria and local 

manual controls were added to the “B” and “C” steam dump valves in order to eliminate the 

need for the pre-existing fire barrier and Thermo-Lag on the raceways. In areas of the plant 

where a barrier remained necessary for compliance with Appendix R, Thermo-lag was removed 

and Darmatt KM-1 was installed. The Callaway Plant notified NRC that the issues identified in 

GL 92-08 had been completed as of December 31, 1996. 

As noted above, the Callaway Plant use Darmatt KM-1 ERFBS for protection of redundant trains 

located in the same fire area that satisfies 10 CFR 50, Appendix R, III.G requirements. The fire 

barriers were tested and installed according to the guidance provided in GL 86-10, Supplement 
6-5 

1 with any deviations from the tested configurations evaluated against GL 86-10. NUREG 0830, 

supplement 3 provides NRC determination that the use of a 1-hour rated barrier at Callaway 

was found acceptable. Ampacity derating testing was provided to NRC on December 11, 1996. 

Darmatt KM-1 was added to additional raceways requiring protection where Thermo-Lag was 

not present. 

6.8 Calvert Cliffs Nuclear Power Plant, Units 1 and 2

There are no ERFBS in use at Calvert Cliffs Nuclear Power Plant, Units 1 and 2. 

6.9 Catawba Nuclear Station (Catawba), Units 1 and 2

Catawba Nuclear Station (Catawba) uses Hemyc ERFBS as a 1-hour rated barrier to provide 

compliance with Appendix R. Hemyc is used in both Units Auxiliary Feedwater (AFW) Pump 

rooms, with each pump room containing approximately 91 m (183 m total) (300 linear feet (600 

linear feet total)). Following IN 2005-07, the licensee evaluated their use of Hemyc fire barrier 

and determined that the Hemyc ERFBS does not meet the required 1-hour fire rating. As 

compensatory measure, the licensee has implemented additional control on transient 

combustible/flammable materials entering these affected areas and established continuous fire 

watches under certain circumstances. On February 28, 2006, the licensee submitted its intent 

to voluntarily transition the Catawba Fire Protection Licensing Basis to NFPA 805 in accordance 

with 10 CFR 50.48(c). The NFPA 805 transition process is expected to bring the Hemyc 

concerns to resolution. However, if the licensee decides to not transition, then they will have to 

submit exemption requests providing justification for the specific Hemyc configurations, or 

modify these configurations to come into compliance. A discussion of NFPA 805 is provided 

above in Section 3, “ERFBS Regulations.” 

6.10 Clinton Power Station, Unit 1

Clinton Power Station (CPS) currently uses 3M Interam ERFBS where required to ensure 

separation of redundant trains in the same fire zone. Clinton Power Station originally utilized 

167 m (547 linear feet) of 1-hour Thermo-Lag 330-1 cable tray fire barriers and 45 m (149 linear 

feet) of 3-hour fire barriers at 10 different locations throughout the plant. In addition, CPS uses 

34 m (112 linear feet) of 1-hour conduit fire barriers and 31 m (103 linear feet) of 3-hour conduit 

fire barriers. Following issuance of GL 92-08, CPS implemented a Thermo-Lag corrective 

actions program to document the station’s engineering evaluations to ensure the Thermo-Lag 

ERFBS provide the necessary level of protection. A letter dated June 26, 1998 from NRC 

declared that CPS should proceed with corrective actions in accordance with the plant’s 

proposed schedule of completion by December 31, 1998. However, Clinton ultimately 

eliminated dependence on Thermo-Lag as a credited fire barrier through several different 

methods, including: modification of the existing design to provide divisional separation through 

rerouting of cables/conduits, installation other barrier designs, or development of deviations. 

By letter dated September 29, 1998, NRC recognized that CPS Thermo-Lag 330-1 corrective 

actions and requested information in accordance with GL 92-08 were complete. 

The 3M Interam ERFBS used at CPS were installed in the late 1990’s. Engineering evaluations 

were conducted for these installations, including a review of the fire barrier design, materials, 

and installation configurations to ensure the ERFBS capability to provide the needed level of 

protection. In addition, CPS had Promatec Technologies Inc. provide test reports documenting 

acceptability of the 3M Interam E-54C system installed at CPS, in accordance with Appendix R 
6-6 

Section III.G.2.b and GL 86-10, Supplement 1. NRC Inspection Report 50-461/98026(DRS) 

documented that the licensees combustibility assessment adequately demonstrated that the 3M 

material used inside containment (i.e., Interam E-54C) was noncombustible per NRC guidance 

and testing conducted by OPL (January 17, 1995) and UL (September 26, 1983). 

6.11 Columbia Generating Station

Columbia Generating Station (CGS) credits approximately 600 feet of Darmatt KM-1 to ensure 

the necessary level of protection of redundant trains located in a single fire area. The Darmatt 

KM-1 ERFBS are installed in 1- and 3-hr rated designs. CGS documented its Darmatt KM-1 

qualification in Fire Protection File 1.2.3, Item 2, which concludes that the Darmatt 

configurations are installed and bounded by the fire testing of Darmatt KM-1 performed in 

accordance with GL 86-10, Supplement 1. See Section 5.3 above. 

CGS credits approximately 250 feet of 3M Interam 3-hour barrier to ensure the necessary level 

of protection of redundant trains located in a single fire area R-1. The 3M Interam ERFBS are 

installed in a 3-hr rated design. CGS documented 3M Interam qualification in Fire Protection 

File 1.2.2, Item 1, which concludes that the 3M Interam configurations used at CGS are installed 

and bounded by the fire testing performed in accordance with GL 86-10. 

CGS credits approximately 2700 feet of Whittaker fire-rated mineral insulated (MI) cable 

(company now called Meggitt) to ensure the necessary level of protection of redundant trains 

located in a single fire area. The Whittaker MI cable ERFBS are 3-hr rated, but located in both 

1- and 3-hr fire areas. In 3-hr fire areas, Whittaker MI cable is typically routed on the ceiling to 

prevent fire-induced debris impacts. CGS documented Whittaker MI cable qualification in Fire 

Protection File 1.11, Item 2, which concludes that the CGS Whittaker MI cable configurations 

are installed and bounded by the fire testing performed in accordance with ASTM E-119 and 

unique functionality testing. A modification was performed to address Information Notice (IN) 

2006-02. 

CGS originally credited approximately 5,500 feet of Thermo-lag 330-1 to comply with Appendix 

R commitments and Regulatory Guide 1.75. The Thermo-Lag 330-1 ERFBS were installed in 1- 

and 3-hr rated designs. Following issuance of GL 92-08, CGS abandoned reliance on ThermoLag 330-1 to meet Appendix R. Thermo-Lag 330-1 is still credited as a RG 1.75 electrical 

separation barrier and for structural steel fireproofing coating on instrument tube supports, and 

one cable tray support. CGS documented Thermo-Lag 330-1 qualification in Fire Protection File 

1.12, Item 2. Most Thermo-Lag ERFBS were abandoned in place which created concerns with 

combustible loading (IN 92-82), seismic & hanger support loading (IN 95-49 Supplement 1), and 

ampacity derating (IN 92-46 & 94-22). Each of these issues was resolved. Ampacity derating 

values for CGS are well within prescribed safety margins and no cable rerouting or resizing is 

necessary. 

6.12 Comanche Peak Steam Electric Station, Units 1 and 2

Comanche Peat Steam Electric Station (CPSES) uses Thermo-Lag 330-1 ERFBS to protect 

redundant trains located within a single fire area to satisfy fire protection program licensing 

commitments. CPSES had approximately 5500 linear feet of a 1-hour Thermo-Lag 330-1 

ERFBS installed for Unit 1 and approximately 4700 linear feet of 1-hour ERFBS for Unit 2. 

The licensee directly qualified most ERFBS configurations by conducting a series of fire 

endurance tests that were performed to a site-specific test methodology and acceptance criteria 

approved by the NRC staff. In addition, all ERFBS configurations, including those not directly 
6-7 

tested, have been evaluated in accordance with GL 86-10 guidance to ensure they are capable 

of providing the necessary fire endurance capability. The licensee also performed site-specific 

testing to determine appropriate electrical cable ampacity derating factors. 

The NRC accepted closure of all Thermo-Lag ERFBS GL 92-08 technical issues (i.e., fire 

endurance capability, cable-ampacity derating factors, and seismic considerations) installed in 

CPSES Unit 2 via NUREG-0797, Supplements 26 and 27 dated February and April of 1993, 

respectively. Subsequently, the licensee performed additional fire endurance testing and 

implemented design upgrade modifications to address qualification of Thermo-Lag ERFBS 

configurations for Unit 1. The licensee received NRC acceptance for closure of all Thermo-Lag 

ERFBS GL 92-08 technical issues for Unit 1 via NRC correspondence dated May 14, 1999. In 

addition, an NRC safety evaluation dated June 14, 1995, concluded that there are no significant 

safety hazards at CPSES resulting from the ampacity derating concerns associated with the use 

of Thermo-Lag fire barriers to enclosed cables. 

CPSES uses approximately 800 linear feet of Hemyc as a RES inside each unit’s containment 

(1600 linear feet for both units). There are no applications at CPSES where Hemyc is used to 

provide a 1- or 3-hour fire barrier for separation of redundant post fire safe shutdown circuits. 

All other uses of Hemyc at CPSES relate to its licensing basis. In a letter dated December 20, 

2007, the licensee informed NRC that after evaluating new information regarding NRC’s testing 

of Hemyc; it concluded that the CPSES’s use of Hemyc as a radiant energy shield continues to 

meet its licensing basis. Regional NRC staff verified that the licensee had appropriately 

dispositioned the issue. (IR 05000445/2008006 and 05000446/208006, July 3, 2008) 

6.13 Cooper Nuclear Station

Cooper originally used a 1-hour rated Thermo-Lag 330-1 ERFBS to protect approximately 

15.2 m (50 feet) of conduit. The Thermo-Lag was used in three separate locations; two in the 

cable spreading room and one in the cable expansion room. As of February 3, 1994, Cooper 

does not rely on Thermo-Lag for fire protection purposes. Two non-rated radiant energy shields 

located in the cable spreading room and one radiant energy shield in the cable expansion room 

were modified and the Thermo-Lag 330-1 removed. The Thermo-Lag ERFBS were removed 

and replaced with Promat-H material from Eternit or the cables that required protection were rerouted to comply with Appendix R. 

In a letter from NRC dated May 30, 1995, NRC determined that the CNS response to GL 92-08 

was acceptable. CNS stated that all three installations of Thermo-Lag 330-1 were sufficiently 

spaced to be considered as open-air installations per National Electric Code and did not require 

ampacity derating testing beyond the conduit itself. The conduit installations themselves are 

not further derated by the proximity of the Thermo-Lag material. 

6.14 Crystal River Unit 3 Nuclear Generating Station

Crystal River Unit 3 Nuclear Generating Station (CR-3) uses Thermo-Lag and Mecatiss ERFBS 

to provide separation and/or safe shutdown purpose in accordance with the CR-3 licensing 

basis. The estimated total of Thermo-Lag 330-1 used to cover cable trays is 651 m (2,135 feet) 

and the estimated total used to cover conduit is 1,711 m (5,615 feet). This equates to 

approximately 44 m2

 (471 ft2) of Thermo-Lag. 

To resolve Thermo-Lag deficiencies identified in the mid 1990’s, the licensee installed Mecatiss 

ERFBS on 71 circuits required for Appendix R safe shutdown, re-routed cables, installation of 
6-8 

additional sprinkler systems to protect existing Thermo-Lag installations (exemption) or reevaluation of Safe Shutdown Analysis credited alternative equipment and shutdown procedures. 

NRC approved an exemption from the regulations related to the use of enhanced sprinkler 

protection instead of Thermo-Lag barrier upgrade in the CR-3 auxiliary building. The use of 

Mecatiss ERFBS at CR-3 was approved by NRC in letter and SE dated January 29, 1997. 

By letter dated November 7, 1997 NRC determined that all ampacity related concerns have 

been resolved and the licensee has provided adequate technical basis to ensure that all of 

ERFBS enclosed cables are operating within acceptable ampacity limits. 

6.15 Davis Besse Nuclear Power Station, Unit 1 and Perry Nuclear Power Plant Unit 1

Davis Besse Nuclear Power Station (DBNPS) originally relied on Thermo-Lag to meet 

requirements of 10CFR50 Appendix R, to support commitments made in several exemptions in 

Appendix R, and to satisfy the plants’ licensing commitments. Approximately 740 linear feet of 

1-hour Thermo-Lag was used to cover conduits and 1000 ft2

 covered boxes. Approximately 170 

linear feet of 3-hour Thermo-Lag was used to cover conduits and 860 ft2

 to cover boxes. 

Approximately 170 ft2

 was used in radiant energy shield applications, and 2200 ft2 of ThermoLag was applied to structural steel for fire-proofing. 

On February 20, 1996, Toledo Edison informed NRC of its decision to replace installed ThermoLag with alternate materials. Engineering analysis showed that at least four applications of 

Thermo-Lag were allowed exemptions due to modified control circuitry in the Davis Besse Heat 

Exchanger Pump Room, determination that fire barriers were not actually required on structural 

columns in a pump room, relocation of a circuit through penetration P2P5F, and depowering of 

electrical pumps that are no longer needed for plant safety. All Thermo-Lag was either removed 

or abandoned in place, and final modifications were completed by December 22, 1998. 

DBNPS and Perry Nuclear Power Plant Unit 1 used 3M Interam E50 Flexible mat to replace 

Thermo-Lag 330-1 for circuits, Mandoval Fendolite to replace structural steel, and Promat-H 

cement board or 3M Interam E50 Flexible mat to replace Thermo-Lag for fire dampers. 

6.16 Diablo Canyon Nuclear Power Plant, Units 1 and 2

Diablo Canyon Nuclear Power Plant (DCNPP) uses 3M and Pyrocrete as raceway fire barrier 

protection for redundant trains located in the same fire area to satisfy Appendix R requirements. 

The licensee verified that the installed ERFBS configurations were bounded by the tested 

configurations. Any deviations from the tested configuration were evaluated and those 

configurations not bounded by the test specimen were independently tested. 

In the past, DCNPP Units 1 and 2 had used approximately 550 linear feet of a 1-hour and 65 m 

(212 linear feet) of a 3-hour Thermo-Lag ERFBS to protect conduits. In addition, there was 8 m2

(87 ft2

) of Thermo-lag used to protect miscellaneous components. The licensee re-analyzed the 

need for the Thermo-Lag and determined that 40 m (130 feet) of conduits and 2 m2

 (24 ft2) were 

needed. The remainder of the Thermo-Lag was replaced by 3M or Pyrocete materials. 

 
6-9 

6.17 Donald C. Cook Nuclear Power Plant, Units 1 and 2

Donald C. Cook (DC Cook) uses Thermo-Lag, Mecatiss, and Darmatt fire barriers to provide 

protection to various components within the plant. Prior to issuance of GL 92-08, DC Cook 

used Thermo-Lag 330-1 ERFBS exclusively to provide separation of redundant equipment. 

Following issuance of GL 92-08, the licensee took several approaches to resolve the ThermoLag barrier issues at DC Cook, including; re-assessment of the need for fire barrier protection, 

the replacement of Thermo-Lag with alternate fire barrier materials Darmatt KM-1 (see Section 

5.3 above), and the continued limited use of Thermo-Lag as a fire area boundary. 

These efforts resulted in Thermo-Lag no longer relied upon as a fire barrier to provided 

separation of redundant equipment within the same fire area per the requirements of section 

III.G.2 of 10 CFR 50, Appendix R. Thermo-lag is only relied on to provide separation between 

fire areas in the Unit 1 and Unit 2 hot shutdown panel enclosures. This application of ThermoLag was qualified by field testing. In addition, Thermo-Lag is used at DC Cook in the Unit 1 CD 

Diesel Generator Room and the Unit 2 AB Diesel Generator Room, in conjunction with the 

existing fire detection and fire suppression system. This barrier configuration has also been 

evaluated for compliance with 10 CFR 50, Appendix R, Section III.G.2(c). By letter and SE 

dated July 14, 1999, NRC concluded that the application of ampacity derating methodology 

used at CNP involve no significant safety hazards. 

DC Cook Units 1 and 2 use Mecatiss® ERFBS as a cable tray 1-hour fire wrap in one fire zone 

to achieve compliance with 10 CFR, Appendix R, Section III.G.2.(b). Mecatiss® was installed at 

D.C. Cook in accordance with a Brand Fire Protection Service Manual which identified the fire 

test reports supporting the DC Cook applications. Brand Fire Protection Services provided 

support during installation of the Mecatiss® barrier at DC Cook. 

Darmatt KM-1 is used at DC Cook and was installed as a replacement to most of the ThermoLag barriers previously used at the plant to support compliance with Appendix R train 

separation. All Darmatt barriers were installed by Transco Products, Inc. using an approved 

plant procedure based on vendor recommended procedures for installation of Darmatt KM-1. 

Fire test reports supporting the DC Cook Darmatt applications are identified in the procedure. 

By SE dated July 14, 1999, NRC staff found no significant safety hazards associated with the 

application of the ampacity derating methodology used for DC Cook. 

6.18 Dresden Nuclear Power Station, Units 1 and 2

Dresden Nuclear Power Station uses 3M Interam ERFBS on all electrical raceways where a fire 

barrier is required to ensure separation of redundant trains in the same fire zone. There are 

seven locations within the power station which utilize approximately 5.3 m2

 (57.2 ft2) of 3M 

Interam on cable trays. Four of the locations contain two or three cable trays wrapped and 

bundled together. Dresden Nuclear Power Station commissioned an independent review of the 

3M ERFBS installation and fire tests in 1994. Following the review, those configurations 

installed at the plant that didn’t met the acceptance guidance provided in GL 92-08, were 

documented. 

 
6-10 

6.19 Duane Arnold Energy Center

Thermo-Lag ERFBS was initially installed at Duane Arnold Energy Center (DAEC) as ERFBS, 

steel coating and fireproofing and miscellaneous fire barrier installations such as penetration 

seals to meet 10 CFR 50.48 or Appendix R requirements. Approximately 64 m (211 linear feet) 

of a 1-hour and 264 m (865 linear feet) of a 3-hour Thermo-Lag ERFBS were installed at DEAC. 

The licensee resolved Thermo-Lag issues by performing safe shutdown reanalysis, rerouted 

cables, removed and replaced Thermo-Lag with Darmatt KM-1 ERFBS. In addition to using 

Thermo-Lag as an ERFBS, DAEC also used Thermo-Lag to construct structural steel 

fireproofing/barriers, penetration seals and door jam fire proofing. These non-ERFBS 

application have been resolved by the licensee; in some cases by performing independent fire 

testing. 

DAEC uses Darmatt KM-1 ERFBS installed on certain electrical raceways in Fire Zone 2A. 

DAEC does have an approved exemption for the use of an untested flexible conduit wrapping 

material (Hemyc) as documented in Letter dated October 14, 1987. DAEC is no longer utilizing 

this exemption and no longer has Hemyc installed. 

NRC accepted DAEC ampacity derating methodology in its letter and SE dated January 26, 

1999. 

Industry chemical testing program confirmed the consistency of Thermo-lag material used at 

DAEC and supports the use of generic fire tests and other data developed by NEI and others. 

6.20 Joseph M. Farley Nuclear Plant

Joseph M. Farley Nuclear Plant (FNP) requested a Kaowool related Appendix R exemption 

which was approved by NRC in 1985 & 1986. The 1986 exemption relied on Kaowool for 

protection of several cables in the Service Water Intake Structure. In light of the issues raised 

with the performance of the Kaowool EFRBS, the licensee re-evaluated the Appendix R 

program and determined that it no longer required the use of Kaowool as an ERFBS. To 

comply with Appendix R, without using Kaowool, the licensee performed approximately 35 

modifications to eliminate its reliance on Kaowool. Some of these modifications included the 

use of Meggitt fire-rated cable, which was approved by NRC in SER dated February 13, 2006 

and March 22, 2006. 

FNP uses Promat-H board to construct cable tray enclosures to provide separation of redundant 

trains located in a single fire area. Promat-H material was tested and qualified to ASTM E-119-

88 full scale wall assembly and small scale ceiling assembly by Performance Contracting Inc., 

under Omega Point Project No. 8806-90254 (Promat Report SR90-005). The acceptance 

criteria used to qualify this barrier assembly was ASTM E-119-88, which the licensee stated met 

the acceptance criteria of GL 86-10 Supplement 1. 

FNP also uses 3M Interam E-50 Series wrap material and/or 45B formulated silicone elastomer 

at penetrations for the stairwell cable tray enclosures. 3M Interam E-50 wrap used at FNP has 

been tested in accordance with the acceptance criteria specified in GL 86-10 Supplement 1, for 

the configurations found within the plant. The 45B formulated silicone elastomer was tested in 

accordance with test conditions prescribed in ASTM E-119. 

 
6-11 

6.21 Fermi-2

In the past, Fermi-2 had used approximately 40 linear feet of a 3-hour Thermo-Lag 330-1 

ERFBS to protect cable trays and approximately 1000 ft2

 for miscellaneous barriers. The 

licensee removed or replaced the Thermo-Lag with 3M material. 

Approximately 450 linear feet of 3M Interam E-54A material is installed at Fermi-2 to provide a 

1-hour rated barrier. A majority of the 3M material is located in the auxiliary building basement 

and on the plant’s fifth floor to protect redundant cable trays and conduits within the same fire 

area per Appendix R requirements. Additional 1-hour 3M E-54A was installed on cable trays 

and cable tray supports and on a conduit in the Auxiliary building first floor mezzanine and cable 

tray areas. The additional 3M material was installed by December 2006. 3M Interam E-54A 

ERFBS qualification tests were performed using the requirements of GL 86-10 Supplement 1. 

Older 3M M-20 and CS-195 material from the 1980s was removed as well from various cable 

trays and support barriers. The two 3M materials were installed in the auxiliary building in the 

1980s in order to create a fire-safe portion of the building and replaced with 3M Interam E-54A 

fire barrier material. 

6.22 James A. Fitzpatrick Nuclear Power Plant

James A. Fitzpatrick Nuclear Power Plan (JAFNPP) relies on Hemyc ERFBS to separate 

required safe shutdown equipment located in the same fire area. On September 27, 2006, NRC 

issued a SE approving JAFNPP’s request for an exemption from 10 CFR 50.48. NRC regional 

integrated inspection report 05000333/200605, January 19, 2007, ADAMS Accession No. 

ML073390309 documents NRC inspectors’ verification of the Hemyc fire barrier issue for 

JAFNPP. 

In addition to the use of Hemyc at JAFNPP, FP-60 is also used to separate redundant trains 

located in a single fire area. For this application of FP-60, the licensee requested and received 

an exemption from NRC related to Appendix R requirements. The exemption was granted 

because the isolated area containing FP-60 fire wrap met NRCs three defense-in-depth 

conditions of preventing fires from starting, detecting, controlling, and extinguishing those that 

do occur, and to preserve safe shut-down of the plant from fire and fire extinguishing methods. 

JAFNPP received an exemption from NRC because there are no ignition sources in the area, 

there is a smoke detection and sprinkler system in-place, and fire wrap is used around the 

electrical cables providing 30 minutes of fire damage protection and approximately 52 minutes 

of functionality protection. 

6.23 Fort Calhoun Station (FCS), Unit 1

FCS uses several ERFBS to protect redundant trains of safe shutdown equipment in 

accordance with Appendix R requirements. These ERFBS include: 3M Interam E50A, 

Pyrocrete, and Pabco barriers. The licensee stated in its response letter go GL 2006-03, that 

installation and inspection procedures have verified that these ERFBS are installed in a manner 

consistent with tested configurations and any deviations were evaluated with the guidance 

provided in GL 86-10, supplement 1. 

 
6-12 

6.24 R.E. Ginna Nuclear Power Plant

R.E. Ginna Nuclear Power Plant (Ginna) credited the Hemyc fire barrier system as a one hour 

fire rated barrier for Appendix R compliance purposes. Although Ginna's Appendix R analysis 

does not require any three hour fire rated Hemyc or MT configurations, there is one barrier 

location where the MT system is used to meet a one hour requirement (located on a source 

range nuclear instrument preamplifier to provide additional protection). The Hemyc system is 

also used in the Containment Building as a radiant energy shield, which is considered operable 

since the Hemyc system is non-combustible. 

Ginna has approximately 130 m (425 feet) of Hemyc conduit wrap installed on conduits ranging 

in sizes from 1.3 cm to 6.4 cm (0.5 to 2.5 in) in diameter. In addition, there is approximately 30 

m (100 ft) of Hemyc wrap installed on a single 61 cm (24 in) cable tray. Conduit wrap is directly 

applied, while the tray wrap is installed using the standard vendor design consisting of Hemyc 

wrap installed on a frame assembly that provides an air space between the wrap assembly and 

the raceway. 

One three hour MT barrier (approximately four feet) is used to provide additional protection for a 

source range nuclear instrument preamplifier in the event of a fire. The Appendix R and fire 

analysis requirement for the location only requires a one hour fire barrier, which is the rating for 

other barriers in this area of the plant. 

Hemyc configurations are located in the following plant areas: Battery Room, Intermediate 

Building Clean Side Basement, and Auxiliary Building Intermediate Floor and Basement level. 

The barrier material provides protection for the following systems/circuits: AC and DC Power 

Distribution, Steam Generator pressure indication, Source Range Nuclear Instrumentation, and 

Chemical and Volume Control System charging pump power. 

Based on a review of NRC Information Notice 2005-07, all Hemyc configurations that are 

required for rated protection of circuits were determined to not be conforming to Ginna's current 

licensing basis and declared inoperable on April 6, 2005. 

All Hemyc configurations that are required for rated protection of circuits have been declared 

inoperable. Hourly fire watch tours have been in place since April 6, 2005 and were 

implemented in accordance with site procedures. Additional compensatory measures, or 

changes to the current measures, may be considered based on NRC lN 97-48, Regulatory 

Issue Summary 2005-07, and future industry guidance. 

Ginna has voluntarily committed to transition to NFPA 805 as stated in the letter of intent to 

NRC dated December 19, 2005, with an enforcement discretion period of three years. A project 

plan implementation schedule to transition to NFPA 805 has been developed. Based on the, 

outcome of the fire probabilistic risk assessment and modeling analysis, the Hemyc wrap will be 

replaced with an approved fire rated material, left as is, or eliminated through the use of change 

evaluations. In the event that Ginna does not transition, then they will have to submit exemption 

requests to the NRC providing justification for the specific Hemyc configurations, or modify 

these configurations to come into compliance. A discussion of NFPA 805 is provided above in 

Section 3, “ERFBS Regulations.” 

 
6-13 

6.25 Grand Gulf Nuclear Station

Grand Gulf Nuclear Station (GGNS) uses two types of ERFBS to provide Appendix R protection 

of redundant trains required to safely shutdown the plant, they are; Thermo-Lag and 3M 

Interam. Thermo-Lag 330 is currently used in the Control and Auxiliary buildings and by letter 

dated April 21, 1997, NRC concluded that the GGNS program plan is acceptable to resolve the 

Thermo-Lag 330 issues identified in GL 92-08. Both Thermo-Lag and 3M barriers used at 

GGNS are qualified by fire tests in accordance with guidance provided in GL 86-10 

Supplement 1. 

GGNS in the past used Kaowool in several Appendix R applications. Following the issuance of 

IN 93-41 and subsequent meeting with NRC, the licensee of GGNS began evaluation possible 

solutions for the issues with Kaowool. GGNS initially intended to re-qualify the fire resistance 

rating and determine the overall acceptability of the Kaowool fire wrap system. Field walk 

downs and destructive examinations revealed additional installation deficiencies. It then 

became apparent to the licensee that Kaowool wrap would have to be completely reworked for 

any hope of qualification. The licensee then chose to replace and re-analysis (with risk-insights) 

the use of Kaowool and its replacement where still required with a 3M Interam ERFBS. By letter 

and SE dated September 29, 2006, NRC determined that the replacement of Kaowool ERFBS 

with 3M Interam material was acceptable for resolution of the Kaowool issues. 

6.26 Shearon Harris Nuclear Plant

Shearon Harris Nuclear Plant (HNP) has used Thermo-Lag 330-1 to satisfy 10 CFR 50.48 

separation requirements, licensing commitments, and conditions associated with its Fire 

Protection Program. Only 32 linear feet of a 1-hour rated Thermo-Lag 330-1 barrier were used 

to protect conduit raceways. In addition, 3270 sq. ft. of Thermo-Lag 330-1 barrier were used to 

protect area enclosures, partial height walls and door fireproofing. 

HNP uses approximately 6,500 linear feet of Hemyc and 1200 linear feet of MT ERFBSs to 

satisfy Appendix R requirements. HNP has voluntarily committed to 10 CFR 50.48(c) to 

transition to NFPA 805, which it believes will resolve the Hemyc and MT issues by application of 

technical evaluations that consider potential adverse effects, risk, defense-in-depth, and safety 

margins as an acceptable alternative. In the event that HNP does not transition to NFPA 805, 

then they will have to submit exemption requests to the NRC providing justification for the 

specific Hemyc configurations, or modify these configurations to come into compliance. 

A discussion of NFPA 805 is provided above in Section 3, “ERFBS Regulations.” 

In addition to the use of Hemyc and MT, HNP also uses Thermo-Lag 330-1 and 3M Interam E54A barriers to provide Appendix R related equipment `protection. Both of these materials were 

tested per the guidance of GL 86-10 supplement 1 for specific applications used at HNP. 

Vendor testing was used for the 3M material and proprietary HNP fire testing was performed to 

qualify the Thermo-Lag installations. 

6.27 Edwin I. Hatch Nuclear Plant

Edwin I. Hatch Nuclear Plant (Hatch) uses Promat-H material to construct cable tray ERFBS 

required for separation of redundant trains located within a single fire area. The licensee 

(Sothern Company) stated that “Promat-H is a material tested in accordance with UL standard 

263, “Fire Tests of Building Construction and Materials,” which references ASTM E-119 and 

NFPA 251 tests.” Promat-H configurations used at Hatch were tested and qualified to ASTM E-
6-14 

119-83 by Performance Contracting, Inc. under Omega Point Project No. 8806-90254 (Promat 

Report SR90-005). 

The test acceptance criteria used were that of ASTM E119-83 Section 16 “Conditions of 

Acceptance” which meets the acceptance criteria of GL 86-10, Supplement 1. This criterion 

allows a maximum temperature rise of 250 degrees Fahrenheit above the initial temperature. 

(ADAMS Accession No. ML072060088) Testing on Promat-H included time-temperature tests, 

full scale fire testing on the wall, and small scale fire testing on the ceiling, all of which is 

documented in Promat Report SR90-005. The initial ambient temperature used during 

experimentation was 75 degrees Fahrenheit. 

Hatch used approximately 1,250 linear feet of FP-60 in its river intake structure, and procured 

approximately 4,000 linear feet for installation in its Control Building and Reactor Building. 

Hatch installed its Kaowool barriers in 1984. On April 18, 1984, NRC granted Hatch an 

exemption for the use of Kaowool in the river intake structure with the area-wide automatic fire 

suppression system not required for the entire river intake structure. On January 2, 1987, 

another exemption was granted to the extent that a 20-foot separation was not required for 

cable in conduit and cable in trays wrapped with Kaowool blankets. The Kaowool ERFBS used 

at Hatch were subsequently replaced with FP-60 material in the 1992-1993 timeframe because 

of wear and degradation of the Kaowool material. The addition of the 2-mil aluminum skin 

covering provides protection to the Kaowool ceramic material. Hatch also uses Kaowool to 

provide physical separation RG 1.75 and to reduce combustible loading in a given fire area for 

compliance with Appendix A to Branch Technical Position APCSB 9.5-1. The licensee has 

submitted an evaluation to Region II staff that Kaowool is not used as a 1-hour fire barrier. 

The Regional staff’s review indicates that this application is acceptable. 

6.28 Hope Creek Generating Station

Hope Creek Generating Station does not use any ERFBS. 

6.29 Indian Point Nuclear Generating Units 2 and 3 (IP-2 and IP-3)

Hemyc ERFBS is used at Indian Point Nuclear Generating Units 2 and 3 (IP-2 and IP-3) to 

provide separation and/or safe shutdown protection for compliance with Appendix R 

requirements. Approximately 31 linear meters (102 linear ft) of Hemyc is used in IP-2 and 

approximately 90 linear meters (295 linear ft) is used in IP-3. 

Exemptions from the requirements of Appendix R have been granted for each case where the 

Hemyc ERFBS is used and credited to provide a fire resistance rating of 30 minutes or one 

hour. The exemptions were granted based on minimal fire challenge and other mitigating 

defense-in-depth factors. 

IP-3 also uses Hemyc as a RES inside containment. As part of closeout actions associated with 

GL 2006-03, NRC inspection staff verified that appropriate corrective actions were taken while 

Hemyc ERFBS were considered inoperable, and that Hemyc ERFBS upgrade modifications, 

where required, had been completed. 

IP-2 also uses 3M Interam E-54 for Appendix R purposes, configured as a 3-hour rated ERFBS 

outside the reactor containment, and as a RES inside the reactor containment. The 3M Interam 

E-54A installations were evaluated to ensure the capability to provide the necessary level of 

protection at the time the barriers were installed, and were reevaluated to confirm their 
6-15 

adequacy after issuance of IN 95-52. 

6.30 Kewaunee Power Station

Kewaunee Power Station uses 3M Interam E-50A endothermic mat to meet 3-hour rated 

configurations on conduits. These conduit ERFBS were installed in accordance with UL design 

listing (UL Electrical Circuit Protective System (FHIT) No. 7). 

Although not used to provide Appendix R protection, Kewaunee Power Station also uses a 3-

hour fire-rated Marinite board/Kaowool/Flameastic electrical circuit large pull box protective 

enclosure. 

6.31 LaSalle County Station, Units 1 and 2

LaSalle County Station (LCS) initially relied on Thermo-Lag 330-1 barriers to meet 10 CFR 

50.48 regulations and to provide separation between redundant electrical systems. Darmatt 

KM-1 material was installed as a qualified replacement for the 112 linear feet of Thermo-Lag 

330-1 fire barrier as part of LCS response to GL 92-08. Therefore, LCS now uses Darmatt KM1 fire barriers in areas where a fire barrier is required to ensure separation of redundant trains in 

the same fire zone. By letter dated January 17, 1997, the licensee of LCS informed NRC that 

all Thermo-Lag 330-1 ERFBS material had been replaced with Darmatt KM-1 material. By letter 

and SE dated December 22, 1999, NRC staff determination that all ampacity derating concerns 

were resolved for LCS Units 1 and 2, and the licensee provided an adequate technical basis to 

ensure that all of the fire barrier enclosed cables are operating within acceptable limits. 

LCS also uses a limited amount of Kaowool fire barrier in one reactor building to augment the 

approximately 12 m (40-foot) spatial separation between cabling of redundant trains, and 

extends protection out to 15 m (50 feet) from the redundant cable. NRC has approved use of 

Kaowool in this limited application due to lack of automatic fire suppression in the area. 

The Kaowool used has a performance rating of 90 minutes and is layered approximately 7.6 cm 

(3.0 in) thick along the length of fire-protected area. 

6.32 Limerick Generating Station Units 1 and 2 and Peach Bottom Atomic Power Station, 

Units 2 and 3

Limerick Generating Station (LGS) and Peach Bottom Atomic Power Station (PBAPS) use 

Darmatt KM-1 and Thermo-Lag where a fire barrier is required to ensure separation of 

redundant trains the same fire area. As a result of GL 92-08, both sites implemented a ThermoLag corrective actions plan that documented the analysis, testing, and modifications to ensure 

ERFBS relied upon to provide separation of redundant safe shutdown trains within the same fire 

area provide the necessary level of protection. 

LGS and PBAPS both use Thermo-Lag 330-1 ERFBS to comply with their fire protection plans. 

The licensee uses this barrier to protect electrical power and control cables for systems and 

components used for achieving and maintaining safe shutdown conditions. Thermo-Lag was 

also used to provide physical independence (RG 1.75) and in some instances, both physical 

independence and safe shutdown capability. One- and three-hour Thermo-lag installations are 

used at both sites accounting for approximately 1450 m (4,750 feet) of Thermo-Lag at LGS and 

1341 m (4,400 feet) of Thermo-Lag at PBAPS. In response to GL 92-08, the licensee identified 

that it had not performed plant specific fire endurance tests of Thermo-Lag 330-1 material, but 

relied on the manufactures (TSI) and other licensee tests to qualify the licensees’ installations. 
6-16 

Safe shutdown re-analysis was completed to minimize reliance on Thermo-Lag 330-1 by use of 

operation actions and economically justifiable plant modifications and identification of cables 

that require protection by some type of ERFBS. Destructive examination of a sample of 

Thermo-Lag installations was performed at LGS to ensure that the Thermo-Lag installation was 

assembled with materials of acceptable quality (void of cracks, voids, and deformations). 

A NRC inspection team reviewed the design and qualification testing for the Darmatt KM-1 

electrical raceway fire barriers, and performed a walk down of installed barriers for the selected 

areas. This review was performed to verify that the selected items of the fire barrier system met 

their design and licensing bases. No findings of significance were identified. (ADAMS 

Accession No. ML020080162) 

By letter dated September 21, 1998, NRC informed the licensee that all information requested in 

GL 92-08 had been received and all actions related to Thermo-Lag 330-1 ERFBS used at LGS, 

except ampacity derating, had been closed out. LGS completed all of its Thermo-lag related 

corrective actions by September 1999 and PBAPS actions were completed by October 1999. 

Safety Evaluation dated January 12, 2000, documents NRC staff evaluation of the Thermo-Lag 

ampacity derating issues at the PBAPS and LGS. The staff found that the ampacity derating 

analysis results are acceptable and there are no significant safety hazards associated with the 

application of the licensee ampacity derating methodology. 

6.33 McGuire Nuclear Station, Unit 1 and 2

Thermo-Lag was initially used at McGuire Nuclear Station (McGuire) but cable that used 

Thermo-Lag ERFBS to provide the required protection have been replaced with a fire resistive 

electrical cable manufactured by Meggitt Safety Systems (previously known as Whittaker 

Electronic Systems) for several “A” train cables that are not separated by greater than 20ft from 

redundant “B” train cables. This electrical cable is a type of mineral insulated cable and the use 

of this cable at McGuire has been approved by NRC SE dated January 13, 2003. 

McGuire uses approximately 20 linear feet of Hemyc ERFBS in Unit 1 and 44 linear feet in 

Unit 2, as a 1-hour rated barrier for compliance with Appendix R requirements. In response 

NRC and industry testing results, the licensee determined that their use of Hemyc does not 

meet the 1-hour fire rating to comply with McGuire licensing basis. As compensatory measure, 

the licensee has implemented additional control on the types of materials introduced into areas 

containing Hemyc and performs routine fire watches in the affected areas. On April 18, 2006, 

McGuire licensee submitted it intent to transition to NFPA 805 in accordance with 10 CFR 

50.48(c). The licensee expects to resolve all issues related to the Hemyc ERFBS during the 

NFPA 805 transition process. In the event that McGuire does not transition to NFPA 805, then 

they will have to submit exemption requests to the NRC providing justification for the specific 

Hemyc configurations, or modify these configurations to come into compliance. A discussion of 

NFPA 805 is provided above in Section 3, “ERFBS Regulations.” 

6.34 Millstone Power Station, Units 2 and 3

Millstone Power Station Unit 3 (Millstone 3) used a 1-hour rated Thermo-Lag 330-1 ERFBS to 

protect approximately 40 ft conduits containing Appendix R required cables. The licensee 

replaced the Appendix R required cables with a 1-hour fire rated cable, to eliminate its reliance 

on Thermo-Lag materials. Currently, Millstone Unit 3 does not use any ERFBS to separate 
6-17 

redundant trains located within the same fire area. Compliance with Appendix R is achieved for 

Unit 3 by physical separation, water curtains or other approved deviations. 

Millstone Power Station Unit 2 (Millstone 2) uses Thermo-Lag 330 and 770 ERFBS to protect 

conduit, cable trays and junction boxes. All Thermo-Lag used in Unit 2 were installed in 

accordance with the Omega Point Laboratories and NEI tests and didn’t deviate from tested 

configurations. 

In a letter dated May 9, 2002, Millstone 2 received a letter from the NRR stating that the 

ampacity derating issues were resolved due to the fact that the Millstone 2 had provided all 

necessary information mentioned in GL 92-08. (ML020700197) 

Millstone 2 uses Thermo-Lag 330 and 770 ERFBS to protect conduit, cable trays and junction 

boxes. All Thermo-Lag used in Millstone 2 were installed in accordance with the Omega Point 

Laboratories and NEI tests and didn’t deviate from tested configurations. 

6.35 Monticello Nuclear Generating Plant, Unit 1

Monticello used approximately 21 m (70 ft) of a 3-hour rated Thermo-Lag 330-1 ERFBS design 

to protect conduits. The licensee rerouted two sections of these cables and also removed 

Thermo-Lag 330-1 in the plant in order to eliminate its reliance on the material. All material was 

removed and cables rerouted during the 1993 plant refueling. As a result, Monticello no longer 

utilizes any ERFBS to provide separation of redundant trains located in the same fire area. 

NRC replied by letter on May 27, 1993 that the issue is considered closed and Monticello NGP 

provided necessary information with regards to GL 92-08 and 10 CFR 50, Appendix R. 

6.36 Nine Mile Point Nuclear Station, Units 1 and 2

Nine Mile Point Nuclear Station (NMP) previously used a small quantity of Thermo-Lag 330-1 to 

ensure safe shutdown capability and to meet the requirements of 10CFR50.48. The ThermoLag being used provided 3-hour fire protection in three locations in both NMP Units 1 and 2. 

There are nine conduit enclosed cables (3.8 cm (1.5 in) diameter) that utilize Thermo-Lag 330-1 

in the missile barrier enclosure within Diesel Generator 103 Room which are intended to provide 

separation between Diesel Generator 102 and 103 control cables located within missile shield. 

There is also 3-hour, 2.5 cm (1.0 in) thick Thermo-Lag applied to HVAC duct work in the Turbine 

Building running from the Control Room to the Auxiliary Control Room. There are also very 

small quantities of conduit barriers installed in NMP1. 

NMP Unit 2, a composite conduit box enclosure made of tube steel and angled framing had a 

coating of 1 inch thick, 3-hour Thermo-Lag fire barrier applied. 3-hour Thermo-Lag 330-1 was 

also used to provide separation for a safe shutdown area from an adjacent transformer yard in 

lieu of a fire damper in the outside wall. In addition, Thermo-Lag was installed in Unit 2 to 

provide separation of diesel day tank rooms from the diesel generator room. This installation is 

used in lieu of fire dampers on each end of an HVAC duct at the room’s boundaries. 

In a letter from Niagara Mohawk Power Corporation dated January 30, 1996, NMPC stated that 

no Thermo-Lag 330-1 fire barriers performing a safety function of separating redundant safe 

shutdown trains of equipment remained at Nine Mile Point. One application of Thermo-Lag was 

abandoned in place and the remaining applications were removed completely. 
6-18 

6.37 North Anna Power Station, Units 1 and 2

North Anna Power Station (NAPS) Units 1 and 2 use ERFBS made of 3M Interam E-53A series 

mat to provide a 1-hour rated fire barrier to protect power cables to a charging and component 

cooling water pump. These applications of 3M use an additional layer of E-53A series mat than 

the tested configuration, to improve fire resistance and ensured the 1-hour rating would be 

achieved. 

Approximately 20 m (65 linear feet) and 5 m2

 (50 ft2) of Thermo-Lag was replaced by 3M 

material and with gypsum board. An additional 12 m2

 (128 ft2) of Thermo-Lag was addressed 

by engineering evaluations. 

6.38 Oconee Nuclear Station Units 1, 2, and 3

Oconee Nuclear Station (Oconee) does not use any ERFBS for compliance with NRC 

regulations. However, Oconee does use Hemyc blanket pads to cover three wall penetration 

seals which provide additional thermal margins. The actual penetration seals do not rely on the 

application of the Hemyc pads to meet their 3-hour fire endurance rating. The three 

penetrations have the Hemyc covering total approximately 3 m2

 (35 ft2). 

6.39 Oyster Creek Nuclear Generating Station

Oyster Creek Nuclear Generating Station (OCGS) used to rely on approximately 322 m (1055 ft) 

of 1- and 3-hour Thermo-Lag fire barriers on various conduits and boxes in seven different 

areas of the plant. 

OCGS originally intended to declare exemptions from GL 92-08, noting that Thermo-Lag 

applications did not protect electrical cables regarding safe shutdown of the nuclear plant. 

However, after examining cost of a 100 percent upgrade of the fire barrier system, the 

exemptions were withdrawn and a complete new barrier system was planned. Bounding tests 

were performed utilizing guidance provide in GL 86-10, Supplement 1 and any deviations from 

the fire tests were documented, evaluated, and addressed. Materials considered for the new 

fire barrier wraps were Darmatt, Versawrap, and Mecatiss. OCGS now uses a combination 

Thermo-Lag/Mecatiss ERFBS, along with a standalone Mecatiss barrier and a standalone 3M 

Interam ERFBS. Approximately 321 m (1055 linear feet) of Thermo-Lag located on 1-hour 

conduit and 1-hour boxes was replaced along with approximately 6 m (20 linear feet) of 3-hour 

conduit. 

On January 30, 2001, OCGS provided NRC with a letter stating that all corrective actions 

required by GL 92-08 regarding Thermo-Lag deficiencies were completed by December 31, 

2000. 

6.40 Palisades Nuclear Plant

Palisades Nuclear Plant (PNP) uses concrete as a rated 1-hour fire barrier to separate 

redundant trains within the same fire area. The barrier was constructed by enclosing a conduit 

and pull box with concrete. 

Palisades initially used a 1- and 3-hour Thermo-Lag barrier to protect 53 linear meters (174 

linear ft) of conduit and two junction boxes. The licensee replaced 43 linear meters 

(140 linear ft) with a 1-hour rated fire cable and embedded 4 ft and associated junction boxes in 
6-19 

concrete. The remaining 30 linear feet was rerouted to provide the required separation. 

PNP completed a written response to NRC on January 6, 1997 stating that the proposed 

corrective actions for the plant’s Thermo-Lag installations were complete. 

6.41 Palo Verde Nuclear Generating Station Units 1, 2, and 3

Palo Verde Nuclear Generating Station (PVNGS) uses Thermo-Lag ERFBS to provide 

protection as required by Appendix R. PVNGS does not utilize any 1-hour or 3-hour fire barriers 

required for cable trays. A large amount of fire barrier material for cable raceways was found 

unnecessary and nearly 80 percent of the Thermo-Lag at the nuclear station was removed. 

PVNGS has about 215 m (705 linear feet) of Thermo-Lag 330-1 installed for 1-hour conduit 

barriers. Palo Verde also has approximately 76 m2

 (820 ft2) of Thermo-Lag 330-1 utilized for 

3-hour HVAC and cable tray support barriers. About 58 m2

 (625 ft2) of Thermo-Lag is being 

used for 1-hour junction box barriers, and there is also about 43 m2

 (460 ft2) of radiant energy 

heat shield Thermo-Lag installed for conduits. 

In a letter dated June 11, 1998, NRC stated that all corrective actions for the resolution of the 

Thermo-Lag issues identified in GL 92-08 had been implemented and the actions tracked by 

TAC Nos. M85583, M85584, and M85585 were complete. 

Palo Verde conducted ampacity evaluations for specific Thermo-Lag 330-1 enclosed raceways. 

Testing performed on cables in Palo Verde Unit 1 was declared sufficient for Units 2 and 3 as 

well due to replicated configurations and materials. As of December 24, 1997, all ampacity 

issues associated with Thermo-Lag fire barriers were resolved for all three nuclear station units. 

6.42 Peach Bottom Atomic Power Station, Units 2 and 3

See Section 6.32 Limerick Generating Station Units 1 and 2 and Peach Bottom Atomic Power 

Station above. 

6.43 Perry Nuclear Power Plant Unit 1

See Section 6.15 Davis Besse Nuclear Power Station, Unit 1 and Perry Nuclear Power Plant 

Unit 1. 

6.44 Pilgrim Nuclear Power Station

Mecatiss and 3M Interam ERFBS are used at Pilgrim Nuclear Power Station to provide 

protection of electrical and instrumentation cables associated with equipment that provides safe 

shutdown capability in accordance with Appendix R. These barriers were installed subsequent 

to GL 86-10 supplement 1 and IN 95-52, were evaluated against these criteria and addressed 

the indentified concerns. 

6.45 Point Beach Nuclear Plant, Units 1 and 2

Point Beach Nuclear Plant Units 1 and 2 utilize 3M Interam E-50 Series ERFBS on selected 

raceways to provide separation between redundant shutdown trains to meet the separation of 

criteria of Section III.G.2.c of 10 CFR 50, Appendix R. The configurations were installed at 

PBNP before guidance provided in GL 86-10 supplement 1 was available, were qualified in 

accordance with ASTM E-119 and ANI/MAERP fire test specifications, available at the time of 
6-20 

the installation. All 3M barriers installed post GL 86-10 Supplement 1 were qualified to the 

acceptance criteria provided in that guidance. 

Some of the items tended to in order to comply with 10 CFR 50 include upgrading control 

building walls which could be ignited by turbine fires to a 3-hour rating, including fire dampers, 

fire doors, and penetration seals. The walls of the cable spreading room and diesel generator 

room were also upgraded to a 3-hour fire rating. The viewing window was also upgraded to a 

two-hour fire rating, as well as the walls of the control room were upgraded to a two-hour fire 

rating that separates the service building and general auxiliary building ventilation exhaust filters 

from the remainder of the auxiliary building. 

6.46 Prairie Island Nuclear Generating Plant Units 1 and 2

Prairie Island Nuclear Generating Plant (PINGP), Units 1 and 2 use Darmatt KM-1 and 3M 

Interam E50 series ERFBS to provide Appendix R safe shutdown circuit protection. These two 

barriers were qualified for a 1-hour fire rating in accordance with GL 86-10 Supplement 1 

guidance. These two ERFBS are not used inside containment; instead Marinite is used to 

provide radiant energy shields inside containment. 

Applications of Kaowool at the nuclear plant were removed due to the fact that they are no 

longer required by 10CFR50, Appendix R. All applications of Kaowool fire barrier were 

analyzed before removal to make sure they are necessary to comply with 10CFR50. Prairie 

Island determined that several installations of the fire barrier were unnecessary, and also that 

several locations were in need of a fire barrier. Field testing showed that some barriers met the 

required 20 foot separation criteria, allowing Kaowool to be removed and not replaced with 

upgraded fire barriers. Cables were also rerouted during a scheduled power outage to meet 

separation criteria and reduce the plant’s reliance on fire barrier applications. 

Through NRC approval and by letter dated December 27, 2000, Prairie Island Nuclear 

Generating Plant declared its completion date for Kaowool replacement and cable rerouting as 

February 28, 2001. 

6.47 Quad Cities Nuclear Power Station, Units 1 and 2

Quad Cities Nuclear Power Station (QCNPS) uses several different types of ERFBS to ensure 

separation of redundant trains in the same fire zone, including, Darmatt KM-1, Versa Wrap, and 

3M Interam. 

In 1994, QCNPS commissioned an independent review of the 3M Interam ERFBS installation 

and fire tests. The review evaluated installation configurations and test data the meet industry 

standards and GL 86-10 sup 1 acceptance criteria with the instillations at QCNPS. Where plant 

configurations that didn’t bound the acceptable test configurations, a plant modification was 

performed to ensure the installed fire barrier was bounded by a tested configuration. 

QCNPS uses Darmatt KM-1 and Versa Wrap 1-hour rated ERFBS. These barriers were 

installed in the late 1990’s and an engineering evaluation for the modifications included a review 

of the fire barrier endurance testing to ensure the capability of these two ERFBS. 

 
6-21 

6.48 River Bend Station, Unit 1

River Bend Station (RBS) relies on Thermo-Lag 330 to provide the protection to safe shutdown 

circuits required by Appendix R. Originally, one and three hour Thermo-Lag materials are used 

for safe shutdown purposes at RBS. There was approximately 923 linear feet of 1-hour 

Thermo-Lag material and approximately 366 feet of 3-hour Thermo-Lag installed on cable trays. 

For conduits, there were about 4282 feet of 1-hour material and 1429 feet of 3-hour material. In 

addition, Thermo-Lag was utilized to cover approximately 741 ft2

 of 1-hour and 277 ft2 of 3-hour 

items including junction boxes, instruments, instrument racks, motor operated valves, a ceiling 

assembly, a steel beam, and one radiant energy shield. 

All Thermo-Lag barriers at RBS were declared inoperable on October 26, 1989. In response to 

its failed 3-hour fire endurance testing of Thermo-Lag 330, and supplementary testing by NEI, 

RBS developed a new post-fire safe shutdown analysis to reduce the plant’s dependence on 

Thermo-Lag. In addition new Thermo-Lag configurations replaced the previous ones using new 

materials based on successful NEI test results. By using a combination of rerouting cables and 

revising its safe shutdown analysis, RBS reduced the amount of Thermo-Lag to approximately 

500 feet. All Thermo-Lag configurations at RBS are of a 1-hour application. 

Implementation of the new materials was delayed due to ampacity derating issues. Fire barriers 

at RBS were installed in accordance with TSI Technical Note 20684, but after planning and 

testing new fire barrier configurations, RBS became concerned that insufficient experimental 

results would prevent RBS from implementing any upgrades. RBS removed the cable 

configurations from service in order to perform cable degradation tests and reduce overload on 

numerous cables in order to resolve electrical concerns from NRC Electrical Engineering 

Branch and SNL. NRC sent a letter to RBS dated November 15, 1999 stating that there are no 

remaining ampacity derating issues as identified in GL 92-08. 

6.49 H.B. Robinson Steam Electric Plant, Unit 2

Hemyc ERFBS is used at H.B. Robinson Steam Electric Plant (Robinson) as a 1-hour fire rated 

barrier to protect conduits in accordance with Appendix R. The use of Hemyc at HBRSEP was 

granted by NRC in exemptions dated October 25, 1984 and October 17, 1990. Approximately 

120 linear feet of Hemyc is installed in the Component Cooling Water Pump Room to protect the 

pump power cables. This application includes two 10.16 cm (4 in) and two 7.62 cm (3 in) 

conduits. Following notification of the Hemyc fire testing failures, the licensee considered these 

Hemyc barriers inoperable and undertook compensatory measures until such barriers could be 

determined operable. On June 10, 2005, the licensee notified that it intended to transition to 

NFPA 805 and would disposition any Hemyc related issues then. However as a proactive 

measure, the licensee intends to replace the Hemyc with an ERFBS that has been tested and 

qualified to the required rating per guidance provided in GL 86-10 supplement 1. By letter dated 

August 2, 2007, the licensee notified NRC that all Hemyc installations had been removed and 

replaced with a 1-hour fire rated 3M Interam E-54A ERFBS. NRC inspection staff verified the 

licensees’ installation of the 3M ERFBS, documented in IR 05000261/2007007 and Exercise of 

Enforcement Discretion, dated December 20, 2007. In the event that H.B. Robinson does not 

transition, then they will have to submit exemption requests to the NRC providing justification for 

the specific Hemyc configurations, or modify these configurations to come into compliance. 

A discussion of NFPA 805 is provided above in Section 3, “ERFBS Regulations.” 

MT fire barrier material is used at Robinson to cover both sides of two penetration seals 

containing the steam generator blowdown lines. Therefore, this application of MT material is not 
6-22 

used an ERFBS to protect cables, but to provide added thermal insulation for the expansion and 

contraction of the steam generator blowdown lines. 

6.50 St. Lucie Plant, Units 1 and 2

Approximately 110 feet of Hemyc material is used at St. Lucie Plant as a noncombustible 

radiant energy shield inside Unit 2 containment to satisfy a license basis requirement for 

separation of safe shutdown cables in the event of a fire. In a safety evaluation dated March 27, 

1984, NRC determined that installation of a 1-1/2 inch insulating blanket manufactured by B&B 

Insulation, Inc. for protection of cable tray configuration inside containment was acceptable. 

The noncombustible RESs are installed beneath the lowest redundant Division A & B cable 

trays at each elevation and all conduits inside Unit 2 Containment not separated by 20 feet are 

enclosed with a 1-hour fire-rated barrier. For the St. Lucie plant application, the noncombustible 

RES (Hemyc) are intended to deflect heat away from the protected cables so that it will 

dissipate into the voluminous containment atmosphere. As such, for cable tray applications, 

only the bottom and sides of the lowest cable tray are covered with the Hemyc material. The 

material is attached to the cable tray with staples such that the material will survive a design 

bases event (DBE). In some applications, the licensee uses Mecatiss instead of Hemyc to 

construct the RES. 

B&B Insulation Inc. testing via ASTM E-119-80 and ANI/MAERP Bulletin No. 5 (79) rated the 

Hemyc barrier with a 1-hour fire rating. 

The original application of Thermo-Lag 330-1 material at St. Lucie Plant consisted of 1-hour and 

3-hour fire barrier conduit protection, 3-hour fire area boundary walls and ceilings, and 

containment radiant energy shields. The 1-hour and 3-hour protection installations for conduit 

consisted of one-half inch (minimum) thickness and 2.54 cm (1 in) (minimum) thickness of 

Thermo-Lag 330-1 preformed sections tie-wired or banded tot eh conduit, respectively. 

Thermo-Lag was used to achieve independence of electrical systems and for raceway 

fireproofing, along with a number of walls and wall sections to meet separation requirements. 

St. Lucie Plant also uses Thermo-Lag to provide compliance with Appendix R requirements and 

to achieve 20ft separation of redundant circuits, Thermo-Lag is not an intervening combustible 

in any area where Appendix R, Section III.G.2(b) is credited for by design. The configurations 

used have been qualified by direct testing performed by Fire Protection Evaluation Records 

which documents the Thermo-Lag fire resistance pursuant to GL 86-10. In addition, the 

licensee has ensured that the quality of the Thermo-Lag installed was consistent with tested 

materials and that the critical properties and characteristics of the procured material is within 

acceptable limits. No cable trays are protected with Thermo-Lag material in either unit. 

Following issuance of Bulletin 92-01 the licensee declared all Thermo-lag barriers inoperable 

and implemented compensatory measures. To resolve the Thermo-lag inoperability, the 

licensee preformed the following measures: 

 evaluate where Thermo-lag no longer needed 

 re-route cables through separate fire area 

 inside containment Thermo-lag applications were replaced with or encapsulated in 

stainless steel sheet metal to provide a RES 

 verification of properly installed base layers, 

 upgrades for the 1-hour barrier consisted of reinforcement of seams and joints through 

the addition of stress skins and tie wires and the addition of 1-quarter inch (minimum) 
6-23 

thickness Thermo-Lag 330-1 overlays for conduits smaller than three inches in diameter, 

and 

 3-hour barrier upgrades included reinforcement at conduit and support interfaces with 

the use of wire mesh or stress skin. An additional layers of Thermo-Lag 770-1 mat was 

applied over the base layer (number of layers depended on conduit size and cable fill) 

and an application of a Thermo-Lag 770-1 trowel grade top coat finish. 

By letter dated June 23, 1998, the licensee notified NRC that all corrective actions associated 

with Thermo-Lag resolution had been completed. As identified in its June 23, 1998 letter, the 

licensee uses approximately 335 linear meters (1100 linear ft) of a 1-hour rated and 3 linear 

meters (10 linear ft) of a 3-hour rated Thermo-Lag barrier to protect conduits. No cable trays 

are protected with this barrier. In addition, 158m2

 (1700ft2) of Thermo-Lag material is used to 

provide 3-hour rated walls, floors and ceilings. 

NRC SE dated March 26, 1999, approved the St. Lucie ampacity derating methods of analysis. 

The licensee preformed combustibility loading calculations to document the acceptability of this 

increased combustible loading for each affected fire area and a 10 CFR 50.59 safety evaluation 

including an final safety analysis report change package was issued. 

6.51 Salem Nuclear Generating Station, Units 1 and 2

In response to NRC GL 92-08, Salem Generating Station does not rely on Thermo-Lag 330-1 

for fire protection purposes. SGS relies on approximately 1,981 m (6,500 feet) of fire barrier 

material including Kaowool, 3M FS-195, and 3M InteramTM E-50 Series ERFBS. 

After NRC inspection of the Salem Generating Station between April 14 and 18, 1997, it was 

determined that SGS relied on the same fire wraps and configurations utilized since May of 

1993. On June 6, 1997, SGS notified NRC that it had established a “Cable Raceway Fire Wrap 

Resolution Plan” to update and improve the plant’s fire wrap system. By December 31, 2002, 

Salem reduced the amount of fire barrier materials used, including Kaowool, 3M FS-195, and 

3M E-50, from 6,096 m (20,000 feet) of fire wrap to 1,981 m (6,500 feet) of fire wrap in order to 

improve their outdated fire barrier system and improve plant safety. The plant was updated and 

improved through the use of cross-ties, modified control circuits, cable re-routes, and removal of 

unnecessary Kaowool and 3M fire wrap. 

6.52 San Onofre Nuclear Generating Station Units 2 and 3

San Onofre Nuclear Generating Station (SONGS) originally used Thermo-Lag 330-1 in four 

applications, two of which were only for Unit 1 reactor that has been permanently shutdown. 

The only application where Thermo-Lag was used for Appendix R purposes has been replaced. 

Additionally, the licensee used approximately 256ft2

 of Thermo-Lag 330-1 as a non-cable 

protection related barrier; it has replaced that barrier with Pyrocrete 241. 

Submittals and SER identify that the Cerablanket ERFBS did not meet the entire acceptance 

criteria delineated in the standard fire tests and only maintained circuit integrity for 49 minutes. 

NRC acceptance of the Cerablanket raceway fire barrier material was based on the existence of 

automatic fire detection and suppression systems in the areas in which the barrier material was 

installed, and the site fire department's ability to respond and initiate suppression activities. The 

SER concluded "that the deviations from BTP CMEB 9.5-1, associated with the barrier material, 

are not significant from a fire safety standpoint and are, therefore, acceptable." 
6-24 

Cerablanket has since been replaced by a 3M barrier. The criteria for acceptance of the 3M 

material was based on the cold-side temperature requirements of GL 86-10 and that the 3M 

ERFBS exceeded the endurance time of Cerablanket. In configurations where the 60 minute 

time rating could not be met, the licensee maintained the fire suppression system as described 

in the deviation. 

6.53 Seabrook Station, Unit 1

Seabrook uses 3M InteramTM E-50 series fire wrap system as their sole ERFBS. All redundant 

train cables that required ERFBS protection are routed through conduit and protected with a 

1-hour rated 3M Interam E-50 series ERFBS. The 1-hour fire endurance rating of the 3M 

ERFBS used at Seabrook were qualified by representative fire endurance tests, using 

ASTM E-119 and NRC GL 86-10 acceptance criteria. Following notification of 3M barrier fire 

endurance testing failures the licensee evaluated the impact on its utilization of the 3M ERFBS. 

It found 10 conduits with fill percentages ranging from 4% to 12% (the vendor identifying cable 

trays with less than 15% fill may result in a derated endurance rating). The supplemental 

testing results were extrapolated to evaluate the difference in the thickness of material used at 

Seabrook and the evaluation concluded that the installed 3M Interam E-50 series ERFBS for the 

identified 10 conduits were in fact capable of providing the rated 1-hour protection. All other 

conduits contained greater than 15% fill and therefore, met the new criteria. The smallest 

conduit protected with 3M material at Seabrook is 2.54 cm (1 in) in diameter and there are no 

cable trays which require protection by an ERFBS. 

6.54 Sequoyah Nuclear Plant, Units 1 and 2

A general overview of TVA’s resolution to Thermo-Lag usage is presented in Section 6.4 

Browns Ferry Nuclear Plant, Units 1, 2 and 3, Sequoyah Nuclear Plant, Units 1 &2 above. 

As indicated in its June 30, 1999 letter to NRC, TVA completed its Thermo-Lag modifications to 

Sequoyah Nuclear Plant, which included; installation of an upgraded Thermo-Lag 330-1 barrier 

on conduits smaller than three inches, junction boxes, a cable tray and other applicable 

configurations identified via their Thermo-Lag testing program. In addition, TVA performed a 

Thermo-Lag reduction review which eliminated approximately 1300 linear feet of Thermo-Lag. 

6.55 South Texas Project, Units 1 and 2

Thermo-Lag 330-1 fire barrier systems are used at South Texas Project (STP) to provide both 

1-hour and 3-hour fire barrier separation of safe plant shutdown equipment outside containment. 

The material is also used to provide separation as a radiant energy shield and to achieve 

physical independence of electrical systems. STP installed Thermo-Lag 330-1 based on fire 

endurance tests from TSI which proved to be indeterminate. After further engineering 

evaluation of STP including fire endurance testing of both 1-and 3-hour configurations, STP 

determined that three different applications of Thermo-Lag needed to be removed. 

There were 24 cable trays with Thermo-Lag installed at STP that required removal of the fire 

barrier material. The concern regarding the cable trays had to do with a potential impact on 

cable ampacity. There was also a configuration upgrade in Fire Area 07 of STP of one train of 

Qualified Display Processing System and sequencer control cables. Minor upgrades to the wall 

and box interface to meet the tested configuration have been implemented. The newly installed 

configurations now meet 1-hour fire rating standards consistent with 10CFR50, Appendix R. 

Thermo-Lag was also removed from inside the reactor containment buildings. A small amount 
6-25 

of Thermo-Lag residue was left behind in order to prevent damage to various electrical and 

HVAC components. 

Thermo-Lag is still utilized in several locations outside of the reactor building at South Texas 

Project. The material is used on supports, as a separation barrier to meet RG 1.75 separation 

requirements, and at other locations where there is not an impact on cable ampacity. 

The Thermo-Lag which remains at the plant is bounded by fire load analyses and is not 

considered a fire barrier. 

In a letter to STP and the Houston Lighting and Power Company dated April 4, 1997, NRC 

informed the licensee that the necessary information and modifications regarding GL 92-08 had 

been provided and the actions tracked by TAC Numbers M85606 and M85607 were complete. 

By letter dated January 19, 1999, NRC acknowledged that any ampacity derating concerns at 

STP have been resolved in accordance with GL 92-08. 

6.56 Virgil C. Summer Nuclear Station, Unit 1

Thermo-Lag 330 barrier material is used at five separate locations at Virgil C. Summer Nuclear 

Station (VC Summer). All five installations are installed to provide 1-hour fire barriers in order to 

meet separation requirements of 10CFR50, Appendix R. The fire barrier is used as panels to 

protect cable tray 3308, to protect a 7.62 cm (3 in) conduit that supplies DC power to the Main 

Control Board, to enclose two conduits which contained Nuclear Instrument signal cables, to 

protect Unistrut and threaded rods which suspend a M-board fire barrier, and to protect two 

conduits which provide “A” Train power to the “C” chiller within the plant. 

Fire barrier configurations at VC Summer were installed in accordance with manufacturer’s 

instructions and guidance and the plant itself had never performed any fire endurance testing. 

Ampacity testing in accordance with TSI in 1993 proved that there were significant concerns in 

regards to ampacity derating of the Thermo-Lag 330-1 installations. VC Summer was required 

to address installations of Thermo-Lag to resolve the ampacity derating issues. 

One of the corrective actions VC Summer performed was to modify existing circuits to meet the 

requirements of 10CFR50 Appendix R without relying on Thermo-Lag. Cables were rerouted to 

meet separation criteria. Thermo-Lag was also removed from the VUL21A conduits and a 1-

hour fire rated Gypsum board installed to maintain adequate circuit separation requirements for 

the HVAC system water chiller C transfer switch. In addition, a deviation request to Appendix R 

was submitted and approved by NRC for using Rockbestos Firezone R Cable to replace 

portions of safe shutdown circuits requiring protection to meet the requirements of 10CFR50, 

Appendix R. VC Summer also indicated that all installations of Thermo-Lag at the nuclear 

station were removed and replaced with an alternate fire barrier (e.g., 3M Interam). 

In a letter dated May 5, 1998, NRC informed Virgil C. Summer Nuclear Station that all ampacity 

derating issues as well as Thermo-Lag corrections were resolved as identified by GL 92-08. 

 
6-26 

6.57 Surry Power Station, Units 1 and 2

Surry Power Station does not use any conventional ERFBS materials to protect redundant safe 

shutdown equipment. However, Pyrocrete manufactured by Carboline Company is used at 

Surry in conjunction with a Bio-K-10 mortar produced by Bio-Fire Protection, Inc on fiberglass 

piping. 

Qualification of Pyrocrete 241 has been qualified by Thermal Transmission Test (ref. Tech. 

Report EP-001 1) that uses the ASTM E-119 fire exposure and the failure criteria of an average 

temperature of 250°F or single point temperature 325°F above ambient backside temperature. 

The barrier was installed prior to the issuance of GL 86-1 0 Supplement 1. Pyrocrete 241 has 

also been tested under UL designs N7l5, N716, N717, N7l8 and S706. The Bio K10 mortar has 

been tested in accordance with UL Design No. CAJ5006. Field installations of Pyrocete and 

Bio-K10 mortar do not deviate from tested configurations. 

The Surry Power Station Units 1 and 2 use a combined total of 100 linear feet and 316 ft2

 of 

Thermo-Lag barriers for Appendix R compliance on electrical conduit only. Following the review 

related to GL 92-03, the licensee notified NRC on July 25, 1995, that Thermo-Lag 330-1 is no 

longer relied on for any 1-hour or 3-hour protection. PCI Promatec notified the NRC through 

public comment to this report that Surry also uses 3M Interam ERFBS. 

6.58 Susquehanna Steam Electric Station (SSES), Units 1 and 2

Susquehanna Steam Electric Station (Susquehanna) originally used approximately 15,000 

linear feet of Kaowool and Thermo-Lag ERFBS prior to identification of their deficiencies. The 

majority of Thermo-Lag was constructed using steel, 61 cm (24 inch) wide raceway and is 

intended for 1-hour applications. SSES relies on Thermo-Lag 330-1 to meet safe shutdown 

requirements of 10CFR50 Appendix R and to meet plant licensing commitments. Barrier 

elimination though analysis, modifications to the plant equipment and cabling, and modifications 

and upgrades to approximately 9,000 linear feet of ERFBS were completed by October 5, 1998. 

In addition, all Kaowool fire barriers were eliminated from the plant. 

In a letter dated April 9, 1999, NRC provided response to Susquehanna that all ampacity 

derating issues dealing with cables wrapped in Thermo-Lag 330-1 were operating within 

reasonable limits and issues mentioned in GL 92-08 were resolved. 

Susquehanna uses Darmatt material in only one of its fire barriers installed in the Unit 2 Reactor 

Building. Susquehanna has eliminated the use of Kaowool in its plant for compliance with 

Appendix R regulations. 

6.59 Three Mile Island Nuclear Station, Unit 1

TMI-1 uses a combination of ERFBS to ensure separation of redundant trains in the same fire 

zones. Thermo-Lag was initially installed at the plant to comply with Appendix R requirements. 

Following implementation of a Thermo-Lag corrective action plan, the licensee upgraded or 

replaced Thermo-Lag installations with Mecatiss and in some applications requested 

exemptions for the continued use of Thermo-Lag. In addition, TMI was granted an exemption to 

Appendix R in several specific applications to allow the use of a Rockbestos fire resistant cable 

in lieu of a 1hour fire barrier. 
6-27 

NRC issued two Confirmatory Orders directing TMI-1 to complete final implementation of its 

corrective action program, which was confirmed to be completed by December of 1999. In 

January of 1999, NRC sent a letter to GPU Nuclear stating that all ampacity derating issues with 

regards to GL 92-08 were resolved at the Three Mile Island Nuclear Plant. 

6.60 Turkey Point Nuclear Generating Units 3 and 4

Turkey Point Nuclear Generating Units 3 and 4 (Turkey Point) use Thermo-Lag ERFBS to 

provide raceway protection in accordance with Appendix R. The Thermo-Lag system designs 

are based on direct qualification testing or fire resistance equivalency evaluations performed 

using guidance from GL 86-10 and supplement 1. Approximately 14,608 linear feet and 1,287 

sq ft of a 1-hour rated thermo-lag ERFBS and 602 linear feet and ≤38sq ft of a 3-hour rated 

thermo-lag ERFBS are used at Turkey Point. 

Thermo-Lag 330-1 is used as an RES inside containments, approximately 700 feet in both units. 

To address the combustibility issues related to Thermo-Lag materials, the licensee replaced or 

encased the RES Thermo-lag barriers with stainless steel overlays. Outside containment, 

Turkey Point uses Thermo-Lag a 1-hour and 3-hour rated fire barriers. Approximately 600 feet 

in both units were upgraded with a Thermo-Lag 770-1 overlay of existing barriers. 

Turkey Point requested exemption from upgrading Thermo-Lag fire barriers in 10 different 

locations within Units three and four. Exemptions were granted by NRC in a letter dated June 

15, 1998 because either the fire zones and barriers met the 20 foot separation criteria or the 

cables located inside the raceways were not needed for the plant’s safe shutdown. Fire Zone 

106R was denied an exemption because there was only a 10 foot separation, falling short of the 

criteria from Appendix R. Turkey Point completed all planning and upgrades by December 31, 

1999. 

NRC SE dated March 26, 1999, approved the Turkey Point ampacity derating methods of 

analysis. 

The samples provided to NEI for chemical composition testing indicated that the Turkey Point 

samples were consistent with other samples provide by industry and meet the acceptance 

criteria set by this testing program. 

Exemption dated February 24, 1998 grants the use of a 25-minute fire rated ERFBS in lieu of a 

1-hour fire barrier system as required by Section III.G.2 of Appendix R 

Exemption dated October 8, 1998 grants the use of a 25-minute fire rated ERFBS in lieu of a 

3-hour barrier as required by Section III.G.2 of Appendix R. 

Exemption dated May 4, 1999, grants the use of a 25-minute fire rated ERFBS in lieu of a 

3-hour barrier as required by Section III.G.2 of Appendix R, for fire zone 106R. 

6.61 Vermont Yankee Nuclear Power Station

Vermont Yankee Nuclear Power Station (VYNPS) initially utilized Hemyc ERFBS to protect 

selected raceways to meet the separation requirements of 10 CFR 50, Appendix R. VYNPS 

completed its replacement of Hemyc ERFBS on systems credited in the VY Safe Shutdown 

Capability Analysis supporting compliance with Appendix R on July 28, 2005. Any Hemyc 

material that remains in the plant is not relied on for Appendix R compliance. 
6-28 

Thermo-Lag was used to a very limited extent at VYNPS (5 conduits two 3/4”, one 3” and one 4” 

in a 3-hour configuration to achieve physical independence of electric power systems, 

approximately 48 linear feet). The two 3/4” conduits were removed as a result of equipment 

upgrades related to RG 1.97 suppression chamber water level and temperature upgrades. 

VYNPS did not perform its own independent testing of Thermo-Lag 330-1 ERFBS. VYNPS 

applied a 10% ADF based on ITL report No. 84-10-5 and a 50% ADF for all raceways that 

contain power cables. To eliminate reliance on Thermo-Lag 330-1 ERFBS at VYNPS, the 

licensee rerouted raceways to meet the 20 foot separation criteria (with detection and 

suppression). In other instances, the licensee replaced the existing Thermo-Lag materials with 

a qualified 3-hour fire wrap manufactured by 3M Company (3M Interam E-54A Flexible Fire 

Barrier Wrap). Based on derating factors provided by the vendor, VYNPS used an ADF of 30% 

in the design analysis for application of the 3M material. By letters dated June 1 and 28, 1993, 

the licensee informed NRC that it no longer relied on Thermo-Lag 330-1 material to achieve 

compliance with the requirements of 10 CFR 50, Appendix R. NRC notified VYNPS that actions 

required to address issues identified in GL 92-08 had been completed in its letter dated April 12, 

1995. 

Previous Hemyc or Thermo-Lag applications that required protection are now protected with 3M 

Interam® E-54A material used to construct ERFBS with a design rating of 1-hour. After 

receiving NRC IN 95-52 regarding 3M Interam test results, the licensee performed engineering 

evaluations on its use of 3M to determine that all 3M Interam® ERFBS installed at VY provide 

adequate fire barrier performance. In addition, the adequacy of the replacement barrier is also 

based on the vendors test results for conduit size and fire-wrap configurations that are 

determined to be bounded by acceptable test results summarized in IN 95-52. NRC inspection 

staff determined that there were no performance deficiencies associated with the licensees’ 

replacement of the Hemyc material with the 3M Interam ERFBS. 

6.62 Vogtle Electric Generating Plant, Units 1 and 2

Vogtle Electric Generating Plant (Vogtle) initially used approximately 247 linear meters (810 

linear ft) and 102 m2

 (1100 ft2) of 3-hour rated Thermo-Lag 330-1 ERFBS to protect raceways 

(conduits and cable trays) and junction boxes, respectively. The Thermo-lag was use to meet 

the requirements of Appendix R and to provide physical independence of electrical systems. 

Following the issuance of GL 92-08 the licensee notified NRC via letter dated May, 10, 1995, 

that upon further review and conversations with NRC staff, the licensee decided to remove 

Thermo-Lag 330-1 materials form its Vogtle plant. Vogtle decided to resolve the Thermo-Lag 

issue by rerouting circuits, re-evaluation of safe shutdown equipment requirements, and 

redefinition of existing fire areas. 

3M Interam E53C, E54A, and E54C materials are used at Vogtle to construct ERFBS. These 

materials have been tested in accordance with GL 86-10, Supplement 1, as documented in test 

reports Omega Point Laboratory CTP-2005, 14540-99416; Vogtle Document AX3AJ08-00001. 

Vogtle also protects some conduits and junction boxes with a cementitious spray-applied fire 

resistant coating per UL design Y707 and Y708. The masonry unit assemblies, composite 

assemblies of structural materials, and spray applied coatings were tested in accordance with 

UL Standard 263, “Fire Tests of Building Construction Material,” which references ASTM E-119 

and NFPR 251 tests. 

 
6-29 

6.63 Waterford Steam Electric Station, Unit 3

Waterford Steam Electric Station Unit 3 (Waterford 3) credits Hemyc ERFBS as a 1-hour fire 

rated barrier for Appendix R compliance along with using Hemyc in the containment building as 

a RES. Waterford 3 uses approximately 2000 feet of Hemyc conduit wrap installed on conduits 

ranging in sizes from 3⁄4 to 5 inches in diameter. 1200 feet of Hemyc wrap installed on 24” wide 

cable trays, 7 electrical junction boxes and 5 containment electrical penetrations. Conduits, 

electrical junction boxes and containment penetration boxes are directly wrapped with Hemyc. 

Tray wrap is installed using the standard vendor design consisting of Hemyc wrap installed on a 

frame assembly that provides an air space between the wrap assembly and the raceway. 

Hemyc is credited in 19 fire areas/zones. 

NRC approved Waterford 3 use of Hemyc wrap in SER NUREG-0787 Supplement 5 Section 

9.5.1.4. That acceptance was based on testing performed by an independent laboratory using 

visual inspection and circuit integrity as acceptance criteria to the standard ASTM E-119 1-hour 

fire test exposure. However, based on NRC insights from its testing of Hemyc, the licensee 

determined that the Hemyc installed at Waterford 3 does not conform to the licensing basis and 

has been declared inoperable. While the Hemyc ERFBS remains inoperable the licensee has 

implemented the compensatory measures identified in its Technical Requirements Manual, 

which require a continuous fire watch on at least one side of the affected assembly, or verify the 

operability of the fire detectors on at least one side of the inoperable assembly and establish an 

hourly fire watch patrol. The licensee produced a Hemyc resolution plan, which includes 

qualification testing, resolution under NFPA 805, and partial replacement/upgrades. In the 

event that Waterford does not transition, then they will have to submit exemption requests to the 

NRC providing justification for the specific Hemyc configurations, or modify these configurations 

to come into compliance. A discussion of NFPA 805 is provided above in Section 3, “ERFBS 

Regulations.” 

Waterford 3 also uses the 3M Interam ERFBS in 1- and 3-hour rated configurations. 

The licensee stated that the 3M system is qualified by various fire tests conducted by 

independent testing laboratories consistent with the guidance provided in GL 86-10 supp 1. 

In addition, the licensee noted that, “3M Interam is the only ERFBS approved by Entergy for use 

in future installations at Waterford 3 Nuclear Station.” 

6.64 Watts Bar Nuclear Plant, Unit 1

Watts Bar Nuclear Plant Unit 1 (WBN) utilizes approximately 600 linear feet of Thermo-Lag 330-

1 conduit fire barrier material to meet the requirements of 10CFR50 Appendix R, Section III G.2. 

The Thermo-Lag is applied to the Unit 1 Reactor Building Annulus. 

WBN underwent a four phase testing program to analyze the condition of Thermo-Lag 330-1 

utilized in the plant. Phase 1 involved testing and creating a set of acceptance criteria from the 

actual Thermo-Lag material used in fire, ampacity, and seismic testing. Phase 2 included 

chemical and physical material properties testing of previously procured Thermo-Lag 330-1 from 

circa 1985. Phase 3 involved additional procurement of Thermo-Lag during WBN fire barrier 

installation. Phase 4 included installation of 3-hour fire barrier material in the Watts Bar Nuclear 

Plant. Approximately 30 m (100 feet) of Thermo-Lag 770-1 was installed in the plant after being 

tested according to the criteria established in Phase 1. 

Testing performed by the TVA showed that Thermo-Lag 330-1 is reliable for use in WBNP and 

could be used to protect electrical raceways in 1-hour fire protection applications. NRC gave 
6-30 

notification on January 6, 1998 that the Watts Bar Nuclear Plant had sufficiently provided 

necessary information and performed the actions requested in GL 92-08 and action tracked by 

TAC number M85622. 

Letter dated January 6, 1998 provides the SER related to the ampacity derating of Thermo-Lag 

330-1 used in the WBN Unit 1. In that SER, the staff found that there are no significant safety 

hazards introduced with the use of ampacity test program results for cables enclosed by the 

subject Thermo-Lag fire barrier configurations at WBN Unit 1. 

TVA also performed a detailed chemical analysis program of the Thermo-Lag material used in 

WBN Unit 1. Its four phase test program included Thermogravimetric analysis (TGA) (an 

empirical test method which develops a control decomposition curve for materials. This 

analysis provides verification that samples possess equivalent ratios of compounds.), Infrared 

(IR) spectroscopy (IR is used to identify organic and inorganic compounds in a material, this 

analysis demonstrates the distinct wave lengths as absorbed by specific compounds in the 

material), density (density testing is used to determine the weight and consistency of the 

material), Board Sear Strength (used to provide additional assurance of reliable mechanical 

properties for seismic qualification). Phase 1 verify consistency between various batches of 

material used in actual fire, ampacity, and seismic qualification testing. Phase II verify new old 

stock material is acceptable for use and made of consistent properties. Phase III testing of 

material prior to installations. Phase IV testing of thermo-lag 770-1. 

6.65 Wolf Creek Generating Station, Units 1 and 2

Wolf Creek Generating Station (Wolf Creek) initially installed Thermo-Lag 330-1 type ERFBS to 

meet 10 CFR 50.48(a) requirements along with meeting the requirements of RG 1.75 physical 

independence of electrical system criteria. Approximately 675 linear feet of 1- and 3-hour 

Thermo-Lag 330-1 material was installed in cable trays and conduits in Wolf Creek to meet 

50.48(e) and about 810 linear feet is used to meet RG 1.75. Following issuance of GL 92-08, 

detailed discussion with NRC staff and with other industry licensees, Wolf Creek chose to 

replace the Thermo-Lag barriers with an alternate material instead of justifying the continued 

use of Thermo-Lag. Wolf Creek resolved these thermo-lag issues by one for four solutions, (1) 

re-analysis of safe shutdown to demonstrate barrier is not needed, (2) modify the plant such that 

barrier is no longer needed for safe shutdown, (3) re-route wrapped conduits and raceways, or 

(4) replace Thermo-Lag 330-1 with Darmatt KM-1 material. Thermo-Lag 330-1 barriers not 

removed were left installed in the plant and evaluated and added to the plant combustibility 

loading for applicable fire areas. By letter dated June 23, 2006, NRC concluded that based on 

the licensees May 31, 2006 letter responding to GL 06-03, “the fire barrier systems at Wolf 

Creek, that separate redundant safe shutdown trains located within the same fire area, have 

been designed and installed in accordance with current NRC guidance.” 

NRC issued an SER to Wolf Creek on April 6, 1998, stating that based on the staffs review, the 

licensees ampacity derating analysis results are acceptable and there are no significant hazards 

associated with the licensees’ ampacity derating methodology used at Wolf Creek. 

Wolf Creek sent five (5) samples of Thermo-Lag material they use in the plant to NUCON 

International, Inc. for Pyrolysis Gas Chromatography testing. The test results showed that all 

five samples are consistent in terms of chemical composition. 
7-1 

7. Summary of Findings 

(1) Use of ERFBS in NPPs is a direct result of the 1975 Brown Ferry Fire and the 

subsequent NRC fire protection regulations. The rush for NPPs to achieve 

compliance with the new regulation and wide use of ERFBS resulted in problems with 

proper testing, design, installation, maintenance, and ability of the barrier to perform 

its desired function. 

(2) If ERFBS are properly designed, tested, configured, installed, inspected, and 

maintained, there is reasonable assurance that they will provide the fire resistance of 

the tested configuration. 

(3) Plant specific deficiencies have been, and will continue to be found on occasion 

during routine licensee surveillances and NRC inspections. Fire protection defense in 

depth provides reasonable assurance that such deficiencies will not present an undue 

risk to the public health and safety. 

(4) A large number of fire endurance tests have established the fire-resistive capabilities 

of the ERFBS material, designs, and constructions installed in NPPs. The test results 

support the conclusion that the regulatory requirements can be met by these fire 

barrier systems. 

(5) Satisfactory NRC guidance on testing ERFBS, including performance, design, and 

acceptance criteria are available in Supplement 1 to GL 86-10. Availability of this 

guidance earlier would have eliminated many ERFBS problems identified in the past. 

(6) The potential problems that were raised about ERFBS have been addressed. The 

staff did not find safety-significant plant-specific problems nor did it find problems with 

potential generic implications. 

 
7-2 

This page intentionally left blank. 
8-1 

8. CONCLUSION 

The implementation of Appendix R and acceptable use of ERFBS has taken considerable time 

to ensure the adequate protection of the systems needed to safely shutdown a plant in 

response to a fire. The promulgation of the rule, publishing of guidance to the licensees, 

confirmatory testing, and ongoing maintenance and inspection demonstrated that the ERFBS 

installed in nuclear power plants are sufficient to maintain defense-in-depth when combined with 

other defense-in-depth measures. 

On the basis of the information found and assessed the staff concluded that the general 

condition of ERFBS used in industry is satisfactory. The staff did not find plant-specific 

problems of safety significance or concerns with generic implications. Even though the staff has 

concluded that the use of ERFBS in industry is satisfactory, it expects that plant-specific 

deficiencies will occasionally be found during future licensee surveillances and NRC 

inspections. However, likelihood of these occurrences is greatly reduced from the extensive 

historical testing and past NRC involvement with ERFBS issue resolution and clear NRC 

guidance. 

 
8-2 

This page intentionally left blank. 
9-1 

9. DEFINITIONS 

Ablation – the process of ablating, such as, surgical removal or by loss of part (as ice from a 

glacier or the outside of a nose cone) by melting or vaporization.[3]

Air Drop – lengths of electrical cable supported at each end with no use of continuous raceway 

support.[4]

Ampacity Derating Factor – A numeric value representing the fractional reduction from a base 

ampacity cable rating. Ampacity derating factors are associated with specific installation 

conditions.[2]

Ampacity Correction Factor – A numeric value equal to one minus the ampacity derating 

factor.[2]

Cable Tray – A raceway resembling a ladder (called ladder back) and usually constructed of 

steel or aluminum. Other styles of trays include solid-bottom and channel type. [2]

Combustible Material – Any material that will burn or sustain the combustion process when 

ignited or otherwise exposed to fire conditions. [1]

Compensatory Measures – interim step to restore operability or to otherwise enhance the 

capability of structures, systems, and components important to safety until the final 

corrective action is complete. [1]

Electrical Raceway Fire Barrier System – Non-load-bearing partition type envelope system 

installed around electrical components and cabling that are rated by test laboratories in 

hours of fire resistance and are used to maintain safe-shutdown functions free of fire 

damage. [1]

Endothermic – characterized by or formed with absorption of heat.[3]

Exothermic – characterized by or formed with evolution of heat.[3]

Fire Barrier – Those components of construction (walls, floors and their supports), including 

beams, joists, columns, penetration seals or closures, fire doors and fire dampers that 

are rated by approving laboratories in hours of resistance to fire and are used to prevent 

the spread of fire.[1]

Fire Resistance – The ability of an element of building construction, component, or structure to 

fulfill, for a stated period of time, the required load-bearing functions, integrity, thermal 

insulation, or other expected duty specified in a standard fire resistance test. [1]

Fire-Resistance Rating - The time that materials of a test assembly have withstood a standard 

ASTM E-119 fire exposure and have successfully met the established test acceptance 

criteria. [1]

Free of Fire Damage – the structure, system or component under consideration is capable of 

performing its intended function during and after the postulated fire, as needed. [1]
9-2 

Intumescence – the property of a material to swell when heated: intumescent materials in bulk 

and sheet form are used as fire-proofing agents. [3]

Noncombustible – material which in the form in which it is used and under the conditions 

anticipated, will not ignite, burn, support combustion, or release flammable vapors when 

subjected to fire or heat.[1]

Raceway - An enclosed channel of metal or nonmetallic materials designed expressly for 

holding wires, cables, or busbars, with additional functions as permitted by code. 

Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, 

intermediate metal conduit, liquid-tight flexible conduit, flexible metallic tubing, flexible 

metal conduit, electrical nonmetallic tubing, electrical metallic tubing, underfloor 

raceways, cellular concrete floor raceways, cellular metal floor raceways, surface 

raceways, wireways, and busways.[1]

Radiant Energy Shield (RES) – is a shield designed to provide protection from redundant 

essential raceways or fire safe shutdown equipment against the radiant energy from an 

exposure fire. RES are typically installed within containment. [1]

Standard Test Fire Exposure – Fire exposure as specified in ASTM E-119 or NFPA 251.[7]

Stress Skin – A pretreated open weave carbon steel mesh used to provide a mechanical base 

for application of Thermo-Lag 330-1 bulk grade material during manufacture of 

prefabricated thermo-Lag materials It is also used as a mechanism to externally 

reinforced joints and seams between the prefabricated Thermo-Lag materials forming 

protective envelops. [6]

Sublimation – The process by which solids are transformed directly to the vapor state or vise 

versa without passing through the liquid phase.[6]

Thermo-Lag – A water-based, thermally-activated fire-resistant coating that operates on the 

principle of sublimation with partial intumescences. The performance of the product is 

based on the integrated effect of sublimation, heat blockage derived from endothermic 

reaction and decomposition and increased thermal resistance of a char layer developed 

through intumescences and the effect or reradiating.[6]

Thermal-Short – A path (typically metallic) where heat from an external source (fire) can be 

conducted into the ERFBS and cause failure of the protected electrical component.[4]

Definition References: 

1. NRC Regulatory Guide 1.189, Rev. 1, “Fire Protection for NPPs,” March 2007. 

2. IEEE Standard 848-1996, “Standard Procedure for the Determination of the Ampacity 

Derating of Fire Protected Cables,” The Institute of Electrical and Electronics Engineers, 

Inc., 345 East 47th Street, New York, NY 10017-2394, USA. 

3. Merriam-Webster Dictionary, 2010 

4. Author, 2009 

5. NUREG-0800, SRP 9.5-1 

6. TVA Thermo-Lag 330-1 Design Standard 

7. GL 86-10 Supplement 1 
10-1 

10. REFERENCES 

1. NRC NUREG-1742, Vol. 1, “Perspectives Gained from the Individual Plant Examinations of 

External Events (IPEEE) Program,” April 2002. 

2. NRC NUREG-1778, Draft Report for Comment, “Knowledge Base for Post-Fire SafeShutdown Analysis,” January 2004 

3. NRC NUREG/CR-5088, “Fire Risk Scoping Study: Investigation of Nuclear Power Plant Fire 

Risk, Including Previously Unaddressed Issues,” January 1989. 

4. NRC NUREG/CR-6042, Rev. 2, “Perspective on Reactor Safety,” March 2002. 

5. NUREG/CR-0596, “A Preliminary Report on Fire Protection Research Program Fire Barriers 

and Suppression (September 15, 1978, Test).” 

6. NUREG-0800, “Standard Review Plan for the Review of Safety Analysis Reports for Nuclear 

Power Plants: LWR Edition,” March 2009. 

7. M.H. Salley, “An Examination of the Methods and Data Used to Determine Functionality of 

Electrical Cables When Exposed to Elevated Temperatures as a Results of a Fire in a 

Nuclear Power Plant,” University of Maryland Masters of Science Thesis, 2000, U.S. NRC 

(ADAMS Accession No. ML051450082). 

8. NRC Information Notice 84-09, “Lessons Learned From NRC Inspections of Fire Protection 

Safe Shutdown Systems (10 CFR 50, Appendix R),” February 13, 1984. 

9. NRC Generic Letter 86-10, “Implementation of Fire Protection Requirements,” April 24, 

1986. 

10. NRC Information Notice 91-47, "Failure of Thermo-Lag Fire Barrier Material to Pass Fire 

Endurance Test," August 6, 1991. 

11. NRC Information Notice 91-79, “Deficiencies Found in Thermo-Lag Fire barrier Installation,” 

December 6, 1991. 

12. NRC Information Notice 92-18, “Potential for Loss of Remote Shutdown Capability During a 

Control Room Fire,” February 28, 1992. 

13. NRC Information Notice 92-46, “Thermo-Lag Fire Barrier Review Team Findings, Current 

Fire Endurance Tests, and Ampacity Calculation Errors,” June 23, 1992. 

14. NRC Information Notice 92-46, Attachment 1, “Final Report – Special Review Team for the 

Review of Thermo-Lag Fire Barrier Performance,” April 21, 1992. 

15. NRC Bulletin 92-01, “Failure of Thermo-Lag 330 Fire Barrier System to Maintain Cabling in 

Wide Cable Trays and Small Conduits Free from Damage,” June 24, 1992. 
10-2 

16. NRC Information Notice 92-55, “Current Fire Endurance Test Results for Thermo-Lag Fire 

Barrier Material,” July 27, 1992. 

17. NRC Bulletin 92-01, Supplement 1, “Failure of Thermo-Lag 330 Fire barrier System to 

Perform its Specified Fire Endurance Function,” August 28, 1992. 

18. NRC Information Notice 92-82, “Results of Thermo-Lag 330-1 Combustibility Testing,” 

December 15, 1992. 

19. NRC Generic Letter 92-08, “Thermo-Lag 330-1 Fire Barriers,” December 17, 1992. 

20. NRC Information Notice 93-40, “Fire Endurance Test Results for Thermal Ceramics FP-60 

Fire Barrier Material,” May 26, 1993. 

21. NRC Information Notice 93-41, “One Hour Fire Endurance Test Results for Thermal 

Ceramics Kaowool, 3M Company FR-195 and 3M Company Interam E-50 Fire Barrier 

Systems,” May 28, 1993. 

22. NRC Information Notice 94-22, “Fire Endurance and Ampacity Derating Test Results for 3-

hour Fire Rated Thermo-Lag 330-1 Fire Barriers,” March 16, 1994. 

23. NRC Generic Letter 86-10, Supplement 1, “Fire Endurance Test Acceptance Criteria for Fire 

Barrier Systems Used to Separate Redundant Safe Shutdown Trains Within the Same Fire 

Area,” March 25, 1994. 

24. NRC Information Notice 94-22, “Thermo-Lag 330-660 Flexi-Blanket Ampacity Derating 

Concerns,” May 13, 1994. 

25. NRC Information Notice 91-79, Supplement 1, “Deficiencies Found in Thermo-Lag Fire 

barrier Installation,” dated August 4, 1994. 

26. NRC Information Notice 94-86, “Legal Actions Against Thermal Science, Inc., Manufacturer 

of Thermo-Lag,” December 22, 1994. 

27. NRC Information Notice 95-27, “NRC Review of Nuclear Energy Institute, Thermo-Lag 330-1 

Combustibility Evaluation Methodology Plant Screening Guide,” .May 31, 1995. 

28. NRC Information Notice 95-32, “Thermo-Lag 330-1 Flame Spread Test Results,” August 10, 

1995. 

29. NRC Information Notice 95-49, “Seismic Adequacy of Thermo-Lag Panels,” October 27, 

1995. 

30. NRC Information Notice 95-52, “Fire Endurance Test Results for Electrical Raceway Fire 

Barrier Systems Constructed from 3M Interam Fire Barrier Materials,” November 14, 1995 

31. NRC Information Notice 94-86, Supplement 1, “Legal Actions Against Thermal Science, Inc., 

Manufacturer of Thermo-Lag,” November 15, 1995. 

32. NRC Information Notice 97-59, “Fire Endurance Test Results of Versawrap Fire Barriers,” 

August 1, 1997. 
10-3 

33. NRC Information Notice 95-49, Supplement 1, Seismic Adequacy of Thermo-Lag Panels,” 

December 10, 1997. 

34. NRC Information Notice 95-52, Supplement 1, “Fire Endurance Test Results for Electrical 

Raceway Fire Barrier Systems Constructed from 3M Interam Fire Barrier Materials,” 

March 17, 1998. 

35. NRC Information Notice 2005-07, “Results of Hemyc Electrical Raceway Fire Barrier System 

Full Scale Fire Testing,” dated April 1, 2005. (ADAMS Accession No. ML050890089) 

36. NRC Generic Letter 2006-03, “Potentially Nonconforming Hemyc and MT Fire Barrier 

Configurations,” April 10, 2006. 

37. SECY 83-269, “Fire Protection Rules for Future Plants,” July 5, 1983. 

38. NRC SECY-99-204, “Kaowool and FP-60 Fire Barriers,” August 4, 1999. (NUDOCS 

Accession No. 9909140100) 

39. SECY-94-127, SECY-94-128, “Staff Requirements – Briefing on Status of Thermo-Lag 

(SECY-94-127, SECY 94-128), 10:00 A.M., Friday, May 20, 1994, Commissioners’ 

Conference Room, One White Flint North, Rockville, Maryland (Open to Public 

Attendance),” dated May 26, 1994. (NUDOCS Accession No. 9406010141) 

40. SECY-96-012, “Weekly Information Report – For the Weeks Ending January 5 and January 

12, 1996,” dated January 18, 1996. 

41. OIG Inspection Report, “Inspection of NRC Staff’s Acceptance and Review of Thermo-Lag 

330-1 Fire Barrier Material,” dated August 12, 1992, US NRC (NUDOCS Accession No. 

9209250301) 

42. NRC Regulatory Guide 1.189, Rev. 1, “Fire Protection for NPPs,” March 2007. 

43. NRC Appendix A to Branch Technical Position APCSB 9.5-1, “Guidelines for Fire Protection 

for NPPs Docketed Prior to July 1, 1976,” August 23, 1976. 

44. Sandia Report, SAND94-0146, “An Evaluation of the Fire Barrier System Thermo-Lag 

330-1,” Steven P. Nowlen, Steven Ross, September 1994. 

45. NRC Technical Report, “Re-assessment of NRC Fire Protection Program,” February 27, 

1993. (NUDOCS Accession No. 9504190313) 

46. SFPE Handbook of Fire Protection Engineering, 4th ed., Society of Fire Protection 

Engineers, Quincy, Massachusetts, 02269, 2008. 

47. American Nuclear Insurers, ANI Information Bulletin #5 (79), “ANI/MAERP Standard Fire 

Endurance Test Method To Qualify a Protective Envelope for Class 1E Electrical Circuits,” 

July 1979. 

48. American Society for Testing and Materials, Standard E-119, “Standard Test Methods for 

Fire Tests of Building Construction and Materials.” 
10-4 

49. Underwriter Laboratories (UL) Standard Subject 1724, “Outline of Investigation for Fire Tests 

for Electrical Circuit Protection Systems.” 

50. American Society for Testing and Materials, Standard E-136, “Standard Test Method for 

Behavior of Materials in a Vertical Tube Furnace at 750 degree C.” 

51. American Society for Testing and Materials, Standard E-84, “Standard Test Method for 

Surface Burning Characteristics of Building Materials.” 

52. Letter from Robert M. Latta (U.S. NRC) to D.L. Farrar (Commonwealth Edison Company), 

“Safety Evaluation of 1-hour Fire-Rated Darmatt KM-1 Fire Barrier System Application at the 

LaSalle County Station,” dated November 20, 1995. (NUDOCS Accession No. 9511270272) 

53. Letter from J.C. Linville (U.S. NRC) to O.D. Kingsley (Exelon Generation Company, LLC), 

“NRC Triennial Fire Protection Inspection Report No. 50-352/01-14, 50-353/01-14,” dated 

January 7, 2002. (ADAMS Accession No. ML020080162) 

54. Letter from D.M. Skay (U.S. NRC) to O.D. Kingsley (Commonwealth Edison Company), 

“Closure of ampacity derating issues for fire barriers at Lasalle County Station, Units 1 and 2 

(TAC NOS. MA3323 and MA 3324)” dated December 22, 1999. (ADAMS Accession No. 

ML993620265) 

55. Letter from B.C. Buckley (U.S. NRC) to J.A. Hutton (PECO Energy Company), “Safety 

Evaluation Addressing Thermo-Lag Related Ampacity Derating Issues, Peach Bottom 

Atomic Power Station, Units 2 and 3, and Limerick Generating Station, Units 1 and 2 (TAC 

NOS. MA3404, MA3405, MA3872, and MA3873)” (ADAMS Accession No. ML003677255) 

56. Letter from E.E. Fitzpatrick (Indiana Michigan Power) to U.S. NRC, “Donald C. Cook Nuclear 

Plant Units 1 and 2 Response to Generic Letter (GL) 92-08, Thermo-Lag 330-1 Fire 

Barriers,” dated December 27, 1996. (NUDOCS Accession No. 9701060108) 

57. Letter from M.A. Peifer (Indiana Michigan Power) to U.S. NRC, “Donald C. Cook Nuclear 

Plant Units 1 and 2 60 Day Response To Nuclear Regulatory Commission Generic Letter 

2006-03: Potentially Nonconforming Hemyc And Mt Fire Barrier Configurations,” dated 

June 1, 2006. (ADAMS Accession No. ML061600213) 

58. Letter from J.F. Stang (U.S. NRC) to R.P. Powers (Indiana Michigan Power), “Completion of 

Licensing Action for Generic Letter 92-08, ‘Thermo-Lag 330-1 Fire Barriers’ for Donald C. 

Cook Nuclear Power Plant Units Nos. 1 and 2, TAC Nos. M85538 and M85539.” (NUDOCS 

Accession No. 9808310265) 

59. Letter from J.N. Hannon (U.S. NRC) to P. Gunter (Nuclear Information and Resource 

Service), “Completion Status for the 1998 Thermo-Lag 330-1 Confirmatory Orders (TAC No. 

MC2248),” dated April 23, 2004. (ADAMS Accession No. ML041120065) 

60. Letter from A. Marion (NEI) to J.N. Hannon (NRC), “Promatec Hemyc 1-hour and MT 3-hour 

Fire Barrier Systems,” dated April 25, 2001. (ADAMS Accession No. ML011220179) 

61. NRC Inspection Report No. 50-400/99-13, “Fire Protection Inspection,” dated February 3, 

2000. (ADAMS Accession No. ML003685341) 
10-5 

62. Inspection Report No. 50-369/00-09 & 50-370/00-09, “McGuire Nuclear Station – NRC 

Inspection Report,” dated December 15, 2000 (ADAMS Accession No. ML003778709) 

63. Letter from A.Marion (NEI) to J.N. Hannon (NRC), “Promatec Hemyc 1-hour and MT 3-hour 

Fire Barrier Systems,” dated April 25, 2001 (ADAMS Accession No. ML011220179) 

64. Memorandum from D.C. Lew (NRC) to J. Hannon (NRC), “Preliminary Pass/Fail Test 

Results for Hemyc 1-hour Rated Electrical Raceway Fire Barrier Systems,” Dated March 28, 

2005 (ADAMS Accession No. ML050880176) 

65. NRC Confirmatory Fire Performance Testing of Hemyc and MT ERFBS Test Reports and 

Related Documentation, dated April 29, 2005. (ADAMS Accession No. ML051190026) 

66. Meeting Summary (US NRC), Summary of Meeting to Discuss Kaowool and FP-60 Fire 

Barriers, dated January 5, 2000 (ADAMS Accession No. ML003673753) 

67. NRC Safety Evaluation (US NRC), “Safety Evaluation by The Office of Nuclear Reactor 

Regulation Related to Amendment No. 170,” dated September 26, 2006. 

68. Licensee Event Report 1999-014-03, “Kaowool Fire Barrier Outside 10 CFR 50 Appendix R 

Design Basis,” dated May 17, 2006. (ADAMS Accession No. ML061420145) 

69. Memorandum from E.W. Weiss (NRC) to R. Emch (NRC), “Review of Virgil C. Summer 

Nuclear Station Testing of Kaowool Fire Barrier Systems on December 28, 1999,” dated 

November 6, 2000. (ADAMS Accession No. ML003766962) 

70. NRC letter and SER, G.S. Vissing to M. Kansler (Entergy), James A. FitzPatrick Nuclear 

Power Plant, “Exemption from Certain Requirements of Section III.G.2.c of Appendix R to 10 

CFR 50,” dated May 29, 2001. (TAC No. MB0395) (ADAMS Accession No. ML010790125) 

71. Test Report provided by Southern California Edison (SCE), “Test for fire protection for 

complete fire engulfment of cable trays and conduits containing grouped electrical 

conductors,” report date October 24, 1978. (NUDOCS Accession No. 8403220024) 

72. NRC letter to South Carolina Electric & Gas, “Review of Virgil C. Summer Nuclear Station 

Testing of Kaowool Fire Barrier Systems on December 28, 1999 (TAC No. MA9190),” dated 

February 20, 2001. (ADAMS Accession No. ML010510405) 

73. NRC Letter to Florida Power Corporation, “Crystal River Nuclear Generating Plant Unit 3 – 

Review Of Report On Test Of Mecatiss Fire Barrier Material In Morestel, France, December 

1994 (TAC No. M91772),” dated April 7, 1995. (NUDOCS Accession No. 9504140139) 

74. Letter from to US NRC, from FPC, “Report on Test of Mecatiss Fire Barrier Material in 

Morestel France, December 1994,” dated March 6, 1995. (NUDOCS Accession No. 

9503130329) 

75. Letter from G.L. Boldt (FPC) to US. NRC, “Response to NRC Staff Questions on Test of 

Mecatiss Fire Barrier Material in Morestel France, December 1994,” dated May 17, 1995. 

(NUDOCS Accession No. 9505240353) 
10-6 

76. Letter from FPC, to US NRC, “Mecatiss Fire Barrier Endurance Test Results,” dated March 

30, 1996. (NUDOCS Accession No. 9604030021) 

77. Safety Evaluation of Mecatiss Fire Barrier Test Program (TAC No. M91772), dated January 

29, 1997 (NUDOCS Accession No. 9701310024) 

78. Meeting Summary, “Summary Of Meeting on February 28, 1995, Regarding Thermo-Lag 

Resolution Issues,” March 10, 1995. (NUDOCS Accession No. 9503160355) 

79. Memorandum from E. Connell and P. Madden to K.S. West, “trip to underwriters laboratories 

(UL) – Florida Power Corporation Mecatiss Fire barrier fire endurance testing program (TAC 

No. M91772),” dated July 16, 1996. (NUDOCS Accession No. 9701140282) 

80. NRC Inspection Report, “Fort Calhoun Station – NRC Triennial Fire Protection Inspection 

Report 05000285/2008009,” dated September 24, 2008. (ADAMS Accession No. 

ML082690060) 

81. NRC Inspection Report, “Surry Power Station- NRC Triennial Fire Protection Inspection 

Report 05000280/2006009 and 05000281/2006009,” dated August 11, 2006. (ADAMS 

Accession No. ML062260007) 

82. NRC Inspection Report, “NRC Inspection Report 50-275/97-17; 50-323/97-17 and Notice of 

Violation,” dated October 29, 1997. (NUDOCS Accession No. 9711050064) 

83. Letter from D.P. Dise (Niagra Mohawk Power Corporation) to T.A. Ippolito (NRC), “Submittal 

of ITL testing report of Pyrocrete,” dated August 11, 1980. (NUDOCS Accession No. 

8008180498) 

84. Letter from D.P. Dise (Niagra Mohawk Power Corporation) to T.A. Ippolito (NRC), “Submittal 

of Vendor Report on Thermal Transmission of Pyrocrete 241 at Varying Thicknesses,” dated 

April 17, 1979. (NUDOCS Accession No. 8005090346) 

85. Fire Endurance Test, “Omega Point Fire Endurance Test of Versawrap Raceway Fire 

Barrier Systems for Conduits and Cable Trays,” dated April 29, 1998. 

(http://www.nofire.com/approvals/TechManual_Aircraft_Nuclear_Utility.pdf) 

86. Darchem Engineering, “Darchem Thermal Protection Brochure,” Stillington, United Kingdom. 

http://www.esterline.com/Portals/8/Darchem/PDF/DTP_Brochure.pdf 

87. SwRI Test Report 1208-001, “Nuclear Component Qualification Test Report for the Generic 

Seismic Qualification of 3M Interam E-50D 3-hour Fire Protection System,” dated July 1986 

(NUDOCS Accession No. 9308040186) 

88. SwRI Test Report Project No. 01-7912(2), “Qualification Fire Test of a Protective Envelope 

System,” dated June 1985. (NUDOCS Accession No. 9308040254) 

89. IEEE Standard 848-1996, “Standard Procedure for the Determination of the Ampacity 

Derating of Fire Protected Cables,” The Institute of Electrical and Electronics Engineers, 

Inc., 345 East 47th Street, New York, NY 10017-2394, USA. 
10-7 

90. Memorandum from T.E. Murley (Director NRR) to all 5 regional administrators, “Staff Review 

of Responses to NRC Bulletin 92-01 – Failure Of Thermo-Lag 330 Fire Barrier System,” 

dated September 21, 1992. (NUDOCS Accession No. 9209300154) 

91. Letter from John N. Hannon (U.S. NRR) to Paul Gunter (Reactor Watchdog Project), 

“Completion Status for the 1998 Thermo-Lag 330-1 Confirmatory Orders (TAC No. 

MC2248),” dated April 23, 2004. (ADAMS Accession No. ML041120065) 

92. Letter from C.E. McCracken (U.S. NRC) to A.C. Thadani (U.S. NRC) ‘’Results of ThermoLag 330 Combustibility Testing Performed by NIST, Report of Test FR 3989,” dated October 

8, 1992. (NUCOCS Accession No. 9210190176) 

93. Letter from C.E. McCracken (U.S. NRC) to A. Marion (NEI), “Concludes that NRC Staff Will 

Not Accept use of NEI Application Guide to Justify use of Thermo-Lag Materials where 

Noncombustible Materials Specified by NRC Regulations,” dated March 13, 1995. 

(NUDOCS Accession No. 9503200111) 

94. Promatec Procedure IP-8400, “Fabrication of INSULCO/HEMYC Cable Protection System 

Components,” dated March 7, 1985. (NUDOCS Accession No. 9308270288) 

95. Meeting Summary, “Summary Of November 19, 1993, Meeting Between NRC Staff And 

NUMARC On Industry Thermo-Lag Fire Barrier Test Program,” dated December 1, 1993. 

(NUDOCS Accession No. 9312130295) 

96. Letter from R.P. Zimmerman (U.S. NRC) to C.K. McCoy (Georgia Power Company), 

“Follow-up To The Request For Additional Information Regarding Generic Letter 92-08, 

Issued Pursuant To 10 CFR 50.54(F),” dated December 30, 1994. (NUDOCS Accession No. 

9501100141) 

97. Memorandum from Commissioner I. Selin (U.S. NRC) to J.M. Taylor (U.S. NRC), “Inspector 

General’s Inspection of the NRC Staff’s Acceptance and Review of Thermo-Lag 330-1 Fire 

Barrier Material,” dated August 17, 1992. (NUDOCS Accession No. 9209250291) 

98. Letter from L.J. Callan (NRC) to T.E. Murley (NRC), “Request for additional information 

regarding generic letter 92-08, ‘thermo-lag 330-1 fire barriers’,” dated December 20, 1993 

(NUDOCS Accession No. 9401050138) 

99. Letter from L.J. Callan (NRC) to R.A. Stratman (Centerior Service Company), “Request For 

Additional Information Regarding Generic Letter 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’ 

Pursuant to 10 CFR 50.54(f),” dated December 20, 1993. (NUDOCS Accession No. 

9312300259) 

100. Letter from Commonwealth Edison Co. to U.S. NRC, “Response to NRC Request for 

Additional Information Regarding Fire Testing of the Darmatt KM-1 Fire Protection 

System,” dated June 2, 1995. (NUDOCS Accession No. 9506080643) 

101. Memorandum from S. West (U.S. NRC) to L.B. March (U.S. NRC), “Trip Report – Trip to 

UL to observe three hour fire test of one and three hour Versawrap raceway fire barrier 

systems,” dated May 9, 1997. (NUDOCS Accession No. 9705130324) 
10-8 

102. Transco Procedure No. TIOAP 9.20 for installation of KM-1 Fire Barrier Systems for 

Electrical Raceway Systems. (NUDOCS Accession No. 9501050344) 

103. Letter from Commonwealth Edison Co. to U.S. NRC, “Corporate Quality Verification Dept 

Audit G-94-80, addressing Thermo-Lag Test Program,” dated September 8, 1994. 

(NUDOCS Accession No. 9409130203) 

104. Trip Report from D. Oudinot to K.S. West, “Trip Report Concerning Fire Endurance 

Testing of Darmatt KM-1 Fire Barrier Systems,” dated February 14, 1996. (NUDOCS 

Accession No. 9602150357) 

105. Letter from K.R. Cotton (U.S. NRR) to Steve Byrne (South Carolina Electric & Gas Co.), 

“Review of Virgil C. Summer Nuclear Station Testing of Kaowool Fire Barrier Systems on 

December 28, 1999 (TAC No. MA9190),” dated February 20, 2001. (ADAMS Accession 

No. ML010510405) 

106. Letter from J.B. Archie (South Carolina Electric & Gas) to U.S. NRC, “Virgil C. Summer, 

60-Day Response to NRC Generic Letter 2006-03: Potentially Non-Conforming Hemyc 

and MT Fire Barrier Configurations,” dated June 5, 2006. (ADAMS Accession No. 

ML061590311) 

107. Letter from J.B. Archie (South Carolina Electric & Gas) to U.S. NRC, “Virgil C. Summer, 

60-Day Response to NRC Generic Letter 2006-03: Potentially Non-Conforming Hemyc 

and MT Fire Barrier Configurations – Request for Additional Information,” dated August 4, 

2006. (ADAMS Accession No. ML062220348) 

108. U.S. NRC, “Edwin I. Hatch Nuclear Power Plant – NRC Triennial Fire Protection 

Inspection Report 05000321/2006006 and 05000366/2006006,” dated May 31, 2006 

(ADAMS Accession No. ML061520335) 

109. Letter from C.E. McCracken (U.S. NRC) to A. Marion (NEI), “NEI Application Guide for 

Evaluation of Thermo-Lag 330 Fire Barrier Systems,” dated October 16, 1995 (NUDOCS 

Accession No. 9510250078) 

110. Letter from Union Electric to NRC, “Darmatt Qualification Tests,” February 26, 1997 

(NUDOCS Accession No. 9703100121) 

111. Faverdale Technology Centre, “Test report for a 1 hour fire hose stream tests on Darmatt 

KM1 fire protection systems to ASTM E119 NRC GL 86/10 Supplement 1,” dated January 

9, 1994. (NUDOCS Accession No. 9801270098) 

112. Letter From T.S.O’Neil (Exelon Generation Company, LLC) to U.S. NRC, “60-Day 

Response to Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc and MT Fire 

Barrier Configurations,’” dated June 6, 2006. (ADAMS Accession No. ML061640343) 

113. Letter from J.E. Booker (Gulf States Utilities Company) to U.S. NRC, “NRC Bulleting 92-

01, Supplement 1,” dated April 14, 1993. (NUDOCS Accession No. 9304200036) 

114. Letter and SE, “River Bend Station, Unit 1 – Thermo-Lag Related Ampacity Derating 

Issues,” dated November 15, 1999. (ADAMS Accession No. ML993350552) 
10-9 

115. Letter from R.J. King (Entergy) to U.S. NRC, “NRC Generic Letter 2006-03, dated April 10, 

2006, "Potentially Nonconforming Hemyc and MT Fire Barrier Configurations",” dated June 

1, 2006. (ADAMS Accession No. ML061570394) 

116. Letter from R.J. King (Entergy Operations, Inc.) to U.S. NRC, “Supplemental Response to 

Request for Additional Information (re: Ampacity Derating), Generic Letter 92-08,” dated 

June 28, 1996. (NUDOCS Accession No. 9607080463) 

117. Letter from Duquesne Light Company to U.S. NRC, “Response to Request for Additional 

Information for BVPS Unit No. 1, NRC Generic Letter 92-08, “Thermo-Lag 330-1 Fire 

Barriers,” dated March 21, 1994. (NUDOCS Accession No. 9403280372) 

118. Beaver Valley Power Station – NRC Inspection Report 50-344/02-04, 50-412/02-04, dated 

May 30, 2005. (ADAMS Accession No. ML021510069) 

119. Letter from J.F. Lucas (Progress Energy) to U.S. NRC, “Response To NRC Generic Letter 

2006-03, "Potentially Nonconforming Hemyc Ant) Mt Fire Barrier Configurations’,” dated 

June 08, 2006. (ADAMS Accession No. ML061640136) 

120. H.B. Robinson Steam Electric Plant - NRC Triennial Fire Protection Inspection Report 

05000261/2007007 and Exercise of Enforcement Discretion, December 20, 2007. 

(ADAMS Accession No. ML073620541) 

121. Letter from J.A. Stall (Florida Power and Light Company) to U.S. NRC, “Potentially 

Nonconforming Hemyc and MT Fire Barrier Configurations,” dated June 9, 2006. (ADAMS 

Accession No. ML061640269) 

122. Letter from J.A. Stall (Florida Power and Light Company) to U.S. NRC, “Generic Letter 

92-08 Corrective Actions,” dated June 23, 1998. (NUDOCS Accession No. 9806290310) 

123. Letter from C.O. Thomas (U.S. NRC) to T.F. Plunkett (Florida Power and Light Company), 

“Closeout Report For The Ampacity Derating Issues Related To Generic Letter 92-08, 

‘Thermo-Lag 330-1 Fire Barriers’ – St. Lucie Plants, Units 1 And 2, And Turkey Point, 

Units 3 And 4.” Dated March 26, 1999. (NUDOCS Accession No. 9904020172) 

124. Letter from A.E. Scherer (Southern California Edison) to U.S. NRC, “Response to Request 

for Additional Information on Response to Generic Letter 2006-03,” dated June 18, 2007. 

(ADAMS Accession No. ML071710548) 

125. Letter from G.St. Pierre (FPL Energy Seabrook, LLC) to U.S. NRC, “Response to Request 

for Additional Information Regarding Resolution of Generic Letter 2006-03, Potentially 

Nonconforming Hemyc and MT Fire Barrier Configurations,” dated July 10, 2007. (ADAMS 

Accession No. ML071990101) 

126. Letter from T.C. Feigenbaum (North Atlantic Energy Service Corporation) to U.S. NRC, 

“Response to Generic Letter 92-08 (TAC NO. 85603),” dated March 31, 1993. (NUDOCS 

Accession No. 9304130290) 

127. Letter from P. Salas (TVA) to U.S, “Sequoyah Nuclear Plant (SQN) – Final Closeout 

Regarding Resolution of Thermo-Lag 330-1 Fire Barrier Upgrades,” dated June 30, 1999. 

(NUDOCS Accession No. 9907080120) 
10-10 

128. Letter from S.E. Thomas (Houston Light & Power Company) to U.S. NRC, “Closure of 

Thermo-Lag Concerns at the South Texas Project,” dated February 8, 1999. (NUDOCS 

Accession No. 9902120175) 

129. Letter from U.S. NRC to W.T. Cottle (Houston Lighting & Power Company), “Completion of 

licensing action for generic letter 92-08, Thermo-Lag 330-1 fire barriers,” dated April 4, 

1997. (NUDOCS Accession No. 9704080234) 

130. Letter from S.L.Rosen (Houston Light & Power Company) to U.S. NRC, “Thermo-Lag 330-

1 Fire Barriers,” dated April 16, 1993. (NUDOCS Accession No. 9304190275) 

131. Letter from J.L. Skolds (SCE&G) to U.S. NRC, “Response to NRC Generic Letter 92-08 

Thermo-Lag 330-1 Fire Barriers,” dated February 17, 1993. (NUDOCS Accession No. 

9302230141) 

132. Letter from L.M. Padovan (U.S. NRC) to G.J. Taylor (Sothern Carolina Electric Company), 

“Thermo-Lag Related Ampacity Derating Issues and Completion Of Licensing Action For 

Generic Letter (GL) 92-08,” dated May 5, 1998. (NUDOCS Accession No. 9805080208) 

133. NRC letter and SE, “Thermo-Lag Related Ampacity Derating Issues and Completion of 

Licensing Action for Generic Letter (GL) 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’ for Virgil 

C. Summer Nuclear Station,” dated May 5, 1998. (NUDOCS Accession No. 9805080208) 

134. Letter from G.T. Bischof (Virginia Electric and Power Co.) to U.S. NRC, “Kewaunee Unit 1, 

Millstone Units 2 & 3, North Anna Units 1 & 2, Surry Units 1 & 2, Generic Letter 2006-03, 

“Potentially Non-Conforming HEMYC and MT Fire Barrier Configurations, “Response to 

Request for Additional Information,” dated May 31, 2007. (ADAMS Accession No. 

ML071520515) 

135. Letter from U.S. NRC to J.P. O’Hanlon (Virginia Electric and Power Company), 

“Completion of Licensing Action for Generic Letter 92-08, ‘Thermo-Lag 330-1 Fire 

Barriers,’ for Surry Power Station Units 1 & 2,” dated May 14, 1997. (NUDOCS Accession 

No. 9705190306) 

136. Letter from R.E. Martin (U.S. NRC) to O.J. Zeringue (TVA), “Completion Of Licensing 

Action For Generic Letter 92-08, ‘Thermo-Lag 330-1 Fire Barriers,” And Supplemental 

Safety Evaluation Report On Ampacity Issues Related To Thermo-Lag Fire Barriers For 

Watts Bar Nuclear Plant, Unit 1. (NUDOCS Accession No. 9804090170) 

137. Letter from D.V. Kehoe (TVA) to U.S. NRC, “Watts Bar Nuclear Plant, Request for 

Additional Information (RAI) Regarding GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers’,” dated 

December 18, 1995 (ADAMS Accession No. ML072890454) 

138. Letter from R.R. Baron (TVA) to U.S. NRC, “Response to RAI Regarding GL 92-08, 

‘Thermo-Lag Fire Barriers’,” dated March 22, 1995. (NUDOCS Accession No. 

9503310004) 

139. Letter and SE, “Completion of Licensing Actions for Generic Letter 92-08 and 

Supplemental Safety Evaluation Report on Ampacity Issues Related to Thermo-Lag Fire 
10-11 

Barriers for Watts Bar Nuclear Plant, Unit 1,” dated January 6, 1998. (ADAMS Accession 

No. ML073240205) 

140. J.A. Fitzpatrick Nuclear Power Plant Exemption from the Requirements of 10 CFR Part 50, 

Appendix R, dated September 27, 2008. (ADAMS Accession No. ML062190377) 

141. Letter from L.M. Stinson (Southern Company) to U.S. NRC, “NRC Generic Letter 2006-03 

Response,” dated June 9, 2006. (ADAMS Accession No. ML061600376) 

142. Letter from M. Stevins (Luminant) to U.S. NRC, “Additional Information Provided 

Regarding NRC Generic Letter 2006-03, “Potentially Nonconforming Hemyc and MT Fire 

Barrier Configurations,” dated December 20, 2007. (ADAMS Accession No. 

ML073620447) 

143. Letter from D.W. Coleman (Energy Northwest) to U.S. NRC, “Completion of Thermo-Lag 

330-1 Fire Barrier Corrective Actions,” dated January 19, 2000. (ADAMS Accession No. 

ML003678400) 

144. Letter from J.V. Parrish (WPPSS) to U.S. NRC, “Changes to Thermo-Lag 330-1 

Resolution Plan,” dated September 26, 1997. (ADAMS Accession No. ML041320336) 

145. NRC Triennial Fire Protection Inspection Report 05000445/2008/006 and 

05000446/2008006, Comanche Peak Steam Electric Station Units 1 and 2, dated July 3, 

2008. (ADAMS Accession No. ML081890579) 

146. Letter from K.D. Young (Ameren UE) to U.S. NRC, “Supplemental Information for the 60-

day Response to NRC Generic Letter 2006-03,” dated July 17, 2006. (ADAMS Accession 

No. ML062060383) 

147. Letter from G.F. Dick (U.S. NRC) to O.D. Kingsley (Commonwealth Edison Group), 

“Thermo-Lag Related Ampacity Derating Issues, Byron Station, Units 1 and 2, and 

Braidwood Station, Units 1 and 2,” dated November 2, 1999. (ADAMS Accession No. 

ML993200165) 

148. Safety Evaluation Related to Generic Letter 92-08 Ampacity Derating Issues Byron Station 

Units 1 and 2, Braidwood Station Units 1 and 2, dated November 2, 1999. (ADAMS 

Accession No. ML993200165) 

149. Letter for T.W. Alexion (U.S. NRC) to J.W. Yelverton (Entergy Operations, Inc.), 

“Response to NRC Bulleting 92-001, Supplement 1, ‘Failure of Thermo-Lag 330 Fire 

Barrier System’”, dated January 22, 1993. (NUCOCS Accession NO. 9301270011) 

150. Letter from G. Kalman to U.S. NRC, “Response to GL 92-08, Regarding Configurations 

and Amounts of Thermo-Lag Fire Barriers Installed in Plant and Cable Loading,” dated 

June 21, 1994. (NUDOCS Accession No. 9406270024) 

151. Letter from T.A. Marlow (Entergy Operations, Inc.) to U.S. NRC, “Response to Generic 

Letter 2006-03, Potentially Nonconforming Hemyc and MT Fire Barrier Configurations,” 

dated June 7, 2006. (ADAMS Accession No. ML061720459) 
10-12 

152. Letter from D. Holland (U.S. NRC) to J.S. Forbes (Entergy Operations, Inc.), “Evaluation of 

Arkansas Nuclear One, Units 1 and 2, Response to Generic Letter 2006-03, ‘Potentially 

Nonconforming Hemyc and MT Fire Barrier Configurations’,” dated September 29, 2006. 

(ADAMS Accession No. ML062620115) 

153. Letter from J.D. Sieber (Duquesne Light Company) to U.S. NRC, “Provides Response to 

Request for Additional Info. Re. GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’” dated March 

21, 1994. (NUDOCS Accession No. 9403280372) 

154. Beaver Valley Power Station – NRC Inspection Report 50-344/02-04, 50-412/02-04, dated 

May 30, 2005. (ADAMS Accession No. ML021510069) 

155. Letter from G.S. Thomas (Duquesne Light Company) to U.S. NRC, “Response to NRC 

Follow-up to Request for Additional Info. Re. GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’ 

for BVPS Unit 2,” dated December 22, 1994. (NUDOCS Accession No. 9412300237) 

156. Letter from Duquesne Light Company to U.S. NRC, “Response to Request for Additional 

Information Regarding Generic Letter 92-08, ‘Thermo-Lag 330-1 Fire Barrier’,” dated 

December 22, 1994 (NUDOCS Accession No. 9412290093) 

157. Letter from D.J. Chrzanowski (Commonwealth Edison) to T.E. Murley (U.S. NRC), 

“Forwards Response to GL 92-08, Thermo-Lag 330-1 Fire Barriers,” dated April 16, 1993. 

(NUDOCS Accession No. 9304260035) 

158. Letter from K.L. Kaup (Commonwealth Edison) to U.S. NRC, “Braidwood Station Status 

Update of Thermo-Lag (GL 92-08) Issues,” dated September 25, 1995. (NUDOCS 

Accession No. 9510020266) 

159. Letter from G.F. Dick, Jr. (U.S. NRR) to I.M. Johnson (Commonwealth Edison), 

“Completion of Licensing Action for GL 92-08 – Braidwood Station, Units 1 and 2,” dated 

May 13, 1997. (NUDOCS Accession No. 9705150355) 

160. Letter from D.M. Benyak (AmerGen Energy, Exelon Generation Company, LLC) to U.S. 

NRC, “Additional Info. Supporting the 60-Day Response to Generic Letter 2006-03, 

Potentially Nonconforming Hemyc and MT Fire Barrier Configurations,” dated May 31, 

2007. (ADAMS Accession No. ML071520085) 

161. Letter from G.W. Morris (Tennessee Valley Authority) to U.S. NRC, “Browns Ferry, 

Sequoyah, Watts Bar, Potentially Non-Conforming Hemyc and MT Fire Barrier 

Configurations – 60 Day Response,” dated June 7, 2006. (ADAMS Accession No. 

ML061600208) 

162. Letter from D.E.Martin (Office of Nuclear Materials Safety and Safeguards) to S.A. Toelle 

(U.S. Enrichment Corporation), “Response: Request for Additional Information,” dated May 

31, 2006. (ADAMS Accession No. ML061500208) 

163. Letter from R.D. Machon (Tennessee Valley Authority) to U.S. NRC, “Response: Request 

for Additional Information Regarding Generic Letter (GL) 92-08, Thermo-Lag 330-1 Fire 

Barriers,” dated March 22, 1995. (NUDOCS Accession No. 9503290089) 
10-13 

164. Letter from W.O. Long (U.S. NRC) to J.A.Scalice (Tennessee Valley Authority), “Forwards 

SE Which Constitutes Staff Review and Approval of TVA Ampacity Derating Test and 

Analyses for Thermo-Lag Fire Barrier Configurations,” dated July 16, 1999. (NUDOCS 

Accession No. 9907210115) 

165. Letter from D.V. Kehoe (Tennessee Valley Authority) to U.S. NRC, “Results of ThermoLag Testing and Notified NRC that Work Associated with Thermo-Lag Completed for 

Facility, Per GL 92-08,” dated December 18, 1995. (ADAMS Accession No. 

ML072890454) 

166. Letter from R.R. Baron (Tennessee Valley Authority) to U.S. NRC, “WBN – Request for 

Additional Information Regarding Generic Letter (GL 92-08), Thermo-Lag 330-1 Fire 

Barriers,” dated March 22, 1995. (NUDOCS Accession No. 9503310004) 

167. Letter from R.E. Martin (U.S. NRC) to O.J. Zeringue (Tennessee Valley Authority), 

“Completion of Licensing Action for GL 92-08, Thermo-Lag 330-1 Fire Barriers and 

Supplemental Safety Evaluation Report on Ampacity Issues Related to Thermo-Lag Fire 

Barriers for Watts Bar Nuclear Plant Unit 1,” dated January 6, 1998. (ADAMS Accession 

No. ML073240205) 

168. Letter from Carolina Power and Light to U.S. NRC, “Request for Additional Information 

Regarding Generic Letter 92-08, ‘Thermo-Lag 3301-1 Fire Barrier,’ Pursuant to 10 CFR 

50.54(F) – Brunswick Steam Electric Plant, Units 1 and 2, and Shearon Harris Nuclear 

Power Plant, Unit 1,” dated February 15, 1994. (NUDOCS Accession No. 9402180274) 

169. Letter from L.O. DelGeorge (Commonwealth Edison) to U.S. NRC, “Forwards Response to 

NRC Request for Additional Information re GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’” 

dated February 10, 1998. (NUDOCS Accession No. 9402250179) 

170. Letter from J. Hosmer (Commonwealth Edison) to U.S. NRC, “Provides Response to 

Request for Additional Information re GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers’ per 

10CFR50.54(f),” dated December 16, 1994. (NUDOCS Accession No. 9412220241) 

171. Letter from J.B. Hosmer (Commonwealth Edison) to U.S. NRC, “Provides Submitted 

Information as Update to NRC on Status of Actions to Address GL 92-08, ‘Thermo-Lag 

330-1 Fire Barriers,’” dated January 17, 1997. (NUDOCS Accession No. 9701270122) 

172. Letter from T.S. O’Neill (AmerrGen Energy Co., LLC, Exelon Nuclear) to U.S. NRC, “60-

Day Response to Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc and MT Fire 

Barrier Configurations,’” dated June 6, 2006. (ADAMS Accession No. ML061640343) 

173. Letter from Donald F. Schnell (Union Electric) to U.S. NRC, “Closure Notification of 

Thermo-Lag Fire Barrier System Issues for Plant,” dated January 31, 1997. (NUDOCS 

Accession No. 9702070238) 

174. Letter from Donald F. Schnell (Union Electric) to U.S. NRC, “Forwards Response to NRC 

931221 RAI re GL 92-08, “Thermo-Lag 330-1 Fire Barriers,” dated February 10, 1994. 

(NUDOCS Accession No. 9402170325) 
10-14 

175. Letter from J.S. Perry (Illinois Power Company) to S.A. Varga (U.S. NRC), “Response to 

931227 Request for Additional Information re GL 92-08, Thermo-Lag 330-1 Fire Barriers,” 

dated February 9, 1994. (NUDOCS Accession No. 9403040225) 

176. Letter from J.B. Hopkins (U.S. NRC) to J.V. Sipek (Clinton Power Station), “Completion of 

Licensing for Generic Letter 92-08, Thermo-Lag 330-1 Fire Barriers,” dated September 29, 

1998. (NUDOCS Accession No. 9810020229) 

177. Letter from T.S. O’Neill (AmerGen Energy Company, LLC and Exelon Nuclear) to U.S. 

NRC, “60-Day Response to Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc 

and MT Fire Barrier Configurations,’” dated June 6, 2006. (ADAMS Accession No. 

ML061640343) 

178. Letter from D.M. Benyak (AmerGen Energy Company, LLC and Exelon Nuclear) to U.S. 

NRC, “Braidwood Station, Units 1 and 2, and Clinton, Unit 1, Additional Information 

Supporting the 60-Day Response to Generic Letter 2006-03, ‘Potentially Nonconforming 

Hemyc and MT Fire Barrier Configurations,’” dated May 31, 2007. (ADAMS Accession 

No. ML071520085) 

179. Letter from W.S. Oxenford (Energy Northwest) to U.S. NRC, “Columbia, Response to 

Generic letter 2006-003, ‘Potentially Nonconforming Hemyc and MT Fire Barrier 

Configurations,’” dated June 9, 2006. (ADAMS Accession No. ML061710470) 

180. Letter from C.G. Sorenson (Washington Public Power Supply System) to U.S. NRC, 

“Columbia Response to Generic letter 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’” dated 

April 13, 1993. (ADAMS Accession No. ML041320331) 

181. Letter from D.H. Jaffe (U.S. NRC) to C.L. Terry (Texas Utilities Electric Company), 

“Forwards Safety Evaluation Accepting Licensee Response to GL 92-08, ‘Thermo-Lag 

330-1 Fire Barriers,’ dated 921217, for Comanche Peak Electric Station, Unit 1,” dated 

May 14, 1999. (NUDOCS Accession No. 9905190038) 

182. Letter from F.W. Madden (TXU Power) to U.S. NRC, “Comanche Peak – 60-Day 

Response to NRC Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc and MT 

Fire Barrier Configurations,” dated June 8, 2006. (ADAMS Accession No. ML061660092) 

183. Letter from G.R. Horn (Nebraska Public Power District) to U.S. NRC, “Response to 

Additional Information re GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers – 10CFR50.54(f),’” 

dated February 9, 1994. (NUDOCS Accession No. 9402160296) 

184. Letter from J.R. Hall (U.S. NRC) to G.R. Horn (Nebraska Public Power District), “Advises 

that Util. 930416 Response to GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers’ Acceptable and 

Actions Complete,” dated May 30, 1995. (NUDOCS Accession No. 9506140408) 

185. Letter from G.R. Horn (Nebraska Public Power District) to U.S. NRC, “Forwards Response 

to GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’ Including Qualification of Thermo-Lag Fire 

Barriers and Basis for Ampacity Derating Factors Protected by Thermo-Lag Barriers,” 

dated April 16, 1993. (NUDOCS Accession No. 9304210293) 

186. Letter from P.M. Beard, Jr. (Florida Power Corporation) to U.S. NRC, “Response to 

Additional Information Request on Generic Letter 92-08, ‘Thermo-Lag Fire Barriers,’ 
10-15 

Pursuant to 10 CFR 50.54(f),” dated February 9, 1994. (NUDOCS Accession No. 

9402160141) 

187. Letter from J.P. Cowan (Florida Power Corporation) to S.J. Collins (U.S. NRC), “Response 

to NRC Letter ‘Confirmatory Order Modifying License’ Regarding the Final Implementation 

Date for the Crystal River Unit 3 (CR-3) Thermo-Lag Resolution Program,” dated May 25, 

2000. (ADAMS Accession No. ML003722384) 

188. Memorandum from J.A. Calvo (U.S. NRC) to F.J. Hedbon (Florida Power Corporation), 

“Safety Evaluation Report Addressing Thermo-Lag Related Ampacity Derating Issues for 

Crystal River (TAC No. M91772),” dated November 7, 1997. (NUDOCS Accession No. 

9711200235) 

189. Letter from J.K. Wood (Centerior Energy) to L.J. Callan (U.S. NRC), “Response to 

10CFR50.54(f) Request for Additional Information Regarding Generic Letter 92-08, 

‘Thermo-Lag 330-1 Fire Barriers’ (TAC No. M85542),” dated February 11, 1994. 

(NUDOCS Accession No. 9402240321) 

190. Letter from D. Jacobs (Pacific Gas and Electric Company) to U.S. NRC, “60-Day 

Response to NRC Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc and MT 

Fire Barrier Configurations,’” dated June 6, 2006. (ADAMS Accession No. ML061720079) 

191. Letter from E.E. Fitzpatrick (Indiana Michigan Power Company) to U.S. NRC, “Donald C. 

Cook Nuclear Plant Units 1 and 2 Response to Generic Letter 92-08, ‘Thermo-Lag 330-1 

Fire Barriers,’” dated December 27, 1996. (NUDOCS Accession No. 9701060108) 

192. Letter from M.A. Pfeifer (Indiana Michigan Power) to U.S. NRC, “60-Day Response to 

NRC Generic Letter 2006-03: Potentially Nonconforming Hemyc and MT Fire Barrier 

Configurations,” dated June 1, 2006. (ADAMS Accession No. ML061600213) 

193. Letter from J.F. Stang (U.S. NRC) to R.P.Powers (Indiana Michigan Power Company), 

“Closeout of Generic Letter 92-08 Related Issues Involving Ampacity Derating of ThermoLag (TAC Nos. MA3387 and MA3388),” dated July 14, 1999. (NUDOCS Accession No. 

9907220068) 

194. Dresden Nuclear Power Station, “Dresden Station Units 2 and 3, 3M Fire Wrap 

Qualification Evaluation, NTSC Project 99-40540, Dresden Report No. 12-N208-05,” dated 

December 31, 1999. (ADAMS Accession No. ML011910445) 

195. Letter from T.S. O’Neill (AmerGen Energy Company, LLC and Exelon Nuclear) to U.S. 

NRC, “60-Day Response to Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc 

and MT Fire Barrier Configurations,’” dated June 6, 2006. (ADAMS Accession No. 

ML061640343) 

196. Letter from J.F. Franz, Jr. (IES Utilities Inc.) to S.J. Collins (U.S. NRC), “Forwards DAEC 

Thermo-Lag Final Resolution Report Which Summarizes Thermo-Lag Installations,” dated 

October 31, 1997. (NUDOCS Accession No. 9711130377) 

197. Letter from J.A. Stall (Florida Power and Light Company) to U.S. NRC, “60-Day Response 

to NRC Generic Letter 2006-03, Potentially Nonconforming Hemyc and MT Fire Barrier 

Configurations,” dated June 9, 2006. (ADAMS Accession No. ML061640269) 
10-16 

198. Letter from J.F. Franz (IES Industries Inc.) to L.J. Callan (U.S. NRC) “Response To NRC 

Request For Additional Information Regarding Generic Letter 93-08, ‘Thermo-Lag 330-1 

Fire Barriers’, Pursuant To 10CFR50.54(F) – Duane Arnold Energy Center,” Dated 

February 14, 1994. (NUDOCS Accession No. 9403010160) 

199. Letter from K.Young (IES Utilities Inc.) to W.T.Russel (U.S. NRC) “Fire Endurance Testing 

of Thermo-Lag 330-1 Fire Barrier Material,” dated November 22, 1994) (9711130377 – 

letter from J.F.Franz (IES Utilities Inc.) to S.J. Collins (U.S. NRC) “Thermo-Lag Final 

Resolution Report,” dated October 31, 1997. (NUDOCS Accession No. 9412050112) 

200. Letter from R.J. Laufer (U.S. NRC) to E.Protsch (IES Utilities) “Safety Evaluation 

Addressing Thermo-Lag Related Ampacity Derating Issues – Duane Arnold Energy Center 

(TAC NO. 82809),” Dated January 26, 1999. (NUDOCS Accession No. 9901290062) 

201. Letter from D. Morey (Southern Nuclear Operating Company, Inc) to U.S. NRC, “Joseph 

M. Farley Nuclear Plant Plans to Address Kaowool Issues Kaowoll Fire Barrier Meeting 

Request,” dated May 1, 2000. (ADAMS Accession No. ML003712374) 

202. Letter from D.K. Cobb (Detroit Edison Energy) to U.S. NRC, “Fermi 2 Response to 

Generic Letter 2006-03, Potentially Nonconforming HEMYC and MT Fire Barrier 

Configurations,” dated June 9, 2006. (ADAMS Accession No. ML061660087) 

203. Letter from P. Dietrich (Entergy Nuclear Northwest) to U.S. NRC, “Response to Generic 

Letter 2006-03, Potentially Nonconforming Hemyc and MT Fire Barrier Configurations,” 

dated June 7, 2006. (ADAMS Accession No. ML061650025) 

204. Letter from G.S. Vissing (U.S. NRC) to M. Kansler (Entergy Nuclear Operations, Inc), 

“Exemption from the Requirements of Section III.G.2.c of Appendix R to 10 CFR Part 50 

(TAC No. MB0395,” dated May 29, 2001. (ADAMS Accession No. ML010790125) 

205. Letter from H.J. Faulhaber (Omaha Public Power District) to U.S. NRC, “Fort Calhoun 

Station Unit No. 1, Supplemental Response to General Letter 2006-03, ‘Potentially 

Nonconforming Hemyc and MT Fire Barrier Configurations,’” dated August 2, 2006. 

(ADAMS Accession No. ML070850193) 

206. Letter from J.M. Heffley (Constellation Energy Group) to U.S. NRC, “Calvert Cliffs and 

Nine Mile Point, Units 1 and 2 and R.E. Ginna – Response to Generic Letter 2006-03, 

Potentially Nonconforming Hemyc and MT Fire Barrier Configurations,” dated June 9, 

2006. (ADAMS Accession No. ML061650026) 

207. Letter from B. Vaidya (U.S. NRC) to W.R. Bryan (Entergy Operations, Inc), “Grand Gulf 

Nuclear Station – Issuance of Amendment Re: Proposed Resolution of Kaowool Issues 

(TAC No. MC8180),” dated September 29, 2006. (ADAMS Accession No. ML062140354) 

208. Letter from C.J. Gannon, Jr. (Progress Energy) to U.S. NRC, “Shearon Harris Unit 1 30-

Day Response to NRC Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc and 

MT Fire Barrier Configurations,’” dated April 28, 2006. (ADAMS Accession No. 

ML061240052) 
10-17 

209. Letter from C.J. Gannon, Jr. (Progress Energy) to U.S. NRC, “Shearon Harris Nuclear 

Power Plant Unit 1 60-Day Response to NRC Generic Letter 2006-03, ‘Potentially 

Nonconforming Hemyc and MT Fire Barrier Configurations,’” dated June 9, 2006. 

(ADAMS Accession No. ML061710062) 

210. Letter from L.M. Stinston (Southern Nuclear Operating Company, Inc.) to U.S. NRC, 

“Joseph M. Farley, Edwin I. Hatch, and Vogtle, NRC Generic Letter 2006-03 Response,” 

dated June 9, 2006. (ADAMS Accession No. ML061600376) 

211. U.S. NRC, “Edwin I. Hatch Nuclear Power Plant – NRC Integrated Inspection Report 50-

321/01-03, 50-366/01-03,” dated July 26, 2001. (ADAMS Accession No. ML012080121) 

212. Letter from G.P. Barnes (PSEG Nuclear, LLC) to U.S. NRC, “Hope Creek Response to 

Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc and MT Fire Barrier 

Configurations,’” dated June 7, 2006. (ADAMS Accession No. ML061660080) 

213. Letter from M.A. Cunningham (U.S. NRC) to J.A. Grobe (U.S. NRC), “Hemyc and MT 

Electrical Raceway Fire Barrier System Closeout Actions,” dated December 17, 2008. 

(ADAMS Accession No. ML083090083) 

214. Letter from F.R. Dacimo (Entergy) to U.S. NRC, “Indian Point, Units 2 and 3, Response to 

Generic Letter 2006-03, Potentially Nonconforming Hemyc and MT Fire Barrier 

Configurations,” dated June 8, 2006. (ADAMS Accession No. ML061720091) 

215. Letter from G.T. Bischof (Virginia Electric and Power Company) to U.S. NRC, “Kewaunee 

Unit 1, Millstone Units 2 and 3, North Anna Units 1 and 2, Surry Units 1 and 2, Generic 

Letter 2006-03, ‘Potentially Nonconforming HEMYC and MT Fire Barrier Configurations’ 

Response to Request for Additional Information,” dated May 31, 2007. (ADAMS 

Accession No. ML071520515) 

216. Letter from D.J. Chrzanowski (Commonwealth Edison) to T.E. Murley (U.S. NRC), 

“Forwards Response to GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’” dated April 16, 1993. 

(NUDOCS Accession No. 9304260035) 

217. Letter from T.S. O’Neill (AmerGen Energy Company, LLC and Exelon Nuclear) to U.S. 

NRC, “60-Day Response to Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc 

and MT Fire Barrier Configurations,’” dated June 6, 2006. (ADAMS Accession No. 

ML061640343) 

218. Letter from D.M. Skay (U.S. NRC) to I. Johnson (Commonwealth Edison Company), 

“Completion of Licensing for Generic Letter 92-08, ‘Thermo-Lag 330-1 Fire Barriers – 

LaSall County Station (TAC Nos. M85563 and M85564),’” dated April 23, 1997. 

(NUDOCS Accession No. 9704290218) 

219. Letter from G.A. Hunger, Jr. (PECO Energy Co.) to U.S. NRC, “Peach Bottom, Units 2 and 

3 and Limerick, Units 1 and 2, Request for Additional Information Regarding Generic 

Letter 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’” dated February 4, 1994. (ADAMS 

Accession No. ML041040462) 

220. Letter from G.A. Hunger, Jr. (PECO Energy Co.) to U.S. NRC, “Peach Bottom Atomic 

Power Station, Units 2 and 3, Limerick Generating Station, Units 1 and 2, Response to 
10-18 

NRC Generic Letter 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’” dated April 16, 1993. 

(NUDOCS Accession No. 9304220215) 

221. U.S. NRC, “IR 05000352/2001-014, IR 05000353/2001-014, on 12/10-12/21/2001, Exelon 

Nuclear, Limerick Generating Station, Units 1 and 2. Fire Protection. No Violations 

Noted,” dated January 7, 2002. (ADAMS Accession No. ML020080162) 

222. Letter from B.C. Buckley (U.S. NRC) to G.D. Edwards (PECO Energy Co.), “Informs of 

Completion of Licensing Action for GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’ dated 

921217 for Plant Units 1 and 2,” dated September 21, 1998. (NUDOCS Accession No. 

9809240274) 

223. Letter from T.S. O’Neill (AmerGen Energy Company, LLC and Exelon Nuclear) to U.S. 

NRC, “60-Day Response to Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc 

and MT Fire Barrier Configurations,’” dated June 6, 2006. (ADAMS Accession No. 

ML061640343) 

224. Letter from B.C. Buckley (U.S. NRC) to J.A. Hutton (PECO Energy Co.), “Safety 

Evaluation Addressing Thermo-Lag Ampacity Derating Issues, Peach Bottom Atomic 

Power Station, Units 2 and 3, and Limerick Generating Station, Units 1 and 2 (TAC Nos. 

MA3404, MA3405, MA3872, and MA3873),” dated January 12, 2000. (ADAMS Accession 

No. ML003677253) 

225. Letter from H.B. Barron (Duke Energy) to U.S. NRC, “Response to NRC Generic Letter 

2006-03, Potentially Nonconforming Hemyc and MT Fire Barrier Configurations,” dated 

June 7, 2006. (ADAMS Accession No. ML061640310) 

226. Letter from G.T. Bischof (Virginia Electric and Power Company) to U.S. NRC, “Generic 

Letter 2006-03, ‘Potentially Nonconforming HEMYC and MT Fire Barrier Configurations,’ 

Response to Request for Additional Information,” dated May 31, 2007. (ADAMS 

Accession No. ML071520515) 

227. Letter from R.B. Ennis (U.S. NRC) to J.A. Price (Dominion Nuclear Connecticut, Inc.), 

“Completion of Staff Review Related to Ampacity Derating Issues Associated with Generic 

Letter 92-08 (TAC No. MA3392),” dated May 9, 2002. (ADAMS Accession No. 

ML020700197) 

228. Letter from R.B. Samworth (U.S. NRC) to R.O. Anderson (Northern States Power 

Company), “Generic Letter 92-08 – Thermo-Lag 330-1 Fire Barriers (TAC M85573),” dated 

May 27, 1993. (NUDOCS Accession No. 9305070350) 

229. Letter from C.D. Terry (Niagara Mohawk Power Corporation) to U.S. NRC, “Response to 

931222 Request for Additional Information re GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’ 

per 10CFR50.54(f),” dated February 10, 1994. (NUDOCS Accession No. 9402170065) 

230. Letter from C.D. Terry (Niagara Mohawk Power Corporation) to U.S. NRC, “Response to 

Request for Additional Information Dated September 15, 1994, Regarding Generic Letter 

92-08, ‘Thermo-Lag 330-1 Fire Barriers,’ (TAC No. M85575)” dated December 14, 1994. 

(NUDOCS Accession No. 9412190124) 
10-19 

231. Letter from G.T. Bischof (Virginia Electric and Power Company) to U.S. NRC, “Generic 

Letter 2006-03, ‘Potentially Nonconforming HEMYC and MT Fire Barrier Configurations,’ 

Response to Request for Additional Information,” dated May 31, 2007. (ADAMS 

Accession No. ML071520515) 

232. Meeting Summary, “Summary of May 2, 1997, Meeting Regarding Completion of 

Installation of Thermal Lag Fire Barriers,” dated May, 28, 1997. (NUDOCS Accession No. 

9706020134) 

233. Letter from T.S. O’Neill (AmerGen Energy Company, LLC and Exelon Nuclear) to U.S. 

NRC, “60-Day Response to Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc 

and MT Fire Barrier Configurations,’” dated June 6, 2006. (ADAMS Accession No. 

ML061640343) 

234. Letter from E.J. Weinkam (Nuclear Management Company, LLC) to U.S. NRC, “Response 

to Generic Letter 2006-03: Potentially Nonconforming Hemyc and MT Fire Barrier 

Configurations,” dated June 8, 2006. (ADAMS Accession No. ML061600209) 

235. Letter from W.L. Stewart (Arizona Public Service Company) to U.S. NRC, “Response to 

the Follow-Up to the Request for Additional Information Regarding Generic Letter 92-08, 

Issued Pursuant to 10CFR50.54(f),” dated December 22, 1994. (NUDOCS Accession No. 

9412290093) 

236. Letter from J.L. Levine (Arizona Public Service Company) to U.S. NRC, “Summary of 

Major Work Activities that have Recently Been Completed to Resolve Remaining Open 

Actions re GL 92-08, ‘Thermo-Lag 330-1 Fire Barriers,’” dated December 24, 1997. 

(NUDOCS Accession No. 9801050050) 

237. Letter from M.A. Balduzzi (Entergy Nuclear Operations, Inc.) to U.S. NRC, “Response to 

NRC Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc and MT Fire Barrier 

Configurations,” dated June 6, 2006. (ADAMS Accession No. ML061640132) 

238. Letter from E.J. Weinkam (Nuclear Management Company, LLC) to U.S. NRC, “Response 

to Generic Letter 2006-03: Potentially Nonconforming Hemyc and MT Fire Barrier 

Configurations,” dated June 8, 2006. (ADAMS Accession No. ML061600209) 

239. Letter from C.W. Fay (Wisconsin Electric Power Company) to H.R. Denton (U.S. NRC), 

“Docket Nos. 50-266 and 50-301: Status of Fire Protection Modifications, Point Beach 

Nuclear Plant, Units 2 and 3,” dated March 18, 1981. (NUDOCS Accession No. 

8103250393) 

240. Letter from E.J. Weinkam (Nuclear Management Company, LLC) to U.S. NRC, “Response 

to Generic Letter 2006-03: Potentially Nonconforming Hemyc and MT Fire Barrier 

Configurations,” dated June 8, 2006. (ADAMS Accession No. ML061600209) 

241. Letter from J.M. Solymossy (Nuclear Management Company, LLC) to U.S. NRC, “Prairie 

Island Nuclear Generating Plant Safety Evaluation Summary Report,” dated December 10, 

2003. (ADAMS Accession No. ML033530476) 
10-20 

242. Letter from T.S. O’Neill (Exelon Generation Company, LLC) to U.S. NRC, “60-Day 

Response to Generic Letter 2006-03, ‘Potentially Nonconforming Hemyc and MT Fire 

Barrier Configurations,’” dated June 6, 2006. (ADAMS Accession No. ML061640343) 

243. Letter from J.J. Fargo (Entergy Operations, Inc.) to S.A. Varga (U.S. NRC), “Response to 

NRC Letter Requesting Additional Information Regarding Generic Letter 92-08, ‘ThermoLag 330-1 Fire Barriers,’ Pursuant to CFR 50.54(f),” dated February 9, 1994. (NUDOCS 

Accession No. 9402240188) 

244. Letter from R.J. King (Entergy Operations, Inc) to U.S. NRC, “NRC Generic Letter 2006-

03, dated April 10, 2006, ‘Potentially Nonconforming Hemyc and MT Fire Barrier 

Configurations,’” dated June 1, 2006. (ADAMS Accession No. ML061570394) 

245. Letter from J.F. Lucas (Progress Energy) to U.S. NRC, “Response to NRC Generic Letter 

2006-03, ‘Potentially Nonconforming Hemyc and MT Fire Barrier Configurations,’” dated 

June 8, 2006. (ADAMS Accession No. ML061640136) 

246. Letter from J.A. Stall (Florida Power and Light Company) to U.S. NRC, “Generic Letter 92-

08 Corrective Actions,” dated June 23, 1998. (NUDOCS Accession No. 9806290310) 

247. Letter from C.O. Thomas (U.S. NRC) to T.F. Plunkett (Florida Power and Light Company), 

“Closeout Report for the Ampacity Derating Issues Related to Generic Letter 92-08, 

‘Thermo-Lag 330-1 Fire Barriers’ – St. Lucie Plants, Units 1 and 2, And Turkey Point, Units 

3 and 4,” dated March 26, 1999. (NUDOCS Accession No. 9904020172) 

248. Meeting Summary (U.S. NRC), “NRC Status Meeting Regarding Raceway Fire Barrier 

Project,” dated April 5, 2001. (ADAMS Accession No. ML011780094) 

249. Meeting Summary (U.S. NRC), “Summary of Meeting Between the Nuclear Regulatory 

Commission (NRC) Staff and PSEG Nuclear LLC on April 5, 2001 to Discuss Status of 

PSEG’s Electrical Cable Raceway Fire Barrier Project,” dated June 26, 2001. (ADAMS 

Accession No. ML011430238) 

250. Letter from A.E. Scherer (Southern California Edison) to U.S. NRC, “Response to Request 

for Additional Information on Response to Generic Letter 2006-03,” dated June 18, 2007. 

(ADAMS Accession No. ML071710548) 

251. Letter from T.C. Feigenbaum (North Atlantic Energy Service Corporation) to the U.S. NRC, 

“Response to Generic Letter 92-08 (TAC No. 85603),” dated March 31, 1993. (NUDOCS 

Accession No. 9304140290) 

252. Letter from S.E. Thomas (South Texas Project Electric Generating Station) to U.S. NRC, 

“South Texas Project Units 1 and 2 Thermo-Lag Confirmatory Order Completion Notice,” 

dated February 8, 1992. (ADAMS Accession No. ML040990180) 

253. Letter from T.W. Alexion (U.S. NRC) to W.T. Cottle (South Texas Project Electric 

Generating Station), “Completion of Licensing Action for Generic Letter 92-08, ThermoLag 330-1 Fire Barriers,” dated April 4, 1997. (NUDOCS Accession No. 9704080234) 

254. Letter from U.S. NRC to Houston Lighting and Power Company, “Safety Evaluation by the 

Office of NRR Related to Ampacity Derating Issues, STP Nuclear Operating Company, 
10-21 

Docket Nos. 50-498 and 50-499, South Texas Project Units 1 and 2 (STP),” dated January 

19, 1999. (NUDOCS Accession No. 9901250034) 

255. Letter from L.M. Padovan (U.S. NRC) to G.J. Taylor (South Carolina Electric and Gas 

Company), “Thermo-Lag Related Ampacity Derating Issue and Completion of Licensing 

Action for Generic Letter 92-08, Thermo-Lag 330-1 Fire Barriers, for Virgil C. Summer 

Nuclear Station,” dated May 5, 1998. (NUDOCS Accession No. 9805080208) 

256. Letter from G.T. Bischof (Virginia Electric and Power Company) to U.S. NRC, “Kewaunee 

Unit 1, Millstone Units 2 and 3, North Anna Units 1 and 2, Surry Units 1 and 2, Generic 

Letter 2006-03, Potentially Nonconforming HEMYC and MT Fire Barrier Configurations, 

Response to Request for Additional Information,” dated May 31, 2007. (ADAMS 

Accession No. ML071520515) 

257. Letter from R.G. Bryam (Pennsylvania Power and Light, Inc.) to U.S. NRC, “Susquehanna 

Steam Electric Station, Resolution of Thermo-Lag Issues,” dated May 4, 1998. (ADAMS 

Accession No. ML041040513) 

258. Letter from R.G. Bryam (Pennsylvania Power and Light, Inc.) to U.S. NRC, “Susquehanna 

1 and 2 Status of Fire Protection Corrective Actions, in Response to NRC Confirmatory 

Order Regarding Fire Barriers,” dated April 28, 2000. (ADAMS Accession No. 

ML003711917) 

259. Letter from B.T. McKinney (Pennsylvania Power and Light, Inc.) to U.S. NRC, 

“Susquehanna Response to Generic letter 2006-03, Potentially Nonconforming Hemyc 

and MT Barrier Configurations,” dated June 9, 2006. (ADAMS Accession No. 

ML061660076) 

260. Letter from T.G. Colburn (U.S. NRC) to J.W. Langenbach (GPU Nuclear Corporation), 

“Generic Letter 92-08 Closeout Report – Thermo-Lag Related Ampacity Derating Issues 

for Three Mile Island, Unit 1 (TAC No. MA3340),” dated January 22, 1999. (NUDOCS 

Accession No. 9901260477) 

261. Letter from T.F. Plunkett (Florida Power and Light Company) to L.F. Callan (U.S. NRC), 

“Response to Request for Additional Information – Generic Letter 92-08 Thermo-Lag 330-

1 Fire Barrier,” dated February 7, 1994. (NUDOCS Accession No. 9402150406) 

262. Letter from R.J. Hovey (Florida Power and Light Company) to U.S. NRC, “Informs that Util. 

Proceeding With Design and Will Commence Implementation of Fire Barrier Upgrades for 

Fire Zones. Util. Will Aggressively Pursue Implementation of Thermo-Lag Fire Barrier 

Upgrades to Be Complete No Later Than 991231,” dated June 15, 1998. (NUDOCS 

Accession No. 9806220249) 

263. Letter from C.O. Thomas (U.S. NRC) to T.F. Plunkett (Florida Power and Light Company), 

“Closeout Report for the Ampacity Derating Issues Related to Generic Letter 92-08, 

Thermo-Lag 330-1 Fire Barriers – St. Lucie Plants, Units 1 and 2, And Turkey Point, Units 

3 and 4,” dated March 26, 1999. (NUDOCS Accession No. 9904020172) 

264. Letter from D.A. Reid (Vermont Yankee Nuclear Power Corporation) to U.S. NRC, 

“Addresses Concerns Delineated in GL 92-08 re Thermo-Lag 330 Fire Barriers, Per NRC 

Bulletin 92-001,” dated April 16, 1993. (NUDOCS Accession No. 9304190144) 
10-22 

265. Letter from J/P. Pelletier (Vermont Yankee Nuclear Power Corporation) to U.S. NRC, 

“Completion of Actions to Address NRC Generic Letter 92-08, Thermo-Lag Fire Barriers,” 

dated June 28, 1993. (NUDOCS Accession No. 9307020175) 

266. NRC Inspection Report, “NRC Integrated Inspection Report 05000271-06-005,” dated 

January 19, 2007. (ADAMS Accession No. ML070190286) 

267. Letter from J. M. DeVincentis (Vermont Yankee Nuclear Power Station) to U.S. NRC, 

“Vermont Yankee Nuclear Power Station – Status of Hemyc Fire Barrier Wrap at Vermont 

Yankee,” dated August 17, 2005. (ADAMS Accession No. ML0523405090) 

268. Letter from C.K. McCoy (Georgia Power Company) to U.S. NRC, “Response to Request 

for Additional Information Regarding Generic Letter 92-08, Thermo-Lag Fire Barriers,” 

dated May 10, 1995. (NUDOCS Accession No. 9505180590) 

269. Letter from L.M. Stinson (Southern Nuclear Operating Company) to U.S. NRC, “Joseph M. 

Farley, Edwin I. Hatch and Vogtle, NRC Generic Letter 2006-03 Response,” dated June 9, 

2006. (ADAMS Accession No. ML061600376) 

270. Letter from J.A. Ridgel (Entergy Operations, Inc.) to U.S. NRC, “Response to Generic 

Letter 2006-03, Potentially Nonconforming Hemyc and MT Fire Barrier Configurations,” 

dated June 7, 2006. (ADAMS Accession No. ML061600210) 

271. Letter from R.A. Muench (Wolf Creek Nuclear Operating Corporation) to U.S. NRC, 

“Additional Information Regarding Thermo-Lag Fire Barriers,” dated June 20, 1996. 

(NUDOCS Accession No. 9606250350) 

272. Letter from J. Donohew (U.S. NRC) to R.A. Muench (Wolf Creek Nuclear Operating 

Corporation), “Closeout of Response to Generic Letter 2006-03, Potentially 

Nonconforming Hemyc and MT Fire Barrier Configurations,” dated June 23, 2006. 

(ADAMS Accession No. ML061650179) 

273. Letter from K.M. Thomas (U.S. NRC) to O.L. Maynard (Wolf Creek Operating 

Corporation), “Safety Evaluation Addressing Thermo-Lag Related Ampacity Derating 

Issues for the Wolf Creek Generating Station,” dated April 6, 1998. (NUDOCS Accession 

No. 9804140367) 

274. Letter from R.C. Hagan (Wolf Creek Nuclear Operating Corporation) to U.S. NRC, 

“Supplemental Response to the Follow Up to the Request for Additional Information 

Regarding Generic Letter 92-08,” dated July 27, 1995. (NUDOCS Accession No. 

9507030329) 

275. Letter from R.W. Brown (Peak Seals, Inc) to P.M. Madden (U.S. NRC), “Listed Documents 

Re Three Hour Fire Endurance Test on 3M Interam Fire Barrier Wrap Sponsored by Peak 

Seals,” dated August 7, 1995. (NUDOCS Accession No. 9509050173) 

276. Fire Endurance Test, “Omega Point Fire Endurance Test of 3M Interam Mat Fire 

Protective Envelopes (24 in. and 6 in. Cable Trays, 5 in., 3 in., and 1 in. Conduits, 2 in. Air 

Drop and a 12 in. x 12 in. by 8 in. Junction Box,” dated August 2, 1995. (NUDOCS 

Accession No. 9509070113) 
10-23 

277. Letter from T. Dogan (Vectra) to R. Brown (Peak Seals, Inc.), “E-50 Series Fire Endurance 

Test Evaluation,” dated August 1, 1995. (NUDOCS Accession No. 9709090341) 

278. Memorandum from A. Singh (U.S. NRC) to C.E. McCracken (U.S. NRC), “Trip to Omega 

Point Laboratories, 3M Company Interam 1-Hour Raceway Fire Barrier Fire Endurance 

Test (TAC No. M82809),” dated May 25, 1995. (NUDOCS Accession No. 9506090198) 

279. Test Report provided by Peak Seals Inc., “Test Plan Number CTP-1199, One (1) Hour Fire 

Endurance Test, 3M Interam Fire Wrap,” report date May 4, 1995. (NUDOCS Accession 

No. 9507140090) 

280. Test Report Provided by Omega Point Laboratories, “ASTM E136-94, Behavior of 

Materials in a Vertical Tube Furnace at 750oC, 3M E-50 Interam Series Mat,” report date 

January 17, 1995. (NUDOCS Accession No. 9705050067) 

281. Letter from R.W. Brown (Peak Seals, Inc.) to L.B. Marsh (U.S. NRC), “Inform that Peak 

Seals has become Master Distributor of 3M Interam Fire Wrap Sys for Commercial 

Nuclear Power Plants, Response to Specific Questions,” dated October 3, 1997. 

(NUDOCS Accession No. 9802040354) 

282. Letter from J.K. Wood (Centerior Energy) to U.S. NRC, “Combustibility Testing of 3M 

Interam Material,” dated February 7, 1997. (NUDOCS Accession No. 9702200311) 

283. Letter from Vermont Yankee Nuclear Power Corporation to U.S. NRC, “Completion of 

Actions to Address NRC Generic Letter 92-08: Thermo-Lag Fire Barriers,” dated June 28, 

1993. (NUDOCS Accession No. 9307020175) 

284. Letter from R. Licht (3M Fire Protection Products) to C.E. McCracken (U.S. NRC), 

“Acknowledges Receipt of 930504 Letter Requesting Info on 3M Fire Barrier Systems for 

Protection of Electrical Raceways. Informs that 3M Would Like to Supply Requested Info 

in Three Parts, Covering Flexible Wrap Systems, Rigid Panel Systems, and FS195 

Systems,” dated May 18, 1993. (NUDOCS Accession No. 9308310099) 

285. Letter from D.R. Coy (3M Ceramic Materials Department), “Discusses NUMARC Meeting 

931201-02 re Performance of Certain Fire Barrier materials. 3M Additional Test SVC 

Program Will Provide Technical Support, Supply of 3M Fire Protection Products, and Fire 

Testing at Cottage Grove Facility,” dated January 14, 1994. (NUDOCS Accession No. 

9401310171) 

286. Letter from K.W. Howell (Underwriters Laboratories, Inc.) to B.J. Youngblood (U.S. NRC), 

“Qualification of 3M Fire Wrap,” dated October 22, 1984. (NUDOCS Accession No. 

8410240232) 

287. Test Report provided by Detroit Edison, “TSI Technical Note 42584, Analysis of the 

Thermal Response of the Junction between a Partially Protected Member Which 

Protrudes the Thermo-Lag 330 Fire Barrier and a Cable Tray,” report date April 1984. 

(NUDOCS Accession No. 8408080299) 
10-24 

288. Letter from R.L. Tedesco (U.S. NRC) to R.L. Mittl (Public Service Electric and Gas 

Company), “Salem Cable Tray Fire Barrier Evaluation; Docket Nos. 50-311/272,” dated 

March 18, 1981. (NUDOCS Accession No. 8103240604) 

289. Letter from D.R. Coy (3M Ceramic Materials Department), “Informs that 3M Will be 

Providing Complete Document Package for 3M Interam E-50 Series Material, 1-and-3 

Hour Systems, Including Fire Test Reports, per 10CFR50, App R,” dated August 3, 1993. 

(NUDOCS Accession No. 9308120140) 

290. Letter from D.R. Coy (3M Ceramic Materials Department), “Advises that 3M Will Continue 

to Supply Interam E-50 Series Materials and all Peripheral 3M Fire Protection Products 

Used in Installation Process Under Original Nuclear Product Designations,” dated March 

1, 1994. (NUDOCS Accession No. 9403170125) 

291. Test Report Provided by 3M Fire Protection Products, “3M Fire Test Reports 94-27 and 

94-42, re Upgrading TSI Material for 3-Hour Conduit Systems using 3M’s Interam E-50 

Series Mats,” dated March 17, 1994. (NUDOCS Accession No. 9403280162) 

292. Letter from Dwight E. Nunn (Tennessee Valley Authority) to U.S. NRC, “Watts Bar Nuclear 

Plant (WBN) – 3M Fire Barrier Material, Cable Compressive Load Testing,” dated June 17, 

1994. (NUDOCS Accession No. 9406240089) 

293. Letter from D.R. Coy (3M Fire Protection Products) to Nuclear Power Utility Customers, 

“Letter Advising that Effective 950628 3M Fire Protection Products Certified Nuclear 

Installer Program Will End and that Peak Seals, Inc Will Become Exclusive Supplier of 3M 

Fire Protection Products, Effective 950629,” dated April 28, 1995. (NUDOCS Accession 

No. 9505230123) 

294. Test Report Provided by 3M Fire Protection Products, “Results of Fire Test Conducted on 

Latest NRC Criteria With 3M Interam E-50 Series Material,” dated May 25, 1995. 

(NUDOCS Accession No. 9506220297) 

295. Test Report Provided by U.S. NRC, “Trip to Omega Point Laboratories – Peak Seals 3M 

Interam Raceway Fire Barrier Fire Endurance Test Program (April 20, 1995) (TAC No. 

M82809),” dated May 1, 1995. (NUDOCS Accession No. 9507140050) 

296. 3M Fire Protection Products, “3M Advanced Training Program: 3M Interam E-50 Series 

Fire Protection Systems for the Nuclear Industry,” dated June 15, 1993. (NUDOCS 

Accession No. 9308040286) 

297. Meeting Summary, “Meeting on Fire Endurance Test Acceptance Criteria with the Nuclear 

Management and Resources Council,” dated November, 20 1992. (NUDOCS Accession 

No. 9212080298) 

298. Letter from C.E. McCracken (U.S. NRC) to R.R. Licht (3M Fire Protection Products), “NRC 

Intent to Review Fire Barrier Systems Used by Licensees Re Compliance with NRC Fire 

Protection Requirements,” dated May 4, 1993. (NUDOCS Accession No. 9403170119) 

299. SwRI Test Report, “Ampacity Derating of Fire-Protected Cables in Conduit / Cable Trays 

Using 3M Incorporated’s Passive Fire Protection Systems Identified as 3M Interam E-50A, 
10-25 

E-50D, E-53A, and E-50D/E-53A,” dated September, 30 1986 (NUDOCS Accession No. 

9308040280) 

300. 3M Fire Protection Products, “3M Interam E-50 Series Fire Protection Mat, 1-Hour Flexible 

Wrap System for Electrical Raceways, Installation Booklet Including Quality Assurance 

Guidelines and Typical Drawings,” dated June 19, 1987. (NUDOCS Accession No. 

9308040230) 

301. Test Report Provided by Twin City Testing Corporation, “Qualification Fire Tests of the 3M 

Interam E-50D Fire Protection Mat for 3-Hour Rated Electrical Raceways,” dated March 

1986. (NUDOCS Accession No. 9308040267) 

302. SwRI Test Report No. 01-7912, “Qualification Fire Test of a Protective Envelope System,” 

dated June 1984. (NUDOCS Accession No. 9308040243) 

303. 3M Fire Protection Products, “3M Interam E-54A Fire Protection Mat, 3-Hour Flexible 

Wrap System for Electrical Raceways, Installation Booklet Including Quality Assurance 

Guidelines and Typical Drawings,” dated October 27, 1987. (NUDOCS Accession No. 

9308040228) 

304. 3M Fire Protection Products, “3M Interam E-50 Series 1-hour and 3-hour Flexible Wrap 

Fire Protection Systems.” (NUDOCS Accession No. 9308040224) 

305. SwRI Project Report No. 01-7912a(1), “Qualification Fire Test of a Protective Envelope 

System,” dated June 1985. (NUDOCS Accession No. 9308040263) 

306. Test Report Provided by Twin City Testing Corporation, “Qualification Fire Tests of the 3M 

Interam E-50 Series Fire Protection Mat for 1-Hour Rated Electrical Raceways,” dated 

September 1986. (NUDOCS Accession No. 9308040275) 

307. SwRI Project Report No. 01-7912(2), “Qualification Fire Test of a Protective Envelope 

System,” dated June 1985. (NUDOCS Accession No. 9308040254) 

308. Letter from R. Licht (3M Fire Protection Products) to C.E. McCracken (U.S. NRC), 

“Response to Questions Noted in 930504 Letter and Provides Info Intended to Validate 

Use of 3M Interam E-50 Series 1-Hour and 3 Hour Fire Protection Systems,” dated June 

30, 1993. (NUDOCS Accession No. 9308040054) 

309. Letter from R.W. Brown (Peak Seals) to P.M. Madden (U.S. NRC), “Response: 3M 

Interam Fire Wrap Systems,” dated August 7, 1995. (NUDOCS Accession No. 

9509050173) 

310. Test Report Provided by Central Laboratories Services, “Testing to Determine Ampacity 

Derating Factors for 3M Fire Barrier Wrapped Conduits and Air Drops, Job Number 94-

0357, Revision 0,” dated February 3, 1994. (NUDOCS Accession No. 9403030227) 

311. SwRI Test Report No. 01-8818-208/-209d, “Ampacity Derating of Fire-Protected Cables in 

Conduit/Cable Trays Using 3M Incorporated’s Passive Fire Protection Systems Identified 

as 3M Interam E-50A (Verification Tests),” dated October 6, 1986. (NUDOCS Accession 

No. 9308040249) 
10-26 

312. SwRI Test Report No. 1208-001, “Nuclear Component Qualification Test Report for the 

Generic Seismic Qualification of 3M Interam E-50D 3-Hour Fire Protection System,” dated 

July 1986. (NUDOCS Accession No. 9308040186) 

313. Test Report Provided by 3M Fire Protection Products, “3M Fire Test #92-115: 3-hour Fire 

Protection on Conduits with the 3M Interam E-50 Series Mats,” dated August, 6, 1992. 

(NUDOCS Accession No. 9308040119) 

314. Test Report Provided by 3M Fire Protection Products, “3M Fire Test #87-79: 3-hour Fire 

Protection on a Cable Tray With the 3M Interam E-50 Series Mats,” dated July 24, 1992. 

(NUDOCS Accession No. 9308040106) 

315. Test Report Provided by 3M Fire Protection Products, “3M Fire Test #92-167: 1-hour Fire 

Protection on 1” Sch. 40 Steel Conduits Using the 3M Interam E-53A Mats,” dated June 

25, 1993. (NUDOCS Accession No. 9308040101) 

316. Test Report Provided by 3M Fire Protection Products, “3M Fire Test #92-141: 1-hour and 

3-Hour Fire Protection on 1” Sch. 40 Steel Conduits Using the 3M Interam E-54A Mats,” 

dated August 27, 1992. (NUDOCS Accession No. 9308040099) 

317. Test Report Provided by 3M Fire Protection Products, “3M Fire Test #87-40: 1-hour Fire 

Protection on a Cable Tray With the 3M Interam E-50 Series Materials,” dated April 3, 

1992. (NUDOCS Accession No. 9308040097) 

318. Test Report Provided by 3M Fire Protection Products, “3M Fire Test Report #87-57: 3M 

Chemolite Building 66, Large Scale Furnace,” dated May 27, 1987. (NUDOCS Accession 

No. 9308040094) 

319. Test Report Provided by 3M Fire Protection Products, “3M Fire Test #87-76: 60 Minute 

Fire Protection on Conduits with Interam E-53A Mat and FireDam 150 Caulk,” dated June 

25, 1987. (NUDOCS Accession No. 9308040090) 

320. Letter from R. Licht (3M Ceramic Materials) to C.E. McCracken (U.S. NRC), “Response to 

Questions Noted in 930504 Letter and Provides Info Intended to Validate Use of 3M 

Interam E-50 Series 1-Hour and 3-Hour Fire Protection Systems,” dated June 30, 1993. 

(NUDOCS Accession No. 9308040054) 

321. Letter from J.S. Marshall (Texas Utilities Services) to S. Burwell (U.S. NRC), “Comanche 

Peak Steam Electric Station Fire Qualification Test Report Transmittal,” dated October 29, 

1981. (NUDOCS Accession No. 8112160281) 

322. Letter from R.L. Tedesco (U.S. NRC) to R.J. Gary (Texas Utilities), “Comanche Peak Tray 

Fire Barrier Evaluation,” dated December 1, 1981.(NUDOCS Accession No. 8112300294) 

323. Letter from S.C. Black (U.S. NRC) to W.J. Cahill (Texas Utilities), “Thermo-Lag 

Acceptance Methodology for Comanche Peak Steam Electric Station – Unit 2,” dated 

October 29, 1992. (NUDOCS Accession No. 9211040234) 

324. Letter from J.S. Perry (Clinton Power Station) to S.A. Varga (U.S. NRC), “Illinois Power’s 

Response to the Nuclear Regulatory Commissions Request for Additional Information 
10-27 

Regarding Generic Letter 92-09, ‘Thermo-Lag 330-1 Fire Barriers,’” dated February 9, 

1994. (NUDOCS Accession No. 9403040225) 

325. Letter from J.J. Kelly Jr. (TU Electric) to U.S. NRC, “Comanche Peak Steam Electric 

Station (CPSES) – Unit 1 Fire Endurance Test Report,” Dated March 2, 1999. (NUDOCS 

Accession No. 9903110179) 

326. TU Electric sponsored test report performed by OPL, “One Hour Fire Endurance Test Of 

Articles Protected With Thermo-Lag® Fire Barrier System, Project No. 12340-102571, Test 

Scheme 13-3,” dated February 25, 1999. (NUDOCS Accession No. 9903110227) 

327. 45 FR 76602 – Federal Register Vol. 45, No. 225 dated Wednesday, November 19, 1980, 

“10 CFR Part 50 Fire Protection Program for Operating Nuclear Power Plants.” 

328. “Thermo-Lag 330-1 Combustibility Evaluation Methodology Plant Screening Guide,” 

NUMARC, dated October 12, 1993 (NUDOCS Accession No. 9310210224). 

329. E-mail from P.L. Campbell on behalf of General Electric to NRCREP Resource, 

“Response from “Comment on NRC Documents,” dated November 20, 2009. (ADAMS 

Accession No. ML093430234) 

330. Letter from F.W. Madden (Luminant Generation Company LLC) to M.T. Lesar (U.S. NRC), 

“Comanche Peak Steam Electric Station; Docket Nos. 50-445 and 50-446; NUREG-1924, 

“Electric Raceway Fire Barrier Systems (ERFBS) in Nuclear Power Plants, Draft Report for 

Comment,” dated December 2, 2009. (ADAMS Accession No. ML093441088) 

331. Letter from J.C. Butler (NEI), to M.T. Lesar (U.S. NRC), “Industry Comments on Draft 

NUREG 1924, ‘Electric Raceway Fire Barrier Systems in U.S. Nuclear Power Plants’,” 

dated December 3, 2009. (ADAMS Accession No. ML093500089) 

332. Letter from D.P. Helker (Exelon Nuclear), to M.T. Lesar (U.S. NRC), “Comments 

Concerning Draft NUREG-1924, ‘Electric Raceway Fire Barrier Systems (ERFBS) in 

Nuclear Power Plants’,” dated December 7, 2009. (ADAMS Accession No. 

ML100050209) 

333. E-mail from W. Harper (Energy Northwest) to G.J. Taylor (U.S. NRC), “RE: NUREG 1924 

Edits for Columbia Generating Station,” dated December 7, 2009. (ADAMS Accession No. 

ML101030790) 

334. E-mail from A. Holder (Nuclear Generation Group) to A. Klein (U.S. NRC), “Draft NUREG 

1924,” dated December 8, 2009. (ADAMS Accession No. ML101030781) 

335. E-mail from F.J. Wyant (Sandia National Laboratories), to G.J. Taylor (U.S. NRC), “Review 

of Draft NUREG-1924,” dated January 7, 2010. (ADAMS Accession No. ML101030775) 

336. E-mail from S.P. Nowlen (Sandia National Laboratories), to G.J. Taylor (U.S. NRC), 

“ERFBS report NUREG-1924,” dated January 11, 2010. (ADAMS Accession No. 

ML101030765) 
10-28 

337. NRC Inspection Report, “Clinton Inspection Report 50-461/98026(DRS) And Notice Of 

Enforcement Discretion,” dated December 13, 1998. (NUDOCS Accession No. 

9812180152) 

338. OPL Ampacity Derating Test Report, “Ampacity Derating of Fire Protected Cables, Project 

No. 8610-102166, Electrical Test to Determine the Ampacity Derating of a Protective 

Envelope for Class 1E Electrical Circuits” dated December 23, 1997. (ADAMS Accession 

No. ML101300320) 

339. OPL Ampacity Derating Test Report, “Ampacity Derating of Fire Protected Cables, Project 

Nos. 8610-102164 and 102165, Electrical Test to Determine the Ampacity Derating of a 

Protective Envelope for Class 1E Electrical Circuits” dated December 26, 1997. (ADAMS 

Accession No. ML101300321) 

340. OPL Ampacity Derating Test Report, “Ampacity Derating of Fire Protected Cables, Project 

No.14540-100770, Electrical Test to Determine the Ampacity Derating of a Protective 

Envelope for Class 1E Electrical Circuits” dated December 5, 1996. (ADAMS Accession 

No. ML101300301) 

341. OPL Ampacity Derating Test Report, “Ampacity Derating of Fire Protected Cables, Project 

No. 14540-99074 and 99075, Electrical Test to Determine the Ampacity Derating of a 

Protective Envelope for Class 1E Electrical Circuits” dated March 25, 1996. (ADAMS 

Accession No. ML101300295) 

342. OPL Combustibility Test Report, “ASTM E136-94 Behavior Of Materials in a Vertical Tube 

Furnace at 750oC, 3M E-50 INTERAMTM SERIES MAT, Project No. 14540-99234,” dated 

January 17, 1995 (ADAMS Accession No. ML101300314) 

343. Wyle Laboratories Test Report, “Final Report CTP-2010 Design Basis Accident Testing on 

3M IneramTM Flexible Fire Wrap, Report No. 46979-1,” dated July 27, 1998. (ADAMS 

Accession No. ML101300325) 

344. OPL Fire Endurance Test Report, “Fire Endurance Test of 3M InteramTM Mat Fire 

Protective Envelopes (24 in. and 6 in., 2 in. Air Drop and a 12 in. X 12 in. x8 in. Junction 

Box), Project No. 14540-99123,” dated December 5, 1995. (ADAMS Accession No. 

ML101300310) 

345. OPL Fire Endurance Test Report, “Fire Endurance Test of 3M InteramTM Fire Wrap Fire 

Protective Envelope, Project No. 8610-102570,” dated May 19, 1998. (ADAMS Accession 

No. ML101300322) 

346. OPL Fire Endurance Test Report, “Fire Endurance Test of 3M InteramTM Mat Fire 

Protective Envelopes (6 in. wide and 24 in. by 4 in. Deep Steel Ladder-Back Cable Trays, 

Project No. 14540-99417,” dated September 22, 1997. (ADAMS Accession No. 

ML101300319) 

347. OPL Fire Endurance Test Report, “Fire Endurance Test of 3M InteramTM Mat Fire 

Protective Envelopes (5 in., 3in., and 1 in. Conduits and a 12 in. x 12 in. x 8 in. Junction 

Box, Project No. 14540-99416,” dated February 26, 1996. (ADAMS Accession No. 

ML101300318) 
10-29 

348. Letter from R.W. Brown (PCI Promatec) to M.H. Salley (U.S. NRC), “Comments on Draft 

Report NUREG-1924 Electric Raceway Fire Barrier Systems in U.S. Nuclear Power 

Plants,” dated April 30, 2010. (ADAMS Accession No. ML101300259) 

 
10-30 

This page intentionally left blank. 
A-1 

Appendix A The Browns Ferry Fire 

On March 22, 1975, a major fire occurred at the Browns Ferry Nuclear Plant (BFN), located 

near Decatur, Alabama. At the time of the fire, it was the largest nuclear power plant (NPP) in 

the world, having three units with a maximum design power output of about 3195 MWe. Unit 1 

began operation on August 1, 1974, while Unit 2 came online on March 1, 1975. Unit 3 was 

under construction at the time of the fire and had its own control room, while Units 1 and 2 

shared a common space for the control of the respective units. It is important to realize that 

BFN was the first nuclear plant operated by Tennessee Valley Authority (TVA) and, at the time 

of the fire, Unit 1 had only been in operating for 8 months while Unit 2 had only accumulated 21 

days of operation. 

The fire lasted for over 7 hours, damaged over 1,600 electrical cables, and resulted in a loss of 

all Unit 1 and many Unit 2 emergency core cooling systems used to maintain reactor safety. 

Figure A-1 shows some of the damage caused by the fire. In this particular case, the fire was 

intense enough to melt the aluminum conduit and insulation around the conductors. All that 

remained was the bare copper conductors seen at the center of the photo. 

Figure A-1: Photograph of Conduit Damaged from Fire (NUREG/BR-0361) 

The following provides a brief summary of what occurred on March 22, 1975, and the lessons 

learned from the most severe U.S. NPP fire to date. Please refer to NUREG/BR-0361, “The 

Browns Ferry Nuclear Plant Fire of 1975 and the History of NRC Fire Regulations,” for a 

detailed discussion of the fire and supporting documentation. 

 
A-2 

A,1 The Fire Event

The fire was initiated by a small lit candle being used to check for air leakage between the cable 

spreading room (CSR) and the reactor building. The fossil fuel plant technicians commonly 

used this method to check for condenser leakage, and it was passed on to the early nuclear 

industry as a means to check the effectiveness of the seal operation. At about 12:20 p.m., the 

candle flame ignited some polyurethane foam used as part of a temporary cable penetration 

seal. Because of the pressure differential between the reactor building and the CSR, the fire 

propagated into the Unit 1 reactor building. This resulted in two fires across the fire wall—one in 

the CSR and another in the Unit 1 reactor building. 

In the CRS, the technician attempted to beat out the fire with his flashlight and, when that failed, 

they discharged several carbon dioxide (CO2) fire extinguishers that also were unsuccessful in 

extinguishing the fire. The operators in the main control roomf were made aware of the fire 

about 15 minutes after it initially started. About 40 minutes after fire initiation, the assistant shift 

engineer initiated the CSR evacuation alarm and then proceeded to actuate the in situ CO2

Cardox fire-extinguishing system. However, safety measures had been intentionally taken to 

disable the Cardox system while the cable penetration inspections were being conducted. 

Power had been removed to eliminate the potential for the automatic actuation, and a metal bar 

had been installed under the break-out glass used for manual actuation. The delay in making 

the system available resulted in actuating the Cardox system about 50 minutes after the fire 

began. The Cardox system flushed the CSR with enough CO2 to displace most of the oxygen. 

However, the Cardox system was actuated three times in over 2 hours and was unable to 

completely extinguish the fire. The fire in the CSR was finally put out 4 hours after it started by 

the use of manual fire suppression efforts (extinguishers). 

When the plant firefighting personnel found the fire in the reactor building, it was burning in 

cable trays that were about 6.1 m (20 feet) above the second floor of the reactor building. After 

setting up a ladder to reach the fire, CO2 extinguishers were unsuccessfully discharged into the 

fire. The application of the CO2 extinguishers would exhaust the surface flames of the fire but 

was not able to extinguish the deep-seated burning in the cables. As a result, when 

extinguishing efforts ceased, the cables would re-ignite and continue burning. Firefighting 

efforts were further complicated by the loss of ventilation and lighting systems. In addition, a 

shortage of self contained breathing apparatus existed because plant operators were using a 

number of these devices while manually aligning valves in an attempt to get the reactor in a 

shutdown cooling mode. About 7 hours after the fire started, the plant superintendent agreed to 

use water on the fire (the local fire chief had suggested using water 5 hours prior—at 2:00 p.m.). 

Shortly after application of the water, the fire was declared out 7.5 hours after it started. 

A.2 Plant Response to the Fire

Twenty minutes after the fire started, Unit 1 operators noted anomalous behavior of controls and 

instrumentation for systems designed to provide emergency cooling of the reactor core. Over 

the next several minutes, the fire caused equipment to spuriously actuate, which resulted in a 

growing number of incidents. These included the automatic actuation of pumps and equipment 

that, when the operators determined they should be shutdown, would automatically start up 

again. 

The Unit 1 reactor was manually scrammed about 30 minutes after the fire initiated, shutting the 

reactor down and stopping the nuclear fission chain reaction. However, decay heat continued 

to be generated by the radioactive decay of the fuel, requiring continuous long-term cooling of 
A-3 

the core to ensure core damage would not occur. Shortly after the reactor scram, a number of 

instrumentation lights indicating the status of the plant went out. Soon after, the main-steamisolation valves (MSIVs) closed automatically eliminating the current method of decay heat 

removal. Closure of the MSIVs hampered the core-cooling efforts in two ways—(1) by closing 

off the methods of removing heat and (2) by stopping the flow of steam to the turbine driven 

feedwater pump. 

The fire had disabled the High Pressure Coolant Injection and Reactor Core Isolation Cooling 

systems. Consequently, the only method of keeping water on the core was through the use of 

the control-rod-drive (CRD) system pump at a flow rate of about 400 liters per minute (105 

gallons per minute), resulting in the water level in the reactor vessel to begin decreasing. To 

avoid core damage, the operators had to reduce the pressure within the reactor coolant system 

and then manually realign the condensate booster system to supply water to the core. The 

mode of cooling continued to provide adequate cooling until around 6:00 p.m. a loss of control 

air system prevented manual control of the pressure relief valves. This resulted in the CRD 

system to again be the only method to supply cooling water to the core. 

After the fire was declared out, smoke began to clear and the reliance on breathing apparatus 

decreased so that a more orderly approach to obtaining shutdown cooling could be taken. 

Around 9:50 p.m., control to the relief valves was restored, the reactor was depressurized, and 

the condensate booster pump again pumped cooling water into the reactor. Additional coolingwater makeup was provided throughout the incident, and additional alternatives could have 

been used to provide makeup water with the reactor at either high or low pressure. It is 

believed that at no time during the event did the water level drop below the top of active fuel. 

A.3 Lessons Learned from Browns Ferry Fire

The fire caused an estimated physical damage of $10 million and resulted in two operating units 

to be incapacitated for over a year. In addition to the above-mentioned costs, additional costs of 

around $10 million were incurred each month for replacement power. 

Fire Prevention

Grouped electrical cables are more flammable than most people believed prior to the fire. The 

use of open flames to detect leaks, the frequency of occurrence of small fires as a part of the 

leak detection process, the ease with which the cable insulation was ignited, and the spread of 

flames—all constituted a significant fire hazard. 

Use of Water

The extent of damage caused by the fire is attributable to the length of time the fire burned. The 

reluctance to use water on the fire (for fear of conductor shorting) was a position held by many 

licensees at the time—a position they felt would reduce the likelihood of causing spurious 

equipment operation. However, the failures caused by the fire as it continued to burn were 

largely responsible for the difficulties encountered in bringing the plant to a safe-stable state, 

and the fire was extinguished rather quickly when water was finally applied. Hence, the main 

lesson learned is that, if initial attempts to extinguish a cable fire with non-water means are 

unsuccessful, water should be used. Water is the best extinguishing agent available for most 

potentially deep-seated fires in nuclear power plants and the sooner a fire is extinguished, the 

less total damage results. 
A-4 

Redundant System Separation and Independence

The damage to electrical power and control circuits resulted in the loss of redundant 

subsystems and equipment. This caught the nuclear industry off guard in light of the 

independence and separation criteria that had been applied in the initial design of the plants. 

The principal causes of these failures were found to be the failure to recognize potential sources 

of failure in safety equipment (i.e., interconnection of safety and non-safety equipment) and the 

identification that use of conduit to isolate cables form their redundant counterparts did not 

protect the cables adequately. 

A.4 Additional Information

Numerous documents discuss the 1975 BFN fire. The most recent and comprehensive 

document is NUREG/BR-0361, “The Browns Ferry Nuclear Plant Fire of 1975 and the History of 

NRC Fire Regulations,” dated February 2009. This brochure provides a great overview of the 

event and supporting details and documents in an enclosed DVD. The brochure is available on 

the NRC website.
B-1 

Appendix B Ampacity Derating 

When current flows in a conductor, heat is produced because every conductor offers some 

resistance to the flow of current. The National Electric Code® (NEC) (American National 

Standards Institute (ANSI)/NFPA 70)) defines ampacity as “the current (in amperes) a conductor 

can carry continuously under the conditions of use without exceeding its temperature rating.” 

The current-carrying capacity of a particular conductor is dictated by its “ampacity” (that is, how 

many amperes it can handle). Ampacity is a function of the cross-sectional area or diameter of 

the wire and its material type (e.g., copper or aluminum) and cable insulation condition for basic 

installation conditions. For more complex installation conditions, Institute of Electrical and 

Electronic Engineers (IEEE) 835 provides more extensive and detailed tables. For installations 

involving cables in open cable trays, National Electrical Manufacturers Association (NEMA) 

WC51-1991/icae P-54-440 should be consulted. Larger-diameter wires have larger crosssection areas and can safely carry more electrical current without overheating. The ampacity 

rating of a specific conductor may be obtained from tables in the NEC. These tables are based 

on the size of the wire, the maximum allowable operating temperature of the insulation material, 

and the installation conditions. 

Cables routed in electrical raceways are derated to ensure that systems have sufficient capacity 

and capability to perform their intended safety functions. The nominal ampacity values include 

a safety margin that is sufficient for most installations. However, there are instances where 

application of the NEC ampacity tables is insufficient. Cables routed in raceways enclosed in 

fire barriers require additional derating because of the insulating effect of the fire barrier 

materials. For example, although the addition of fire barrier wrap around cable trays and 

conduits will affect the ampacity of a conductor, the NEC tables do not address this problem. 

Several inches of fire barrier material can have a significant effect on the ampacity rating 

specified in the NEC tables. NRC requires that cable derating due to the use of fire retardant 

coatings be considered by utilities during plant design or when design changes are made to 

existing electrical system configurations. Since there are no derating tables in the NEC for this 

kind of situation, calculations must be performed to determine the current carrying capacity of 

the enclosed cables. 

% _ 100  

o

o f

I

I I

Ampacity Derating (Equation B-1) 

Where: Io = Current in amperes required to attain a temperature of 90°C for the baseline 

case 

If = Current in amperes required to attain a temperature of 90°C for the system as 

protected by the passive fire protection system 

Four conditions exist which complicates establishing uniform ampacity values: 

1. An infinite number of configurations exist when one considers the vast number of cable 

sizes, cable types, and cable loading in the vast number of electrical raceways with the 

vast range of ambient temperatures. 

2. The heat transfer mechanisms of radiation, conduction, and convection are very 

interactive and transient in fire protected electrical raceways. Meticulous attention to 
B-2 

detail, patience to allow conditions to stabilize, and conservatism are required for reliable 

ampacity testing. 

3. The National Electric Code, Insulated Cable Engineers Association publications, and 

other publications list only very general ampacity values which tend to be conservative 

and do not consider fire protected electrical raceways. 

4. No nationally accepted standard ampacity test exists for fire protected cables, although 

Underwriters Laboratories has a proposed standard, and a different proposed standard 

was informally submitted at the April 1986 meeting of the Insulated Conductors 

Committee of the Institute of IEEE. 

IEEE Standard 848 

IEEE standard 848-1996, “IEEE Standard Procedure for the Determination of the Ampacity 

Derating of Fire-Protected cables,” provides a testing procedure for use in establishing the 

ampacity and ampacity derating factor for cables protected by ERFBS. This method involves 

maintaining the room temperature constant at 40°C and adjusting the current flowing through 

the cable to maintain the cable at 90°C. A baseline case without an ERFBS is conducted 

followed by the same test specimen protected with an ERFBS. The difference in the current 

flow (ampacity) is calculated in fractional terms and referred to as the ampacity derating factor. 

The following provides more detail on this testing approach. 

The standard requires a 40% cable fill in the cable tray and conduit tests containing 600V rated 

copper conductor cables with XLPE insulation and a CSPE jacket. Although the standard 

suggests a 2.54 cm (1 in) and 10.16 cm (4 –in) conduit sizes for testing, if significant ERFBS 

design differences exist for different size conduits, then tests shall consist of conduits sizes to 

bound the specific configurations. The average surface emissivity is also required to be 

documented as the test results can be affected by the conduits emissive properties. 

For a cable tray test, a 60.96 cm (24 in) wide cable tray is to be filled with three layers of cable,. 

Both cable trays and conduits must be at least 12 ft in length and oriented horizontally to 

represent worst case conditions. Air drop configurations do not require a cable fill fraction, but 

must be representative of field applications. For cable temperature measurements, Type T 

(copper/constantan) 24 AWG maximum thermocouples are to be used to measure the 

temperature of a cables copper conductors at various locations. To accurately measure the 

conductor temperatures, a small incision in made axially along the cable jacket and insulation 

and the thermocouple junction is placed in direct contact with the conductor strand. The 

incisions are closed by placing a single layer wrap of glass-reinforced electrical tape around the 

cut. 

To evaluate the ampacity derating for the ERFBS, a baseline ampacity measurement of an 

unprotected assembly is needed for comparison to the ampacity measurement with an applied 

ERFBS. For either scenario, the circuit is energized with a 60 Hz single-phase source sufficient 

to cause the conductor to reach 90 °C (194 °F) at the central location of the cable within the 

enclosure. The standard also specifies temperature range limits for the various thermocouple 

locations. The single-phase source (typically a current source) is adjusted such that the 

conductor maintains the 90°C (194°F) temperature and these ampacity values are recorded 

when the system has been determined to reach steady state condition, which is when: 

 
B-3 

a) A minimum of 3-hours has elapsed since the last adjustment of current 

level or perturbation of the system occurred. 

b) The rate of change of the average of thermocouple readings at the hot 

spot does not exceed ±0.2°C (±0.36°F) per hours for conduit, tray, and 

free-air drop. 

To ensure that the average thermocouple temperature rise does not exceed the ±0.2°C change 

per hour, the standard provides a linear regression analysis method using the least-square 

method. 

During the entire test, room enclosure is maintained at a 40 ± 2 °C (104 ± 3.6 °F) temperature. 

In addition, induced air currents within the room enclosure and radiant energy from the heat 

source should not impinge upon the test assembly. 

At the conclusion of the tests, the final conductor temperature and ambient temperature may not 

match 90 °C (194 °F) and 40 °C (104 °F) respectively. The standard provides a normalization 

method which computes the normalized current as follows: 

 ( )( )

( )( ) '

'

' '

c a c

c a c

T T T

T T T I I  

   

 (Equation B-2) 

where 

 I’ is normalized current, amperes 

 I is test current at equilibrium, amperes 

 Tc is hottest conductor temperature at center at equilibrium, °C 

 Ta is measured enclosure ambient temperature, °C 

 Tc’ is normalized conductor temperature = 90°C 

 Ta’ is normalized ambient temperature = 40°C 

α is 234.5 for copper and 228.1 for aluminum 

Following the normalization, the ampacity derating factor can be found by the following 

equation, 

  

100  

o

o f

I

I I

ADF (Equation B-3) 

where 

 Io is the normalized current for the baseline condition, amperes 

 If is the normalized current for the passive fire-protected cable system or cable 

penetration fire stop system, amperes 

 ADF is the ampacity derating factor, % 

 
B-4 

This page intentionally left blank. 
C-1 

Appendix C Summaries of NRC Generic Communications on 

ERFBS 

NRC has issued a number of generic communications regarding ERFBS. Summaries of the 

issues that were addressed in these generic communications are presented below. 

Bulletins (BLs) 

Bulletin 92-01 

Bulletin No. 92-01, “Failure of Thermo-Lag 330 Fire Barrier System to Maintain Cabling in Wide 

Cable Trays and Small Conduits Free from Fire Damage,” June 24, 1992 informed the licensees 

that NRC has determined that the 1- and 3-hour pre-formed assemblies installed on small 

conduit and wide cable trays (wider than 36 cm (14 inches)) do not provide the level of safety as 

required by NRC requirements. The bulletin requested plants that use Thermo-Lag 330-1 to 

identify areas in the plant where it is used and where it is used to protect either small diameter 

conduit or wide trays that provide safe shutdown capability, the licensee should implement the 

appropriate compensatory measures. 

Bulletin 92-01, Supplement 1

Failure of Thermo-Lag 330 Fire Barrier System to Perform its Specified Fire Endurance 

Function, August 28, 1992, alerts licensees and permit holder of additional apparent failure in 

fire endurance testing performed for Texas Utilities Electric Company associated with the 

Thermo-Lag 330 fire barrier system which many plants have installed to protect safe shutdown 

capability. The bulletin requested identification of areas where Thermo-Lag 330 is used and to 

implement appropriate compensatory measures until the licensee can declare the fire barriers 

operable on the basis of applicable tests demonstrating appropriate 1- or 3-hour performance. 

Generic Letters (GLs) 

Generic Letter 86-10 

Generic Letter 86-10, “Implementation of Fire Protection Requirements,” April 24, 1986, 

provides guidance as to acceptable methods of satisfying Commission regulatory fire protection 

requirements. GL 86-10 also contained two enclosure, 1 “Interpretations of Appendix R,” 

provided NRCs interpretation of the Appendix R regulations, and enclosure 2 “Appendix R 

Questions and Answers,” provides NRC answers to questions raised at and subsequent to an 

Appendix R workshop. Section 3.2 of enclosure 2, “Appendix R Questions and Answers,” to GL 

86-10 provides NRC acceptance criteria on the 325°F temperature criterion. 

Generic Letter 86-10, Supplement 1 

Generic Letter 86-10, Supplement 1, “Fire Endurance Test Acceptance Criteria for Fire Barrier 

Systems Used to Separate Redundant Safe Shutdown Trains Within the Same Fire Area” 

March 25, 1994, provides guidance and acceptance criteria as to how NRC will review and 

evaluate the adequacy of fire endurance tests and fire barrier systems proposed by licensees or 

applicants. Supplement 1 was issued to (1) clarify the applicability of the test acceptance 

criteria in GL 86-10 to raceways fire barrier systems, (2) specify a set of fire endurance test 

acceptance criteria that are acceptable for demonstrating the fire barrier systems can perform 

the required fire-resistive function and maintain the protected safe shutdown train free of fire 

damage, (3) specify acceptable options for hose stream testing, and (4) specify criteria for cable 
C-2 

functionality testing when a deviation is necessary, such as when the fire barrier temperature 

rise criteria are exceeded or the test specimen cables sustain visible damage. 

Generic Letter 92-08 

Generic Letter 92-08 “Thermo-Lag 330-1 Fire Barriers, December 17, 1992,” requested 

additional information to verify that licensees using Thermo-Lag 330-1 ERFBS comply with NRC 

regulations. The issuance of GL 92-08 was stimulated by NRCs concern that the Thermo-Lag 

330-1 ERFBS may not provide the level of fire endurance intended by the licensees, and that 

may results in licensees not meeting the requirements of 10 CFR 50.48 and GDC 3. The GL 

requested information related to (1) fire endurance qualification testing, (2) ampacity derating of 

cables enclosed in Thermo-Lag 330-1 barrier, and (3) the licensees evaluation and application 

of the results of tests conducted to determine the fire endurance ratings and the ampacity 

derating factors of Thermo-Lag 330-1 barriers. 

Generic Letter 2006-03 

Generic Letter 2006-03, “Potentially Nonconforming HEMYC and MT Fire Barrier 

Configurations,” requested licensees to evaluate their facilities to confirm compliance with the 

existing applicable regulatory requirements in light of the information provided in the GL and, if 

appropriate, take additional actions. 

Information Notices (INs) 

Information Notice 91-47 

Information Notice 91-47, “Failure of Thermo-Lag Fire Barrier Material to Pass Fire Endurance 

Test,” August 6, 1991, gave licensees information on the fire endurance test performed by Gulf 

States Utilities Company on a Thermo-Lag 330-1 fire barrier installed on wide aluminum cable 

tray and the associated fire test failure. IN 91-47 alerted licensees with problems that could 

result from the use of or improper installation of Thermo-Lag material to satisfy the electrical 

raceway fire protection requirements for safe shutdown components specified in Section III.G.2 

of Appendix R to 10 CFR 50. These Thermo-Lag ERFBS problems included not following 

manufacture installation procedures, missing stress skin and/or structural ribbing, and lack of 

documentation on qualification for large cable trays. 

Information Notice 91-79 

Information Notice 91-79, “Deficiencies in the Procedures for Installing Thermo-Lag Fire Barrier 

Materials,” December 6, 1991, identified problems that could results from improperly installed 

Thermo-Lag 330-1 fire barriers that are used to satisfy NRC fire protection requirements for safe 

shutdown components. After NRC review and discussion of the installation details with various 

Thermo-Lag 330-1 users, numerous variations were identified. At the time of issuance of IN 91-

79, NRC had not been able to verify that all of the specific installation variations observed had 

been qualified by independent qualification testing or engineering analysis. 

Information Notice 92-46 

Information Notice 92-46, “Thermo-Lag Fire Barrier Material Special Review Team Final Report 

Findings, Current Fire Endurance Tests, and Ampacity Calculation,” June 23, 1992, presented 

information on failed Thermo-Lag 330-1 testing conducted by Texas Utilities for large cable 

trays and small cable conduits, mathematical errors found in the calculation of cable ampacity 

derating factors for Thermo-Lag fire resistive barriers, and provided the Special Review Team 

Final Report as an attachment. The attached report identified that some licensees have not 
C-3 

adequately reviewed and evaluated the fire endurance and ampacity test results for applicability 

to the Thermo-Lag fire barrier systems installed in their facilities. Additional findings included, 

incomplete or indeterminate fire test results, barrier installations that were not constructed in 

accordance with vendor-recommended installation procedures, incomplete installation 

procedures, and as-built fire barrier configurations that may not have been qualified by a valid 

fire endurance test or evaluated in accordance with the guidance of GL 86-10. 

IN 92-46, “Thermo-Lag Fire Barrier Material Special Review Team Final Report Findings, 

Current Fire Endurance Tests, and Ampacity Calculation Errors,” was issued to provide 

information of the findings of NRC’s Thermo-Lag Special Review Team, current Thermo-Lag 

330 fire resistance testing being conducted by Texas Utilities and Thermal Science, Inc., and 

errors found in the calculation of cable ampacity derating factors for Thermo-Lag fire resistive 

barriers. 

Information Notice 92-55 

IN 92-55, “Current Fire Endurance Test Results for Thermo-Lag Fire Barrier Material, July 27, 

1992,” provided a brief summary of the Thermo-Lag 330 small scale testing results obtained by 

the National Institute of Standards and Technology (NIST). NIST conducted both 1-hour and 3-

hour small scale fire endurance tests to determine the fire resistive properties of Thermo-Lag 

330 pre-formed panels. The 1-hour barrier exceeded the temperature rise criteria in 22 

minutes, while the 3-hour barrier lasted 2 hours and 20 minutes before exceeding the 

acceptance criteria. 

Information Notice 92-82 

IN 92-82, “Results of Thermo-Lag 330-1 Combustibility Testing, December 15, 1992,” provided 

information on the results of Thermo-Lag 330-1 combustibility testing that was conducted by 

NIST. Using ASTM E-136 and ASTM E-1354 testing standards, these tests revealed that 

Thermo-Lag 330-1 fire barrier material is combustible. Each thermo-Lag specimens tested 

exhibited a weight loss of greater than 50 percent and exhibited flaming beyond 30 seconds. 

Information Notice 93-40 

Fire Endurance Test Results for Thermal Ceramics FP-60 Fire Barrier Material, May 26, 1993, 

alerted addresses of the results of the fire endurance and ampacity derating test report 

submitted by Thermal Ceramics on the FireMaster FP-60 fire barrier system and the results of 

NRC staff reviews. 

Information Notice 93-41 

One Hour Fire Endurance Test Results for Thermal Ceramics Kaowool, 3M Company FS-195 

and 3M Company Interam E-50 Fire Barrier Systems,” May 28, 1993. IN 93-41 identified 

deficiencies associated with various fire barrier testing reviewed during an NRC reverification 

inspection conducted by NRC inspectors at the Salem Nuclear Generating Station in 1993. 

Information Notice 94-22

IN 94-22, “Fire Endurance and Ampacity Derating Test Results for 3-hour Fire-Rated ThermoLag 330-1 ire Barriers,” March 16, 1994, provided information on the preliminary results of the 

fire endurance and ampacity derating tests of Thermo-Lag 330-1 fire barriers conducted by 

NRC at Underwriter Laboratories, Inc. 

 
C-4 

Information Notice 94-34 

IN 94-34,”Thermo-Lag 330-660 Flexi-Blanket Ampacity Derating Concerns,” dated May 13, 

1994, alerted addresses to a potential problem involving the use of non-conservative ampacity 

derating data by licensees based on previous representations by the vendor, Thermal Science, 

Inc. 

Information Notice 94-86 

“Legal Actions against Thermal Science, Inc. Manufacturer of Thermo-Lag,” December 22, 

1994. IN 94-86 provided information to addresses on the grand jury indictment of Thermal 

Science, Inc. and Rubin Feldman, President, for allegedly making false statement to NRC and 

others concerning the fire barrier material known as Thermo-Lag. The IN also identified that, in 

a separate legal action, Industrial Testing Laboratories, Inc., and Alan M. Siegel, President, 

pleaded guilty to making and aiding and abetting the making of false statements concerning 

Thermo-Lag. 

Information Notice 94-86, Supplement 1

“Legal Actions Against Thermal Science, Inc., Manufacturer of Thermo-Lag,” November 15, 

1995. Supplement 1 to IN 94-86 provided the Federal jury finding Thermal Science, Inc. (TSI), 

and its president, Rubin Feldman, not guilty of making false statements about the role of 

Industrial Testing Laboratories (ITL) in the qualification testing of Thermo-Lag fire barriers. 

Information Notice 95-27 

NRC Review of Nuclear Energy Institute, “Thermo-Lag 330-1 Combustibility Evaluation 

Methodology Plant Screening Guide,” May 31, 1995, provided the results of NRC staff review of 

NEI Combustibility Evaluation Methodology. NRC staff informed NEI that it will not accept the 

use of the NEI methodology to justify the use of Thermo-Lag materials, or other material such 

as fire retardant plywood or cable jackets, as noncombustible where noncombustible materials 

are specified by NRC fire protection requirements. 

Information Notice 95-32 

Thermo-Lag 330-1 Flame Spread Test Results, August 10, 1995. IN 95-32 provided the results 

of NRC flame spread testing of Thermo-Lag 330-1 fire barriers. 

Information Notice 95-49

Seismic Adequacy of Thermo-Lag Panels, October 27, 1995. IN 95-49 identified two specific 

NRC concerns related to the possibility of varying physical composition of the Thermo-Lag 

barrier in use across industry and the actual weights of Thermo-Lag use in plants. 

Information Notice 95-49, Supplement 1 

Seismic Adequacy of Thermo-Lag Panels, December 10, 1997, provided the results of NRC 

sponsored mechanical properties testing of Thermo-Lag 330-1 fire barrier material performed by 

the National Institute of Standards and Technology (NIST). The results of the testing indicated 

significantly lower mechanical properties than those used by the vendor to demonstrate the 

seismic adequacy of Thermo-Lag 330-1 panels. 

Information Notice 95-52

“Fire Endurance Test Results for Electrical Raceway Fire Barrier Systems Constructed from 3M 

Company Interam Fire Barrier Materials,” November 14, 1995. IN 95-52 provided the result of 

industry testing of 3M Interam fire barrier materials. 

 
C-5 

Information Notice 95-52, Supplement 1

Fire Endurance Test Results for Electrical Raceway Fire Barrier Systems Constructed from 3M 

Company Interam Fire Barrier Materials,” March 17, 1998, identified additional fire endurance 

testing failures associated with a 3-hour 3M Interam Fire barrier system. 

Information Notice 97-59 

Fire Endurance Test Results of Versawrap Fire Barriers, August 1, 1997. IN 97-59 provides a 

summary of the testing results and several failures identified by NRC staff during a fire 

endurance test conducted at UL for Transco Products, Inc. of Chicago, Illinois. 

Information Notice 97-70 

Potential Problems with Fire Barrier Penetration Seals, September 19, 1997. IN 97-70 identified 

problems with installed fire barrier penetration seals that have gone undetected as a result of 

inadequate surveillance inspection procedures and inadequate acceptance criteria. 

Information Notice 99-17 

Problems Associated with Post-Fire Safe-Shutdown Circuit Analysis, June 3, 1999. IN 99-17 

identified potential problems associated with post-fire safe-shutdown circuit analysis. These 

potential problems could result in a vulnerability to fire-induced circuit failures that could prevent 

the operation or lead to malfunction of equipment necessary to achieve and maintain post-fire 

safe shutdown. 

Information Notice 05-07 

Results of Hemyc Electrical Raceway Fire Barrier System Full Scale Fire Testing, April 1, 2005. 

IN 2005-07 informed addressees of the results of Hemyc electrical raceway fire barrier system 

(ERFBS) full-scale fire tests. The Hemyc ERFBS did not perform for one hour as designed 

because shrinkage of the Hemyc ERFBS occurred during the testing. 
C-6 

This page intentionally left blank. 
D-1 

Appendix D Supplemental Test Result Summaries 

APPENDIX D 

TABLE OF CONTENTS 

Table Page

D.1 General Caution on use of Information in Appendix D ................................................ D-2 

D.2 3M ERFBS ................................................................................................................... D-2 

D.2.1 3M InteramTM E-50 Series ........................................................................................... D-2 

D.2.2 3M Rigid Panel System Testing ................................................................................. D-31 

D.3 Thermo-Lag 330-1 ..................................................................................................... D-38

D.3.1 NUMARC Phase 1 Testing ........................................................................................ D-38 

D.3.2 NUMARC Phase 2 Testing ........................................................................................ D-43 

D.3.3 Texas Utilities (TU) Electric Co. Tests for Comanche Peak Steam Electric Station .. D-50 

D.3.4 Tennessee Valley Authority Tests for Watts Bar Nuclear Power Plant ..................... D-66 

D.4 References ................................................................................................................ D-83 

 
D-2 

D.1 General Caution on use of information in Appendix D

This section provides information on supplement testing completed on various ERFBS. It is 

included in this report for completeness. Note that a majority of this testing was conducted prior 

to publishing of NRC guidance on testing ERFBS. Therefore, the following test results may not 

represent qualified ERFBS. 

D.2 3M ERFBS

D.2.1 3M InteramTM E-50 Series 

D.2.1.1 OPL Ampacity Testing Project No. 14540-99074 and 14540-99075 

ERFBS: E54A Report Date: March 25, 1996 

Test Procedure: IEEE P848 Test Dates: October 4 – 25, 1995 

Post GL 86-10 Design 

Materials used: 

E-54A, InteramTM T-49 Tape, InteramTM FireDamTM 150 Caulk, 3M ScotchTM Brand Premium 

Grade Filament Tape P-898, 1⁄2 in x 0.020 in type 304 stainless steel banding straps and clips 

1 in diameter galvanized RSC

12 ft long conduit, 13 ft long 4/C 10AWG, 36.36% fill actual, ERFBS Three (3) layers of Interam 

E-54A @ 0.4” nominal thickness (1.2” total nominal thickness) 

12 Thermocouples 24 gauge Type T, Copper-Constantan (±0.5% Limits of Error), in direct 

contact with the top surface of the cable conductor, located 4@center, 4@36in to left of center, 

4@36in to right of center 

4in diameter galvanized RSB

12 ft long conduit, 12 3/C 6AWG 13 ft long cables, 42.19% fill actual, ERFBS Three (3) layers of 

Interam E-54A @ 0.4” nominal thickness (1.2” total nominal thickness) 

36 Thermocouples 24 gauge Type T, Copper-Constantan (±0.5% Limits of Error), in direct 

contact with the top surface of the cable conductor, located 12@center, 12@36in to left of 

center, 12@36in to right of center (i.e., 3 TC on each cable) 

The results of this testing are shown below in Table D-1. 

 
D-3 

Table D-1. 3M Interam E54A Ampacity Results 1" & 4" Conduits

Test Item 

Current 

(Amps) 

Conductor 

Temp (oC) 

Room Temp 

(oC) 

Corrected 

Current* 

(Amps) 

Ampacity 

Derating 

Factor % 

1” Conduit 

Baseline 31.67 90.7 40.2 31.55 - - - 

1” Conduit 

with ERFBS 29.10 90.6 40.4 29.07 7.86 

4” Conduit 

Baseline 25.60 89.3 29.2 25.55 - - - 

4” Conduit 

with ERFBS 22.93 89.4 40.9 23.26 8.96 

* The corrected current values are calculated using IEEE P848/D16 

D.2.1.2 OPL Ampacity Testing Project No. 14540-100770

ERFBS: E54A Report Date: December 5, 1996 

Test Procedure: IEEE P848 Test Dates: August 1 – October 10, 1996 

Post GL 86-10 Design 

Materials used: 

E-54A, InteramTM T-49 Tape, InteramTM FireDamTM 150 Caulk, 3M ScotchTM Brand Premium 

Grade Filament Tape P-898, 1⁄2 in x 0.020 in type 304 stainless steel banding straps and clips 

24 in Wide Cable Tray

24in wide x 4in deep cable tray assembly, 12 ft long, 96 3/C 6AWG, 58.90% actual fill, ERFBS 3 

layers of Interam E54A @ 0.4” nominal thickness 

15 Thermocouples 24 gauge Type T, Copper-Constantan (±0.5% Limits of Error), in direct 

contact with the top surface of the cable conductor, located 5@center, 5@36in to left of center, 

5@36in to right of center and all were within the second layer of cables (there were a total of 3 

layers of cables). 

The results of this testing are shown below in Table D-2. 

 Table D-2. 3M InteramTM E54A Ampacity Results 12" Wide Cable Tray

Test Item 

Current 

(Amps) 

Conductor 

Temp (oC) 

Room Temp 

(oC) 

Corrected 

Current* 

(Amps) 

Ampacity 

Derating 

Factor % 

24” Tray 

Baseline 28.34 90.2 40.7 28.49 - - - 

24” Tray 

with ERFBS 14.43 90.7 39.5 14.28 49.88 

* The corrected current values are calculated using IEEE P848/D16 
D-4 

D.2.1.3 OPL Ampacity Test Project No. 8610-102164 and 8610-102165

ERFBS: E54A Report Date: December 26, 1997 

Test Procedure: IEEE P848 Test Dates: November 17 – 25, 1997 

Post GL 86-10 Design 

Materials used: 

E-54A, InteramTM T-49 Tape, InteramTM FireDamTM 150 Caulk, 3M ScotchTM Brand Premium 

Grade Filament Tape P-898, 1⁄2 in x 0.020 in type 304 stainless steel banding straps and clips 

1 in diameter galvanized RSC

12 ft long conduit, 13 ft long 4/C 10AWG, 36.36% fill actual, ERFBS five layers of Interam E-54A 

@ 0.4” nominal thickness (1.2” total nominal thickness) 

12 Thermocouples 24 gauge Type T, Copper-Constantan (±0.5% Limits of Error), in direct 

contact with the top surface of the cable conductor, located 4@center, 4@36in to left of center, 

4@36in to right of center 

4in diameter galvanized RSB

12 ft long conduit, 12 3/C 6AWG 13 ft long cables, 42.19% fill actual, ERFBS five layers of 

Interam E-54A @ 0.4” nominal thickness (1.2” total nominal thickness) 

36 Thermocouples 24 gauge Type T, Copper-Constantan (±0.5% Limits of Error), in direct 

contact with the top surface of the cable conductor, located 12@center, 12@36in to left of 

center, 12@36in to right of center (i.e., 3 TC on each cable) 

The results of this testing are shown below in Table D-3. 

Table D-3. 3M Interam E54A Ampacity Results 

Test Item 

Current 

(Amps) 

Conductor 

Temp (oC) 

Room Temp 

(oC) 

Corrected 

Current* 

(Amps) 

Ampacity 

Derating 

Factor % 

1” Conduit 

Baseline 31.67 90.7 40.2 31.55 - - - 

1” Conduit 

with ERFBS 25.12 90.0 40.1 25.15 20.29 

4” Conduit 

Baseline 29.59 90.6 39.2 29.21 - - - 

4” Conduit 

with ERFBS 19.20 89.5 38.6 19.01 34.92 

* The corrected current values are calculated using IEEE P848/D16 

 
D-5 

D.2.1.4 OPL Ampacity Testing Project No. 8610-102166 

ERFBS: E54A Report Date: December 23, 1997 

Test Procedure: IEEE P848 Test Dates: October 27 – November 10, 1997 

Post GL 86-10 Design 

Materials used: 

E-54A, InteramTM T-49 Tape, InteramTM FireDamTM 150 Caulk, 3M ScotchTM Brand Premium 

Grade Filament Tape P-898, 1⁄2 in x 0.020 in type 304 stainless steel banding straps and clips 

24 in Wide Cable Tray

24in wide x 4in deep cable tray assembly, 12 ft long, 96 3/C 6AWG, 58.90% actual fill, ERFBS 

six layers of Interam E54A @ 0.4” nominal thickness 

15 Thermocouples 24 gauge Type T, Copper-Constantan (±0.5% Limits of Error), in direct 

contact with the top surface of the cable conductor, located 5@center, 5@36in to left of center, 

5@36in to right of center and all were within the second layer of cables (there were a total of 3 

layers of cables). 

The results of this testing are shown below in Table D-4. 

Table D-4. 3M InteramTM E54A Ampacity Results 12” Wide Cable Tray 

Test Item 

Current 

(Amps) 

Conductor 

Temp (oC) 

Room Temp 

(oC) 

Corrected 

Current* 

(Amps) 

Ampacity 

Derating 

Factor % 

24” Tray 

Baseline 28.34 90.2 40.7 28.49 - - - 

24” Tray 

with ERFBS 12.36 90.8 40.7 12.36 56.62 

* The corrected current values are calculated using IEEE P848/D16 

D.2.1.5 OPL Fire Endurance Test Report Project No. 14540-99416

ERFBS: E54A Report Date: February 26, 1996 

Acceptance Criteria: GL 86-10 Supplement 1 Test Dates: January 22, 1996 

Post GL 86-10 Design Fire Test Duration: 3-hr 

All conduits were supported by a common trapeze type hanger formed from Unistrut P1000 

channel. The blockouts in the concrete floor slab were sealed with Five Star Grout, installed to 

the full thickness of the slab. In addition to the 3M InteramTM, Dow Corning 732 

adhesive/sealant and FireDamTM FD-150 Caulk were used to fill gaps and seams and T-49 

Aluminum Foil Tap to secure overlap joints. 

5in Conduit Assembly

5in diameter galvanized RSC and fittings assembled into an “U-shaped” configuration, having 

an overall horizontal dimension of 102in. and an overall vertical dimension of 76in. at each leg. 

One leg had a 90 degree radius elbow, while the other used an iron condulet LB. Five layers of 

3M InteramTM E54A mat material. 
D-6 

3in Conduit Assembly

3in diameter galvanized RSC and fittings assembled into an “U-shaped” configuration, having 

an overall horizontal dimension of 102in. and an overall vertical dimension of 76in. at each leg. 

One leg had a 90 degree radius elbow, while the other used an iron condulet LB. The vertical 

section containing the condulet also transitioned into a steel junction box (12 in x 12 in x 8 in). 

Five layers of 3M InteramTM E54A mat material to protect the conduit and six layers to protect 

the junction box. 

1in Conduit Assembly

1in diameter galvanized RSC and fittings assembled into an “U-shaped” configuration, having 

an overall horizontal dimension of 102in. and an overall vertical dimension of 76in. at each leg. 

One leg had a 90 degree radius elbow, while the other used an iron condulet LB. Five layers of 

3M InteramTM E54A mat material. 

Table D-5. 3M InteramTM E54A Fire Endurance Testing 1", 3", & 5" RSC (OPL)

Thermocouple Location 

Max. Individual 

Temperature oC (oF) 

Max Average 

Temperature oC (oF) 

5” Steel Conduit 

Conduit Surface 153 (307) 117 (243) 

Bare #8 Wire in Conduit 132 (269) 108 (227) 

3” Steel Conduit 

Conduit Surface 153 (307) 114 (237) 

Bare #8 Wire in Conduit 132 (270) 153 (220) 

1” Steel Conduit 

Conduit Surface 192 (377) 153 (307) 

Bare #8 Wire in Conduit 174 (346) 148 (299) 

Steel Junction Box 107 (224) 101 (213) 

 Acceptance Criteria: Single pt. T≤196oC; Average T≤154oC 

Results

All raceway items met the requirements of the TEST PLAN for a fire resistance rating of three 

hours. The TEST PLAN followed GL 86-10 Supplement 1 guidance as it related to acceptance 

criteria of the fire exposure and hose stream test. 

D.2.1.6 OPL Fire Endurance Test Report Project No. 14540-99417 

ERFBS: E54A Report Date: September 22, 1997 

Acceptance Criteria: GL 86-10 Supplement 1 Test Dates: August 21, 1997 

Post GL 86-10 Design Fire Test Duration: 3-hours 

Both cable tray assemblies were supported by a common trapeze type hanger formed from 

3x4.1 steel channel. The blockouts in the concrete floor slab were sealed with Dow Corning 3-

6548 RTV silicone foam material. In addition to the 3M InteramTM, Dow Corning 732 

adhesive/sealant and FireDamTM FD-150 Caulk were used to fill gaps and seams and T-49 
D-7 

Aluminum Foil Tap to secure overlap joints. 

6” Cable Tray

B-Line Systems, Inc. 6 in. wide by 4 in. deep, ladder back cable tray, assembled into an “Ushaped” configuration having a horizontal dimension of 104 in. and a vertical dimension of 76 in. 

at each leg. Six layers of 3M InteramTM E54A mat. 

24” Cable Tray

B-Line Systems, Inc. 24 in. wide by 4 in. deep, ladder back cable tray, assembled into a “Ushaped” configuration having a horizontal dimension of 104 in. and a vertical dimension of 76 in. 

at each leg. Six layers of 3M InteramTM E54A mat. 

Table D-6. 3M InteramTM E54A Fire Endurance Testing Steel Cable Trays (OPL) 

Thermocouple Location 

Max. Individual 

Temperature oC (oF) 

Max Average 

Temperature oC (oF) 

6” Cable Tray 

Front Tray Side Rail 159 (319) 124 (256) 

Rear Tray Side Rail 167 (333) 129 (264) 

Bare #8 Wire on Rungs 151 (303) 119 (247) 

24” Cable Tray 

Front Tray Side Rail 163 (325) 133 (271) 

Rear Tray Side Rail 157 (315) 132 (269) 

Bare #8 Wire on Rungs 142 (287) 111 (231) 

Acceptance Criteria: Single pt. T≤214oC; Average T≤172oC

Results

Following the hose stream test, the outermost layer of 3M material on the supports and raceway 

assemblies had become dislodged by the water hose stream. 

For the 6 in wide cable tray, the 6th (outermost) layer of 3M material was completely dislodged 

by the hose stream test. The 5th layer was also mostly eroded from the water stream. The 4th

layer foil covering was intact and the mat material itself uncharred, however the material was 

completely discolored (green). The 3rd layer foil covering was intake, as well as the mat 

material, and this layer was only partially discolored. The 2nd layer, the standoff between the 2nd

and 1st layer and the 1st layer were completely intake and uncharred. Much of the material 

covering the supports underneath the tray was washed away during the water hose stream. 

The material (in all layers and/or areas which survived the water stream) was completely 

discolored (green) in the vicinity of the support member. 

The 24 in. wide cable tray assembly had the 6th (outermost) layer of 3M material completely 

dislodged by the hose stream test. The 5th layer was also mostly eroded from the water stream. 

The 4th layer foil covering was intact and the mat material itself uncharred, however the material 

was completely discolored (green). The 3rd layer foil covering was intact, as well as the mat 

material, and this layer was only partially discolored. The 2nd layer, the standoff between the 2nd

and 1st layer and the 1st layer were completely intact and uncharred. Much of the material 

covering ths supports underneath the tray was washed away during the water hose stream. 

The material (in all layers and/or areas which survived the water stream) was completely 
D-8 

discolored (green) in the vicinity of the support member. 

The report concluded that, “all of the raceway item evaluated in the fire exposure test, clad with 

3M InteramTM Mat material met the requirements of the TEST PLAN,” which based its 

acceptance criteria and followed the guidance of GL 86-10 Supplement 1. 

D.2.1.7 OPL Test Report Project No. 8610-102570 

ERFBS: E54A Report Date: May 19, 1998 

Acceptance Criteria: GL 86-10 Supplement 1 Test Dates: March 19, 1998 

Post GL 86-10 Design Fire Test Duration: 3-hour 

Article 1: Three 4” diameter conduits and three 2” diameter conduits (conduits 1-6). Five layers 

 of 3M InteramTM E54A. 

Article 2: Steel junction box of dimensions 36” x 19” x 10” (Junction Box #3). Six layers of 3M 

 InteramTM E54A. 

Article 3: Steel junction box 12” x 12” x 8” with one face against the concrete (Junction Box #1). 

 Six layers of 3M InteramTM E54A. 

Article 4: 1” diameter RSC with multiple interfering items (conduit #10 (1” diameter), conduits 11 

(2” diameter), and conduit 12 (4” diameter)). Five layers of 3M InteramTM E54A. 

Article 5: A trapeze hanger configuration consisting of 1⁄2” -13 threaded rod and P-1001 

 UnistrutTM. Five layers of 3M InteramTM E54A within 12 in. of critical item and four layers 

 for the remainder of the length. 

Article 6: 4” diameter RSC in close proximity to concrete (conduit #9). Five layers of 3M 

 InteramTM E54A. 

Article 7: Steel Junction Box 12” x 12” x 8” with one face against the concrete (Junction Box #2). 

 Six layers of 3M InteramTM E54A. 

Table D-7. 3M Interam E54A Fire Endurance Test Conduits & Junction Boxes (OPL) 

Thermocouple Location 

Max. Individual 

Temperature oC (oF) 

Max Average 

Temperature oC (oF) 

Conduit #1 

Bare #8 Conductor 128 (262) 108 (226) 

Conduit Surface 145 (293) 110 (230) 

Conduit #2 

Bare #8 Conductor 108 (226) 96 (204) 

Conduit Surface 111 (232) 95 (203) 

Conduit #3 

Bare #8 Conductor 116 (240) 98 (208) 

Conduit Surface 129 (264) 102 (215) 

Conduit #4 

Bare #8 Conductor 103 (217) 92 (197) 

Conduit Surface 98 (208) 92 (197) 

Acceptance Criteria: Single pt. T≤198oC; Average T≤155oC
D-9 

Table D-7. 3M Interam E54A Fire Endurance Test Conduits & Junction Boxes (OPL) 

(Continued) 

Thermocouple Location 

Max. Individual 

Temperature oC (oF) 

Max Average 

Temperature oC (oF) 

Conduit #5 

Bare #8 Conductor 128 (262) 102 (216) 

Conduit Surface 142 (287) 109 (228) 

Conduit #6 

Bare #8 Conductor 106 (222) 94 (202) 

Conduit Surface 109 (229) 94 (202) 

Conduit #9 

Conduit Surface 144 (292) 118 (244) 

Conduit #10 

Bare #8 Conductor 206 (403) 152 (306) 

Conduit Surface 209 (409) 164 (328)

Junction Box #1 117 (243) 152 (306)

Junction Box #2 989 (1813) 918 (1684) 

Junction Box #3 123 (253) 112 (233)

Trapeze Hangers 753 (1387) 579 (1075) 

Acceptance Criteria: Single pt. T≤198oC; Average T≤155oC

Results

Articles #1-3, and #6 met the requirements of the TEST PLAN and therefore provide a 3-hour 

fire endurance rating based on criteria specified in GL 86-10 Supplement 1. Article #7 failed 

prior to the hose stream test when its protective barrier fell off at approximately 68 minutes into 

the testing. Article 4 failed to meet the temperature rise criteria at approximately 174 minutes of 

the 180 minute qualification test. 

Table D-8. 3M Interam E54A Test Results (OPL Project No. 8610-102570)

Test Item 

# layers of ERFBS 

E54A 

Fire Endurance Rating 

(minutes) 

Article 1 (Conduits 1-6) 5 180 

Article 2 (Junction Box #3) 6 180 

Article 3 (Junction Box #1) 6 180 

Article 4 (Conduit #10) 5 174 

Article 6 (Conduit #9) 5 180 

Article 7 (Junction Box #2) 6 68 
D-10 

D.2.1.8 OPL Test Report Project No. 14540-99123 

ERFBS: E54A Report Date: December 5, 1995 

Acceptance Criteria: GL 86-10 Supplement 1 Test Dates: November 28, 1995 

Post GL 86-10 Design Fire Test Duration: 3-hr 

The two cable trays were supported by a common trapeze type hanger formed from 3x4.1 steel 

channel. The three conduit assemblies were supported on a common trapeze type hanger 

formed from UnistrutTM P1000 channel. The blockouts in the concrete slab were sealed with 

Dow Corning 3-6548 RTV silicone foam material. Electrical cables (power, control, and 

instrumentation) were installed in both cable tray assemblies. Table D-9 identifies the percent 

cable fill in each cable tray. 

6” Cable Tray

B-Line Systems Inc., 6 in. wide x 4 in. deep, ladder back cable tray, assembled into a “Ushaped” configuration having a horizontal dimension of 104 in. and a vertical dimension of 76 in. 

at each leg. Five layers of 3M InteramTM E54A. 

24” Cable Tray

B-Line Systems Inc., 24 in. wide x 4 in. deep, ladder back cable tray, assembled into a “Ushaped” configuration having a horizontal dimension of 104 in. and a vertical dimension of 76 in. 

at each leg. A 2in. conduit stub assembly transitioned through the upper steel deck, extending 

8 in. below the deck insulation, forming an air drop which transitioned into the center of the 

horizontal section of the 24 in. cable tray. Five layers of 3M InteramTM E54A. 

5” Conduit

5 in. diameter galvanized RSC and fittings assembled into a “U-shaped” configuration having an 

overall horizontal dimension of 102 in. and an overall vertical dimension of 76 in. at each leg. 

One leg of the conduit assembly transitioned through the upper steel deck into a standard 

radius 90 degree elbow while the other end used an iron condulet LB. Five layers of 3M 

InteramTM E54A. 

3” Conduit

3 in. diameter galvanized RSC and fittings assembled into a “U-shaped” configuration having an 

overall horizontal dimension of 102 in. and an overall vertical dimension of 76 in. at each leg. 

One leg of the conduit assembly transitioned through the upper steel deck into a standard 

radius 90 degree elbow while the other end used an iron condulet LB. The vertical leg 

connected to the condulet LB also transitioned through a junction box (12 in. x 12 in. x 8in.). 

The top of the junction box was located 12 in. below the insulated steel deck. Five layers of 3M 

InteramTM E54A. 

1” Conduit

1 in. diameter galvanized RSC and fittings assembled into a “U-shaped” configuration having an 

overall horizontal dimension of 102 in. and an overall vertical dimension of 76 in. at each leg. 

One leg of the conduit assembly transitioned through the upper steel deck into a standard 

radius 90 degree elbow while the other end used an iron condulet LB. Five layers of 3M 

InteramTM E54A. 
D-11 

Table D-9. 3M Interam E54A Fire Endurance Test Tray & Conduits (OPL)

Thermocouple Location 

Cable Fill 

(% Actual) 

Max. Individual 

Temperature oC 

(oF) 

Max Average 

Temperature oC 

(oF) 

6” Cable Tray 19.43 

Front Tray Side Rail 223 (433) 196 (384) 

Rear Tray Side Rail 225 (437) 197 (387) 

Bare #8 Wire under Rungs 208 (406) 173 (344) 

Bare #8 Wire on Rungs 191 (376) 159 (318) 

24” Cable Tray 14.72 

Front Tray Side Rail 211 (412) 188 (371) 

Rear Tray Side Rail 215 (419) 187 (369) 

Bare #8 Wire under Rungs 128 (263) 113 (235) 

Bare #8 Wire on Rungs 142 (287) 127 (261) 

5” Steel Conduit 

Conduit Surface 201 (393) 163 (325) 

Bare #8 Wire 189 (373) 126 (259) 

3” Steel Conduit 

Conduit Surface 233 (452) 214 (418) 

Bare #8 Wire 224 (436) 184 (363) 

1” Steel Conduit 

Conduit Surface 269 (517) 244 (472) 

Bare #8 Wire 264 (507) 238 (461) 

2” Conduit Air Drop 

Bare #8 Wire in Conduit 170 (338) 146 (294) 

Conduit Stub 172 (342) 167 (333) 

Steel Junction Box 209 (409) 198 (389) 

Acceptance Criteria: Single pt. T≤199oC; Average T≤157oC
D-12 

D.2.1.9 SwRI Project No. 01-7912 (June 1984) 

ERFBS: E50A Desired Rating: 1-hr 

Test Procedure: ANI/MAERP Test Slab: 10’ x 12’ x 1’ 

Ambient Temperature: Acceptance Temperature: 

Thermocouples: Spaced every 12” embedded in cable bundles (no bare conductor) 

Hose Stream: 2-1⁄2” Playpipe, 1-1/8” tip, nozzle pressure 30psi, applied 20’ from system, for 2.5 

 minutes 

Furnace: 8’ x 10’ 

Furnace control: 7 thermocouples (three above cable tray, four below) 

Cable Type: N/A 

Table D-10. E-50A 1-hr (SwRI 01-7912) 

Raceway Type Barrier Protection Cable Fill Rating 

2 in dia. Conduit Five layers of E-50A 40% 1 - control 1 - hr 

5 in dia. Conduit Four layers of E-50A 40% 

3-(p), 9-(c),34-(i) 

1 – hr 

Cable Tray No. 1 

(Solid bottom) 

Four layers of E-50A Single Layer 

7-(p), 13-(c), 25-(i) 

1 – hr 

Cable Tray No. 2 

(Solid bottom) 

Four layers of E-50A 40% 

13-(p), 47-(c),166-

(i) 

1 – hr 

Cable Tray No. 3 

(Ladder back) 

Four layers of E-50A Single Layer 

7-(p), 13-(c),25-(i) 

1 – hr 

a

Air Drop 1 Six layers of E-50A 1-(p), 1-(c),1-(i) 1 – hr 

Air Drop 2 Six layers of E-50A 1 – (c) 1 – hr 

Air Drop 3 Six layers of E-50A 1-(p), 1-(c),1-(i) 1 - hr 

a Significant heat damage to outer jackets of cables. The insulation on the interior 

conductors appears intact. Some heat discoloration of tray. 

(p) = power cable (c) = control cable (i) = instrument cable

Post hose stream test observations indicated that some of the 3M fire-proofing material was 

dislodged by the hose stream. 
D-13 

D.2.1.10 SwRI Project 01-7912a(1) (June 1985) 

ERFBS: E-50A Desired Rating: 1-hr 

Test Procedure: ANI/MAERP Test Slab: 10’ x 13.5’ x 1’ (3000 psi concrete) 

Ambient Temperature: 64°F 

Thermocouples: Spaced every 12” embedded in cable bundles (no bare conductor) 

Hose Stream: 2-1⁄2” Playpipe, 1-1/8” tip, nozzle pressure 30psi, applied less than 20’ from 

 system, for 2.5 minutes. 

Furnace control: 7 thermocouples (three above cable tray, four below) 

Cable Type: (XLPE/PVC); Power (300 mcm); Control (7/c 12AWG); Instrument (2/c 16 AWG) 

Table D-11. E-50A 1-hr (SwRI 01-7912a(1)) 

Raceway Type Barrier Protection Cable Fill 

1-hr Max. 

Temp °C (°F) Rating 

2 in Conduit 4 layer of E-50A 1 – control 102 (215) 1-hr 

Cable tray No 1 

(ladder back) 4 layer of E-50A 

7 – power 

13 – control 

25 – instrument 

164 (328) 1-hr 

Cable Tray No 2 

(ladder back) 4 layer of E-50A 

13 – power 

47 – control 

166 - 

instrument 

102 (215) 1-hr 

Note: all supports were protected with 4 layers of E-50A up to 16” from cable tray

At approximately 51 minutes into test, a 300mcm located in Cable Tray No. 2 experienced a 

short circuit to ground. Post test inspections revealed that a screw used to affix a thermocouple 

had penetrated the insulation of the cable causing the short. The hose stream testing dislodged 

some of the 3M fire barrier material. The 2/c #16 AWG instrument cable showed signs of 

shrinkage in the two cable tray tests. There was no other cable damaged noted in the final test 

report. 
D-14 

D.2.1.11 UL R10125, 86NK2919 (July 1986) 

ERFBS: E-50D Desired Rating: 3-hr 

Test Procedure: UL Subject 1724 Test Slab: 8” thick concrete 

Ambient Temperature: 68°F Acceptance Temperature: 

Hose Stream: 4 minutes, 1-1/8” dia. nozzle, 30psi, 20 ft from center of test assembly 

Furnace control: 10 Thermocouples located approximately 12-inches from underside of floor 

 assembly. 

Cable Type: (XLPE/PVC); Control (7/c 12AWG); Instrument (2/c 16AWG) 

Table D-12. UL Test of 3M E-50D 3-hr (R10125, 86NK2919) 

Raceway Type Barrier 

Protection 

Cable Fill 1-hr Max Temp 

Rise °C (°F) 

Rating

5” dia. steel conduit 5 layers of E-50D 2 – control 

2 – instrument 

121 (250) 

conduit surface 

3-hr 

Junction Box 

10”x10”x6” 

5 layers of E-50D 133 (271) 

box surface 

3-hr 

Air drop 5 layers of E-50D 4 – control 

4 – instrument 

144 (291) 

bare #8 

3-hr 

Each conductor in each electrical cable was energized and monitored for circuit integrity 

throughout the fire endurance test. No through openings developed in the electrical circuit 

protective systems through which the conduit system, junction box, or cable air drop could be 

seen. No electrical faults occurred in any of the electrical cables within the ERFBS. 
D-15 

D.2.1.12 SwRI Project 01-7912(2) (June 1985) 

ERFBS: E-50A Desired Rating: 1-hr 

Test Procedure: ANI/MEARP Test Slab: 10’ x 12’ x 1’ (3000 psi) 

Ambient Temperature: Acceptance Temperature: 

Thermocouples: embedded into cable bundles and spaced at 12-inch intervals. 

Hose Stream: 2-1⁄2” Playpipe, 1-1/8” nozzle, 30 psi, 2.5 minutes, 20ft from test assembly 

Furnace control: 7 thermocouples (three 12” above cable trays and four 12” below) 

Cable Type: Power (300mcm); Control (7/c 12AWG); Instrument (2/c 16AWG) 

Table D-13. E-50A 1-hr (SwRI 01-7912(2)) 

Raceway Type Barrier 

Protection 

Cable Fill Rating 

2-Inch Conduit 5 layers of E-50A Min. Fill 

1 – control 

1-hr 

5-Inch Conduit 4 layers of E-50A 40% Fill 

3 – power 

9 – control 

34 – instrument 

1-hr 

Cable Tray No 1 

(Solid back) 

4 layers of E-50A Single Layer 

7 – power 

13 – control 

25 – instrument 

1-hr 

Cable Tray No 2 

(Solid back) 

4 layers of E-50A 40% Fill 

13 – power 

47 – control 

166 – instrument 

1-hr 

Cable Tray No 3 

(Ladder back) 

4 layers of E-50A Single Layer 

7 – power 

13 – control 

25 – instrument 

1-hr 

Air Drop No 1 6 layers of E-50A 1 – power 

1 – control 

1 – instrument 

1-hr 

Air Drop No 2 6 layers of E-50A 1 – control 1-hr 

Air Drop No 3 6 layers of E-50A 1 – power 

1 – control 

1 – instrument 

1-hr 

Junction Box 5 layers of E-50A 1-hr 

Supports 2 layers of E-50A 1-hr 

Post test examination immediately after the hose stream test identified that some of the 3M fireproofing material was dislodged by the hose stream. Examination of the cables indicated that 

cable tray No 3 experienced significant heat damage to the outer jackets of cables. The 
D-16 

insulation on the interior conductors appeared to be intact and there was some heat 

discoloration of the tray. 

D.2.1.13 UL R10125-3, 84NK23288 (May 1986) 

ERFBS: E-50A Desired Rating: 3-hr 

Test Procedure: UL Subject 1724 Test Slab: 8” thick concrete 

Ambient Temperature: 72°F Acceptance Temperature: 

Thermocouples: Thermocouples were placed on exterior of raceways, exterior of cables and on 

 bare No. 8 AWG conductor 

Hose Stream: 2.5 minutes, 1-1/8 in nozzle, 30psi, applied ~17feet from center of test assembly 

Furnace control: 16 Thermocouples placed 12 inches beneath furnace floor 

Cable Type: Power (300mcm XLPE/XLP); Control (7/c 12AWG XLPE/PVC); 

 Instrument (2/c 14AWG XLPE/PVC) 

Table D-14. UL Subject 1724 Test Results of E-50A 3-hr (R10125-3, 84NK23288) 

Test 

Article 

# 

Raceway 

Type 

Barrier 

Protection Cable Fill 

Max. Temp 

Rise ∆T 

°C (°F) Rating

1 

24” wide Cable 

Tray Open 

Ladder Type 

5 Layers of 

E-50A 

Single Layer 

10 – Power 

13 – Control 

26 - Instrument

113 (235) 

3-hr 

Bare #8 Upper 115 (239) 

Bare #8 Lower 85 (185) 

2 

2” dia. Conduit 5 Layers of 

E-50A 

1 – Power 

1 – Control 

1 – Instrument 

134 (274) 

3-hr 

Bare #8 129 (264) 

Approximately 1 minute into test, CS-195 used at the floor interface as part of the penetration 

seal began to burn, the flaming continued for 30 minutes. Results section of report concluded 

that, no openings developed in the ERFBS through which the cable tray or conduit systems 

could be seen and no electrical faults occurred in any of the electrical cables within the electrical 

circuit protective systems. 

D.2.1.14 UL R10125-3, 84NK2919 (June 1986) 

ERFBS: E-50D Desired Rating: 3-hr 

Test Procedure: UL Subject 1724 Test Slab: 8” thick concrete 

Ambient Temperature: Acceptance Temperature: 

Furnace control: Ten Thermocouples located ~12inches below assembly floor 

Cable Type: (XLPE/PVC); Control (7/c 12AWG); Instrument (2/c 16AWG) 
D-17 

Table D-15. UL Subject 1724 Test Results for E-50D 3-hr (R10125-3, 84NK2919) 

Raceway 

Type 

Barrier 

Protection Cable Fill 

Max. Temp 

Rise ∆T 

°C (°F) Rating

5” dia. steel 

conduit 

5 Layers of E-50D 2 – Control 

2 – Instrument 

1 – Bare #8 

121 (250) 3-hr 

Junction Box 

10”x10”x6” 

5 Layers of E-50D 133 (271) 3-hr 

Air Drop 5 Layers of E-50D 4 – Control 

4 – Instrument 

1 – Bare #8 

144 (291) 3-hr 

D.2.1.15 UL R10125, 82NK21937 (March 1985) 

ERFBS: E-50A Desired Rating: 1-hr 

Test Procedure: UL Subject 1724 Test Slab: 8” thick concrete 

Ambient Temperature: 88°F 

Thermocouples: Bare No. 8 

Hose Stream: 30psi, 2.5 minutes 

Furnace control: Not specified 

Cable Type: Bare No. 8 AWG 

Table D-16. UL Subject 1724 Test Results of E-50A 1-hr (R10125, 82NK21937) 

Raceway Type Barrier 

Protection 

Cable Fill Rating 

2” conduit 4 layers of E-50A 1 – bare #8 57min 

Air Drop 5 layers of E-50A 1 – bare #8 57min 

Cable Tray 2 layers of E-50A 1 – bare #8 57min 

Junction Box 

12”x12”x6” 

Single layer of 

M20A 

Single layer of CS195 on a steel 

framework. 

1 – bare #8 57min 

The water hose stream test eroded the outer layer of mate wrap on the conduit, air drop, and 

cable tray system as well as the intumescent sheet enclosure around the junction box. A 

separation was present at the interface of the conduit wrap and the drop-out cable wrap through 

which the conduit and the No. 8 AWG bare copper conductor were visible. 
D-18 

D.2.1.16 ULR10125, 82NK21937 (March 1985) 

ERFBS: E-50A Desired Rating: 1-hr 

Test Procedure: Subject 1724 Test Slab: 8” thick concrete 

Ambient Temperature: 88°F 

Thermocouples: Cables, cable tray, and support 

Hose Stream: 30psi, 2.5 minutes 

Furnace control: Not specified 

Cable Type: (XLPE/PVC); Power (300mcm); Control (7/c 12AWG); Instrument (2/c 16AWG) 

Table D-17. UL Testing Results for E-50A 1-hr (R10125, 82NK21937) 

Raceway Type Barrier 

Protection 

Cable Fill Rating 

24” Cable Tray 3 layers of E-50A 40% 

21 – Power 

32 – Control 

221 – Instrument 

1-hr 

No electrical faults developed in any of the electrical cables within the fire barrier system during 

the fire exposure test, during the move to the hose stream test area or during the hose stream 

test. The water hose stream test did erode the outer layer of mat wrap on the cable tray 

system, but no through opening developed in the ERFBS through which the cable tray or cables 

could be seen. Within the ERFBS the cable PVC jacketing of the 7/c control cable did 

experience bubbling near the top of the cable tray inside riser elbow. 

D.2.1.17 UL R10125, 82NK21937 (March 1985) 

ERFBS: E-50A Desired Rating: 1-hr 

Test Procedure: Subject 1724 Test Slab: 8” thick concrete 

Ambient Temperature: 88°F Acceptance Temperature: 

Thermocouples: Cables, cable tray, and support 

Hose Stream: 30psi, 2.5 minutes 

Furnace control: Not specified 

Cable Type: (XLPE/PVC); Power (300mcm); Control (7/c 12AWG); Instrument (2/c 16AWG) 

Table D-18. E-50A UL Test Results (R10125, 82NK21937) 

Raceway Type Barrier 

Protection 

Cable Fill Rating 

24” Cable Tray 3 layers of E-50A Single layer 

10 – Power 

13 – Control 

33 – 

Instrument 

55 min 

No electrical faults developed in any of the electrical cables within the fire barrier system during 

the fire exposure test, during the move to the hose stream test area or during the hose stream 

test. The water hose stream test did erode the outer layer of mat wrap on the cable tray 
D-19 

system, but no through opening developed in the ERFBS. Within the ERFBS the cable PVC 

jacketing of the 7/c control cable did experience melting at the inside riser elbow. 

D.2.1.18 UL R10125, 84NK23299 (May 1985) 

ERFBS: E-50A Desired Rating: 1-hour 

Test Procedure: Subject 1724 Test Slab: 8” thick concrete 

Ambient Temperature: 57°F 

Thermocouples: conduit, bare No. 8AWG, cables 

Hose Stream: Not specified 

Furnace control: 9 thermocouples located ~12” below test deck floor 

Cable Type: (XLPE/PVC) Instrument (2/c 16 AWG) 

Table D-19. E-50A UL Test Results (R10125, 84NK23299) 

System 

No. Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp 

Rise ∆T 

°C (°F) Rating 

1 2” dia. steel conduit 5 layers of E-50A 1- Instrument 

1-Bare No. 8 

136 (277) 1-hr 

2 3” dia. steel conduit 5 layers of E-50A 1- Instrument 

1-Bare No. 8 

120 (248) 1-hr 

3 3” dia. steel conduit 5 layers of E-50A 1- Instrument 

1-Bare No. 8 

169 (336) 59 min 

4 3” dia. steel conduit 4 layers of E-50A 1- Instrument 

1-Bare No. 8 

238 (460) 46 min 

5 3” dia. steel conduit 6 layers of E-50A 1- Instrument 

1-Bare No. 8 

126 (259) 1-hr 

Systems 3-5 were installed with a nominal 1⁄2 gap between all of the butt seams and were 

covered with one layer of Type T-49 tape. This assembly method is no recommended, but 

provided a worst case scenario for testing. 

After 1 minute of fire exposure, steam began issuing form the ends of the conduit fire barrier 

systems which protruded from the test furnace. By 10 minutes, steam and water droplets were 

issuing from the ends of the conduit. The steaming and dripping continued throughout the 

testing. During the last 10 minutes of the fire endurance test, the light emitting diodes (LED’s) 

associated with the conductors and ground of the two-conductor No. 16AWG cables in System 

3 and 4 flickered on for a moment and then remained off for the remainder of the fire test. 

PVC jacketing on the cables was melted such that the individual insulated conductors were 

visible in several locations. Beneath the PVC jacket, the XLPE insulation appeared 

undamaged. 
D-20 

D.2.1.19 3M Fire Test Report #86-78 (June 1986) 

ERFBS: E-54A with steel banding on only the 

exterior wrap 

Desired Rating: 3-hr 

Test Procedure: ANI/MAERP, UL#263 Test Slab: 70” x 56” x 8” (3000psi) concrete 

Ambient Temperature: 20°C (68°F) 

Thermocouples: attached to cables 

Hose Stream: 2.5 minutes, 1-1/8” nozzle, 30psi, 20 feet from test assembly 

Furnace: 3M’s Top Loading Furnace (61” x 47” x 30”) 

Furnace control: Not specified 

Cable Type: (XLPE/PVC); Control (7/c 12AWG); Instrument (2/c 14AWG) 

Table D-20. E-54A 3M Test Results #86-78 

Raceway Type Barrier Protection Cable Fill 

Avg. 

Temp. 

°C (°F) 

Max 

Temp 

°C (°F) Rating

2” steel conduit 

close to slab 4 layers of E-54A 

2 – control 

2 – instrument 

1 – Bare #8 

182 (360) 216 (420) <3hr 

Three 2” steel 

conduits enclosed 

in common barrier 

4 layers of E-54A 

Per Conduit

2 – control 

2 – instrument 

1 – Bare #8 

143 (289) 168 (335) 3hr 

All cables were energized with 120Vdc during the entire test and no loss of circuit integrity was 

detected. After the 2.5 minutes hose stream test, two of the original four layers of InteramTM E54A ma were still securely attached to the conduit bundle. 

D.2.1.20 3M Fire Test Report #92-115 (August 1992) 

ERFBS: E-54A Desired Rating: 3-hr 

Test Procedure: ASTM E-119 Test Slab: Not Specified 

Ambient Temperature: 23°C (73°F) 

Thermocouples: Conduit, cable, bare #8 conductor 

Hose Stream: None Furnace: 3M large scale furnace (63” x 52” x 52”) 

Furnace control: 4 thermocouples Cable Type: Control 7/c 12AWG 

Table D-21. E-54A 3M Test Results #92-115 

Raceway Type Barrier 

Protection 

Cable Fill Rating 

4” dia. steel conduit 5 layers of E-54A 1 – 7/c 12AWG 

1 – bare #8 

160 

min 

4” dia. steel conduit 3+2 layer system 

of E-54A 

1 – 7/c 12AWG 

1 – bare #8 

177 

min 

1” dia. steel conduit 6 layers of E-54A 1 – 7/c 12AWG 

1 – bare #8 

3-hr 
D-21 

One of the 4” dia. steel conduit has a 3+2 layer type system installation of the E-54A ERFBS. 

This method of assembly consisted of applying the 3 layer section first to the conduit and then 

applying a 2 layer assembly on top of the 3 layers previously applied. FireDam 150 Caulk was 

used to fill the space between the two layer assemblies and between the butt joints of adjacent 

layer assemblies. 

D.2.1.21 3M Fire Test Report #87-82 (July 1987) 

ERFBS: E-54A Desired Rating: 3-hr 

Test Procedure: ASTM E-119 Test Slab: Not Specified 

Ambient Temperature: 29°C (83°F) Acceptance Temperature: 

Thermocouples: Conduit, cable, bare #8 conductor 

Hose Stream: None 

Furnace: 3M large scale furnace (63” x 52” x 52”) 

Furnace control: 4 thermocouples 

Cable Type: Control 7/c 12AWG 

Table D-22. E-54A 3M Test Results #87-82 

Raceway Type Barrier 

Protection 

Cable Fill Rating 

5” dia. steel conduit 3+2 layer system 

of E-54A 

1 – control 

1 – bare No. 8 166 min 

D.2.1.22 3M Fire Test Report (July 1992) 

ERFBS: E-54A Desired Rating: 3-hr 

Test Procedure: ASTM E-119 Test Slab: Not Specified 

Ambient Temperature: 29°C (84°F) Acceptance Temperature: 

Thermocouples: Cable tray, cable, bare #8 

Hose Stream: None 

Furnace: 3M large scale furnace (63” x 52” x 52”) 

Furnace control: 4 thermocouples 

Cable Type: Control 7/c 12AWG 

Table D-23. E-54A 3M Test Results (July 1992) 

Raceway Type Barrier 

Protection 

Cable Fill Rating 

24” wide cable tray 

open ladder back 

5 layers of E-54A 1 – control 

1 – bare No. 8 

158 

min 
D-22 

D.2.1.23 3M Test Report #92-167 (June 25, 1993) 

ERFBS: E-53A Desired Rating: 1-hr 

Test Procedure: ASTM E-119 Test Slab: 70” x 56” x 4” (3000 psi concrete) 

Ambient Temperature: 22°C (71°F) 

Thermocouples: Conduit, cable, bare #8 

Hose Stream: Method not specified 

Furnace: 3M large scale furnace (63” x 49” x 39”)(1.6m x 1.2m x 1.0m) 

Furnace control: 4 thermocouples 

Cable Type: Control 7/c 12AWG 

Table D-24. E-53A 3M Test Results #92-167 

Raceway Type 

Barrier 

Protection Cable Fill 

Avg. Temp. 

@1-hr °C (°F) 

Max Temp 

@1-hr °C (°F) Rating

1” dia. steel 

conduit 

3 layers of E53A without 

collars around 

radius bend 

seams 

1 – control 

1 – bare #8 

201 (394) 221 (430) <1-hr 

1” dia. steel 

conduit 

3 layers of E53A with 3” 

collars around 

radius bend 

seams 

1 – control 

1 – bare #8 

174 (346) 212 (413) <1-hr 

D.2.1.24 3M Fire Test Report #92-141 (August 1992) 

ERFBS: E-54A Desired Rating: 1- and 3-hours 

Test Procedure: ASTM E-119 Test Slab: 70” x 56” x 4.5” (3000 psi concrete) 

Ambient Temperature: 21°C (70°F) Acceptance Temperature: 

Thermocouples: Conduit, cable, bare #8 

Hose Stream: Method not specified 

Furnace: 3M large scale furnace (63” x 49” x 39”)(1.6m x 1.2m x 1.0m) 

Furnace control: 4 thermocouples 

Cable Type: Control 7/c 12AWG 

Table D-25. E-54A 3M Test Results #92-141 

Raceway Type Barrier Protection Cable Fill Rating 

1” dia. steel conduit 3 layers of E-54A 1 – control 

1 – bare #8 

1-hr Failure at 106 min 

1” dia. steel conduit 5 layers of E-54A 1 – control 

1 – bare #8 

3-hr Failure >180 min 

After the hose stream test, the two innermost layers of E-54A applied to conduit # 2 remained 

intake. The surface of conduit #1 was exposed after the water hose stream test, however, this 
D-23 

barrier was exposed to the full 3-hour exposure, even though it was only designed for the 1-hr 

rating. This is likely why the exposure of the conduit following the hose stream test. 

D.2.1.25 3M Fire Test Report #87-40 (April 1992) 

ERFBS: E-54A Desired Rating: 1- and 3-hour 

Test Procedure: ASTM E-119 Test Slab: 70” x 56” x 4.5” (3000 psi concrete) 

Ambient Temperature: 14°C (58°F) 

Thermocouples: Cable tray, cables 

Hose Stream: Method not specified 

Furnace: 3M large scale furnace (63” x 49” x 39”)(1.6m x 1.2m x 1.0m) 

Furnace control: 4 thermocouples 

Cable Type: Control (7/c 12AWG), Power (1/c 250mcm) 

Table D-26. E-54A 3M Test Results #87-40 

Raceway Type 

Barrier 

Protection Cable Fill 

Avg. Temp 

@ 1-hr 

°C (°F) 

Max. Temp @ 

1-hr °C (°F) Rating 

12” cable tray 

aluminum 

2 layers of E54A 1 – control 

1 – power 190 (374) 222 (432) <1-hr 

After the water hose stream, the surface of the cable tray remained fully covered by at least one 

layer of E-54A mat. 

D.2.1.26 3M Fire Test Report #87-57 (May 1987) 

ERFBS: E-53A and E-54A Desired Rating: 1-hr 

Test Procedure: ANI/MAERP, ASTM E-119 Test Slab: 70” x 56” x 8” Concrete 

Ambient Temperature: 20°C (68°F) Acceptance Temperature: 

Thermocouples: cables 

Hose Stream: 2.5 minute, 30psi, 1-1/8” nozzle, 2-1/2” playpipe, 20 ft from assembly 

Furnace: 3M Large Scale top loading furnace (61” x 47” x 30”) 

Furnace control: Not specified (10 thermocouples were located within furnace) 

Cable Type: (XLPE/PVC), Power (250mcm), Control (7/c 12AWG), Instrument (2/c 14AWG) 

Table D-27. E-53A & E-54A 3M Test Results #87-57 

Raceway Type 

Barrier 

Protection Cable Fill 

Avg. Temp @ 

60 min °C (°F) Rating

5” dia. steel conduit 3 layers of E-53A 1 – power 

2 – control 

2 – instrument 

1 – bare #8 

142 (288) 1-hr 

5” dia. steel conduit 2 layers of E-54A 1 – power 

2 – control 

2 – instrument 

1 – bare #8 

166 (331) <1-hr 
D-24 

FireDam 150 was applied prior to installation of mats and after the mat is banded. Both 

conduits survived the water hose stream test and all electrical circuit continuity paths were intact 

for the full fire test and at the completion of the hose stream tests. 

D.2.1.27 3M Fire Test Report (June 1987)

ERFBS: E-53A Desired Rating: 1-hr 

Test Procedure: ASTM E-119 Test Slab: 

Ambient Temperature: 24°C (75°F) Acceptance Temperature: 

Thermocouples: Conduit, cable, bare #8 

Hose Stream: None 

Furnace: 3M Large Scale Furnace (63” x 52” x 52”) (1.6m x 1.3m x 1.3m) 

Furnace control: 4 thermocouples 

Cable Type: control (7/c 12AWG) 

Table D-28. 3M E-53A Test Results (June 1987) 

Conduit # Raceway Type Barrier Protection Cable Fill Rating 

1 2” dia. steel conduit 3 layers of E-53A applied 

as a single mat 

1 – control 

1 – bare #8 

51 min 

2 2” dia. steel conduit 3 layers of E-53A 

1st two layers applied as 

single mat and final layer 

applied separately 

1 – control 

1 – bare #8 

58 min 

3 2” dia. steel conduit Same as Conduit 1 with 

addition of collars 

overlapping 2” of mat 

1 – control 

1 – bare #8 

61 min 

(1-hr) 
D-25 

D.2.1.28 Twin Cities Testing Corporation Tests #86-17, #86-18, #86-19 (February 5-7, 1986) 

ERFBS: E-50D (equivalent to E-54A) – 5 

layers 

Desired Rating: 3-hour 

Test Procedure: ANI/MAERP Test Slab: 70” x 56” x 8” concrete 

Thermocouples: Taped to jackets of cables, spaced every 10.5 inches 

Hose Stream: 2-1⁄2” Playpipe, 1-1/8” tip, nozzle pressure 30psi, applied less than 20’ from 

system, for 2.5 minutes. 

Furnace: 63” x 49.5” x 28” 

Cable Type: (XLPE/PVC); Power (250mcm); Control (7/c 12 AWG); Instrument (2/c 12 AWG) 

Table D-29. Twin Cities Testing 3M E-50D Test Results 

Fire 

Test 

# 

Raceway 

Type 

Barrier 

Protection Cable Fill 

Avg. Temp 

@3-hr 

°C (°F) 

Max. Temp 

@3-hr 

°C (°F) Rating

86-17 12” Cable 

Tray 

1⁄2 solid, 1⁄2 

ladder 

5 wraps E50D Single Layer 

5 - power 

7 - control 

14 - instrument 

1- bare #8 

134 (274) 111 (326) 3-hr 

 Air Drop 5 wraps E50D 1 - control 

1 - instrument 

1- bare #8 

133 (272) 101 (291) 3-hr 

86-18 5” dia. 

Conduit 

5 wraps E50D 2 - control 

2 - instrument 

1- bare #8 

124 (255) 141 (286) 3-hr 

 Junction Box 

10” x 10” x 6” 

5 wraps E50D 4 - control 

4 - instrument 

1- bare #8 

101 (214) 144 (214) 3-hr 

86-19 Cable Tray 5 wraps E50D 40% 

16 - power 

26 - control 

76 - instrument 

1- bare #8 

101 (214) 163 (231) 3-hr 

Testing was conducted at 3M facilities with independent inspection of installation and 

verification of test results don by Twin Cities Testing Corporation of St. Paul, Minnesota. After 

completion of the water hose testing, at least two of the original five layers remained completely 

intact on all test articles. Post test inspection of the cables found no blistering, charring, melting, 

or noticeable deterioration of any insulation. 
D-26 

D.2.1.29 Twin Cities Testing Corporation Tests #86-79, #86-80, #86-81 (July 1, 1986) 

ERFBS: E-53A & E-54A Desired Rating: 1-hour 

Test Procedure: ANI/MAERP Test Slab: 70” x 56” 8” concrete 

Hose Stream: 2-1⁄2” Playpipe, 1-1/8” tip, nozzle pressure 30psi, applied 20’ from system, for 2.5 

minutes. 

Furnace: 61” x 47” x 30” (3M’s top load, large scale, propane fired) 

Cable Type: (XLPE/PVC); Power (250mcm); Control (7/c 12 AWG); Instrument (2/c 14 AWG) 

Table D-30. Twin Cities Testing 3M E-50 Series 1-hr Test Results 

Fire 

Test # 

Raceway 

Type 

Barrier 

Protection Cable Fill 

Avg. 

Temp. @ 

1-hr °C (°F)

Max. Temp 

@ 1-hr 

°C (°F) Rating 

86-79 5” dia. 

aluminum 

conduit 

3 layers E53A 2 - control 

2 - instrument 

1 - bare #8 

87 (188) 99 (211) 1-hr 

 5” diameter 

steel conduit 

3 layers E53A 2 - control 

2 - instrument 

1 - bare #8 

82 (179) 103 (218) 1-hr 

 Junction Box 3 layers E54A 2 - control 

2 - instrument 

2 - bare #8 

99 (210) 99 (211) 1-hr 

86-80 24” wide 

aluminum 

cable tray 

1 layer E-54A 

 + 

1 layer E-53A 

Single Layer 

10 - power 

14 - control 

28 - 

instrument 

2 - bare #8 

96 (204) 173 (343) 1-hr 

 Aluminum 

cable tray 

1 layer E-54A 

 + 

1 layer E-53A 

40% fill 

24- power 

29 - control 

108 - 

instrument 

2- bare #8 

102 (215) 106 (222) 1-hr 

86-81 Air drop 3 layers E54A 4 - control 

4 - instrument 

1 - bare #8 

98 (209) 114 (237) 1-hr 
D-27 

D.2.1.30 SwRI Ampacity Testing of E-50 Series (November 1985) 

For these ampacity tests, three types of cables were installed in a horizontal cable tray. Current 

was applied to the cables and measurements were taken of the copper conductors 

temperatures and current flow through each cable type under various ambient temperature 

conditions. The results from this testing are shown in Table D-31. 

Table D-31. SwRI Ampacity Testing Results at 20°C 

Item # Test Specimen Description 

Ampacity Derating Factor % * 

250mcm 3/c - #8 3/c - #16 

1 Tray with Solid Top 22.3 19.5 16.1 

2 Tray with Solid Top & T-49 Tape 22.9 19.8 16.2 

3 Tray with Solid Top & Bottom 33.8 31.8 27.5 

4 Tray with Solid Top & Bottom & Tape 31.8 30.4 25.7 

5 Tray + 4 Layers of E-50A 

with Solid Top & Bottom 

48.6 50.7 48.6 

6 Tray + 4 Layers of E-50A 42.6 46.4 41.8 

7 Tray + 4 Layers of E-50A + Tape 40.4 44.7 39.4 

8 Tray + 10 Layers of E-50A 47.4 52.1 49.3 

9 Tray + 10 Layers of E-50A + Tape 44.6 50.1 46.7 

* Ampacity Derating factors are based on ambient temperatures of 20°C. 

These results indicated that as the ambient temperature increased, the ampacity derating factor 

also increased. 

D.2.1.31 SwRI Ampacity Testing (April 1987) 

This testing was conducted to determine if the ampacity derating of two layers of E-54A mat 

protecting an open-ladder cable tray meets the requirements of Bechtel Power Corporation for 

use at the South Texas Project (STP). Only one type of power cable was used for this testing— 

namely, a 3/c #6AWG Okonite Power cable. This test was conducted for 60 minutes. 

The baseline (no barrier) configuration resulted in 32.1A of current and when protected with two 

layers of E-54A ERFBS, the current dropped to 17.3, an ampacity derating factor of 46.1 

percent. 

100% 46.1%

32.1

32.1 17.3

   ADF 
D-28 

D.2.1.32 SWRI Testing (June 1986) 

SwRI performed ampacity testing on a 10.1 cm (4.0-in) diameter conduit configuration against 

various 3M ERFBSs. The conduit was filled with 20 3/c #6 AWG cables or 69 percent conduit 

fills. 

Table D-32. Ampacity Results SwRI Conduits 

Item # Test Specimen Description 

Final Current 

(Amps) 

Ampacity Derating 

Factor % 

1 Baseline 24.0 0.00 

2 E-50A 1-hr 18.9 21.3 

3 E-50 Series 1-hr 18.5 22.9 

4 E-50 Series 1-hr with 3M ECP-2200 black 

coating 

20.2 15.8 

5 M-20A 1-hr 14.9 37.9 

6 M-20A 1-hr with 3M ECP-2200 black coating 15.5 35.4 

7 E-50D 3-hr 17.0 29.2 

D.2.1.33 SwRI Ampacity Testing Project No. 01-8818-208/-209(1) (June 1986) 

Table D-33 shows ampacity results from SwRI tray and conduit tests. 

Table D-33. Ampacity Results SwRI Tray/Conduit 

Item # Test Specimen Description 

Final 

Current 

(Amps) 

Ampacity Derating 

Factor % 

1 Baseline – Open Tray 24.6 0.00 

2 Baseline – Conduit 23.7 0.00 

3 Baseline – Tray solid bottom 20.0 18.7 

4 Baseline – Tray solid bottom and 

top 

14.7 40.2 

5 Tray – E50A 1-hr 13.1 46.7 

6 Conduit – E-50A 1-hr 18.8 20.7 

7 Tray – E-50D 3-hr 11.2 54.5 

8 Conduit – E-50D 3-hr 17.2 27.4 

9 Tray – E-50D/E-53A 1-hr 14.5 41.1 

10 Conduit – E-53A 1-hr 18.6 21.5 

11 Conduit – E-53A 1-hr with ECP 

2200 black coating 

20.1 15.2 
D-29 

D.2.1.34 SwRI Ampacity Testing (October 1986) 

This test series involved ampacity derating testing of a 61.0 cm (24.0 in) wide steel cable tray 

ladder-back type and 10.1 cm (4.0 in) diameter steel conduit filled to 100 percent visual fill with 

3/c XLPE/CSPE #6 AWG cables. Unfortunately, the report does not document any baseline 

ampacity values for these configurations to determine the ampacity derating factors to apply for 

raceways protected with the E-50A ERFBS. 

Table D-34. Ampacity Results SwRI without Baseline 

Item # Test Specimen Description 

Final 

Current 

(Amps) 

Ampacity 

Derating Factor 

% 

1 Tray protected with E-50A 1-hr wrap 13.3 No data reported 

2 Conduit protected with E-50A 1-wrap 18.9 No data reported 

D.2.1.35 3M Ampacity Report (April 1985) 

3M conducted ampacity testing using a 10.1 cm (4-in) diameter schedule 40 galvanized steel 

conduit, using numerous E-50A mat wrapping configurations. The conduit was loaded with 

three 500MCM, 600V copper cables with a maximum operating temperature of 90°C. shows 

the results of this testing. As you can see from the data below, the addition of the high 

emissivity black tape actually improves the ampacity rating. 

Table D-35. 3M Ampacity Results Conduit 

Item # Test Specimen Description 

Final 

Current 

(Amps) 

Ampacity 

Derating Factor 

% 

1 Baseline 476 0.00 

2 High emissivity black tape 506 - 6 

3 Five Layers of E-50A mat 383 19.5 

4 Five Layers of E-50A mat with 

Black Tape 404 15.1 

5 Ten Layers of E-50A mat 358 24.8 

6 Ten Layers of E-50A mat with 

Black Tape 374 21.4 
D-30 

D.2.1.36 UL Testing E-50A (May-September 1985) 

UL tested the ampacity of cables located in a 45.7 cm (18-in) wide ladder back cable tray 

protected with various layers of 3M ERFBS. The cable tray fill included 29 3/c # 16 AWG XLPE 

insulated cables, 13 3/c #8AWG non-jacketed, and 13 single-conductor non-jacketed 250MCM19

cables. summarizes the results of this testing. 

Table D-36. UL Ampacity Test Results for E-50A Cable Tray Configurations 

Item # Test Specimen Description 

Ampacity Derating Factor % * 

250mcm 3/c - #8 3/c - #16 

1 Baseline 0.00 0.00 0.00 

2 Metal Top 22.3 19.5 16.1 

3 Metal Top with Black Tape 22.9 19.8 16.2 

4 Metal Top & Bottom 33.8 31.8 27.5 

5 Metal Top & Bottom with Black 

Tape 31.8 30.4 25.7 

6 Four Layers of E-50A mat 42.6 46.4 41.8 

7 Four Layers of E-50A mat with 

Black Tape 40.4 44.7 39.4 

8 Four Layer of E-50A mat over 

Metal Top and Bottom 48.6 50.7 48.6 

9 Ten Layers of E-50A mat 47.4 52.1 49.3 

10 Ten Layers of E-50A mat with 

Black Tape 44.6 50.1 46.7 

* Ampacity Derating factors are based on tests conducted at an ambient temperature of 20°C. 

D.2.1.37 UL Ampacity Testing E-54A (October 1986) 

UL tested the ampacity of 3M E-54A 2 layer system in a 61.0 cm (24-in) wide open ladder-back 

cable tray. Cable loading included 71 3/c #6 Okonite insulated and Okolon jacketed cable, for a 

maximum fill depth of 3-5/8 inches. documents the results. 

Table D-37. UL Ampacity Test Results for E-54A 1-hour Cable Tray Configurations 

Item # Test Specimen Description 

Final Current 

(Amps) 

Ampacity Derating 

Factor % 

1 Baseline 32.1 0.00 

2 2 Layers of E-54A mat 1-hr 17.3 46.1 

 

19 MCM is equal to 1000 circular mils, where 1 circular mil is a unit of area equal to the area of a circle 1 

mil in diameter. Large cable conductors will typically be denoted by MCM, with smaller conductors using 

the AWG designation in the USA. 
D-31 

D.2.2 3M Rigid Panel System Testing 

D.2.2.1 UL Project 82NK2193, R10125 

ERFBS: M20-A / CS-195 

Thermocouples: Cable jacket 

Desired Rating: 1 –hour 

Per the request of 3M, UL reviewed temperature data and made recommendations as to the 

qualification of previous tests, to the acceptance criteria of the temperature of the largest cable 

jacket to not exceed the maximum temperature rise of 250°F above initial starting temperature. 

Test Date: March 3, 1983 

Test Reports: 1.) UL Report R10125-1, -2 dated October 19, 1983, 

 2.) UL Letter Report R10125 dated November 2, 1983, 

Table D-38. UL Interpretations of Previously Completed Test Results 

System 

No. 

Raceway/Cable 

Type Barrier Protection 

Limiting 

Temp. 

°C (°F) 

Max. Temp 

°C (°F) at Time 

(minutes) Rating

A 

Steel cable tray 

open-ladder / 

300MCM 

1 layer of M20-A 

surrounded by single sheet 

of CS-195 composite sheet 

secured to steel channel 

framing 

159 

(319) 

159 (319) @ 

50 

167 (332) @ 

60 

<1-hr 

B 

Steel cable tray 

open-ladder / 

250MCM 

4 layers of M20-A 167 

(333) 

142 (287) @ 

60 1-hr 

C.1 

Rigid steel 

conduit / 

300MCM 

3 layers of M20-A 

40 % cable fill 159 

(318) 88 (190) @ 60 1-hr 

C.2 

Rigid steel 

conduit / 

300MCM 

3 layers of M20-A 

minimum cable fill 159 

(318) 

141 (286) @ 

60 1-hr 

D Air Drop / 

300MCM 

5 layers of M20-A 162 

(323) 

145 (293) @ 

60 1-hr 

E 

Junction Box / 

2/c 14AWG 

2 layers of M20-A 

surrounded by single sheet 

of CS-195 composite sheet 

secured to steel channel 

framing 

163 

(326) 

117 (242) @ 

60 1-hr 
D-32 

D.2.2.2 UL Letter Report dated November 2, 1983 

ERFBS: M20-A (4 layers) Desired Rating: 1-hour 

Test Procedure: ASTM E-119 Test Slab: 8” thick concrete 

Ambient Temperature: 86°F (limiting max. single point temperature 411°F) 

Thermocouples: Bare conductors, cable tray side rails 

Hose Stream: 30 psi for 2.5 minutes 

Cable Type: Bare Copper Conductors (14AWG, 8AWG, 1/0AWG, 250MCM) 

Table D-39. UL Test Report on M20-A 1-hr Cable Tray 

System 

No. Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp 

°C (°F) Rating 

1 

24” wide 

galvanized steel 

cable tray 

4 layers of M20-A 4 bare copper 

conductors 201 (394) 1-hr 

Following the hose stream test, it was noted that the strips of intumescent mat at the horizontal 

member of the trapeze support were washed away, leaving a through opening into the electrical 

circuit protection system through which the bare copper conductors were visible. No other 

through opening was present in the electrical circuit protective system. The test report 

concluded that based on previous testing, had the horizontal support member ERFBS protection 

been covered with a nominal 10 in. wide section of steel hardware cloth secured in place with 

steel banding straps. 

D.2.2.3 UL Letter Report Dated January 19, 1984 

ERFBS: M20-A / CS-195 Desired Rating: 1-hour 

Test Procedure: ASTM E-119 Test Slab: 8” thick concrete 

Ambient Temperature: 89 °F 

Thermocouples: copper conductor and steel of junction box 

Hose Stream: 30 psi, 2.5 minutes; Protective enclosure was intact at the end of the testing. 

Cable Type: Bare copper conductor # 8 AWG 

Table D-40. UL Results for 3M M20-A/CS-195 1-hr Junction Box 

Raceway Type Cable Fill Barrier Protection 

Max. Temp 

Rise ∆T 

°C (°F) Rating

Steel Junction 

Box (12”x12”x6”) 

with 2” Conduit 

Bare copper 

conductor (#8AWG) 

1 layer of M20-A 

surrounded by sheet of 

CS-195 secured to a 

steel framing 

Conduit was wrapped 

with 4 layers of 

InteramTM E-50 Series 

186 (366) 

257 (494) 

< 1-hr 

< 1-hr 
D-33 

D.2.2.4 UL Letter Report Dated April 18, 1984 

ERFBS: M20-A Desired Rating: 1-hr 

Test Procedure: ASTM E-119 Ambient Temperature: 46 °F 

Thermocouples: cable jacket and conduit surface 

Hose Stream: None 

Furnace control: per ASTM E-119 

Cable Type: XLPE / Neoprene 

Table D-41. UL Report on 3M Testing of 3/4, 2, 3-inch Steel Conduits 

System 

No. 

Raceway 

Type 

Barrier 

Protection Cable Fill Max. Temp Rise ∆T °C (°F) Rating 

1 3⁄4” RSC 5 layers of 

M20-A 

1 – 2/c 

16AWG 

303 (578) @ 60 minutes 

Exceeded criteria between 40 

and 50 minutes 

< 1-hr 

2 3” RSC 3 layers of 

M20-A 

17 – 2/c 

16AWG 

210 (410) @ 60 minutes 

Exceeded criteria between 50 

and 60 minutes 

< 1-hr 

3 2” RSC 5 layers of 

M20-A 

1 – 2/c 

16AWG 

317 (602) @ 60 minutes 

Exceeded criteria between 30 

and 40 minutes 

< 1-hr 

The report indicated that at 58 minutes into the test, the light emitting diode (LED) associated 

with the conductors and ground of the 2/c 16AWG cables in the nominal 3in. diameter conduit 

protective system commenced glowing dimly. At the completion of the 60 minute test, the LEDs 

associated with the 3in. diameter conduit were fully illuminated. 

D.2.2.5 UL Letter Report dated August 7, 1984 

ERFBS: M20-A plus CS-195 Desired Rating: 1-hr 

Test Procedure: UL 1724 Test Slab: 36” x 36” x 2” concrete 

Ambient Temperature: 76°F 

Thermocouples: cable, bare conductor, steel surface, air space between M20-A and CS-195 

Hose Stream: 30psi, 1-1/8 in. nozzle, 20 ft away for 30 seconds 

Cable Type: (XLPE/PVC) 2/c 14AWG control/power; Bare copper conductor #8AWG 

Table D-42. UL M20-A 1-hour Test Results 

Raceway Type Barrier Protection Cable Fill 

Max. Temp °C 

(°F) Rating 

Junction Box 

10” x 10” x 6” Steel 

2 layers of M20-A 

1 sheet of CS-195 

attached to steel 

framing 

1- 2/c control 

1 – bare #8 

154 (310) 1-hr 

The report states that, “By 1 min, the intumescent sheet enclosure was flaming and the 

aluminum foil tape was peeling from the corners. The flaming of the intumescent sheet was 
D-34 

profuse until approximately 10 min, at which time the flaming commenced to diminish.” No 

opening developed during the hose stream test, however the intumescent sheet located at the 

bottom of the junction box had eroded away. Examination of the cables inside the junction box 

reveled that the cable jacket had melted and adhered to the bottom and sides of the steel 

junction box. Although continuity testing was not conducted during the test, approximately 30 

minutes following the test, high voltage withstand testing was conducted and found the 

conductors insulation resistance to be infinite at 1000Vdc. However, the time between fire 

testing and electrical testing could have been sufficient to allow the cable to heal any electrical 

damages and these results are somewhat indeterminate. 

D.2.2.6 3M Test Number 84-10 

ERFBS: M20-A Desired Rating: 1-hr 

Test Procedure: ASTM E-119 Ambient Temperature: 50°F 

Thermocouples: Conduit, Unistrut Support 

Hose Stream: None 

Furnace: 3M Large Scale (8’ long x 5’ wide x 6’ high) 

Furnace control: Nine Type K located throughout furnace 

Cable Type: None 

Table D-43. 3M Test Results of M20-A Conduit 1-hr 

System 

No. Raceway Type Barrier Protection 

Avg. Temp 

Rise ∆T 

°C (°F) Rating 

1 2” RSC without 

support 

2 layers of M20-A 201 (393) < 1-hr 

2 2” RCS 

withsupport 

2 layers of M20-A 221 (429) < 1-hr 

3 Unistrut support 2 layers of M20-A in each direction 

from the conduit/support interface 289 (553) < 1-hr 

D.2.2.7 UL Surface Burning Characteristics of Type FS-195 Barrier (June 8, 1982) 

These tests were conducted in accordance with UL 723, “UL Standard Test Method for Surface 

Burning Characteristics of Building Materials.” Three 24’ long samples were prepared by joining 

nominal 2’ x 3’ composite fire barrier sheets mechanically joined. The FS-195 composite sheets 

were nominally 1⁄4” thick intumescent elastomeric material vulcanized to a No. 28 MSG 

galvanized steel plate on one surface and to an aluminum foil covering on the opposite surface. 

In addition, prior to vulcanization, a reinforced hexagonal wire mesh (chicken wire) was placed 

over the elastomeric material, beneath the aluminum foil covering. Each sample was tested 

with the foil facing of the composite fire barrier sheets downward (fire side). For two of the three 

tests, a slit was cut in the aluminum foil facing along the longitudinal centerline of the 24’ long 

samples. The results are shown in . 

 
D-35 

Table D-44. UL 723 Test Results for FS-195 

Test 

No. Product Flame Spread Fuel Contributed 

Smoke 

Developed 

1 Foil Slit 17.53 0 197 

2 Foil Intact 16.57 0 190 

3 Foil Slit 18.88 0 231 

D.2.2.8 3M Test Number 94-27 

ERFBS: Thermo-Lag plus E-54A Desired Rating: 3-hour 

Test Procedure: ASTM E-119 Test Slab: 

Ambient Temperature: 14°C (58°F) Acceptance Temperature: 

Thermocouples: Conduit, between barrier layers 

Hose Stream: Not conducted 

Furnace: 3M Large Scale Furnace (52” wide x 67” high x 78” long) 

Furnace control: 4 thermocouples 

Cable Type: None 

Table D-45. 3M Results of Thermo-Lag upgraded with E-54A 3-hr 2" conduit 

Raceway Type Cable Fill 

Avg. Temp 

Rise ∆T 

°C (°F) 

Max. Temp 

Rise ∆T 

°C (°F) Rating 

2” RSC - Straight Section 

10’ N/A 129 (265) 141 (286) <3-hr 

The average conduit temperature exceeded the average temperature rise criterion at 169 

minutes into the test. Maximum temperature rise was not exceeded. The report indicates that a 

possible area of failure would be the opening of seams in the TSI preformed sections, as no 

trowel grade material was used during installation. In addition, the 3M furnace was tested by UL 

to compare it’s thermal environment the UL test furnace. UL determined that 53 minutes in the 

3M furnace is equivalent to 60 minutes in the UL furnace. A 3-hour correlation was not 

conducted but the report suggests that on a mathematical basis the correlation would be 159 

minutes in the 3M furnace would equate to 180 minutes in the UL furnace. 
D-36 

D.2.2.1 3M Test Number 94-42 

ERFBS: Thermo-Lag plus E-54A 

 3 pre-formed sections of Thermo-Lag 

 3 layers of E-54A 

Desired Rating: 3-hour 

Test Procedure: ASTM E-119 Ambient Temperature: (54°F) 

Thermocouples: Conduit, between barrier layers 

Hose Stream: Not conducted 

Furnace: 4 Thermocouples 

Furnace control: 3M Large Scale Furnace (52” wide x 67” high x 78” long) 

Cable Type: None 

Table D-46. 3M Results of Thermo-Lag upgraded with E-54A 3-hr 1.5" conduit 

Raceway Type Cable Fill

Avg. Temp 

Rise ∆T °C (°F) 

Max. Temp 

Rise ∆T °C (°F) Rating 

1.5” RSC - Straight Section 10’ N/A 131 (268) 167 (333) < 3-hr 

TVA Ampacity Testing 3M M20A

TVA performed ampacity derating testing on the 3M M20A conduit and air drop configurations. 

The testing followed draft Institute of Electrical and Electronic Engineers (IEEE) Standard P848, 

“Procedure for the Determination of the Ampacity Derating of Fire Protected Cables.” The 

testing was conducted at Central Laboratories Services located in Chattanooga, TN. All cables 

tested were Rockbestos Type PXMJ. shows the results of this testing. 

Table D-47. TVA Ampacity Derating of 3M M20A 

Raceway Type Barrier Protection Cable Fill 

Ampacity Derating 

Factor % 

1” dia. conduit 5 layers of 3M 

M20A 

1 – 4/C #10AWG 29 

Air Drop (small) 5 layers of 3M 

M20A 

1 – 4/C #10AWG 42 

Air Drop (large) 5 layers of 3M 

M20A 

8 – 3/C #6 AWG 49 
D-37 

SwRI Ampacity Testing of M20-A/CS-195 ERFBS (Project No. 01-8818-208/-209b)

SwRI test report dated September 29, 1986 documents the results of ampacity derating testing 

conducted on the M20-A and CS-195 Rigid ERFBS. The cables selected were of a 3/c No. 

6AWG cross-linked Polyethylene (XLPE)/chlorosulphonated polyethylene (CSPE) construction. 

The cable conductor temperatures were measured with 24 gauge Type K thermocouples placed 

under the jacket and insulation in contact with the copper conductor. The cable trays and 

conduits were filled to 100-percent visual fill resulting in 122 and 20 cables, respectively. The 

raceways were 30.5 cm (12.0 in) long with the cables extending 0.3 to 0.6 m (1.0 to 2.0 ft) and 

protected with fiberglass blanket insulation. Three 10.2 cm (4.0 in) diameter rigid steel conduit 

(RSC) and three 61.0 cm (24.0 in) wide ladder back cable trays were used. The calculated fill 

depth for the cable tray was 7.4 cm (2.9 in). 

Table D-48. SwRI Ampacity Test Results for M20-A and CS-195 

Item # Test Specimen Description 

Final 

Current 

(Amps) 

Ampacity 

Derating Factor 

% 

1 Baseline – Open Tray 24.5 - - - 

2 Baseline – Tray with solid bottom 19.7 19.6 

3 Baseline – Tray with solid bottom 

and top 14.5 40.8 

4 M-20A (4 Layers) 9.9 59.6 

5 CS-195 (1 Layer) / M-20A (1 Layer) 10.0 59.2 

6 M-20A (1 Layer) / CS-195 (1 Layer) 

with ECP 2200 Coating 13.4 45.3 

7 Baseline – Conduit 23.7 - - - 

8 M-20A (5 Layers) 14.7 37.97 

9 M20-A (5 Layers) with ECP 2200 

Coating 15.3 35.44 

 
D-38 

D.3 Thermo-Lag

D.3.1 NUMARC Phase 1 Testing 

These tests were full scale tests, with test tray(s) and/or conduit(s) that vertically 

penetrated the furnace roof, descended into the furnace and bent to a horizontal section 

several feet long ranging from ~2 to ~4 feet below the furnace roof, then bent to a 

vertical ascending section that again penetrated the furnace roof 8 to 9 feet horizontally 

from the first penetration. These “elongated U” shaped test trays and conduits were 

used in all of NUMARC’s Phase 1 Thermo-Lag tests. 

D.3.1.1 NUMARC Project No. 13890-95671, Test 1-1 (October 1993) 

ERFBS: This 1 hr. test evaluated a 36” x 4” steel electric cable tray, with ERFBS 

constructed using Thermo-Lag 330-1, nom. 1⁄2” thickness, with stress skin 

monolithically adhered to the panels on one face. A ~3/16” layer of trowel 

grade THERMO-LAG-330-1 covered the side rail splice plates. Pieces of 330-

069 stress skin were applied over that, then a ~1/16” thick layer of trowel grade 

THERMO-LAG-330-1 was applied over the stress skin. Joints were reenforced in a similar manner. The full width of the tray was then covered with 

stress skins which overlapped the joint and side rail stress skins. These stress 

skins were then covered with a ~1/16 thick layer of trowel grade THERMOLAG. 

Test Procedure: Thermal Science, Inc., 

 TEST PLAN, Rev. 5 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 88°F Desired Rating: 1-hour 

Thermocouples: Every 6” on 2 bare copper wires, one on tray rungs, the other on an 

electric cable. Also, every 6” on both side rails of the cable tray. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x at least 5’ (i.e., a depth sufficient to contain the 3’ vertical extent of 

the test tray) 

Furnace control: : Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: Approx. 1/3 mix of power, control, and inst. cables, 51 total, 15.5% of total 

area 

Table D-49. NUMARC Thermo-Lag Test 1-1 

10.2 Raceway Type 

10.3 Barrier 

Protection Cable Fill 

Max. Temp Rise 

∆T °C (°F) Rating 

B-Line 36” x 4” steel tray 1⁄2” nom. TL 330-1 15.5% 311 (592) 54 min 

The average temperature increase parameter (∆T = 250°F) was exceeded at 59 min., and the 

single point temperature increase parameter (∆T = 325°F) was exceeded at 54 minutes. Also, a 

barrier opening was noted on the assembly following the fire endurance and hose stream test. 

Thus, the assembly did not meet the applicable criteria for a fire resistance period of 60 

minutes. 
D-39 

D.3.1.2 NUMARC Project No. 13890-95673, Test 1-3 (October 1993) 

ERFBS: This 3 hr. test evaluated a 36” x 4” steel electric cable tray, with ERFBS 

constructed using Thermo-Lag 330-1, nom. 1-1/8” thickness, with stress skin 

monolithically adhered to the panels on both faces. Extensive upgrades were 

incorporated into the design, including use of additional 5/8” thick overlay 

Thermo-Lag V-ribbed panels, use of trowel grade Thermo-Lag, use of 330-69 

stress skin material in many places, and lacing panels together with stainless 

steel wire. 

Test Procedure: Thermal Science, Inc., 

 TEST PLAN, Rev. 5 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 89°F Desired Rating: 3-hour 

Thermocouples: Every 6” on 2 bare copper wires, one on tray rungs, the other on an 

electric cable. Also, every 6” on both side rails of the cable tray. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x at least 5’ (i.e., a depth sufficient to contain the 3’ vertical extent of 

the test tray) 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: Approx. 1/3 mix of power, control, and inst. cables, 51 total, 15.5% of total 

area 

Table D-50. NUMARC Thermo-Lag Test 1-3 

10.4 Raceway Type 

10.5 Barrier 

Protection Cable Fill

Max. Temp 

Rise ∆T °C (°F) Rating 

B-Line 36” x 4” steel tray 1” nom. TL 330-1 15.5% 224 (436) 2 hr. 47 min 

The average temperature increase parameter (∆T = 250°F) was exceeded at 2 hours and 54 

minutes, and the single point temperature increase parameter (∆T = 325°F) was exceeded at 2 

hours and 47 minutes. Also, a barrier opening was noted across the bottom center of the 

assembly following the fire endurance and hose stream test. Thus, the assembly did not meet 

the applicable criteria for a fire resistance period of 3 hours. 

D.3.1.3 NUMARC Project No. 13890-95674, Test 1-4 (November 1993) 

ERFBS: This 3 hr. test evaluated a 24” x 4” steel electric cable tray with 5” steel conduit 

air drop, with ERFBS constructed using Thermo-Lag 330-1, nom. 1” thickness, 

with stress skin monolithically adhered to the panels on both faces. Extensive 

upgrades were incorporated into the design, including use of additional 5/8” 

thick overlay Thermo-Lag V-ribbed panels, use of trowel grade Thermo-Lag, 

use of 330-69 stress skin material in many places, and lacing panels together 

with stainless steel wire. Thermo-Lag 330-1 Baseline Pre-shaped conduit 

sections were used for the conduit and air drop assembly, upgraded with use 

of THERMO-LAG-330-1 trowel grade subliming material and 330-69 stress 

skin pieces. Many pieces were stitched together with stainless steel wire. 

Test Procedure: Thermal Science, Inc., 

TEST PLAN, Rev. 5 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 78°F Desired Rating: 3-hr 
D-40 

Thermocouples: Every 6” on 2 bare copper wires, one on tray rungs, the other on an 

electric cable, and every 6” on both side rails of the cable tray. In addition, two lengths 

of bare copper wire, with thermocouples every 6”, were extended down thru the 5 inch 

conduit and air drop assembly into the center of the cable tray to measure temperatures 

in the air drop and conduit. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x at least 5’ (i.e., a depth sufficient to contain the 3’ vertical extent of 

the test tray) 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: Approx. 1/3 mix of power, control, and inst. cables, 34 total, 15.4% of total 

area 

Table D-51. NUMARC Thermo-Lag Test 1-4

Raceway Type 

Barrier 

Protection 

Cable 

Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

B-Line 24” x 4” 

steel tray with 5” 

steel conduit air 

drop 

1” nom. TL 330-1 15.4% 521 (969) Tray – 3-hr 

Air Drop – 1 hr 44 min 

The 24 in. cable tray assembly, clad in nominal 1 in. thick THERMO-LAG 330-1 material with 

upgrades briefly noted above, met requirements of the TEST PLAN for a fire resistance rating of 

three hours. However, the air drop assembly and associated 5 in. conduit stub failed to meet 

the requirements. 

D.3.1.4 NUMARC Project No. 13890-95675, Test 1-5 (November 1993) 

ERFBS: This 3 hr. test was evaluated a 24” x 4” steel electric cable tray with tee section, 

with ERFBS constructed using Thermo-Lag 330-1, nom. 1” thickness, with 

stress skin monolithically adhered to the panels on both faces. Extensive 

upgrades were incorporated into the design, including use of additional 5/8” 

thick overlay Thermo-Lag V-ribbed panels, use of trowel grade Thermo-Lag, 

use of 330-69 stress skin material in many places, and lacing panels together 

with stainless steel wire 

Test Procedure: Thermal Science, Inc., 

TEST PLAN, Rev. 5 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 77°F Desired Rating: 3-hr 

Thermocouples: Every 6” on 2 bare copper wires, one on tray rungs, the other on an 

electric cable, and every 6” on both side rails of the cable tray. Two additional short 

sections of TC-instrumented bare wire were looped into the tee section. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x at least 5’ (i.e., a depth sufficient to contain the 3’ vertical extent of 

the test tray) 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: Approx. 1/3 mix of power, control, and inst. cables, 34 total, 15.4% of total 

area 

 
D-41 

Table D-52. NUMARC Thermo-Lag Test 1-5

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

B-Line 24” x 4” steel tray, 

with tee section 

1” nom. TL 330-1 15.4% 186 (366) 2 hr. 52 min. 

The individual temperature increase parameters were exceeded on the tray rail at 172 minutes, 

and a large section of panel was dislodged during the hose stream exposure, creating an 

opening through which the internal cable tray and its cables were visible. 

D.3.1.5 NUMARC Project No. 13890-95676, Test 1-6 (November 1993) 

ERFBS: This 1 hr. test evaluated a 5” Aluminum Conduit, a 3” Aluminum Conduit, a 3⁄4” 

Aluminum Conduit, an Aluminum Junction Box, and a 3” Steel Conduit, with 

ERFBS constructed using Thermo-Lag 330-1, pre-shaped conduit sections, 

nom. 1⁄2” thickness on the 4 conduits. Thermo-Lag 330-1 nom. 1⁄2” thickness 

baseline panels were used on the LB box designs, the junction box, and the 

support members. Extensive upgrades were incorporated into the design, 

including use of additional 1/4” thick THERMO-LAG-330-1 pre-shaped conduit 

overlay sections, use of trowel grade Thermo-Lag, use of 330-69 stress skin 

material in many places, and use of stainless steel bands throughout as 

appropriate (there are nine (9) pages describing these upgrades). 

Test Procedure: Thermal Science, Inc., 

TEST PLAN, Rev. 5 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 87°F Desired Rating: 1-hr 

Thermocouples: One TC every 6” on one bare copper wire in each of the four conduits, 

one TC every 6” affixed with glass cloth electrical tape to the bottom surface of each 

conduit, and TCs clamped with stainless steel round-head screws to the interior surface 

of the junction box. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x at least 5’ (i.e., a depth sufficient to contain the 3’ vertical extent of 

the test conduit assemblies) 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: There were no electric cables installed in the conduits or in the junction 

boxes. 

Table D-53. NUMARC Thermo-Lag Test 1-6 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

5” Aluminum Conduit 

3” Aluminum Conduit 

3⁄4” Aluminum Conduit 

Aluminum Junction 

Box 

3” Steel Conduit 

1⁄2” nom. TL-330-1 

1⁄2” nom. TL-330-1 

1⁄2” nom. TL-330-1 

1⁄2” nom. TL-330-1 

1⁄2” nom. TL-330-1 

None 

None 

None 

None 

None 

153 (308) 

158 (317) 

83 (181) 

139 (283) 

152 (306) 

1 hr. 

1 hr. 

1 hr. 

1 hr. 

1 hr. 
D-42 

As shown in the above table, all four of the test conduits, and the junction box, met the 

allowable single point maximum temperature increase criterion of 325°F. Although not shown in 

the table, the maximum average temperature increase for any of the 5 was 246°F, which met 

the allowable maximum average temperature increase criterion of 250°F. 

D.3.1.6 NUMARC Project No. 13890-95677, Test 1-7 (November 1993) 

ERFBS: This 3 hr. test evaluated a 5” Steel Conduit, a 3” Steel Conduit, a 3⁄4” Steel 

Conduit, and a Steel Junction Box, with ERFBS constructed using Thermo-Lag 

330-1, pre-shaped conduit sections, nom. 1” thickness on the 3 conduits. 

Thermo-Lag 330-1 nom. 1” thickness baseline panels were used on the LB box 

designs, the junction box, and the support members. Extensive upgrades were 

incorporated into the design, including use of additional 5/8” thick THERMOLAG-330-1 pre-shaped conduit overlay sections, use of trowel grade ThermoLag, use of 330-69 stress skin material in many places, and use of stainless 

steel bands throughout as appropriate (there are nine (9) pages describing 

these upgrades). 

Test Procedure: Thermal Science, Inc., 

TEST PLAN, Rev. 5 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 84°F Desired Rating: 3-hr 

Thermocouples: One TC every 6” on one bare copper wire in each of the four conduits, 

one TC every 6” affixed with glass cloth electrical tape to the bottom surface of each 

conduit, and TCs clamped with stainless steel round-head screws to the interior surface 

of the junction box. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x at least 5’ (i.e., a depth sufficient to contain the 3’ vertical extent of 

the test conduit assemblies) 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: No electric cables were installed in the conduits or the junction box 

Table D-54. NUMARC Thermo-Lag Test 1-7

Raceway Type Barrier Protection Cable Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

5” Steel Conduit 

3” Steel Conduit 

3⁄4” Steel Conduit 

Junction Box 

1” nom. TL-330-1 

1” nom. TL-330-1 

1” nom. TL-330-1 

1” nom. TL-330-1 

None 

None 

None 

None 

566 (1050) 

599 (1110) 

136 (277) 

123 (253) 

1 hr. 56 min.1

1 hr. 52 min. 

3 hr. 

3 hr. 

1Maximum average temperature increase criterion of 250°F exceeded in 1 hr. 53 min. 

As shown in the above table, the two largest test conduits did not meet the allowable single 

point maximum temperature increase criterion of 325°F. The smallest test conduit and the 

junction box did meet the allowable single point maximum temperature increase criterion of 

325°F, and although not shown on the table, they also met the allowable maximum average 

temperature increase criterion of 250°F. 
D-43 

D.3.2 NUMARC Phase 2 Testing 

These tests were full scale tests, with test aluminum tray(s) and/or aluminum conduit(s) that 

vertically penetrated the furnace roof, descended into the furnace and bent to a horizontal 

section several feet long ranging from approximately 2 to 4 feet below the roof, then bent to a 

vertical ascending section that again penetrated the furnace roof 8 to 9 feet horizontally from the 

first penetration. This “elongated U” shape was used in NUMARC Phase 2 Tests 2-1, 2-2, 2-3, 

and 2-9. 

D.3.2.1 NUMARC Project No. 13890-96141, Test 2-1 (April 1994) 

ERFBS: This 1 hr. test evaluated a 6” Aluminum Conduit, a 4” Aluminum Conduit, a 2” 

Aluminum Conduit, and a 3/4” Aluminum Conduit, with ERFBS constructed 

using Thermo-Lag 330-1, pre-shaped conduit sections, nom. 1⁄2” thickness on 

the 4 conduits. Thermo-Lag 330-1 V-ribbed baseline panels, 1⁄2” nom. 

thickness, were used for the LB box designs and the support members. Dow 

Corning 3-6548 RTV silicone foam material was used to seal the blockout 

(where the conduits enter/exit thru the furnace roof). 3Therma-Lag 330-1 

subliming trowel grade material was used to pre-caulk all joints and seams 

between the panels. Internal silicone elastomer (Promatec 45B) seal material 

was installed inside each conduit leg at the level of the furnace top deck, and 

1⁄2” x 0.020” type 304 stainless steel rolled-edge banding straps with wing seals 

were used. 

Test Procedure: NUMARC Phase 2 Test 

Program TEST PLAN, Rev. 0 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 55°F Desired Rating: 1-hr 

Thermocouples: One TC every 6” on one bare copper wire in each of the four conduits, 

one TC every 6” affixed with glass cloth electrical tape to the bottom surface of each 

conduit 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x at least 6’ (i.e., a depth sufficient to contain the ~4’ vertical extent of 

the test conduits) 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: No electric cables were installed in the conduits 

Table D-55. NUMARC Thermo-Lag Test 2-1 

Raceway Type 

Barrier 

Protection 

Cable 

Fill 

Max. Temp 

Rise ∆T °C (°F)1 Rating 

6” Aluminum Conduit 

4” Aluminum Conduit 

2” Aluminum Conduit 

3/4” Aluminum Conduit 

1⁄2” nom. TL-330-1 

1⁄2” nom. TL-330-1 

1⁄2” nom. TL-330-1 

1⁄2” nom. TL-330-1 

None 

None 

None 

None 

152 (305) 

160 (320) 

214 (417) 

524 (976) 

50 min.2

48 min.2

39 min.3

27 min.4

1 the test was terminated at 50 minutes when the last conduit exceeded its first temp. 

 limit criterion (average temperature increase of 250°F, on the 6” conduit) 

2 failed the maximum average temperature increase criterion of 250°F 

3 failed the maximum average temperature increase criterion of 250°F first 

4 failed the maximum single point temperature increase criterion of 325°F, and the 

 maximum average temperature increase criterion of 250°F, at the same time 
D-44 

Additionally, burn-through was noted on the 3⁄4 inch conduit following the fire endurance and 

hose stream tests. 

D.3.2.2 NUMARC Project No. 13890-96142, Test 2-2 (April 1994) 

ERFBS: This 1 hr. test evaluated the following ERFBS: two aluminum conduit 

assemblies (2 inch and 3⁄4 inch), each separately clad with a nominal thickness 

of 1⁄2 inch Thermo-Lag 330-1, with 3M Fire Dam 150 Caulking and Top Coat for 

outdoor applications; and two Box Enclosures of 1⁄2 inch Thermo-Lag 330-1, 

one baseline and one with various upgrades (e.g., use of stainless steel bands 

and stitching with stainless steel wire described in detail in the original test 

report), each box enclosure containing three aluminum conduit assemblies (3 

inch, 2 inch, and 3⁄4 inch). The upgraded box enclosure met the applicable 

requirements for a fire exposure period of one hour, but the two conduit 

assemblies and the non-upgraded box enclosure failed to satisfy these 

requirements. 

Test Procedure: NUMARC Phase 2 Test 

Program TEST PLAN, Rev. 0 

Test Slab: 13’ x 8’ x 6” reinforced concrete 

slab 

Ambient Temperature: 71°F Desired Rating: 1-hr 

Thermocouples: One TC every 6” on one bare copper wire in each of the six conduits, 

and one TC every 6” affixed with glass cloth electrical tape to the bottom surface of each 

conduit. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x at least 5’ (i.e., a depth sufficient to contain the ~3’ vertical extent of 

some of the test conduits) 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: No electric cables were installed in the conduits 

Table D-56. NUMARC Thermo-Lag Test 2-2 

Raceway: 

Barrier 

Protection 

Cable 

Fill 

Max. Temp Rise 

∆T °C (°F) Rating 

Individual Conduits Center 

2” Aluminum Conduit 1⁄2” nom. TL-330-1 None 348 (658) 35 min. 

3⁄4” Aluminum Conduit 1⁄2” nom. TL-330-1 None 731 (1348) 26 min. 

Baseline (left) Box Enclosure 

3” Aluminum Conduit 1⁄2” nom. TL-330-1 None 151 (303)1 Failed2

2” Aluminum Conduit 1⁄2” nom. TL-330-1 None 146 (295)1 Failed2

3⁄4” Aluminum Conduit 1⁄2” nom. TL-330-1 None 141 (285)1 Failed2

1 These conduits all passed the maximum 325°F single point acceptance criterion; they 

 also passed the 250°F maximum average increase criterion (all 3 increased 249°F) 

2 Although the single point and average temperature increase criteria were met, these 

 conduits did not meet the barrier integrity and hose stream requirements. 
D-45 

Table D-56. NUMARC Thermo-Lag Test 2-2 (Continued) 

Raceway: 

Barrier 

Protection 

Cable 

Fill 

Max. Temp Rise 

∆T °C (°F) Rating 

Upgraded(right) Box Enclosure 

3” Aluminum Conduit 1⁄2” nom. TL-330-1 None 113 (235)3 1 hr. 

2” Aluminum Conduit 1⁄2” nom. TL-330-1 None 117 (243)3 1 hr. 

3⁄4” Aluminum Conduit 1⁄2” nom. TL-330-1 None 109 (229)3 1 hr. 

3 These conduits also met the 250°F maximum average temperature increase criterion 

D.3.2.3 NUMARC Project No. 13890-96143, Test 2-3 (April 1994) 

ERFBS: This 3 hr. test evaluated three aluminum conduit assemblies (6 in., 3 in., and 3⁄4 

in.), covered with Thermo-Lag 330-1, 1 in. nominal thickness Pre-Shaped 

sections. The joints between sections were pre-caulked with Thermo-Lag 330-

1 Trowel Grade material. Stainless steel bands were installed on the miter-cut 

wedge shaped pieces fitted to the radial bend portions of the conduits. These 

conduits were removed from the test furnace after all had exceeded the 

applicable acceptance criteria for fire resistance at 102 minutes. 

Test Procedure: NUMARC Phase 2 Test 

Program TEST PLAN, Rev. 0 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 59°F Desired Rating: 3-hr 

Thermocouples: One TC every 6” on one bare copper wire in each of the three conduits, 

one TC every 6” affixed with glass cloth electrical tape to the bottom surface of each 

conduit 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x at least 6’ (i.e., a depth sufficient to contain the ~4’ vertical extent of 

the test conduits) 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: No electric cables were installed in the conduits 

Table D-57. NUMARC Thermo-Lag Test 2-3 

Raceway Type 

Barrier 

Protection 

Cable 

Fill 

Max. Temp Rise 

∆T °C (°F)1 Rating 

6” Aluminum Conduit 1” nom. TL-330-1 None 165 (329) 102 min. 

3” Aluminum Conduit 1” nom. TL-330-1 None 211 (411) 91min. 

3/4” Aluminum Conduit 1” nom. TL-330-1 None 619 (1146) 63min. 

1 the test was terminated at 102 minutes when the last conduit exceeded its temp. limit criteria 

(at 102 min., the 6” conduit reached an average temp. increase of 251°F (over its 250°F 

limit), and a max. temp. increase of 329°F (over its 325°F limit) both at the same time) 
D-46 

D.3.2.4 NUMARC Project No. 13890-96147, Test 2-7 (April 1994) 

This test, the following Test 2-8, and Test 2-10 were full scale tests with test trays that vertically 

penetrated the furnace roof, descended into the furnace and bent to horizontal three feet below 

the furnace roof, then preceded four feet horizontally at which point they exited the furnace 

horizontally thru its front wall.

ERFBS: This 1 hr. test evaluated four aluminum tray assemblies (two 6 in. wide and two 

24 in. wide) covered with Thermo-Lag 330-1, 1⁄2 inch V-ribbed panels. These 

trays were intended to be basically similar to as-installed ERFBS, with minimal 

upgrades, for comparison to the following Test 2-8 which incorporated 

upgrades. 

Test Procedure: NUMARC Phase 2 Test 

Program TEST PLAN, Rev. 0 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 68°F Desired Rating: 1-hr 

Thermocouples: One TC every 6” on each of two bare copper wires in each of the four 

cable trays, one wire on the tray’s bottom rungs under the electric cables on the tray’s 

centerline, and the other directly above on top of the electric cables (both were secured 

by standard electrical plastic tie wraps). A third such wire was secured to the outside 

surface of the cable tray rungs, 1” offset from the tray centerline. In addition, one TC 

every 6” was affixed to both side rails of each of the trays clamped on by screws. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The trays contained an approximate 1/3 each mix of power, control, and 

instrument cables with total areas as shown in the table below. 

Table D-58. NUMARC Thermo-Lag Test 2-7 

Raceway Type 

Barrier 

Protection 

Cable 

Fill 

Max. Temp 

Rise ∆T °C (°F)1 Rating 

Tray A (24” Aluminum) 1⁄2” nom. TL-330-1 15.4% 397 (746) 21 min. 

Tray B (6” Aluminum) 1⁄2” nom. TL-330-1 16.1% 167 (333) 48 min. 

Tray C (6” Aluminum) 1⁄2” nom. TL-330-1 16.1% 167 (333) 48 min. 

Tray D (24” Aluminum) 1⁄2” nom. TL-330-1 15.4% 372 (701) 23 min. 

1 the test was terminated at 48 minutes when the last tray exceeded its temp. limit
D-47 

D.3.2.5 NUMARC Project No. 13890-96148, Test 2-8 (April 1994) 

This test, the previous Test 2-7, and Test 2-10, were full scale tests with test trays that vertically 

penetrated the furnace roof, descended into the furnace and bent to horizontal three feet below 

the furnace roof, then preceded four feet horizontally at which point they exited the furnace 

horizontally thru its front wall.

ERFBS: This 1 hr. test evaluated four aluminum tray assemblies (two 6 in. wide and two 

24 in. wide) covered with Thermo-Lag 330-1, 1⁄2 inch V-ribbed panels. These 

trays were similar to as-installed ERFBS but with significant upgrades, for 

comparison to the previous Test 2-7 which did not incorporate upgrades. 

Upgrades included application of an approximately 3/16 inch thick layer of 

trowel grade Thermo-Lag 330-1 over the TL panel pieces covering the side 

rails and splice plates. Pieces of 330-069 stress skin were folded and stapled 

over the splice plates, and an approximately 1/16 inch thick skim coat of trowel 

grade TL was placed over the stress skin. Stainless steel tie wires and 

circumferential stress skin wraps were also used in numerous parts of the 

improved ERFBS designs. 

Test Procedure: NUMARC Phase 2 Test 

Program TEST PLAN, Rev. 0 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 54°F Desired Rating: 1-hr 

Thermocouples: One TC every 6” on each of two bare copper wires in each of the four 

cable trays, one wire on the tray’s bottom rungs under the electric cables on the tray’s 

centerline, and the other directly above on top of the electric cables (both were secured 

by standard electrical plastic tie wraps). A third such wire was secured to the outside 

surface of the cable tray rungs, 1” offset from the tray centerline. In addition, one TC 

every 6” was affixed to both side rails of each of the trays clamped on by screws. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The trays contained an approximate 1/3 each mix of power, control, and 

instrument cables with total areas as shown in the table below. 

Table D-59. NUMARC Thermo-Lag Test 2-8 

Raceway Type Barrier Protection 

Cable 

Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

Tray A (24” Aluminum) 1⁄2” nom. TL-330-1 15.4% 172 (341) 57 min.1

Tray B (6” Aluminum) 1⁄2” nom. TL-330-1 16.1% 99 (211) 60 min. 

Tray C (6” Aluminum) 1⁄2” nom. TL-330-1 16.1% 99 (210) 60 min. 

Tray D (24” Aluminum) 1⁄2” nom. TL-330-1 15.4% 119 (246) 60 min. 

1 individual temperature increase limit (325°F) exceeded only on the right cable tray side rail 

adjacent to the fire stop (i.e., where the ERFBS passed thru the furnace wall), which the 

licensee attributed to the fire stop and not to failure of the ERFBS. 
D-48 

D.3.2.6 NUMARC Project No. 13890-96149, Test 2-9 (April 1994) 

ERFBS: This 1 hr. test evaluated a single 36” wide aluminum tray with upgrades similar 

to the upgraded 24” tray in test 2-8 that included application of an 

approximately 3/16 inch thick layer of trowel grade Thermo-Lag 330-1 over the 

nominal 1⁄2“ thick TL panel pieces covering the side rails and splice plates. 

Pieces of 330-069 stress skin were folded and stapled over the splice plates, 

and an approximately 1/16 inch thick skim coat of trowel grade TL was placed 

over the stress skin. Stainless steel tie wires and circumferential stress skin 

wraps were also used in numerous parts of the improved ERFBS designs. 

Test Procedure: NUMARC Phase 2 Test 

Program TEST PLAN, Rev. 0 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 68°F Desired Rating: 1-hr 

Thermocouples: One TC every 6” on each of two bare copper wires in the tray, one wire 

on the tray’s bottom rungs under the electric cables on the tray’s centerline, and the 

other directly above on top of the electric cables (both were secured by standard 

electrical plastic tie wraps). A third such wire was secured to the outside surface of the 

cable tray rungs, 1” offset from the tray centerline. In addition, one TC every 6” was 

affixed to both side rails of the tray clamped on by screws. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The tray contained an approximate 1/3 each mix of power, control, and 

instrument cables with total area 15.5% of the tray’s cross-sectional area. 

Table D-60. NUMARC Thermo-Lag Test 2-9

Raceway Type 

Barrier 

Protection 

Cable 

Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

36” Aluminum Tray 1⁄2” nom. TL-330-1 15.5% 159 (319)1 60 min. 

1 This is below the 325°F single point temperature increase criterion. The maximum average 

temperature increase was 212°F, below the 250°F criterion. Additionally, no barrier openings 

were noted on the assembly following the hose stream test.

D.3.2.7 NUMARC Project No. 13890-96150, Test 2-10 (April 1994) 

This test, and Tests 2-7 and 2-8, were full scale tests with test trays that vertically penetrated 

the furnace roof, descended into the furnace and bent to horizontal three feet below the furnace 

roof, then preceded four feet horizontally at which point they exited the furnace horizontally thru 

its front wall.

ERFBS: This 3 hr. test evaluated four aluminum tray assemblies (two 6 in. wide and two 

24 in. wide) covered with Thermo-Lag 330-1, 1 inch thick V-ribbed panels. 

These trays were intended to be basically similar to as-installed ERFBS with 

minimal upgrades. 

Test Procedure: NUMARC Phase 2 Test 

Program TEST PLAN, Rev. 0 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 57°F Desired Rating: 3 hr. 
D-49 

Thermocouples: One TC every 6” on each of two bare copper wires in each of the four 

cable trays, one wire on the tray’s bottom rungs under the electric cables on the tray’s 

centerline, and the other directly above on top of the electric cables (both were secured 

by standard electrical plastic tie wraps). A third such wire was secured to the outside 

surface of the cable tray rungs, 1” offset from the tray centerline. In addition, one TC 

every 6” was affixed to both side rails of each of the trays clamped on by screws. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: ~11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The trays contained an approximate 1/3 each mix of power, control, and 

instrument cables with total areas as shown in the table below. 

Table D-61. NUMARC Thermo-Lag Test 2-10 

Raceway Type 

Barrier 

Protection 

Cable 

Fill 

Max. Temp 

Rise ∆T °C (°F)1 Rating 

Tray A (24” Aluminum) 1” nom. TL-330-1 15.4% 164 (328) 86 min. 

Tray B (6” Aluminum) 1” nom. TL-330-1 16.1% 117 (242) >86 min.2

Tray C (6” Aluminum) 1” nom. TL-330-1 16.1% 112 (233) >86 min.2

Tray D (24” Aluminum) 1” nom. TL-330-1 15.4% >284 (>543) <86 min 

1 The test was terminated at 86 minutes when the last 24” tray (Tray A) exceeded its 325°F 

maximum temperature increase limit. 2 Not determined; neither temperature criteria was exceeded at end of test. 
D-50 

D.3.3 Texas Utilities (TU) Electric Co. Tests for Comanche Peak Steam Electric Station 

These tests were full scale tests, starting with two tests in which conduits vertically penetrated 

the furnace roof, descended into the furnace and bent to a horizontal section ~6 to 8 feet long 3 

feet below the furnace roof, then bent to a vertical ascending section that again penetrated the 

furnace roof 8-1⁄2 feet horizontally from the first penetration (i.e., they were “elongated U-shaped” 

test trays and conduits). Such “elongated U-shaped” test trays and conduits were used in the 

Scheme 9-1 and 9-3 tests below. 

D.3.3.1 TU Electric Report No. 12340-94367a, Scheme 9-1 (November 1992) 

ERFBS: This 1 hr. test used 1⁄2” nominal thickness Thermo-Lag 330-1 Flat panels and Vribbed panels to construct assemblies (e.g., hangers, LBD boxes, radial bends) 

with 5”, 3”, and 3⁄4” diameter conduits clad with 1⁄2” nominal thickness ThermoLag 330-1 pre-shaped conduit sections. Upgrades were used similar to those 

described previously for the Numarc tests. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 8 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 72°F Desired Rating: 1 hr. 

Thermocouples: One TC every 6” on one of the power cables, one of the control cables, 

and one of the instrument cables in each conduit (except for the 3⁄4” conduit which had 

only one instrumented cable) taped to the top surface of the cable with a double wrap of 

glass fiber reinforced electrical tape, plus one TC every 12” taped to the top outside 

surface of each conduit with a short piece of glass cloth electrical tape. 

Hose Stream: Passed 

Furnace: ~11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The conduits contained a ~1/3 mix of power, control, and instrument cables 

with total fill areas as shown in the table below. 

Table D-62. TU Electric Thermo-Lag Test 9-1 

Raceway Type Barrier Protection 

Cable 

Fill 

Max. Temp Rise 

∆T °C (°F)1 Rating2

3⁄4” Steel Conduit 1⁄2” nom. TL-330-1 39.8% 283 (542) 60 min. 

3” Steel Conduit 1⁄2” nom. TL-330-1 44.2% 229 (444) 60 min. 

5” Steel Conduit 1⁄2” nom. TL-330-1 34.9% 284 (543) 60 min. 

1 The max. ∆T values shown in the table are all from thermocouples on the outside of the steel 

conduits, between the steel surface and the Thermo-Lag fire barrier material. The laboratory 

personal attributed the “excessively high temperatures” measured outside the steel conduits 

were due to “electro-chemical reactions caused by saturation of the fiberglass thermocouple 

insulation grading by condensate accumulated on the conduit steel.” 2 All thermocouples on the electric cables inside the conduits showed ∆Ts below the acceptance 

criteria of 250°F maximum average temperature increase and 325°F maximum single point 

increase. The licensee based the stated rating on those values (i.e., the applicable 60 min. 

criteria were met based on cable temperature rises within the conduit). This rating is based on 

site-specific acceptance criteria accepted by the NRC in its October 29, 1992 letter. 
D-51 

D.3.3.2 TU Electric Report No. 12340-94367j, Scheme 9-3 (December 1992) 

ERFBS: This 1 hr. test used 1⁄2” nominal thickness Thermo-Lag 330-1 Flat panels and 

V-ribbed panels to construct assemblies (e.g., hangers, LBD boxes) with 2”, 

11⁄2”, and 3⁄4” diameter conduits clad with 1⁄2” nominal thickness Thermo-Lag 

330-1 pre-shaped conduit sections (with the exception of the 3⁄4” conduit, which 

used 3⁄4” nominal thickness Thermo-Lag 330-1 pre-shaped conduit sections). 

Other upgrades were used similar to those described previously for the Numarc 

tests. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 8 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 65°F Desired Rating: 1 hr. 

Thermocouples: One TC every 6” on one of the power cables, on one of the control cables, and 

on one of the instrument cables in each conduit (except for the 3⁄4” conduit which had only one 

instrumented cable) taped to the top surface of each cable with a double wrap of glass fiber 

reinforced electrical tape, plus one TC every 12” taped to the top outside surface of each 

conduit with a short piece of glass cloth electrical tape. 

Hose Stream: Failed. 

Furnace: ~11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The conduits contained a ~1/3 mix of power, control, and instrument cables with 

total fill areas as shown in the table below. 

Table D-63. TU Electric Thermo-Lag Test 9-3 

Raceway Type Barrier Protection 

Cable 

Fill 

Max. Temp 

Rise ∆T °C (°F)1 Rating2

3⁄4” Steel Conduit 3⁄4” nom. TL-330-1 39.8% 444 (831) Failed 

1-1⁄2” Steel Conduit 1⁄2” nom. TL-330-1 49.5% 538 (1000) Failed 

2” Steel Conduit 1⁄2” nom. TL-330-1 35.8% 424 (796) Failed 

1 The maximum ∆T values shown in the table are all from thermocouples on the outside of the 

steel conduits, between the steel surface and the Thermo-Lag fire barrier material. The 

laboratory personal attributed the “excessively high temperatures” measured outside the steel 

conduits were due to “electro-chemical reactions caused by saturation of the fiberglass 

thermocouple insulation grading by condensate accumulated on the conduit steel.” The 

corresponding maximum ∆T values for cables inside the conduits were 457°F for the 3⁄4”, 

413°F for the 1-1⁄2”, and 358°F for the 2” conduits. Thus the three ∆Ts for the steel conduits 

given in the table, and these three ∆Ts for cables within the conduits, all exceed the maximum 

allowable single point ∆T of 325°F. 2 No loss of circuit integrity occurred during the test and post-fire cable insulation resistance 

tests were within limits. However, the ∆T values for cables inside the conduits exceeded 

allowable limits; and visible cable damage and fire barrier burn through occurred for the 1-1/2” 

and 2” conduits. In addition, the max. single point temperature increases all exceeded by a 

significant margin the maximum allowable 325°F at one hour, so all three conduits failed to 

qualify for one hour. The exact times (less than one hour) at which they exceeded the 325°F 

criterion were not given in the available documentation. The licensee did not credit the results 

of this fire test as part of the Thermo-Lag ERFBS qualification basis at CPSES. 
D-52 

D.3.3.3 TU Electric Report No. 12340-94367c, Scheme 10-1 (December 2, 1992) 

ERFBS: This 1 hr. test evaluated an assembly of two parallel 3” conduits with 

centerlines 8” apart that descended vertically thru the furnace roof to two 

condulets 3’ below the roof, then horizontally 3-1⁄2 feet thru a single horizontal 

1’-6” x 1’ x 6” junction box, then horizontally another 3-1⁄2 feet to two condulets, 

then rose vertically into a vertical 1’-6” x 1’ x 6” junction box, then passed thru 

the furnace roof. The condulet and junction box covers were constructed using 

Thermo-Lag 330-1 Flat Panels of 1⁄2“ nominal thickness; Thermo-Lag 330-1 

Subliming Trowel Grade Material was used to pre-caulk all joints, seams, and 

upgraded areas; and Thermo-Lag 330-1 Pre-Shaped Conduit Sections of 1⁄2“ 

nominal thickness were used on the conduits. Other upgrades were used 

similar to those described previously for the Numarc tests. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 8 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 63°F Desired Rating: 1 hr. 

Thermocouples: One TC every 6” on one of the power cables, on one of the control 

cables, and on one of the instrument cables in each conduit taped to the top surface of 

each cable with a double wrap of glass fiber reinforced electrical tape, and one TC every 

12” taped to the top outside surface of each conduit with a short piece of glass cloth 

electrical tape, plus several TCs inside the junction boxes. 

Hose Stream: Passed. 

Furnace: ~11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The conduits contained a ~1/3 mix of power, control, and instrument cables 

with total fill area 43.4% of the available area inside the conduits. 

Table D-64. TU Electric Thermo-Lag Test 10-1 

Raceway Type Barrier Protection 

Cable 

Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

Front 3” Steel Conduit 1⁄2” nom. TL-330-1 43.4% 581 (1078)1 60 min.2

Rear 3” Steel Conduit 1⁄2” nom. TL-330-1 43.4% 348 (659)1 60 min.2

Horiz. J-Box 1⁄2” nom. TL-330-1 N/A 51 (123) 60 min. 

Vert. J-Box 1⁄2” nom. TL-330-1 N/A 57 (135) 60 min. 

1 The max. ∆T values shown in the table for the conduits are from thermocouples on the outside of the 

steel conduits, between the steel surface and the Thermo-Lag fire barrier material. The laboratory 

personal attributed the “excessively high temperatures” measured outside the steel conduits were due to 

“electro-chemical reactions caused by saturation of the fiberglass thermocouple insulation grading by 

condensate accumulated on the conduit steel.”

2 All thermocouples on the electric cables inside the conduits showed ∆Ts below the acceptance criteria 

of 250°F maximum average temperature increase and 325°F maximum single point increase. The 

licensee based the stated rating for the conduits on those values (i.e., the applicable 60 min. criteria 

“were met” based on cable temperature rises within the conduit). This rating is based on site-specific 

acceptance criteria accepted by the NRC in its October 29, 1992 letter. 
D-53 

D.3.3.4 TU Electric Report No. 12340-94367d, Scheme 10-2 (December 16, 1992) 

Based on the available documentation, this test was apparently a near-repeat of “Scheme 10-1” 

(above) except for differences in their upgrades (e.g., materials and methods used to apply a 

second layer or TL to the junction boxes). The results were not substantially different for the 

two tests. 

ERFBS: This 1 hr. test evaluated an assembly of two parallel 3” conduits with 

centerlines 8” apart that descended vertically thru the furnace roof to two 

condulets 3’ below the roof, then horizontally 3-1⁄2 feet into a single horizontal 

1’-6” x 1’ x 6” junction box, then horizontally another 3-1⁄2 feet to two condulets, 

then rose vertically into a vertical 1’-6” x 1’ x 6” junction box, then passed thru 

the furnace roof. The condulet and junction box covers were constructed using 

Thermo-Lag 330-1 Flat Panels of 1⁄2“ nominal thickness; Thermo-Lag 330-1 

Subliming Trowel Grade Material was used to pre-caulk all joints, seams, and 

upgraded areas; and Thermo-Lag 330-1 Pre-Shaped Conduit Sections of 1⁄2“ 

nominal thickness were used on the conduits. Other upgrades were used 

similar to those described previously for the Numarc tests. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 8 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 69°F Desired Rating: 1 hr. 

Thermocouples: One TC every 6” on one of the power cables, on one of the control 

cables, and on one of the instrument cables in each conduit taped to the top surface of 

each cable with a double wrap of glass fiber reinforced electrical tape, and one TC every 

12” taped to the top outside surface of each conduit with a short piece of glass cloth 

electrical tape, plus several TCs inside the junction boxes. 

Hose Stream: Passed. 

Furnace: ~11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The conduits contained a ~1/3 mix of power, control, and instrument cables 

with total fill area 43.4% of the available area inside the conduits. 

Table D-65. TU Electric Thermo-Lag Test 10-2 

Raceway Type Barrier Protection 

Cable 

Fill 

Max. Temp 

Rise ∆T 

°C (°F)1 Rating 

Front 3” Steel Conduit 1⁄2” nom. TL-330-1 43.4% 511 (951)1 60 min.2

Rear 3” Steel Conduit 1⁄2” nom. TL-330-1 43.4% 818 (1504)1 60 min.2

Horiz. J-Box 1⁄2” nom. TL-330-1 N/A 147 (297) 60 min. 

Vert. J-Box 1⁄2” nom. TL-330-1 N/A 129 (265) 60 min. 

1 The max. ∆T values shown in the table for the conduits are from thermocouples on the outside 

of the steel conduits, between the steel surface and the Thermo-Lag fire barrier material. The 

laboratory personal attributed the “excessively high temperatures” measured outside the steel 

conduits were due to “electro-chemical reactions caused by saturation of the fiberglass 

thermocouple insulation grading by condensate accumulated on the conduit steel.” 2 All thermocouples on the electric cables inside the conduits showed ∆Ts below the acceptance 

criteria of 250°F maximum average temperature increase and 325°F maximum single point 
D-54 

increase. The testing laboratory based the stated rating on those values (i.e., the applicable 

60 min. criteria were met based on cable temperature rises within the conduit). This rating is 

based on site-specific acceptance criteria accepted by the NRC in its October 29, 1992 letter. 

D.3.3.5 TU Electric Report No. 12340-94367e, Scheme 11-1 (January 1993) 

ERFBS: This 1 hr. test evaluated an assembly consisting of a 24” cable tray with air 

drops into the tray from 5”, 3”, 2”, and 1” conduits. The fire barriers protecting 

these trays and conduits were constructed using Thermo-Lag 330-1 flat and VRibbed panels that were 1⁄2“ nominal thickness with factory-applied 350 

Topcoat, Thermo-Lag 330-660 Flexi-Blanket sheets that were 3/8” nominal 

thickness, 330-69 stress skin sheets, 330-660 Subliming Trowel Grade 

material, and 330-1 Trowel Grade subliming compound. Conduits were 

covered with Thermo-Lag 330-1 Pre-Shaped Conduit Sections nominally 1⁄2” 

thick. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 8 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 72°F Desired Rating: 1 hr. 

Thermocouples: One TC every 6” on one of the power cables, on one of the control 

cables, and on one of the instrument cables from each of the conduits that led into the 

tray (on those cables both through the conduits and in the tray) taped to the top surface 

of each cable with a double wrap of glass fiber reinforced electrical tape, and one TC 

every 12” screwed to the tray rails. In addition, two TCs were screwed to each of the 

four conduit protrusions from the tray (i.e., on the junction between each conduit and the 

tray). 

Hose Stream: Passed. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The tray and conduits contained a ~1/3 mix of power, control, and 

instrument cables with total fill area as shown in the table below. 

Table D-66. TU Electric Thermo-Lag Test 11-1 

Raceway Type Barrier Protection 

Cable 

Fill % 

Max. Temp 

Rise ∆T °C (°F) Rating 

1” steel conduit air 

drop 

1⁄2” nom. TL-330-1 36.6 111 (232) 60 min.1

2” steel conduit air 

drop 

1⁄2” nom. TL-330-1 56.1 97 (207) 60 min. 1

3” steel conduit air 

drop 

1⁄2” nom. TL-330-1 52.8 98 (209) 60 min. 1

5” steel conduit air 

drop 

1⁄2” nom. TL-330-1 29.6 104 (219) 60 min. 1

24” steel cable tray 1⁄2” nom. TL-330-1 varied 109 (229) 60 min. 1

1

 This rating is based on site-specific acceptance criteria accepted by the NRC in its October 29, 1992 

letter.
D-55 

D.3.3.6 TU Electric Report No. 12340-95766, Scheme 11-2 (August 1993)

ERFBS: This 1 hr. test evaluated an assembly consisting of a 24” cable tray with air 

drops into the tray from a 2” and a 1-1⁄2” conduit. The fire barriers protecting 

these trays and conduits were constructed using Thermo-Lag 330-1 flat and VRibbed panels that were 1⁄2“ nominal thickness with factory-applied 350 

Topcoat, Thermo-Lag 330-660 Flexi-Blanket sheets that were 1⁄4” nominal 

thickness, 330-69 stress skin sheets, 330-660 Subliming Trowel Grade 

material, and 330-1 Trowel Grade subliming compound. Conduits were 

protected with Thermo-Lag 330-1 Pre-Shaped Conduit Sections nominally 1⁄2” 

thick. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 11 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 92°F Desired Rating: 1 hr. 

Thermocouples: One TC every 6” on one of the power cables, on one of the control 

cables, and on one of the instrument cables within the tray, taped to the top surface of 

each cable with a double wrap of glass fiber reinforced electrical tape, and one TC every 

12” screwed to the tray rails. Within the conduits, the TCs were fastened every 6” to a 

#8 bare copper wire that was loosely wrapped around the cables to be monitored that 

were pulled into each of the conduits that led into the tray. In addition, two TCs were 

screwed to both of the conduit protrusions from the tray (i.e., on the junctions between 

each conduit and the tray). 

Hose Stream: Passed. 

Furnace: ~11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The conduits contained a ~1/3 mix of power, control, and instrument cables 

with total fill area as shown in the table below. 

Table D-67. TU Electric Thermo-Lag Test 11-2 

Raceway Type Barrier Protection 

Cable Fill 

% 

Max. Temp 

Rise ∆T °C (°F) Rating 

1-1⁄2” steel conduit air drop 1⁄2” nom. TL-330-1 49.5 113 (235) 60 min. 

2” steel conduit air drop 1⁄2” nom. TL-330-1 43.5 175 (347) 60 min.1

24” steel cable tray 1⁄2” nom. TL-330-1 ~15 103 (217) 60 min. 

1 The single point ∆T parameter was exceeded on the power cable in the 2” air drop bundle at the 

59-minute mark. However, the test laboratory and the licensee based the 60 minute rating of the 

tested Thermo-Lag ERFBS configurations on the site-specific acceptance criteria accepted by 

the NRC in its October 29, 1992 letter. 
D-56 

D.3.3.7 TU Electric Report No. 12340-95767, Scheme 11-4 (October 1993) 

ERFBS: This 1 hr. test evaluated an assembly containing a box design air drop between 

a bank of cast-in-concrete conduit stubs and two nested 24’ wide cable trays 

clad with nominal 1⁄2” Thermo-Lag 330-1 with various upgrades. The nested 

trays were the typical elongated “U” shape, with the outside/lower tray deeper 

and wider than the inside/upper tray. The parts of the trays that formed the 

bottom parts of the nested “Us” were horizontal, with the concrete stubs 

perpendicular to the trays (also horizontal). A single fire barrier enclosure 

included both trays, and butted up against the concrete structure in which the 

stubs were embedded. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 11 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 91°F Desired Rating: 1 hr. 

Thermocouples: One TC every 6” on one of the power cables, on one of the control 

cables, and on one of the instrument cables within the tray, taped to the top surface of 

each cable with a double wrap of glass fiber reinforced electrical tape. Also, to monitor 

temperatures in the air drop area, bare #8 AWG stranded copper wires instrumented 

with TCs were wrapped loosely around the cables in the volume where electric cables 

were looped from the trays out of the furnace and back (see “Cable Type” below). 

Hose Stream: Failed. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The trays contained a ~1/3 mix of power, control, and instrument cables 

with total fill area as shown in the table below. In each of the two trays, two groups of 

cables (each group consisting of one power, one control, and one instrumentation cable) 

were looped out of the tray, out of the furnace thru one of the conduit stubs, back into 

the furnace thru an adjacent conduit stub, and back into the tray. In the lower tray, the 

looped cable groups exited and entered the tray over its side rail. In the upper tray, the 

cable groups exited and entered the tray between the rungs in the bottom of the tray. 

Table D-68. TU Electric Thermo-Lag Test 11-4 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

Outer cable tray 1⁄2” nom. TL-330-1 16.5% 118 (244) 60 min. 

Inner cable tray 1⁄2” nom. TL-330-1 16.5% 105 (221) 60 min. 

Box design air drop volume 1⁄2” nom. TL-330-1 variable 91 (196) 60 min.1

1

 A through opening in the air drop box design portion of the ERFBS occurred during the hose stream 

test. However the test laboratory and the licensee based the 60 minute rating of the tested Thermo-Lag 

ERFBS configuration on the site-specific acceptance criteria accepted by the NRC in its letter dated 

October 29, 1992.
D-57 

D.3.3.8 TU Electric Report No. 12340-95768, Scheme 11-5 (August 1993) 

ERFBS: This 1 hr. test evaluated three full scale 24” wide steel trays that vertically 

penetrated the furnace roof, descended into the furnace to a radial bend, ran 

horizontally three feet below the furnace roof, and exited the furnace thru its 

front wall about six feet (measured horizontally) from their entrance location. 

The fire barriers protecting these trays were constructed using Thermo-Lag 

330-1 flat and V-Ribbed panels that were 1⁄2“ nominal thickness with factoryapplied 350 Topcoat, 330-69 stress skin sheets, and 330-1 Trowel Grade 

subliming compound. Various upgrade techniques were used in constructing 

the three trays. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 11 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 92°F Desired Rating: 1 hr. 

Thermocouples: Each of the three trays had one TC every 6” on one of the power 

cables, one of the control cables, and one of the instrument cables taped to the top 

surface of the cable with a double wrap of glass fiber reinforced electrical tape, plus one 

TC every 12” along both side rails clamped under a screw head. 

Hose Stream: Right and center trays Passed, left tray Failed. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The trays contained a ~1/3 mix of power, control, and instrument cables 

with total fill area as shown in the table below. 

Table D-69. TU Electric Thermo-Lag Test 11-5 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

Right Cable Tray 1⁄2” nom. TL-330-1 16.5% 132 (270)1 60 min.2

Center Cable Tray 1⁄2” nom. TL-330-1 16.5% 191 (376) Failed 

Left Cable Tray 1⁄2” nom. TL-330-1 16.5% 236 (457) Failed 

1 Below the maximum single point temperature rise criterion of 325°F. The maximum average 

temperature rise in this tray was 210°F, below the 250°F acceptance criterion 2

 The test laboratory and licensee based the 60 minute rating of the tested Thermo-Lag ERFBS 

configuration on the site-specific acceptance criteria accepted by the NRC in its letter dated 

October 29, 1992. 

D.3.3.9 TU Electric Report No. 12340-94367i, Scheme 12-1 (December 1992) 

ERFBS: This 1 hr. test evaluated a 30” wide steel tray that vertically penetrated the 

furnace roof, descended to a radial bend that bent it to a horizontal direction 

three feet below the roof, proceeded four feet in a horizontal section, then bent 

to a vertically ascending section that penetrated the furnace roof ~8 feet 

horizontally from the first penetration. The fire barrier protecting this tray was 

constructed using Thermo-Lag 330-1 flat and V-Ribbed panels that were 1⁄2“ 

nominal thickness with factory-applied 350 Topcoat, 330-69 stress skin sheets, 

and 330-1 Trowel Grade subliming compound. Various upgrade techniques 

were used in constructing the tray. 
D-58 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 8 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 71°F Desired Rating: 1 hr. 

Thermocouples: The tray had one TC every 6” on one of its power cables, one of its 

control cables, and one of its instrument cables taped to the top surface of the cable with 

a double wrap of glass fiber reinforced electrical tape, plus one TC every 12” along both 

side rails clamped under a screw head. 

Hose Stream: Passed. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The tray contained a ~1/3 mix of power, control, and instrument cables with 

total fill area as shown in the table below. 

Table D-70. TU Electric Thermo-Lag Test 12-1 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

30” steel cable tray 1⁄2” nom. TL-330-1 17.1% 144 (292)1 60 min.2

1 This is below the 325°F single point maximum temperature rise criterion. The maximum average 

temperature rise was 201°F, which is below the 250°F acceptance criterion. 2

 The test laboratory and licensee based the 60 minute rating of the tested Thermo-Lag ERFBS 

configuration on the site-specific acceptance criteria accepted by the NRC in its letter dated October 29, 

1992.

D.3.3.10 TU Electric Report No. 12340-94367h, Scheme 12-2 (December 1992) 

ERFBS: This 1 hr. test evaluated a 24” wide steel tray that vertically penetrated the 

furnace roof, descended to a radial bend that bent it to a horizontal direction 

three feet below the roof, proceeded in a horizontal section to a squared bend, 

then vertically ascended through the furnace roof ~8-1⁄2 feet (measured 

horizontally) from the first penetration. In the middle portion of the horizontal 

section, a Tee assembly was installed that could allow connection of a second 

horizontal 24” tray perpendicular to the first tray (such a tray was not actually 

installed – the Tee fitting ended in a firestop). The fire barrier protecting this 

tray and Tee was constructed using Thermo-Lag 330-1 flat and V-Ribbed 

panels that were 1⁄2“ nominal thickness with factory-applied 350 Topcoat, 330-

69 stress skin sheets, and 330-1 Trowel Grade subliming compound. Various 

upgrade techniques were used in constructing the tray. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 8 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 69°F Desired Rating: 1 hr. 

Thermocouples: The tray had one TC every 6” on one of its power cables, one of its 

control cables, and one of its instrument cables taped to the top surface of the cable with 

a double wrap of glass fiber reinforced electrical tape, plus one TC every 12” along both 

side rails clamped under a screw head. 

Hose Stream: Failed. 

Furnace: 11’ x 6’ x 80” 
D-59 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The tray contained a ~1/3 mix of power, control, and instrument cables with 

total fill area as shown in the table below. In the area of the Tee section, the cables 

were looped toward the mouth of the Tee, producing a higher cable loading. 

Table D-71. TU Electric Thermo-Lag Test 12-2 

Raceway Type Barrier Protection 

Cable 

Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

24” steel cable tray 1⁄2” nom. TL-330-1 16.6% 140 (284)1 60 min.2

1 This is below the 325°F single point maximum temperature rise criterion. The maximum 

average temperature rise was 213°F, which is below the 250°F acceptance criterion. 2

 Although no burn through of the ERFBS occurred, a barrier opening occurred during the hose 

stream test where the bottom panel on the Tee section interfaced with the fire stop. However, 

the testing laboratory and licensee based the 60 minute rating of the tested Thermo-Lag 

ERFBS configuration on the site-specific acceptance criteria accepted by the NRC in its letter 

dated October 29, 1992. 

D.3.3.11 TU Electric Report No. 12340-94367l, Scheme 13-1 (December 1992) 

ERFBS: This 1 hr. test evaluated a 12” wide steel tray that vertically penetrated the 

furnace roof, descended to a radial bend that bent it to a horizontal direction 

three feet below the roof, proceeded in a horizontal section to another radial 

bend, then vertically ascended through the furnace roof ~8-1⁄2 feet (measured 

horizontally) from the first penetration. The fire barrier protecting this tray was 

constructed using Thermo-Lag 330-1 flat and V-Ribbed panels that were 1⁄2“ 

nominal thickness with factory-applied 350 Topcoat, 330-69 stress skin sheets, 

and 330-1 Trowel Grade subliming compound. Various upgrade techniques 

were used in constructing the tray. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 8 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 69°F Desired Rating: 1 hr. 

Thermocouples: The tray had one TC every 6” on one of its power cables, one of its 

control cables, and one of its instrument cables taped to the top surface of the cable with 

a double wrap of glass fiber reinforced electrical tape, plus one TC every 12” along both 

side rails clamped under a screw head. 

Hose Stream: Passed. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The tray contained a ~1/3 mix of power, control, and instrument cables with 

total fill area as shown in the table below. 

 
D-60 

Table D-72. TU Electric Thermo-Lag Test 13-1 

Raceway Type Barrier Protection 

Cable 

Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

12” steel cable tray 1⁄2” nom. TL-330-1 14.7% 127 (261)1 60 min.2

1 This is below the 325°F single point maximum temperature rise criterion. The maximum average 

temperature rise was 209°F, which is below the 250°F acceptance criterion. 2

 The testing laboratory and licensee based the 60 minute rating of the tested Thermo-Lag ERFBS 

configuration on the site-specific acceptance criteria accepted by the NRC in its letter dated 

October 29, 1992. 

D.3.3.12 TU Electric Report No. 12340-95769, Scheme 13-2 (August 1993) 

ERFBS: This 1 hr. test evaluated a 12” wide steel tray and a separate 2” conduit that 

both vertically penetrated the furnace roof, descended to radial bends that bent 

them to horizontal directions three feet below the roof, proceeded in horizontal 

sections to another pair of radial bends, then vertically ascended through the 

furnace roof ~8-1⁄2 feet (measured horizontally) from the first penetrations. The 

separate fire barriers protecting the tray and conduit were constructed using 

Thermo-Lag 330-1 flat and V-Ribbed panels that were 1⁄2“ nominal thickness 

with factory-applied 350 Topcoat, 330-69 stress skin sheets, 330-1 Trowel 

Grade subliming compound, and Thermo-Lag 330-1 Pre-Shaped conduit 

sections with 1⁄2“ nominal thickness. Various upgrade techniques were used in 

constructing the separate tray and conduit barriers. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 11 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 92°F Desired Rating: 1 hr. 

Thermocouples: The tray and the conduit each had one TC every 6” on one of their 

power cables, one of their control cables, and one of their instrument cables taped to the 

top surface of the cable with a double wrap of glass fiber reinforced electrical tape. In 

addition, the tray had one TC every 12” along both side rails clamped under a screw 

head, and the conduit had one TC every 12” along its top outside surface, held in 

position by short pieces of Glass Cloth Electrical tape. 

Hose Stream: Failed. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The tray and conduit each contained ~1/3 mixes of power, control, and 

instrument cables with total fill areas shown in the table below. 

Table D-73. TU Electric Thermo-Lag Test 13-2 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp 

Rise °C (°F)1 Rating 

12” Cable Tray 1⁄2” nom. TL-330-1 14.7% 179 (355) Failed2

2” Conduit 1⁄2” nom. TL-330-1 43.5% 234 (454) Failed2

1 These temperature rises are above the 325°F single point maximum temperature 

rise criterion, therefore both the tray and the conduit failed to achieve the 

desired 60 minute qualification. 2

 Minor areas of burn through were observed on the two assemblies prior to hose 
D-61 

stream testing. The licensee does not credit the results of this fire test as part of 

the Thermo-Lag ERFBS qualification basis at CPSES. 

D.3.3.13 TU Electric Report No. 12340-102571, Scheme 13-3 (February 1999) 

ERFBS: This 1 hr. test evaluated two full-scale 2” steel conduit assemblies (A & B), two 

full-scale 12” wide steel ladder back cable tray assemblies (C & D), and a 12” 

wide steel ladder back cable tray segment (E). Each conduit assembly 

penetrated the furnace roof, descended into the furnace to a 90° condulet 

fitting, ran horizontally three feet below the furnace roof, and exited the furnace 

through its front wall about six feet (measured horizontally) from their entrance 

location. Similarly, each full-scale cable tray assembly penetrated the furnace 

roof, descended into the furnace to 90° radial bend fittings, ran horizontally 

three feet below the furnace roof, and exited the furnace through its front wall 

about six feet (measured horizontally) from their entrance location. The 12” 

cable tray segment simply extended vertically downward into the furnace for a 

three foot distance. The fire barriers protecting the conduits and cable trays 

were constructed using Thermo-Lag 330-1 flat and v-rib panels and preshaped conduit half round sections that were 1⁄2” nominal thickness with 

Thermo-Lag 331 topcoat, 330-69 stress skin sheets, and 330-1 trowel grade 

subliming compound. The joints on the condulet fitting enclosure for each 

conduit were upgraded with standard stress skin and trowel grade 

reinforcement. The overall external surface of Conduit A received an additional 

1⁄4” thickness of trowel grade material, while Conduit B did not. Similarly, the 

bottom and side rail surfaces of Cable Tray C received an additional 1⁄4” thick 

trowel grade build-up, while Cable Tray D did not. Finally, the bottom of the 

ERFBS installed on Tray E was sealed with a 12” deep silicone foam fire stop. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 1 (October 26, 1998) 

Test Slab: 13’ x 8’ 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 74°F Desired Rating: 1 hr. 

Thermocouples: The conduits each had one TC every 6" along the outside surface 

clamped under a screw head, and one TC every 6" on the single 5/C 12 AWG cable 

routed inside the conduits. The cable trays each had one TC every 6" on both side rails 

clamped under a screw head. The cable trays also had one TC every 6" on one power, 

control, and instrument cables. 

The TCs on cables were secured to the top of the cables with a double wrap of glass 

fiber reinforced electrical tape. Additionally, the trays each had one TC installed every 6" 

on a single #8 AWG bare copper conductor routed along the longitudinal centerline of 

the trays on top of the enclosed cables. The fire stop assembly had three TCs on its 

unexposed: one located 1" from a side rail, one located 1" from a penetrating cable, one 

located in the fire stop center. 

Hose Stream: Conduit B – Failed; Conduit A, Trays C, D, and E Passed 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on proves located throughout the furnace 

Cable Type: Conduits A & B each contained a single control cable. Trays C & D each 

contained 19 instrumentation cables, and Tray E contained 40 instrumentation cables 

that penetrated through the fire stop. 
D-62 

Table D-74. TU Electric Thermo-Lag Test 13-3 

Raceway Type Barrier Protection Cable Fill 

Max. Temp 

Rise ∆T °C (°F) Rating2

2” Conduit A 5/8” nom. TL-330-1 8.6% 162 (323) 60 min. 

2” Conduit B 1/2" nom. TL-330-1 8.6% 729 (1344)1 Failed 

12” Cable Tray C 5/8” nom. TL-330-1 5.5% 126 (258)1

 59 min. 

12” Cable Tray D 1/2" nom. TL-330-1 4.6% 192 (378)1

 Failed 

12” Cable Tray E 1/2" nom. TL-330-1 11.4% 124 (256) 60 min. 

1

 These temperature rises are above the 325°F single point maximum temperature rise criterion, therefore 

Conduit B and Cable Trays C & D failed to achieve the desired 60 minute qualification. 

2

 For Cable Tray-C, the side rail and bare #8 bare conductor ∆Ts exceeded allowable limits at 59 minutes. 

However, the following acceptance parameters were met: 1) no fire barrier burn through after fire and 

hose stream test; 2) no visible cable damage; 3) the post-fire cable insulation resistance tests were well 

within allowable limits. The licensee credited the results of this fire test for Conduit A, Cable Tray C, and 

Cable Tray E (fire stop) as part of the Thermo-Lag ERFBS qualification basis at CPSES. 

D.3.3.14 TU Electric Report No. 12340-94367m, Scheme 14-1 (December 1992) 

ERFBS: This 1 hr. test evaluated a 30” wide steel tray that vertically penetrated the 

furnace roof, descended to a radial bend that bent it to a horizontal direction 

three feet below the roof, proceeded in a horizontal section to a squared bend, 

then vertically ascended through the furnace roof ~8 feet (measured 

horizontally) from the first penetration. In the middle portion of the horizontal 

section, a Tee assembly was installed that could allow connection of a second 

horizontal 30” tray perpendicular to the first tray (such a tray was not actually 

installed – the Tee fitting ended in a firestop). The fire barrier protecting this 

tray and Tee was constructed using Thermo-Lag 330-1 flat and V-Ribbed 

panels that were 1⁄2“ nominal thickness with factory-applied 350 Topcoat, 330-

69 stress skin sheets, and 330-1 Trowel Grade subliming compound. Various 

upgrade techniques were used in constructing the tray. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 8 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 70°F Desired Rating: 1 hr. 

Thermocouples: The tray had one TC every 6” on one of its power cables, one of its 

control cables, and one of its instrument cables taped to the top surface of the cable with 

a double wrap of glass fiber reinforced electrical tape, plus one TC every 12” along both 

side rails clamped under a screw head. 

Hose Stream: Passed. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The tray contained a ~1/3 mix of power, control, and instrument cables with 

total fill area as shown in the table below. 

 
D-63 

Table D-75. TU Electric Thermo-Lag Test 14-1 

Raceway Type Barrier Protection Cable Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

30” steel cable tray 1⁄2” nom. TL-330-1 17.3% 166 (331)1 60 min.2

1 A single thermocouple (TC 91) located on the front cable tray side rail nearest the fire stop 

assembly exceeded the allowable 325°F single point ∆T criteria by 6°F during the last 1 minute 

of the fire endurance portion of the test. The test laboratory and licensee based the 60 minute 

rating of the tested Thermo-Lag ERFBS configuration on the site-specific acceptance criteria 

accepted by the NRC in its letter dated October 29, 1992. 

D.3.3.15 TU Electric Report No. 12340-95100a, Scheme 15-1 (March 1993) 

ERFBS: This 1 hr. test evaluated a 36” wide steel tray that vertically penetrated the 

furnace roof, descended to a radial bend that bent it to a horizontal direction 

three feet below the roof, proceeded four feet in a horizontal section, then bent 

to a vertically ascending section that penetrated the furnace roof ~8 feet 

horizontally from the first penetration. The fire barrier protecting this tray was 

constructed using Thermo-Lag 330-1 flat and V-Ribbed panels that were 1⁄2“ 

nominal thickness with factory-applied 350 Topcoat, 330-69 stress skin sheets, 

and 330-1 Trowel Grade subliming compound. Various upgrade techniques 

were used in constructing the tray. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 9 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 68°F Desired Rating: 1 hr. 

Thermocouples: The tray had one TC every 6” on one of its power cables, one of its 

control cables, and one of its instrument cables taped to the top surface of the cable with 

a double wrap of glass fiber reinforced electrical tape, plus one TC every 12” along both 

side rails clamped under a screw head. 

Hose Stream: Passed. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The tray contained a ~1/3 mix of power, control, and instrument cables with 

total fill area as shown in the table below. 

 
D-64 

Table D-76. TU Electric Thermo-Lag Test 15-1 

Raceway Type Barrier Protection Cable Fill 

Max. Temp 

Rise ∆T °C (°F) Rating 

36” steel cable tray 1⁄2” nom. TL-330-1 17.4% 107 (224)1 60 min.2

1 This temperature rise is below the 325°F single point maximum temperature rise criterion, 

therefore the tray achieved the desired 60 minute qualification. 2

 The testing laboratory and licensee based the 60 minute rating of the tested Thermo-Lag 

ERFBS configuration on the site-specific acceptance criteria accepted by the NRC in its letter 

dated October 29, 1992. 

D.3.3.16 TU Electric Report No. 12340-95770, Scheme 15-2 (October 1993) 

ERFBS: This 1 hr. test evaluated two air drops with W-008 power cables, each wrapped 

with two layers of Thermo-Lag 330-660 Flexi-blanket (each layer ~1⁄4“ thick), 

that were laid in the same 36” wide x 3” deep (non-ERFBS wrapped) cable 

tray. The outer Flexi-blanket layer of each ERFBS was pre-caulked with a 

layer of Thermo-Lag 330-660 Trowel Grade material, and both layers were 

stainless-steel banded every 6”. Also placed in the tray (for cable fill purposes) 

were three W-020 cables which were neither Thermo-Lag protected nor 

temperature monitored. 

Test Procedure: Texas Utilities Electric 

TEST PLAN, Rev. 11 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 92°F Desired Rating: 1 hr. 

Thermocouples: One TC every 6” was taped to the top surface of each W-008 cable with 

a double wrap of glass fiber reinforced electrical tape. Also, a bare #8 AWG stranded 

copper wire (instrumented with TCs every 6”) was placed in both ERFBS-protected (air 

drop) areas with its W-008 cable. 

Hose Stream: Passed. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: The tray contained the two W-008 power cables each separately protected 

within the previously described ERFBS, and three unprotected W-020 cables wrapped 

together in Siltemp (a high temperature cloth). The fraction of the unprotected 36” x 3” 

cable tray’s area filled with those cables was 4.5%. 

 
D-65 

Table D-77. TU Electric Thermo-Lag Test 15-2 

Raceway Type Barrier Protection 

Cable 

Fill2

Max. Temp Rise 

∆T °C (°F)1 Rating 

Front W-008 ERFBS 1⁄2” nom. Thermo-Lag 330-660 

Flexi-blanket 

2.25% 329 (625) 60 min.3

Rear W-008 ERFBS 1⁄2” nom. Thermo-Lag 330-660 

Flexi-blanket 

2.25% 257 (494) 60 min.3

1 The ∆T values listed above were recorded on the bare #8 AWG stranded wire 

that was positioned inside the Thermo-Lag ERFBS protection each W-008 750 

kCM cables. 2 Fraction of cable tray filled by the W-008 cable; total fraction of cable tray filled = 

4.5% 

3

 Although the ∆T criterion was exceeded on the bare #8 AWG conductor that was 

positioned inside the ERFBS protecting each W-008 cable, the test laboratory 

and licensee based the 60 minute rating of the tested Thermo-Lag ERFBS 

configuration on the site-specific acceptance criteria accepted by the NRC in its 

letter dated October 29, 1992. However, to ensure complete protection of large 

power cables that are wrapped in exposed cable trays, the licensee upgraded 

the installed configurations by adding a third layer of Thermo-Lag 330-660 
D-66 

D.3.4 Tennessee Valley Authority Tests for Watts Bar Nuclear Power Plant 

D.3.4.1 TVA Project No. 11210-94554c, Test 6.1.1 (January 1993) 

ERFBS: This 1 hr. test evaluated two 5” diameter conduit configurations, two 1” diameter 

conduit configurations, and two 2” diameter conduit air drop configurations. 

The conduit configurations were the elongated “U” type previously described, 

each penetrating the furnace roof in two locations about 6 feet apart and 

descending about 3 feet down into the furnace. The air drops were each two 

conduits penetrating the furnace roof in two locations about 3 feet apart, one 

terminating about 7” below the roof, and the other terminating in a radial bend 

just below the furnace roof, with only a bare, TC-instrumented wire between 

the two terminations (the “air drop”). The ERFBS were constructed using 

Thermo-Lag (TL) 330-1 V-ribbed panels ~5/8” thick with stress skin 

monolithically adhered to one face, TL 330-1 Pre-Formed Conduit Sections 

~5/8” thick, and TL 330-1 Subliming Trowel Grade material. Construction 

techniques and upgrades were used similar to those previously described. 

Test Procedure: TVA TEST PLAN RD 

139599 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 65°F Desired Rating: 1 hr. 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs and pulled through each conduit configuration. The TCs were spaced 6” apart on 

the wires in the 1” and 2” conduits, and every 12” on the wires in the 5” conduits. Also, 

TCs were placed every 12” along the bottom surface of each conduit, held in position by 

clamping under the head of a #8 x 32 x 1⁄4” long stainless steel screw in a drilled and 

threaded hole at each location. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: No electric cables were installed in the conduits and air drops. 

Table D-78. TVA Thermo-Lag Test 6.1.1 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp Rise ∆T 

°C (°F) Rating 

5” Conduit (#1) ~5/8” TL 330-1 None 207 (404)1 60 min.1

1” Conduit (#2) ~5/8” TL 330-1 None 866 (1591)2 Failed 

5” Conduit (#3) ~5/8” TL 330-1 None 137 (278)2 60 min. 

1” Conduit (#4) ~5/8” TL 330-1 None 675 (1247)2 Failed 

2” Air Drop (#5) ~5/8” TL 330-1 None 414 (777)2 Failed 

2” Air Drop (#6) ~5/8” TL 330-1 None 206 (402)2 Failed 

1 This temperature rise was from a TC located on a bare #8 wire inside a raceway 

configuration where the licensee argued it was subjected to moisture saturation, 

which caused its inaccurate, artificially high reading. All measurements on conduit 

steel were below the single point maximum acceptable 325°F, and all steel 

conduits maximum average measurements were below the acceptable 250°F.
D-67 

2 These temperature rises were recorded by TCs on the conduit steel, and were 

considered to be accurate. 

D.3.4.2 TVA Project No. 11210-94554a, Test 6.1.2 (January 1993) 

ERFBS: This 1 hr. test was a repeat of Test 6.1.1 with certain upgrades, including the 

addition of a second layer of TL. One each of the 1” and 5” conduits, and one 

of the 2” air drops, had a second ~3/8” thick layer of TL added using additional 

V-ribbed panels and preformed conduit sections. A thin coating of TL-330-1 

Trowel Grade material was applied over the additional layer, with stainless 

steel (stainless steel) tie wires every 4 to 6 inches on top of that. The second 

layer applied to the remaining three configurations consisted of their being 

wrapped with stainless steel knitted wire mesh held in place with stainless steel 

tie wires, then covered with an ~3/8” thick layer of TL-330-1 Trowel Grade 

material, with no tie wire or banding material applied over the trowel material. 

Test Procedure: TVA TEST PLAN RD 

139599 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 61°F Desired Rating: 1 hr. 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs and pulled through each conduit configuration. The TCs were spaced 6” apart on 

the wires in all test specimens. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: No electric cables were installed in the conduits and air drops. 

Table D-79. TVA Thermo-Lag Test 6.1.2 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp Rise ∆T 

°C (°F) Rating 

5” Conduit (#1) ~1” TL 330-1 None 66 (150) 60 min. 

1” Conduit (#2) ~1” TL 330-1 None 96 (204) 60 min. 

5” Conduit (#3) ~1” TL 330-1 None 58 (136) 60 min. 

1” Conduit (#4) ~1” TL 330-1 None 73 (164) 60 min. 

2” Air Drop (#5) ~1” TL 330-1 None 66 (150) 60 min. 

2” Air Drop (#6) ~1” TL 330-1 None 67 (152) 60 min. 

D.3.4.3 TVA Project No. 11210-94943a, Test 6.1.3 (April 1993) 

ERFBS: This 1 hr. test evaluated four conduit configurations (1 in., 2 in., 3 in., and 4 in. 

diameter). They were fire-protected with a nominal thickness of 3/8 in. or 5/8 

in. Thermo-Lag 330-1 with various upgrades. All were configured as the 

elongated “Us” previously described, each penetrating the furnace roof in two 

locations 9 feet apart and descending 3 feet down into the furnace. The 
D-68 

ERFBS were constructed using Thermo-Lag (TL) 330-1 V-ribbed panels,~3/8” 

or ~5/8” thick, with stress skin monolithically adhered to one face, TL 330-1 PreFormed Conduit Section panels ~3/8” thick for the 3” and 2” conduits and ~5/8” 

thick for the 4” and 1” conduits, and TL 330-1 Subliming Trowel Grade material. 

Test Procedure: TVA TEST PLAN RD 

328886 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 76°F Desired Rating: 1 hr. 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs spaced 6” apart and pulled through each conduit configuration. Also, TCs were 

placed every 6” along the bottom surface of each conduit, held in position by clamping 

under the head of a #8 x 32 x 1⁄4” long stainless steel screw in a drilled and threaded 

hole at each location. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: No electric cables were installed in the conduits and air drops. 

Table D-80. TVA Thermo-Lag Test 6.1.3 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp Rise 

∆T °C (°F) Rating1

3” Conduit (#1) ~3/8” TL 330-1 None 72 (162) 60 min. 

2” Conduit (#2) ~5/8” TL 330-1 None 77 (170) 60 min. 

1” Conduit (#3) ~5/8” TL 330-1 None 80 (176) 60 min. 

4” Conduit (#4) ~5/8” TL 330-1 None 143 (289) 60 min. 

1 All maximum average temperature rises were less than the 250°F limit 

D.3.4.4 TVA Project No. 11210-94943b, Test 6.1.4 (April 1993) 

ERFBS: This 1 hr. test evaluated three conduit configurations (3 in. steel, 3 in. 

aluminum, and 1-1⁄2 in. steel) and two generic tube steel support members (2 

in. and 4 in.). They were fire-protected with a nominal thickness of 3/8 in. or 5/8

in. Thermo-Lag 330-1 with various upgrades. The conduits were configured as 

the elongated “Us” previously described, each penetrating the furnace roof in 

two locations 9 feet apart and descending 3 feet down into the furnace. The 

support members each penetrated the furnace roof and down into the furnace 

3 feet, at which point they made a sharp 90° bend and then extended 

horizontally 30”. The ERFBS were constructed using Thermo-Lag (TL) 330-1 

V-ribbed panels,~3/8” or ~5/8” thick, with stress skin monolithically adhered to 

one face, TL 330-1 Pre-Formed Conduit Section panels ~5/8” thick for the 3” 

conduits and ~3/8” thick for the 1-1⁄2 in. conduit, and TL 330-1 Subliming Trowel 

Grade material. 

Test Procedure: TVA TEST PLAN RD 

328886 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 75°F Desired Rating: 1 hr. 
D-69 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs spaced 6” apart and pulled through each conduit configuration. Also, TCs were 

placed every 6” along the bottom surface of each conduit, held in position by clamping 

under the head of a #8 x 32 x 1⁄4” long stainless steel screw in a drilled and threaded 

hole at each location. Thermocouples were similarly affixed to the tube steel supports – 

they were fastened to the top surface of the horizontal sections of the tube steel at 2” 

intervals starting 12” from the exposed ends. Thermocouples were also fastened at 6” 

intervals along the vertical sections of the steel tubes. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: No electric cables were installed in the conduits and air drops. 

Table D-81. TVA Thermo-Lag Test 6.1.4 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp. Rise ∆T 

°C (°F) Rating 

3” Conduit (#1) ~5/8” TL 330-1 None 167 (332) Failed 

1-1⁄2”Conduit (#2) ~5/8” TL 330-1 None 124 (255) 60 min.1

3” Conduit (#3) ~5/8” TL 330-1 None 188 (370) Failed 

1 All maximum average temperature rises were less than the 250°F limit 

The test results for the tubular steel members support the “18 in. rule,” which indicates that 

tubular steel support members should be ERFBS protected starting no less than 18 inches from 

the ERFBS-protected raceways they support. At that location in this test, the 4” support was 

clearly below the 325°F temperature rise limit, and the 2” support was ~2+ °F over that limit, a 

negligible amount given the repeatability of this test method. 

D.3.4.5 TVA Project No. 11210-94943d, Test 6.1.5 (May 1993) 

ERFBS: This 1 hr. test evaluated four steel conduit configurations (1 in., 2 in., 3 in., and 

5 in.), and five steel junction boxes of varying sizes. All junction boxes were 

NEMA 12 and were fastened directly to the underside of concrete slab furnace 

roof. All conduits were positioned as close to the concrete as was feasible and 

practical. The ERFBS were constructed using Thermo-Lag (TL) 330-1 Vribbed panels,~3/8” or ~5/8” thick, with stress skin monolithically adhered to one 

face, TL 330-1 Pre-Formed Conduit Section panels ~5/8” thick for the 5” 

conduits and the first layer of the 1” conduit, and ~3/8” thick for first and second 

layer of the 3” and 2” conduits and the overlay for the 1” conduit, and TL 330-1 

Subliming Trowel Grade material. 

Test Procedure: TVA TEST PLAN RD 

328886 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 73°F Desired Rating: 1 hr. 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs spaced 6” apart and pulled through each conduit configuration. Also, TCs were 

placed every 6” along the bottom surface of each conduit, held in position by clamping 

under the head of a #8 x 32 x 1⁄4” long stainless steel screw in a drilled and threaded 
D-70 

hole at each location. TCs were similarly affixed to the interior of the junction boxes, 

with at least on TC in each square foot of area on each face of the boxes (except for 

each box’s face on the concrete slab). 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace. 

Cable Type: No electric cables were installed in the conduits and air drops. 

Table D-82. TVA Thermo-Lag Test 6.1.5 

Raceway Type 

Barrier 

Protection1 Cable Fill 

Max. Temp Rise 

∆T °C (°F) Rating 

1” Conduit (#1) Thermo-Lag 330-1 None 66 (150) 60 min. 

3” Conduit (#2) Thermo-Lag 330-1 None 108 (226) 60 min. 

2” Conduit (#3) Thermo-Lag 330-1 None 77 (170) 60 min. 

5” Conduit (#4) Thermo-Lag 330-1 None 97 (207) 60 min. 

Junction B (#1) Thermo-Lag 330-1 None 57 (135) 60 min. 

Junction B (#2) Thermo-Lag 330-1 None 79 (175) 60 min. 

Junction B (#3) Thermo-Lag 330-1 None 88 (191) 60 min. 

Junction B (#4) Thermo-Lag 330-1 None 64 (147) 60 min. 

Junction B (#5) Thermo-Lag 330-1 None 105 (221) 60 min. 

1 Varied thicknesses and materials – too detailed for inclusion in this summary 

D.3.4.6 TVA Project No. 11210-94943e, Test 6.1.6 (May 1993) 

ERFBS: This 1 hr. test evaluated three 4 in. steel conduit configurations and one large 

steel junction box (48 x 36 x 12 in.). The ERFBS were constructed using 

Thermo-Lag (TL) 330-1 V-ribbed panels,~3/8” or ~5/8” thick, with stress skin 

monolithically adhered to one face, TL 330-1 Pre-Formed Conduit Section 

panels ~5/8” thick, and TL 330-1 Subliming Trowel Grade material. 

Test Procedure: TVA TEST PLAN RD 

328886 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Ambient Temperature: 72°F Desired Rating: 1 hr. 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs spaced 6” apart and pulled through each conduit configuration. Also, TCs were 

placed every 6” along the bottom surface of each conduit, held in position by clamping 

under the head of a #8 x 32 x 1⁄4” long stainless steel screw in a drilled and threaded 

hole at each location. TCs were similarly affixed to the interior of the junction box, with 

at least on TC in each square foot of area on each face of the box. 

Hose Stream: A test was applied, but no details are given in available documentation. 

Furnace: 11’ x 6’ x 80” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace. 

Cable Type: Ten (10) thermocouples on probes located throughout the furnace. 

 
D-71 

Table D-83. TVA Thermo-Lag Test 6.1.6 

Raceway Type 

Barrier 

Protection1 Cable Fill 

Max. Temp Rise 

∆T °C (°F) Rating 

4” Conduit (#1) Thermo-Lag 330-1 None 121 (250) 60 min. 

4” Conduit (#2) Thermo-Lag 330-1 None 118 (244) 60 min. 

4” Conduit (#3) Thermo-Lag 330-1 None 130 (266) 60 min. 

Junction Box Thermo-Lag 330-1 None 57 (134) 60 min. 

1 Varied thicknesses and materials – too detailed for inclusion in this summary 

D.3.4.7 TVA Project No. 11960-97185, Test 6.1.7 (November 1994) 

ERFBS: This 1-hr. test evaluated three cable tray configurations (18 in. x 4 in., steel) 

and one conduit (3 in. steel). The test qualified installation of Thermo-Lag on 3 

cable trays with adjustable risers at 90o and a conduit with a radial bend. The 

raceways have a horizontal to vertical orientation. They were fire-protected 

with a nominal thickness of 5/8 in. Thermo-Lag 330-1 fire barrier material. Top 

panels of the cable trays had V-Ribs running parallel with the side rails. The 

vertical section of the conduit and vertical support members were covered with 

3M M20A fire wrap, overlapping the installed Thermo-Lag by at least 3 inches. 

Support connectors and voids in channels were filled with Thermo-Lag 330-1 

Trowel Grade/Putty. 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Desired Rating: 1 hr. 

Ambient Temperature: 83°F 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs spaced 6” apart and fastened to cable tray side rails and conduits by clamping 

under the head of a #8 x 32 x 1⁄4” long stainless steel screw. Thermocouples were 

placed in the following locations: one on top of the cable bundle in the left tray, one 

secured to the bottom of the tray rungs in the left tray, one on top of the cable bundle in 

the center tray, one secured to the bottom of the tray rungs in the center tray, one on top 

of the cable tray rungs in the right tray and one pulled through the conduit assembly. 

Hose Stream: The test platform was sprayed with water at a 40o hose angle at a 

pressure of 75 psi. The test setup was sprayed with a 75 gpm water flow rate from a 

distance of 5 feet for a minimum of 5 minutes. 

Furnace: 12’ x 7’ x 79” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: Left Tray – 289, 4C #16 AWG 600V (69.36 lbs. cable/linear foot) 

Center Cable Tray – 26, 4C #16 AWG 600V (6.24 lbs. cable/linear foot) 

Right Tray – 0% Cable Fill 

 
D-72 

Table D-84. TVA Thermo-Lag Test 6.1.7 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp. 

Rise ∆T °C (°F) Rating 

18” Left Cable Tray ~5/8” TL 330-1 289, 3C #16 AWG 67 (153) 60 min. 

18” Center Cable Tray ~5/8” TL 330-1 26, 4C #16AWG 118 (244) 60 min. 

18” Right Cable Tray ~5/8” TL 330-1 None 134 (274) 60 min. 

3” Conduit ~5/8” TL 330-1 None 87 (188) 60 min. 

The average initial temperature for all thermocouples at the start of the test was 90oF, allowing a 

maximum allowable individual thermocouple temperature of 415oF in accordance with ASTM 

E119-88. The cable tray configuration in this test procedure involving Thermo-Lag 330-1 met 

the 1-hour fire resistance rating. The test provided the effects of cable mass on the 

performance of an 45.72 cm (18 in) steel, ladder back cable tray, protected with a TA designed 

nominal 5/8 inch Thermo-Lag 330-1 barrier. The test proved that 1.33 lbs/foot of cable is 

required in order for the 18” cable tray ERFBS to be acceptable. 

D.3.4.8 TVA Project No. 11960-97186, Test 6.1.8 (September 1994) 

ERFBS: This 1-hr. test evaluated two cable tray configurations (18 in. x 4 in., steel) 

connected with a tray cross fitting. They were fire-protected with a nominal 

thickness of 5/8 inch Thermo-Lag 330-1 V-Rib Panel with exterior stress skin 

overlay. TVA provided a cross fitting with two 18 in. wide by 4 in. deep cable 

trays connected to a double cross. Two sections of 18 in. by 4 in. ladderback 

cable tray with 6 in. rung spacing were fitted to one side of the cross fitting. 

Overall tray and double cross dimensions were 144 in. by 72 in. The cable tray 

sections were held in place by a “trapeze” type hanger using 3 in. steel 

channels bolted and welded together 12 in. from the free ends of the tray 

sections. The cable trays had adjustable risers at 90o from horizontal to 

vertical and the 3” conduit had a radial bend. Support connectors and voids in 

channels were filled with Thermo-Lag 330-1 Trowel Grade/Putty. 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Desired Rating: 1 hr. 

Ambient Temperature: 90°F 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs spaced 6” apart and fastened to cable tray rails by clamping under the head of a #8 

x 32 x 1⁄4” long stainless steel screw. Thermocouples were placed in the following 

locations: one extended along the left 18 in. cable tray, on the surface of the tray rungs, 

and right to left, through the special tray fitting. One extended along the right 18 in. 

cable tray, on the surface of the tray rungs, and right to left, through the special tray 

fitting. One passed front to rear, through the left side of the special tray fitting, on the 

surface of the tray rungs, and one passed front to rear, through the right side of the 

special tray fitting, on the surface of the tray rungs. 

Hose Stream: The test platform was elevated to an elevation of 6 ft. and spun at 6-8 

revolutions per minute. The test setup was sprayed with a minimum 75 psi pressure at 

75 gpm from a distance of 5 feet for a 5 minute duration. The test deck was lowered 
D-73 

after 2 minutes of exposure to the hose stream to allow spray to reach the top of the test 

platform. The deck was raised after two additional minutes to spray the bottom again. 

Furnace: 12’ x 7’ x 79” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: No electric cables were installed in the cable trays. 

Table D-85. TVA Thermo-Lag Test 6.1.8 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp. Rise ∆T 

°C (°F) Rating 

Front Tray 18” x 4” ~5/8” TL 330-1 None 94 (202) 60 min. 

Rear Tray 18” x 4” ~5/8” TL 330-1 None 98 (208) 60 min. 

Cross Fitting 

72” x 72” x 4” 

~5/8” TL 330-1 None 82 (180) 60 min. 

All thermocouples located on the cable tray system met test criteria. The average initial 

temperature for all thermocouples at the start of the test was 90oF, allowing a maximum 

allowable individual thermocouple temperature of 415oF in accordance with ASTM E119-88. 

The “double cross” cable tray configuration in this test procedure involving Thermo-Lag 330-1 

met the 1-hour fire resistance rating. 

D.3.4.9 TVA Project No. 11960-97187, Test 6.1.9 (September 1994) 

ERFBS: This 1-hr. test evaluated three stacked cable trays (18 in. x 4 in., steel) clad with 

nominal 5/8 in. Thermo-Lag 330-1 panel with 1/2 in a common enclosure, one 

18 in. by 4 in. steel ladderback cable tray with a solid cover of nominal 5/8 in. 

Thermo-Lag 330-1 Rib Panels, one 5” air drop covered with a first layer of 5/8 

in. and a second layer of 3/8 in. Thermo-Lag 330-1, and one 1 in. air drop 

covered with a first layer of 5/8 in. and a second layer of 3/8 in. Thermo-Lag 

330-1. This test included a “U” shape for the 18 in. cable tray (vertical to 

horizontal to vertical), three nested 18 in. “U” shaped cable trays, and one 

multiple to single cable tray transition. 3M M20A fire material overlaps the 

Thermo-Lag applied on vertical supports by 6 in., and no collars are installed. 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Desired Rating: 1 hr. 

Ambient Temperature: 78°F 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs spaced 6” apart and fastened to cable tray side rails and air drop walls by clamping 

under the head of a #8 x 32 x 1⁄4” long stainless steel screw. Thermocouples were 

installed on tray rungs, centered between the tray rails, in each of the three stacked 

cable trays. Similar wires were also installed under the tray rungs, centered between 

the tray side rails, on the rear cable tray, and in each of the two air drops. 

Hose Stream: The test platform was sprayed with water at a 30o hose angle at a 

pressure of 75 psi while spinning at 6-8 revolutions per minute. The test setup was 

sprayed with a 75 gpm water flow rate from a distance of 5 feet for 5 minutes. 

Furnace: 12’ x 7’ x 79” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 
D-74 

Cable Type: 18” Cable tray with raised cover (#2) – 321, 4C #16 AWG 60 

5” Air drop (#3) – 44, 4C #16 AWG 60 

#1 and 4 did not have any installed electrical cables 

Table D-86. TVA Thermo-Lag Test 6.1.9 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp. 

Rise ∆T °C (°F) Rating 

3-Cable Trays 5/8” TL 330-1 None 129 (264) 60 min. 

1-Cable Tray 5/8” TL 330-1 321, 4C #16 AWG 92 (198) 60 min. 

5” Air Drop 5/8”, 3/8” TL 330-1 44, 4C # 16 AWG 48 (118) 60 min. 

1” Air Drop 5/8”, 3/8” TL 330-1 None 57 (134) 60 min. 

The three stacked cable trays, both in the individually wrapped and common enclosure 

configurations, and the covered rear tray and both air drops evaluated in this test procedure, 

clad with Thermo-Lag 330-1 material and various upgrades such as different thicknesses and 

3M materials as mentioned, met the requirements of the acceptance criterion for a fire 

resistance rating of one hour. 

D.3.4.10 TVA Project No. 11960-97257, Test 6.1.10 (November 1994) 

ERFBS: This 1-hr. test evaluated three different configurations: One small, 2-sided box 

with (2) 1 in. steel conduits protected with nominal 5/8 in. Thermo-Lag 330-1 

panels supported by a Unistrut frame. One inch conduits exited box and were 

wrapped individually with preformed Thermo-Lag 330-1 designs. The second 

configuration was a large 2-sided box with (8) 4 in. aluminum conduits 

protected with 5/8” nominal Thermo-Lag 330-1 Panels supported by a Unistrut 

frame. The conduits were also individually wrapped and exited both sides of 

the box. The third configuration consisted of 4 in. aluminum conduits wrapped 

individually with 5/8” Thermo-Lag 330-1 outside the two-sided box. Panels 

were reinforced with 3” wide panels and a 3” wide piece of stress skin and then 

covered with Thermo-Lag 330-1 Trowel Grade. 

Test Slab: 13’ x 8’ x 10 GA (Steel) with #7 

steel rebar and 10” steel I-beam supports 

Desired Rating: 1 hr. 

Ambient Temperature: 66°F 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs spaced 6” apart and fastened to conduits by clamping under the head of a #8 x 32 x 

1⁄4” long stainless steel screw. Thermocouples were installed in the interior of each of 

the installed conduits and to the surfaces of the cable tray supports and short cable tray 

sections. Those located in the support system were used to monitor the heat flow into a 

protected cable tray from an unprotected cable tray. 

Hose Stream: The test platform was sprayed with water at a 30o hose angle at a 

pressure of 75 psi while spinning at 6-8 revolutions per minute. The test setup was 

sprayed with a 75 gpm water flow rate from a distance of 5 feet for 5 minutes. 

Furnace: 12’ x 7’ x 79” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 
D-75 

Cable Type: Electric cables were not utilized in this test. 

Table D-87. TVA Thermo-Lag Test 6.1.10 

Raceway Type Barrier Protection Cable Fill 

Max. Temp. Rise 

∆T °C (°F) Rating 

Small Box with Conduits 5/8”, 3/8” TL 330-1 None 67 (153) 60 min. 

Large Box with Conduits 5/8” TL 330-1 None 47 (117) 60 min. 

4” Aluminum Conduits 5/8” TL 330-1 None 79 (175) 60 min. 

Each of the two-sided multiple conduit enclosures clad with Thermo-Lag 330-1 fire barrier and 

upgrades met the requirements of the acceptance criterion and qualify for a fire resistance 

rating of one hour. Testing also showed that the maximum temperature of the ambient 

temperature plus 250oF on the configuration’s support system was reached at a distance of 9 

inches away from unprotected cable tray. This distance is conservative since it does not 

consider the additional thermal mass of the protected cable tray assembly. 

D.3.4.11 TVA Project No. 11960-97258, Test 6.1.11 (October 1994) 

ERFBS: This 1-hr. test evaluated four different configurations: The first configuration 

was a group of (7) aluminum conduits ranging from 2-3 in., covered with a 3-

sided enclosure constructed using the Separate Piece Method and a single 

layer of 5/8 in. nominal Thermo-Lag 330-1 V-Rib Panels. A group of (2) 1 in. 

steel conduits were also tested and covered with a 3-sided enclosure 

constructed from a single layer of 5/8 in. Thermo-Lag 330-1 V-Rib Panels using 

the Score and Fold Method. The third test group was (3) 3 in. aluminum 

conduits with a 3-sided enclosure constructed using a single layer of ThermoLag 330-1 V-Rib Panels using the Score and Fold Method. The last test group 

consisted of one large junction box (5’ x 3’ x 2’) covered with 5/8 in. nominal 

Thermo-Lag 330-1 V-Rib panels. The 3-sided ERFBS were installed against 

concrete constructed using anchor bolts and Thermo-Lag 330-1 Trowel Grade 

Material that exceeded its 6-month shelf life but demonstrated acceptable 

testing quality according to the vendor. 

Test Slab: 136” x 151” x 10 GA (Steel) with 

#5 steel rebar supports 

Desired Rating: 1 hr. 

Ambient Temperature: 62°F 
D-76 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs spaced 6” apart and fastened to conduits and junction boxes by clamping under the 

head of a #8 x 32 x 1⁄4” long stainless steel screw. Thermocouples were affixed to the 

interior of the junction boxes in each square foot of area on each face of the boxes with 

exception of the face toward the concrete slab. 

Hose Stream: The test platform was sprayed with water at a 30o hose angle at a 

pressure of 75 psi while spinning at 6-8 revolutions per minute. The test setup was 

sprayed with a 75 gpm water flow rate from a distance of 5 feet for 5 minutes. The spray 

technician was lifted with a platform to allow spray on underside and vertical surfaces. 

Furnace: 10’ x 10’ x 48” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: Electric cables were not utilized in this test. 

Table D-88. TVA Thermo-Lag Test 6.1.11 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp. Rise 

∆T °C (°F) Rating 

(7) 2-3” Aluminum Conduits 5/8” TL 330-1 None 45 (113) 60 min. 

(2) 1” Steel Conduits 5/8” TL 330-1 None 48 (118) 60 min. 

(3) 3” Aluminum Conduits 5/8” TL 330-1 None 51 (124) 60 min. 

(1) 5’ x 3’ x 2’ Junction Box 5/8” TL 330-1 None 71 (160) 60 min. 

Each of the multiple conduit enclosures and the junction box enclosure, clad with Thermo-Lag 

330-1 material and upgrades met the acceptance criteria for a fire resistance rating of one hour. 

The maximum temperatures recorded from the thermocouples did not exceed the ambient 

temperature of 62oF plus maximum temperature rise of 250oF (total 312oF). 

D.3.4.12 TVA Project No. 11960-97259, Test 6.1.12 (October 1994) 

ERFBS: This 1-hr. test evaluated four different configurations: The first configuration 

was a group of (4) 1 in. steel conduits arranged in two rows of two and covered 

with a box made of 5/8 in. nominal Thermo-Lag 330-1 V-Rib Panels, Separate 

Piece Method with stress skin overlay. The second configuration was a group 

of (4) 3 in. steel conduits arranged in two rows of two and covered with a box 

made of 5/8 in. Thermo-Lag 330-1 V-Rib Panels, Score and Fold construction 

with stress skin overlay. The third configuration was a group of (8) 4 in. 

aluminum conduits arranged in 4 rows of 2 and covered with a box made of 

5/8” nominal Thermo-Lag 330-1 V-Rib Panels. The fourth configuration was a 

4 in. steel conduit with junction box (12” x 12” x 60”) covered with 5/8 in. 

nominal Thermo-Lag 330-1 Panels and preformed conduit sections. 

Test Slab: 136” x 151” x 10 GA (Steel) with 

#5 steel rebar supports 

Desired Rating: 1 hr. 

Ambient Temperature: 78°F 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs spaced 6” apart and fastened to conduits by clamping under the head of a #8 x 32 x 

1⁄4” long stainless steel screw. Wires were installed on the interior of each conduit, and 

additionally at 12 in. intervals to the sides of the rear conduits in the group of 1 in. steel 
D-77 

conduits and the group of 3 in. steel conduits per request by USNRC representatives. 

Thermocouples were also placed on every square foot within the junction box. 

Hose Stream: The test platform was sprayed with water at a 30o hose angle at a 

pressure of 75 psi while spinning at 6-8 revolutions per minute. The test setup was 

sprayed with a 75 gpm water flow rate from a distance of 5 feet for 5 minutes. The spray 

technician was lifted with a platform to allow spray on underside and vertical surfaces. 

Furnace: 10’ x 10’ x 48” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: Electric cables were not utilized in this test. 

Table D-89. TVA Thermo-Lag Test 6.1.12 

Raceway Type 

Barrier 

Protection 

Cable 

Fill 

Max. Temp. 

Rise ∆T °C (°F) Rating 

(4) 1” Steel Conduits (#1) 5/8” TL 330-1 None 78 (172) 60 min. 

(4) 3” Steel Conduits (#2) 5/8” TL 330-1 None 71 (160) 60 min. 

(8) 4” Aluminum Conduits (#3) 5/8” TL 330-1 None 72 (161) 60 min. 

4” Steel Conduit, Junction Box (#4) 5/8” TL 330-1 None 100 (212) 60 min. 

Each of the multiple conduit enclosures and the 4 in. conduit/junction box enclosure, clad with 

Thermo-Lag 330-1 material and upgrades met the acceptance criteria for a fire resistance rating 

of one hour. The maximum temperatures recorded from the thermocouples did not exceed the 

ambient temperature of 78oF plus maximum temperature rise of 250oF (total 328oF). 

D.3.4.13 TVA Project No. 11960-97260, Test 6.1.13 (October 1994) 

ERFBS: This 1-hr. test evaluated three different configurations: The first configuration 

was a group of (7) 4 in. steel conduits covered with 5/8 in. nominal Thermo-Lag 

330-1 Panels and pre-shaped conduit sections. The second configuration was 

a 3/4 in. aluminum conduit covered with one layer of 5/8 in. nominal ThermoLag 330-1 and an upgrade of 3/8 in. nominal Thermo-Lag 330-1 fire barrier 

material. The third configuration included on 3/4 in. steel conduit covered with 

one layer of 5/8 in. nominal Thermo-Lag 330-1 and an upgrade of 3/8 in. 

nominal Thermo-Lag 330-1. Installations were positioned in a vertical to 

horizontal to vertical fashion. The score and bend principle was applied at 90o 

radial bends and voids filled with Thermo-Lag 330-1 Trowel Grade and putty. 

The test deck was covered with a 10 GA deck steel with 4 in. dia. pipe sockets 

welded to 3 in. dia. steel pipe legs to hold the assembly at proper level. 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Desired Rating: 1 hr. 

Ambient Temperature: 80°F 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs and fastened to conduits by clamping under the head of a #8 x 32 x 1⁄4” long 

stainless steel screw. Thermocouples were positioned nominally every 6 in. along the 

interior of the conduits to get a realistic measurement of the temperatures. 

Hose Stream: The test platform was sprayed with water at a 30o hose angle at a 
D-78 

pressure of 75 psi while spinning at 6-8 revolutions per minute. The test setup was 

sprayed with a 75 gpm water flow rate from a distance of 5 feet for 5 minutes. 

Furnace: 12’ x 7’ x 79” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: Electric cables were not utilized in this test. 

Table D-90. TVA Thermo-Lag Test 6.1.13 

Raceway Type Barrier Protection 

Cable 

Fill 

Max. Temp. Rise 

∆T °C (°F) Rating 

(7) 4” Steel Conduits 5/8” TL 330-1 None 96 (205) 60 min. 

(1) 3/4” Aluminum Conduit 5/8”, 3/8” TL 330-1 None 63 (145) 60 min. 

(1) 3/4” Steel Conduit 5/8”, 3/8” TL 330-1 None 67 (153) 60 min. 

Each of the ganged conduit enclosures and two individually clad 3/4 in. conduits, clad with 

Thermo-Lag 330-1 material and upgrades met the acceptance criteria for a fire resistance rating 

of one hour. The maximum temperatures recorded from the thermocouples did not exceed the 

ambient temperature of 80oF plus maximum temperature rise of 250oF (total 330oF). 

D.3.4.14 TVA Project No. 11210-98892, Test 6.1.14 (January 1996) 

ERFBS: This 1-hr. test evaluated six different configurations: The first configuration was 

a 1 in. aluminum conduit protected with a minimum 1/2 in. New Old Stock 

(NOS) Thermo-Lag 330-1 displaying a variance in Thermogravimetric Analysis 

plus a nominal 3/8 in. Thermo-Lag 330-1 upgrade preformed section with 

acceptable TGA. The second configuration was a 3 in. aluminum conduit 

protected with nominal 5/8 in. Thermo-Lag 330-1 displaying a slight variance in 

TGA. The third and fourth configurations were 3 in. aluminum conduit 

protected with a minimum 1/2 in. NOS Thermo-Lag 330-1 displaying a variance 

in TGA. The fifth configuration was a 4 in. aluminum conduit protected with a 

minimum 1/2 in. NOS Thermo-Lag 330-1 displaying a variance in TGA. The 

final configuration was a 4 in. aluminum conduit protected with a minimum 1/2 

in. NOS Thermo-Lag 330-1 displaying acceptable TGA. This test not only 

tested the six separate configurations of Thermo-Lag clad conduits, but also 

whether using stainless steel bands, re-soaked pre-formed sections, damaged 

pre-formed sections, and re-certified Trowel Grade Material are acceptable. 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Desired Rating: 1 hr. 

Ambient Temperature: 65°F 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs and fastened to conduits by clamping under the head of a #8 x 32 x 1⁄4” long 

stainless steel screw. Thermocouples were positioned nominally every 6 in. along the 

interior of the conduits to get a realistic measurement of the temperatures. Additional 

thermocouples were installed on the outside of the conduit at predetermined banding 

locations to record thermal effects of stainless steel bands. Two wraps of fiberglass 

reinforced electrical tape were placed on the conduit, at the thermocouple location to 

isolate the thermo-junction from the conduit. 
D-79 

Hose Stream: The test platform was sprayed with water at a 30o hose angle at a 

pressure of 75 psi while spinning at 6-8 revolutions per minute. The test setup was 

sprayed with a 75 gpm water flow rate from a distance of 5 feet for 5 minutes. 

Furnace: 12’ x 7’ x 79” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: Conduit “C” – 5, 7C #16 AWG 600V (0.85 lbs. cable/linear foot) 

Conduit “D” – 16, 7C #16 AWG 600V (2.70 lbs. cable/linear foot) 

Table D-91. TVA Thermo-Lag Test 6.1.14 

Raceway Type Barrier Protection Cable Fill 

Max. Temp. 

Rise ∆T °C (°F) Rating 

1” Aluminum Conduit (A) 1/2”, 3/8” TL330-1 None 72 (161) 60 min. 

3” Aluminum Conduit (B) 5/8” TL330-1 None 149 (300) 60 min. 

3” Aluminum Conduit (C) 1/2” TL330-1 5, 7C # 16 

AWG 

135 (275) 60 min. 

3” Aluminum Conduit (D) 1/2” TL330-1 16, 7C #16 

AWG 

114 (238) 60 min. 

4” Aluminum Conduit (E) 1/2” TL330-1 None 99 (210) 60 min. 

4” Aluminum Conduit (F) 1/2” TL330-1 None 110 (230) 60 min. 

The six conduit configurations evaluated in this test procedure, clad with Thermo-Lag 330-1 

material and upgrades, met the acceptance criteria for a fire resistance rating of one hour. The 

average starting temperature was 65oF and when added to the maximum temperature 

difference of 250oC, none of the test results exceeded the maximum overall temperature of 

315oF. This test also determined that 1/2 in. stainless steel bands are not desirable, but still 

acceptable on existing 3 in. and larger single conduit ERFBS constructed with a single layer of 

old vintage Thermo-Lag 330-1. Additionally, the test proved that soaking a preformed section of 

Thermo-Lag and reinstalling it on a conduit performs well, but shall not be used in the future as 

it is an unacceptable practice. The testing also showed that Thermo-Lag 330-1 Trowel Grade 

Material which passed its 6-month shelf life could still be mixed and used in a normal manner if 

TVAN procedures for recertification are followed. 
D-80 

D.3.4.15 TVA Project No. 11960-97555, Test 6.2.1 (December 1994) 

ERFBS: This 3-hr. test evaluated six different configurations: The first configuration 

consisted of (1) 12 in. wide by 4 in. deep steel ladderback cable tray covered 

with one layer of 1-1/4 in. nominal Thermo-Lag 330-1 V-Rib Panel, reinforced 

in select locations with one layer of stress skin, and upgraded with two layers 

of 3/8 in. nominal Thermo-Lag 770-1 Mat. The second configuration was (1) 

24 in. wide by 4 in. deep steel ladderback cable tray, covered with one layer of 

1-1/4 in. nominal Thermo-Lag 330-1 V-Rib Panel, reinforced in select locations 

with one layer of stress skin, and upgraded with two layers of 3/8 in. nominal 

Thermo-Lag 770-1 Mat. The third configuration was a 12 in. by 12 in. by 60 in. 

steel junction box covered with one layer of nominal 1-1/4 in. Thermo-Lag 330-

1 V-Rib Panels, reinforced with one layer of stress skin, and upgraded with two 

layers of nominal 3/8 in. Thermo-Lag 770-1 Mat. The two ladderback cable 

tray configurations were positioned from horizontal to vertical, and the junction 

box was positioned horizontally. 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Desired Rating: 3 hr. 

Ambient Temperature: 68°F 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs and fastened to conduits and junction box by clamping under the head of a #8 x 32 

x 1⁄4” long stainless steel screw. Thermocouples were installed every six inches on the 

top surface of the cable tray rungs in both trays, on the cable tray side rails, and in every 

square foot of junction box surface area. 

Hose Stream: The test platform was sprayed with water at a 30o hose angle at a 

pressure of 75 psi while spinning at 6-8 revolutions per minute. The test setup was 

sprayed with a 75 gpm water flow rate from a distance of 5 feet for 5 minutes with 

minimal exposure to the top surface of the experimental setup. 

Furnace: 12’ x 7’ x 79” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: Electric cables were not utilized in this test. 

Table D-92. TVA Thermo-Lag Test 6.1.15 

Raceway Type 

Barrier 

Protection Cable Fill 

Max. Temp. Rise ∆T 

°C (°F) Rating 

12” x 4” Steel 

Cable Tray 

1-1/4” TL330-1 

(2) 3/8” TL770-1 

None 69 (156) 180 min. 

24” x 4” Steel 

Cable Tray 

1-1/4” TL330-1 

(2) 3/8” TL770-1 

None 64 (147) 180 min. 

12” x 12” x 60” 

Steel Junction 

Box 

1-1/4” TL330-1 

(2) 3/8” TL770-1 

None 62 (143) 180 min. 

Both of the cable tray configurations (12 in. and 24 in.) and the junction box configuration 

evaluated in this test, clad with Thermo-Lag 330-1 material and upgraded with Thermo-Lag 770-

1 material met the acceptance criteria for a fire resistance rating of over three hours (213 
D-81 

minutes). All cable trays and the junction box assembly were tested with a worst case design 

baseline installation of 1-1/4 in. Thermo-Lag 330-1 material. The testing proved that 3-hour 

EFRBS are achievable as an upgrade to an existing system or as a completely new installation, 

and based upon the resulting time and temperature readings, this installation could have 

reduced quantities of material applied or a longer duration rating. 

D.3.4.16 TVA Project No. 11960-97553, Test 6.2.2 (January 1995) 

ERFBS: This 3-hr. test evaluated six different configurations: The first configuration was 

(1) 24 in. by 4 in. steel ladderback cable tray, covered with one layer of 1-1/4 

in. nominal Thermo-Lag 330-1 V-Rib Panels, reinforced in select locations with 

a layer of stress skin and upgraded with two layers of 3/8 in. nominal ThermoLag 770-1 Mat. The second configuration is identical to the first, except that 

the ladderback cable tray’s dimensions are 12” wide by 4” deep. The third 

configuration is (1) 1 in. galvanized steel conduit covered with one layer of 1-

1/4 in. nominal Thermo-Lag 330-1 preformed conduit sections and upgraded 

with three layers of 3/8 in. nominal Thermo-Lag 770-1 Mat. The fourth 

configuration is identical to the third except the steel conduit is 2 in. instead of 1 

in. The fifth configuration is identical to the third and fourth, but is 5 in. thick 

instead of 1 and 2 inches. The final configuration is (1) 2 in. air drop covered 

with one layer of 1-1/4 in. nominal Thermo-Lag 330-1 Preformed conduit 

sections, reinforced with one layer of stress skin, and upgraded with three 

layers of 3/8 in. nominal Thermo-Lag 770-1 Mat. All configurations in this test 

were aligned in a horizontal to vertical orientation. External stress skin was 

applied on top of a layer of Thermo-Lag 770-1 Trowel Grade. 

Test Slab: 13’ x 8’ x 10 GA (Steel), with 2 

layers of 2” ceramic fiber blanket insulation 

Desired Rating: 3 hr. 

Ambient Temperature: 64°F 

Thermocouples: A single bare #8 AWG stranded copper wire was instrumented with 

TCs and fastened to conduits and junction box by clamping under the head of a #8 x 32 

x 1⁄4” long stainless steel screw. Thermocouples were installed every six inches on the 

top surface of the cable tray rungs in both trays, in the interiors of the three conduits, 

along the cable tray side rails, and the bottom conduit surfaces. 

Hose Stream: The test platform was sprayed with water at a 30o hose angle at a 

pressure of 75 psi while spinning at 6-8 revolutions per minute. The test setup was 

sprayed with a 75 gpm water flow rate from a distance of 5 feet for 5 minutes with 

minimal exposure to the top surface of the experimental setup. 

Furnace: 12’ x 7’ x 79” 

Furnace control: Ten (10) thermocouples on probes located throughout the furnace 

Cable Type: Electric cables were not utilized in this test. 

 
D-82 

Table D-93. TVA Thermo-Lag Test 6.2.2 

Raceway Type Barrier Protection Cable Fill 

Max. Temp. 

Rise ∆T °C (°F) Rating 

24” x 4” Steel Cable 

Tray 

1-1/4” TL330-1 

(2) 3/8” TL770-1 None 61 (142) 180 min. 

12” x 4” Steel Cable 

Tray 

1-1/4” TL330-1 

(2) 3/8” TL770-1 None 68 (155) 180 min. 

1” Galvanized Steel 

Conduit 

1-1/4” TL330-1 

(3) 3/8” TL770-1 None 77 (170) 180 min. 

2” Galvanized Steel 

Conduit 

1-1/4” TL330-1 

(2) 3/8” TL770-1 None 116 (241) 180 min. 

5” Galvanized Steel 

Conduit 

1-1/4” TL330-1 

(2) 3/8” TL770-1 None 74 (166) 180 min. 

2” Air Drop 1-1/4” TL330-1 

(3) 3/8” TL770-1 None 55 (131) 180 min. 

Both of the cable tray configurations (12 in. and 24 in.), all three conduit configurations (5 in., 2 

in., and 1 in.) and the 2 in. air drop configuration evaluated in the test procedure, clad with 

Thermo-Lag 330-1 and Thermo-Lag 770-1 upgrades, met the acceptance criteria for a fire 

resistance rating of over four hours (250 minutes). The tests proved that 3-hour ERFBS are 

achievable as an upgrade to an existing system or as a completely new installation and this 

installation, based upon the resulting time and temperature readings, could have reduced 

quantities of material applied or a longer duration rating. 
D-83 

D.4 References

NEI Application Guide for Evaluation of Thermo-Lag 330 Fire Barrier Systems, NEI, 

1994. (NUDOCS Accession No. 9603150034) 

SwRI Test Report Project No. 01-7912(2), “Qualification Fire Test of a Protective Envelope 

System,” dated June 1985. (NUDOCS Accession No. 9308040254) 

Dresden Nuclear Power Station, “Dresden Station Units 2 and 3, 3M Fire Wrap Qualification 

Evaluation, NTSC Project 99-40540, Dresden Report No. 12-N208-05,” dated December 31, 

1999. (ADAMS Accession No. ML011910445) 

Letter from R.W. Brown (Peak Seals, Inc) to P.M. Madden (U.S. NRC), “Listed Documents Re 

Three Hour Fire Endurance Test on 3M Interam Fire Barrier Wrap Sponsored by Peak Seals,” 

dated August 7, 1995. (NUDOCS Accession No. 9509050173) 

Fire Endurance Test, “Omega Point Fire Endurance Test of 3M Interam Mat Fire Protective 

Envelopes (24 in. and 6 in. Cable Trays, 5 in., 3 in., and 1 in. Conduits, 2 in. Air Drop and a 12 

in. x 12 in. by 8 in. Junction Box,” dated August 2, 1995. (NUDOCS Accession No. 

9509070113) 

Letter from T. Dogan (Vectra) to R. Brown (Peak Seals, Inc.), “E-50 Series Fire Endurance Test 

Evaluation,” dated August 1, 1995. (NUDOCS Accession No. 9709090341) 

Memorandum from A. Singh (U.S. NRC) to C.E. McCracken (U.S. NRC), “Trip to Omega Point 

Laboratories, 3M Company Interam 1-Hour Raceway Fire Barrier Fire Endurance Test (TAC No. 

M82809),” dated May 25, 1995. (NUDOCS Accession No. 9506090198) 

Test Report provided by Peak Seals Inc., “Test Plan Number CTP-1199, One (1) Hour Fire 

Endurance Test, 3M Interam Fire Wrap,” report date May 4, 1995. (NUDOCS Accession No. 

9507140090) 

Test Report Provided by Omega Point Laboratories, “ASTM E136-94, Behavior of Materials in a 

Vertical Tube Furnace at 750oC, 3M E-50 Interam Series Mat,” report date January 17, 1995. 

(NUDOCS Accession No. 9705050067) 

Letter from R.W. Brown (Peak Seals, Inc.) to L.B. Marsh (U.S. NRC), “Inform that Peak Seals 

has become Master Distributor of 3M Interam Fire Wrap Sys for Commercial Nuclear Power 

Plants, Response to Specific Questions,” dated October 3, 1997. (NUDOCS Accession No. 

9802040354) 

Letter from J.K. Wood (Centerior Energy) to U.S. NRC, “Combustibility Testing of 3M Interam 

Material,” dated February 7, 1997. (NUDOCS Accession No. 9702200311) 

Letter from R. Licht (3M Fire Protection Products) to C.E. McCracken (U.S. NRC), 

“Acknowledges Receipt of 930504 Letter Requesting Info on 3M Fire Barrier Systems for 

Protection of Electrical Raceways. Informs that 3M Would Like to Supply Requested Info in 

Three Parts, Covering Flexible Wrap Systems, Rigid Panel Systems, and FS195 Systems,” 

dated May 18, 1993. (NUDOCS Accession No. 9308310099) 
D-84 

Letter from D.R. Coy (3M Ceramic Materials Department), “Discusses NUMARC Meeting 

931201-02 re Performance of Certain Fire Barrier materials. 3M Additional Test SVC Program 

Will Provide Technical Support, Supply of 3M Fire Protection Products, and Fire Testing at 

Cottage Grove Facility,” dated January 14, 1994. (NUDOCS Accession No. 9401310171) 

Letter from K.W. Howell (Underwriters Laboratories, Inc.) to B.J. Youngblood (U.S. NRC), 

“Qualification of 3M Fire Wrap,” dated October 22, 1984. (NUDOCS Accession No. 

8410240232) 

Letter from D.R. Coy (3M Ceramic Materials Department), “Informs that 3M Will be Providing 

Complete Document Package for 3M Interam E-50 Series Material, 1-and-3 Hour Systems, 

Including Fire Test Reports, per 10CFR50, App R,” dated August 3, 1993. (NUDOCS 

Accession No. 9308120140) 

Letter from D.R. Coy (3M Ceramic Materials Department), “Advises that 3M Will Continue to 

Supply Interam E-50 Series Materials and all Peripheral 3M Fire Protection Products Used in 

Installation Process Under Original Nuclear Product Designations,” dated March 1, 1994. 

(NUDOCS Accession No. 9403170125) 

Test Report Provided by 3M Fire Protection Products, “3M Fire Test Reports 94-27 and 94-42, 

re Upgrading TSI Material for 3-Hour Conduit Systems using 3M’s Interam E-50 Series Mats,” 

dated March 17, 1994. (NUDOCS Accession No. 9403280162) 

Letter from Dwight E. Nunn (Tennessee Valley Authority) to U.S. NRC, “Watts Bar Nuclear Plant 

(WBN) – 3M Fire Barrier Material, Cable Compressive Load Testing,” dated June 17, 1994. 

(NUDOCS Accession No. 9406240089) 

Letter from D.R. Coy (3M Fire Protection Products) to Nuclear Power Utility Customers, “Letter 

Advising that Effective 950628 3M Fire Protection Products Certified Nuclear Installer Program 

Will End and that Peak Seals, Inc Will Become Exclusive Supplier of 3M Fire Protection 

Products, Effective 950629,” dated April 28, 1995. (NUDOCS Accession No. 9505230123) 

Test Report Provided by 3M Fire Protection Products, “Results of Fire Test Conducted on Latest 

NRC Criteria With 3M Interam E-50 Series Material,” dated May 25, 1995. (NUDOCS 

Accession No. 9506220297) 

Test Report Provided by U.S. NRC, “Trip to Omega Point Laboratories – Peak Seals 3M 

Interam Raceway Fire Barrier Fire Endurance Test Program (April 20, 1995) (TAC No. 

M82809),” dated May 1, 1995. (NUDOCS Accession No. 9507140050) 

3M Fire Protection Products, “3M Advanced Training Program: 3M Interam E-50 Series Fire 

Protection Systems for the Nuclear Industry,” dated June 15, 1993. (NUDOCS Accession No. 

9308040286) 

Letter from C.E. McCracken (U.S. NRC) to R.R. Licht (3M Fire Protection Products), “NRC 

Intent to Review Fire Barrier Systems Used by Licensees Re Compliance with NRC Fire 

Protection Requirements,” dated May 4, 1993. (NUDOCS Accession No. 9403170119) 

SwRI Test Report, “Ampacity Derating of Fire-Protected Cables in Conduit / Cable Trays Using 

3M Incorporated’s Passive Fire Protection Systems Identified as 3M Interam E-50A, E-50D, E53A, and E-50D/E-53A,” dated September, 30 1986 (NUDOCS Accession No. 9308040280) 
D-85 

3M Fire Protection Products, “3M Interam E-50 Series Fire Protection Mat, 1-Hour Flexible 

Wrap System for Electrical Raceways, Installation Booklet Including Quality Assurance 

Guidelines and Typical Drawings,” dated June 19, 1987. (NUDOCS Accession No. 

9308040230) 

Test Report Provided by Twin City Testing Corporation, “Qualification Fire Tests of the 3M 

Interam E-50D Fire Protection Mat for 3-Hour Rated Electrical Raceways,” dated March 1986. 

(NUDOCS Accession No. 9308040267) 

SwRI Test Report No. 01-7912, “Qualification Fire Test of a Protective Envelope System,” dated 

June 1984. (NUDOCS Accession No. 9308040243) 

3M Fire Protection Products, “3M Interam E-54A Fire Protection Mat, 3-Hour Flexible Wrap 

System for Electrical Raceways, Installation Booklet Including Quality Assurance Guidelines 

and Typical Drawings,” dated October 27, 1987. (NUDOCS Accession No. 9308040228) 

3M Fire Protection Products, “3M Interam E-50 Series 1-hour and 3-hour Flexible Wrap Fire 

Protection Systems.” (NUDOCS Accession No. 9308040224) 

SwRI Project Report No. 01-7912a(1), “Qualification Fire Test of a Protective Envelope 

System,” dated June 1985. (NUDOCS Accession No. 9308040263) 

Test Report Provided by Twin City Testing Corporation, “Qualification Fire Tests of the 3M 

Interam E-50 Series Fire Protection Mat for 1-Hour Rated Electrical Raceways,” dated 

September 1986. (NUDOCS Accession No. 9308040275) 

SwRI Project Report No. 01-7912(2), “Qualification Fire Test of a Protective Envelope System,” 

dated June 1985. (NUDOCS Accession No. 9308040254) 

Letter from R. Licht (3M Fire Protection Products) to C.E. McCracken (U.S. NRC), “Response to 

Questions Noted in 930504 Letter and Provides Info Intended to Validate Use of 3M Interam E50 Series 1-Hour and 3 Hour Fire Protection Systems,” dated June 30, 1993. (NUDOCS 

Accession No. 9308040054) 

Letter from R.W. Brown (Peak Seals) to P.M. Madden (U.S. NRC), “Response: 3M Interam Fire 

Wrap Systems,” dated August 7, 1995. (NUDOCS Accession No. 9509050173) 

Test Report Provided by Central Laboratories Services, “Testing to Determine Ampacity 

Derating Factors for 3M Fire Barrier Wrapped Conduits and Air Drops, Job Number 94-0357, 

Revision 0,” dated February 3, 1994. (NUDOCS Accession No. 9403030227) 

SwRI Test Report No. 01-8818-208/-209d, “Ampacity Derating of Fire-Protected Cables in 

Conduit/Cable Trays Using 3M Incorporated’s Passive Fire Protection Systems Identified as 3M 

Interam E-50A (Verification Tests),” dated October 6, 1986. (NUDOCS Accession No. 

9308040249) 

SwRI Test Report No. 1208-001, “Nuclear Component Qualification Test Report for the Generic 

Seismic Qualification of 3M Interam E-50D 3-Hour Fire Protection System,” dated July 1986. 

(NUDOCS Accession No. 9308040186) 
D-86 

Test Report Provided by 3M Fire Protection Products, “3M Fire Test #92-115: 3-hour Fire 

Protection on Conduits with the 3M Interam E-50 Series Mats,” dated August, 6, 1992. 

(NUDOCS Accession No. 9308040119) 

Test Report Provided by 3M Fire Protection Products, “3M Fire Test #87-79: 3-hour Fire 

Protection on a Cable Tray With the 3M Interam E-50 Series Mats,” dated July 24, 1992. 

(NUDOCS Accession No. 9308040106) 

Test Report Provided by 3M Fire Protection Products, “3M Fire Test #92-167: 1-hour Fire 

Protection on 1” Sch. 40 Steel Conduits Using the 3M Interam E-53A Mats,” dated June 25, 

1993. (NUDOCS Accession No. 9308040101) 

Test Report Provided by 3M Fire Protection Products, “3M Fire Test #92-141: 1-hour and 3-

Hour Fire Protection on 1” Sch. 40 Steel Conduits Using the 3M Interam E-54A Mats,” dated 

August 27, 1992. (NUDOCS Accession No. 9308040099) 

Test Report Provided by 3M Fire Protection Products, “3M Fire Test #87-40: 1-hour Fire 

Protection on a Cable Tray With the 3M Interam E-50 Series Materials,” dated April 3, 1992. 

(NUDOCS Accession No. 9308040097) 

Test Report Provided by 3M Fire Protection Products, “3M Fire Test Report #87-57: 3M 

Chemolite Building 66, Large Scale Furnace,” dated May 27, 1987. (NUDOCS Accession No. 

9308040094) 

Test Report Provided by 3M Fire Protection Products, “3M Fire Test #87-76: 60 Minute Fire 

Protection on Conduits with Interam E-53A Mat and FireDam 150 Caulk,” dated June 25, 1987. 

(NUDOCS Accession No. 9308040090) 

Letter from R. Licht (3M Ceramic Materials) to C.E. McCracken (U.S. NRC), “Response to 

Questions Noted in 930504 Letter and Provides Info Intended to Validate Use of 3M Interam E50 Series 1-Hour and 3-Hour Fire Protection Systems,” dated June 30, 1993. (NUDOCS 

Accession No. 9308040054) 
E-1 

Appendix E Fire Protection Regulations Cited from 10 CFR 50 

Disclaimer: The following has been reproduced from 10 CFR Part 50 and may contain errors. 

This reproduction is only meant to provide a quick reference. An official copy of 

10 CFR Part 50 should be consulted for regulatory matters. 

§ 50.48 Fire protection. 

(a)(1) Each holder of an operating 

license issued under this part or a combined 

license issued under part 52 of this chapter 

must have a fire protection plan that 

satisfies Criterion 3 of appendix A to this 

part. This fire protection plan must: 

(i) Describe the overall fire protection 

program for the facility; 

(ii) Identify the various positions within 

the licensee's organization that are 

responsible for the program; 

(iii) State the authorities that are 

delegated to each of these positions to 

implement those responsibilities; and 

(iv) Outline the plans for fire protection, 

fire detection and suppression capability, 

and limitation of fire damage. 

(2) The plan must also describe specific 

features necessary to implement the 

program described in paragraph (a)(1) of 

this section such as-- 

(i) Administrative controls and personnel 

requirements for fire prevention and manual 

fire suppression activities; 

(ii) Automatic and manually operated fire 

detection and suppression systems; and 

(iii) The means to limit fire damage to 

structures, systems, or components 

important to safety so that the capability to 

shut down the plant safely is ensured. 

(3) The licensee shall retain the fire 

protection plan and each change to the plan 

as a record until the Commission terminates 

the reactor license. The licensee shall retain 

each superseded revision of the procedures 

for 3 years from the date it was superseded. 

(4) Each applicant for a design approval, 

design certification, or manufacturing 

license under part 52 of this chapter must 

have a description and analysis of the fire 

protection design features for the standard 

plant necessary to demonstrate compliance 

with Criterion 3 of appendix A to this part. 

(b) Appendix R to this part establishes 

fire protection features required to satisfy 

Criterion 3 of appendix A to this part with 

respect to certain generic issues for nuclear 

power plants licensed to operate before 

January 1, 1979. 

(1) Except for the requirements of 

Sections III.G, III.J, and III.O, the provisions 

of Appendix R to this part do not apply to 

nuclear power plants licensed to operate 

before January 1, 1979, to the extent that-- 

(i) Fire protection features proposed or 

implemented by the licensee have been 

accepted by NRC staff as satisfying the 

provisions of Appendix A to Branch 

Technical Position (BTP) APCSB 9.5-1 

reflected in NRC fire protection safety 

evaluation reports issued before the 

effective date of February 19, 1981; or 

(ii) Fire protection features were 

accepted by NRC staff in comprehensive 

fire protection safety evaluation reports 

issued before Appendix A to Branch 

Technical Position (BTP) APCSB 9.5-1 was 

published in August 1976. 

(2) With respect to all other fire 

protection features covered by Appendix R, 

all nuclear power plants licensed to operate 

before January 1, 1979, must satisfy the 

applicable requirements of Appendix R to 

this part, including specifically the 

requirements of Sections III.G, III.J, and 

III.O. 

(c) National Fire Protection Association 

Standard NFPA 805. - (1) Approval of 

incorporation by reference. National Fire 

Protection Association (NFPA) Standard 

805, "Performance-Based Standard for Fire 

Protection for Light Water Reactor Electric 

Generating Plants, 2001 Edition" (NFPA 

805), which is referenced in this section, 
E-2 

was approved for incorporation by reference 

by the Director of the Federal Register 

pursuant to 5 U.S.C. 552(a) and 1 CFR part 

51. Copies of NFPA 805 may be purchased 

from the NFPA Customer Service 

Department, 1 Batterymarch Park, P.O. Box 

9101, Quincy, MA 02269-9101 and in PDF 

format through the NFPA Online Catalog 

(http://www.nfpa.org) or by calling 1-800-

344-3555 or (617) 770-3000. Copies are 

also available for inspection at NRC Library, 

Two White Flint North, 11545 Rockville 

Pike, Rockville, Maryland 20852-2738, and 

at NRC Public Document Room, Building 

One White Flint North, Room O1-F15, 

11555 Rockville Pike, Rockville, Maryland 

20852-2738. Copies are also available at 

the National Archives and Records 

Administration (NARA). For information on 

the availability of this material at NARA, call 

(202) 741-6030, or go to: 

http://www.archives.gov/federal_register/co

de_of_federal_regulations/ibr_locations.html

. 

(2) Exceptions, modifications, and 

supplementation of NFPA 805. As used in 

this section, references to NFPA 805 are to 

the 2001 Edition, with the following 

exceptions, modifications, and 

supplementation: 

(i) Life Safety Goal, Objectives, and 

Criteria. The Life Safety Goal, Objectives, 

and Criteria of Chapter 1 are not endorsed. 

(ii) Plant Damage/Business Interruption 

Goal, Objectives, and Criteria. The Plant 

Damage/Business Interruption Goal, 

Objectives, and Criteria of Chapter 1 are not 

endorsed. 

(iii) Use of feed-and-bleed. In 

demonstrating compliance with the 

performance criteria of Sections 1.5.1(b) 

and (c), a high-pressure charging/injection 

pump coupled with the pressurizer poweroperated relief valves (PORVs) as the sole 

fire-protected safe shutdown path for 

maintaining reactor coolant inventory, 

pressure control, and decay heat removal 

capability (i.e., feed-and-bleed) for 

pressurized-water reactors (PWRs) is not 

permitted. 

(iv) Uncertainty analysis. An uncertainty 

analysis performed in accordance with 

Section 2.7.3.5 is not required to support 

deterministic approach calculations. 

(v) Existing cables. In lieu of installing 

cables meeting flame propagation tests as 

required by Section 3.3.5.3, a flameretardant coating may be applied to the 

electric cables, or an automatic fixed fire 

suppression system may be installed to 

provide an equivalent level of protection. In 

addition, the italicized exception to Section 

3.3.5.3 is not endorsed. 

(vi) Water supply and distribution. The 

italicized exception to Section 3.6.4 is not 

endorsed. Licensees who wish to use the 

exception to Section 3.6.4 must submit a 

request for a license amendment in 

accordance with paragraph (c)(2)(vii) of this 

section. 

(vii) Performance-based methods. Notwithstanding the prohibition in Section 3.1 

against the use of performance-based 

methods, the fire protection program 

elements and minimum design 

requirements of Chapter 3 may be subject 

to the performance-based methods 

permitted elsewhere in the standard. 

Licensees who wish to use performancebased methods for these fire protection 

program elements and minimum design 

requirements shall submit a request in the 

form of an application for license 

amendment under § 50.90. The Director of 

the Office of Nuclear Reactor Regulation, or 

a designee of the Director, may approve the 

application if the Director or designee 

determines that the performance-based 

approach; 

(A) Satisfies the performance goals, 

performance objectives, and performance 

criteria specified in NFPA 805 related to 

nuclear safety and radiological release; 

(B) Maintains safety margins; and 

(C) Maintains fire protection defense-indepth (fire prevention, fire detection, fire 

suppression, mitigation, and post-fire safe 

shutdown capability). 

(3) Compliance with NFPA 805. (i) A 

licensee may maintain a fire protection 

program that complies with NFPA 805 as an 

alternative to complying with paragraph (b) 
E-3 

of this section for plants licensed to operate 

before January 1, 1979, or the fire 

protection license conditions for plants 

licensed to operate after January 1, 1979. 

The licensee shall submit a request to 

comply with NFPA 805 in the form of an 

application for license amendment under § 

50.90. The application must identify any 

orders and license conditions that must be 

revised or superseded, and contain any 

necessary revisions to the plant's technical 

specifications and the bases thereof. The 

Director of the Office of Nuclear Reactor 

Regulation, or a designee of the Director, 

may approve the application if the Director 

or designee determines that the licensee 

has identified orders, license conditions, 

and the technical specifications that must be 

revised or superseded, and that any 

necessary revisions are adequate. Any 

approval by the Director or the designee 

must be in the form of a license amendment 

approving the use of NFPA 805 together 

with any necessary revisions to the 

technical specifications. 

(ii) The licensee shall complete its 

implementation of the methodology in 

Chapter 2 of NFPA 805 (including all 

required evaluations and analyses) and, 

upon completion, modify the fire protection 

plan required by paragraph (a) of this 

section to reflect the licensee's decision to 

comply with NFPA 805, before changing its 

fire protection program or nuclear power 

plant as permitted by NFPA 805. 

(4) Risk-informed or performance-based 

alternatives to compliance with NFPA 805.

A licensee may submit a request to use riskinformed or performance-based alternatives 

to compliance with NFPA 805. The request 

must be in the form of an application for 

license amendment under § 50.90 of this 

chapter. The Director of the Office of 

Nuclear Reactor Regulation, or designee of 

the Director, may approve the application if 

the Director or designee determines that the 

proposed alternatives: 

(i) Satisfy the performance goals, 

performance objectives, and performance 

criteria specified in NFPA 805 related to 

nuclear safety and radiological release; 

(ii) Maintain safety margins; and 

(iii) Maintain fire protection defense-indepth (fire prevention, fire detection, fire 

suppression, mitigation, and post-fire safe 

shutdown capability). 

(d)-(3) (Reserved). 

(f) Licensees that have submitted the 

certifications required under § 50.82(a)(1) 

shall maintain a fire protection program to 

address the potential for fires that could 

cause the release or spread of radioactive 

materials (i.e., that could result in a 

radiological hazard). A fire protection 

program that complies with NFPA 805 shall 

be deemed to be acceptable for complying 

with the requirements of this paragraph. 

(1) The objectives of the fire protection 

program are to-- 

(i) Reasonably prevent these fires from 

occurring; 

(ii) Rapidly detect, control, and 

extinguish those fires that do occur and that 

could result in a radiological hazard; and 

(iii) Ensure that the risk of fire-induced 

radiological hazards to the public, 

environment and plant personnel is 

minimized. 

(2) The licensee shall assess the fire 

protection program on a regular basis. The 

licensee shall revise the plan as appropriate 

throughout the various stages of facility 

decommissioning. 

(3) The licensee may make changes to 

the fire protection program without NRC 

approval if these changes do not reduce the 

effectiveness of fire protection for facilities, 

systems, and equipment that could result in 

a radiological hazard, taking into account 

the decommissioning plant conditions and 

activities. 

(65 FR 38190, June 20, 2000; 69 FR 

33550, June 16, 2004; 72 FR 49495, Aug. 

28, 2007)
E-4 

Appendix A to Part 50 – General Design Criteria 3 – Fire Protection 

Structures, systems, and components important to safety shall be designed and located to 

minimize, consistent with other safety requirements, the probability and effect of fires and 

explosions. Noncombustible and heat resistant materials shall be used wherever practical 

throughout the unit, particularly in locations such as the containment and control room. Fire 

detection and fighting systems of appropriate capacity and capability shall be provided and 

designed to minimize the adverse effects of fires on structures, systems, and components 

important to safety. Firefighting systems shall be designed to assure that their rupture or 

inadvertent operation does not significantly impair the safety capability of these structures, 

systems, and components. 

Appendix R to Part 50 – Fire Protection Program for Nuclear Power 

Facilities Operating Prior to January 1, 1979 

I. Introduction and Scope 

This appendix applies to licensed 

nuclear power electric generating stations 

that were operating prior to January 1, 

1979, except to the extent set forth in § 

50.48(b) of this part. With respect to certain 

generic issues for such facilities it sets forth 

fire protection features required to satisfy 

Criterion 3 of Appendix A to this part. 

Criterion 3 of Appendix A to this part 

specifies that "Structures, systems, and 

components important to safety shall be 

designed and located to minimize, 

consistent with other safety requirements, 

the probability and effect of fires and 

explosions." 

When considering the effects of fire, 

those systems associated with achieving 

and maintaining safe shutdown conditions 

assume major importance to safety because 

damage to them can lead to core damage 

resulting from loss of coolant through boil 

off. 

The phrases "important to safety," or 

"safety-related," will be used throughout this 

Appendix R as applying to all safety 

functions. The phrase "safe shutdown" will 

be used throughout this appendix as 

applying to both hot and cold shutdown 

functions. 

Because fire may affect safe shutdown 

systems and because the loss of function of 

systems used to mitigate the consequences 

of design basis accidents under post fire 

conditions does not per se impact public 

safety, the need to limit fire damage to 

systems required to achieve and maintain 

safe shutdown conditions is greater than the 

need to limit fire damage to those systems 

required to mitigate the consequences of 

design basis accidents. Three levels of fire 

damage limits are established according to 

the safety functions of the structure, system, 

or component: 

Safety Function Fire damage limits 

Hot Shutdown... 

Cold Shutdown 

Design Basis Accidents 

One train of equipment 

necessary to achieve hot 

shutdown from either the 

control room or emergency 

control station(s) must be 

maintained free of fire 

damage by a single fire, 

including an exposure fire.1 

Both trains of equipment 

necessary to achieve cold 

shutdown may be damaged 

by a single fire, including an 

exposure fire, but damage 

must be limited so that at least 

one train can be repaired or 

made operable within 72 

hours using onsite capability. 

Design Basis Accidents Both 

trains of equipment necessary 
E-5 

for mitigation of 

consequences following 

design basis accidents may 

be damaged by a single 

exposure fire. 1 Exposure Fire. An exposure fire is a fire in a given area that 

involves either in situ or transient combustibles and is 

external to any structures, systems, or components located 

in or adjacent to that same area. The effects of such fire 

(e.g., smoke, heat, or ignition) can adversely affect those 

structures, systems, or components important to safety. 

Thus, a fire involving one train of safe shutdown equipment 

may constitute an exposure fire for the redundant train 

located in the same area, and a fire involving combustibles 

other than either redundant train may constitute an exposure 

fire to both redundant trains located in the same area. 

The most stringent fire damage limit 

shall apply for those systems that fall into 

more than one category. Redundant 

systems used to mitigate the consequences 

of other design basis accidents but not 

necessary for safe shutdown may be lost to 

a single exposure fire. However, protection 

shall be provided so that a fire within only 

one such system will not damage the 

redundant system. 

II. General Requirements 

A. Fire protection program. A fire 

protection program shall be established at 

each nuclear power plant. The program 

shall establish the fire protection policy for 

the protection of structures, systems, and 

components important to safety at each 

plant and the procedures, equipment, and 

personnel required to implement the 

program at the plant site. 

The fire protection program shall be 

under the direction of an individual who has 

been delegated authority commensurate 

with the responsibilities of the position and 

who has available staff personnel 

knowledgeable in both fire protection and 

nuclear safety. 

The fire protection program shall extend 

the concept of defense-in-depth to fire 

protection in fire areas important to safety, 

with the following objectives: 

To prevent fires from starting; 

To detect rapidly, control, and extinguish 

promptly those fires that do occur; 

To provide protection for structures, 

systems, and components important to 

safety so that a fire that is not promptly 

extinguished by the fire suppression 

activities will not prevent the safe shutdown 

of the plant. 

B. Fire hazards analysis. A fire hazards 

analysis shall be performed by qualified fire 

protection and reactor systems engineers to 

(1) consider potential in situ and transient 

fire hazards; (2) determine the 

consequences of fire in any location in the 

plant on the ability to safely shut down the 

reactor or on the ability to minimize and 

control the release of radioactivity to the 

environment; and (3) specify measures for 

fire prevention, fire detection, fire 

suppression, and fire containment and 

alternative shutdown capability as required 

for each fire area containing structures, 

systems, and components important to 

safety in accordance with NRC guidelines 

and regulations. 

C. Fire prevention features. Fire 

protection features shall meet the following 

general requirements for all fire areas that 

contain or present a fire hazard to 

structures, systems, or components 

important to safety. 

1. In situ fire hazards shall be identified 

and suitable protection provided. 

2. Transient fire hazards associated with 

normal operation, maintenance, repair, or 

modification activities shall be identified and 

eliminated where possible. Those transient 

fire hazards that can not be eliminated shall 

be controlled and suitable protection 

provided. 

3. Fire detection systems, portable 

extinguishers, and standpipe and hose 

stations shall be installed. 

4. Fire barriers or automatic suppression 
E-6 

systems or both shall be installed as 

necessary to protect redundant systems or 

components necessary for safe shutdown. 

5. A site fire brigade shall be 

established, trained, and equipped and shall 

be on site at all times. 

6. Fire detection and suppression 

systems shall be designed, installed, 

maintained, and tested by personnel 

properly qualified by experience and training 

in fire protection systems. 

7. Surveillance procedures shall be 

established to ensure that fire barriers are in 

place and that fire suppression systems and 

components are operable. 

D. Alternative or dedicated shutdown 

capability. In areas where the fire protection 

features cannot ensure safe shutdown 

capability in the event of a fire in that area, 

alternative or dedicated safe shutdown 

capability shall be provided. 

III. Specific Requirements 

A. Water supplies for fire suppression 

systems. Two separate water supplies shall 

be provided to furnish necessary water 

volume and pressure to the fire main loop. 

Each supply shall consist of a storage 

tank, pump, piping, and appropriate 

isolation and control valves. Two separate 

redundant suctions in one or more intake 

structures from a large body of water (river, 

lake, etc.) will satisfy the requirement for 

two separated water storage tanks. These 

supplies shall be separated so that a failure 

of one supply will not result in a failure of 

the other supply. 

Each supply of the fire water distribution 

system shall be capable of providing for a 

period of 2 hours the maximum expected 

water demands as determined by the fire 

hazards analysis for safety-related areas or 

other areas that present a fire exposure 

hazard to safety-related areas. 

When storage tanks are used for 

combined service-water/fire-water uses the 

minimum volume for fire uses shall be 

ensured by means of dedicated tanks or by 

some physical means such as a vertical 

standpipe for other water service. 

Administrative controls, including locks for 

tank outlet valves, are unacceptable as the 

only means to ensure minimum water 

volume. 

Other water systems used as one of the 

two fire water supplies shall be permanently 

connected to the fire main system and shall 

be capable of automatic alignment to the 

fire main system. Pumps, controls, and 

power supplies in these systems shall 

satisfy the requirements for the main fire 

pumps. The use of other water systems for 

fire protection shall not be incompatible with 

their functions required for safe plant 

shutdown. Failure of the other system shall 

not degrade the fire main system. 

B. Sectional isolation valves. Sectional 

isolation valves such as post indicator 

valves or key operated valves shall be 

installed in the fire main loop to permit 

isolation of portions of the fire main loop for 

maintenance or repair without interrupting 

the entire water supply. 

C. Hydrant isolation valves. Valves shall 

be installed to permit isolation of outside 

hydrants from the fire main for maintenance 

or repair without interrupting the water 

supply to automatic or manual fire 

suppression systems in any area containing 

or presenting a fire hazard to safety-related 

or safe shutdown equipment. 

D. Manual fire suppression. Standpipe 

and hose systems shall be installed so that 

at least one effective hose stream will be 

able to reach any location that contains or 

presents an exposure fire hazard to 

structures, systems, or components 

important to safety. 

Access to permit effective functioning of 
E-7 

the fire brigade shall be provided to all 

areas that contain or present an exposure 

fire hazard to structures, systems, or 

components important to safety. 

Standpipe and hose stations shall be 

inside PWR containments and BWR 

containments that are not inerted. 

Standpipe and hose stations inside 

containment may be connected to a high 

quality water supply of sufficient quantity 

and pressure other than the fire main loop if 

plant-specific features prevent extending the 

fire main supply inside containment. For 

BWR drywells, standpipe and hose stations 

shall be placed outside the dry well with 

adequate lengths of hose to reach any 

location inside the dry well with an effective 

hose stream. 

E. Hydrostatic hose tests. Fire hose 

shall be hydrostatically tested at a pressure 

of 150 psi or 50 psi above maximum fire 

main operating pressure, whichever is 

greater. Hose stored in outside hose houses 

shall be tested annually. Interior standpipe 

hose shall be tested every three years. 

F. Automatic fire detection. Automatic 

fire detection systems shall be installed in 

all areas of the plant that contain or present 

an exposure fire hazard to safe shutdown or 

safety-related systems or components. 

These fire detection systems shall be 

capable of operating with or without offsite 

power. 

G. Fire protection of safe shutdown 

capability. 1. Fire protection features shall 

be provided for structures, systems, and 

components important to safe shutdown. 

These features shall be capable of limiting 

fire damage so that: 

a. One train of systems necessary to 

achieve and maintain hot shutdown 

conditions from either the control room or 

emergency control station(s) is free of fire 

damage; and 

b. Systems necessary to achieve and 

maintain cold shutdown from either the 

control room or emergency control station(s) 

can be repaired within 72 hours. 

2. Except as provided for in paragraph 

G.3 of this section, where cables or 

equipment, including associated non-safety 

circuits that could prevent operation or 

cause maloperation due to hot shorts, open 

circuits, or shorts to ground, of redundant 

trains of systems necessary to achieve and 

maintain hot shutdown conditions are 

located within the same fire area outside of 

primary containment, one of the following 

means of ensuring that one of the 

redundant trains is free of fire damage shall 

be provided: 

a. Separation of cables and equipment 

and associated non-safety circuits of 

redundant trains by a fire barrier having a 3-

hour rating. Structural steel forming a part of 

or supporting such fire barriers shall be 

protected to provide fire resistance 

equivalent to that required of the barrier; 

b. Separation of cables and equipment 

and associated non-safety circuits of 

redundant trains by a horizontal distance of 

more than 20 feet with no intervening 

combustible or fire hazards. In addition, fire 

detectors and an automatic fire suppression 

system shall be installed in the fire area; or 

c. Enclosure of cable and equipment 

and associated non-safety circuits of one 

redundant train in a fire barrier having a 1-

hour rating, In addition, fire detectors and an 

automatic fire suppression system shall be 

installed in the fire area; 

Inside noninerted containments one of 

the fire protection means specified above or 

one of the following fire protection means 

shall be provided: 

d. Separation of cables and equipment 

and associated non-safety circuits of 

redundant trains by a horizontal distance of 

more than 20 feet with no intervening 

combustibles or fire hazards; 
E-8 

e. Installation of fire detectors and an 

automatic fire suppression system in the fire 

area; or 

f. Separation of cables and equipment 

and associated non-safety circuits of 

redundant trains by a noncombustible 

radiant energy shield. 

3. Alternative of dedicated shutdown 

capability and its associated circuits,1 

independent of cables, systems or 

components in the area, room, zone under 

consideration should be provided: 

a. Where the protection of systems 

whose function is required for hot shutdown 

does not satisfy the requirement of 

paragraph G.2 of this section; or 

b. Where redundant trains of systems 

required for hot shutdown located in the 

same fire area may be subject to damage 

from fire suppression activities or from the 

rupture or inadvertent operation of fire 

suppression systems. 

In addition, fire detection and a fixed fire 

suppression system shall be installed in the 

area, room, or zone under consideration. 

H. Fire brigade. A site fire brigade 

trained and equipped for fire fighting shall 

be established to ensure adequate manual 

fire fighting capability for all areas of the 

plant containing structures, systems, or 

components important to safety. The fire 

brigade shall be at least five members on 

each shift. The brigade leader and at least 

two brigade members shall have sufficient 

training in or knowledge of plant safetyrelated systems to understand the effects of 

fire and fire suppressants on safe shutdown 

capability. The qualification of fire brigade 

members shall include an annual physical 

examination to determine their ability to 

perform strenuous fire fighting activities. 

The shift supervisor shall not be a member 

of the fire brigade. The brigade leader shall 

be competent to assess the potential safety 

consequences of a fire and advise control 

room personnel. Such competence by the 

brigade leader may be evidenced by 

possession of an operator's license or 

equivalent knowledge of plant safety-related 

systems. 

The minimum equipment provided for 

the brigade shall consist of personal 

protective equipment such as turnout coats, 

boots, gloves, hard hats, emergency 

communications equipment, portable lights, 

portable ventilation equipment, and portable 

extinguishers. Self-contained breathing 

apparatus using full-face positive-pressure 

masks approved by NIOSH (National 

Institute for Occupational Safety and Health-

-approval formerly given by the U.S. Bureau 

of Mines) shall be provided for fire brigade, 

damage control, and control room 

personnel. At least 10 masks shall be 

available for fire brigade personnel. Control 

room personnel may be furnished breathing 

air by a manifold system piped from a 

storage reservoir if practical. Service or 

rated operating life shall be a minimum of 

one-half hour for the self-contained units. 

At least a 1-hour supply of breathing air 

in extra bottles shall be located on the plant 

site for each unit of self-contained breathing 

appratus. In addition, an onsite 6-hour 

supply of reserve air shall be provided and 

arranged to permit quick and complete 

replenishment of exhausted air supply 

bottles as they are returned. If compressors 

are used as a source of breathing air, only 

units approved for breathing air shall be 

used and the compressors shall be 

operable assuming a loss of offsite power. 

Special care must be taken to locate the 

compressor in areas free of dust and 

contaminants. 

I. Fire brigade training. The fire brigade 

training program shall ensure that the 

capability to fight potential fires is 

established and maintained. The program 

shall consist of an initial classroom 

instruction program followed by periodic 
E-9 

classroom instruction, fire fighting practice, 

and fire drills: 

1. Instruction 

a. The initial classroom instruction shall 

include: 

(1) Indoctrination of the plant fire fighting 

plan with specific identification of each 

individual's responsibilities. 

(2) Identification of the type and location 

of fire hazards and associated types of fires 

that could occur in the plant. 

(3) The toxic and corrosive 

characteristics of expected products of 

combustion. 

(4) Identification of the location of fire 

fighting equipment for each fire area and 

familiarization with the layout of the plant, 

including access and egress routes to each 

area. 

(5) The proper use of available fire 

fighting equipment and the correct method 

of fighting each type of fire. The types of 

fires covered should include fires in 

energized electrical equipment, fires in 

cables and cable trays, hydrogen fires, fires 

involving flammable and combustible liquids 

or hazardous process chemicals, fires 

resulting from construction or modifications 

(welding), and record file fires. 

(6) The proper use of communication, 

lighting, ventilation, and emergency 

breathing equipment. 

(7) The proper method for fighting fires 

inside buildings and confined spaces. 

(8) The direction and coordination of the 

fire fighting activities (fire brigade leaders 

only). 

(9) Detailed review of fire fighting 

strategies and procedures. 

(10) Review of the latest plant 

modifications and corresponding changes in 

fire fighting plans. 

Note: Items (9) and (10) may be deleted 

from the training of no more than two of the 

non-operations personnel who may be 

assigned to the fire brigade. 

b. The instruction shall be provided by 

qualified individuals who are 

knowledgeable, experienced, and suitably 

trained in fighting the types of fires that 

could occur in the plant and in using the 

types of equipment available in the nuclear 

power plant. 

c. Instruction shall be provided to all fire 

brigade members and fire brigade leaders. 

d. Regular planned meetings shall be 

held at least every 3 months for all brigade 

members to review changes in the fire 

protection program and other subjects as 

necessary. 

e. Periodic refresher training sessions 

shall be held to repeat the classroom 

instruction program for all brigade members 

over a two-year period. These sessions may 

be concurrent with the regular planned 

meetings. 

2. Practice 

Practice sessions shall be held for each 

shift fire brigade on the proper method of 

fighting the various types of fires that could 

occur in a nuclear power plant. These 

sessions shall provide brigade members 

with experience in actual fire extinguishment 

and the use of emergency breathing 

apparatus under strenuous conditions 

encountered in fire fighting. These practice 

sessions shall be provided at least once per 

year for each fire brigade member. 

3. Drills 

a. Fire brigade drills shall be performed 

in the plant so that the fire brigade can 
E-10 

practice as a team. 

b. Drills shall be performed at regular 

intervals not to exceed 3 months for each 

shift fire brigade. Each fire brigade member 

should participate in each drill, but must 

participate in at least two drills per year. 

A sufficient number of these drills, but 

not less than one for each shift fire brigade 

per year, shall be unannounced to 

determine the fire fighting readiness of the 

plant fire brigade, brigade leader, and fire 

protection systems and equipment. Persons 

planning and authorizing an unannounced 

drill shall ensure that the responding shift 

fire brigade members are not aware that a 

drill is being planned until it is begun. 

Unannounced drills shall not be scheduled 

closer than four weeks. 

At least one drill per year shall be 

performed on a "back shift" for each shift 

fire brigade. 

c. The drills shall be preplanned to 

establish the training objectives of the drill 

and shall be critiqued to determine how well 

the training objectives have been met. 

Unannounced drills shall be planned and 

critiqued by members of the management 

staff responsible for plant safety and fire 

protection. Performance deficiencies of a 

fire brigade or of individual fire brigade 

members shall be remedied by scheduling 

additional training for the brigade or 

members. Unsatisfactory drill performance 

shall be followed by a repeat drill within 30 

days. 

d. At 3-year intervals, a randomly 

selected unannounced drill must be 

critiqued by qualified individuals 

independent of the licensee's staff. A copy 

of the written report from these individuals 

must be available for NRC review and shall 

be retained as a record as specified in 

section III.I.4 of this appendix. 

e. Drills shall as a minimum include the 

following: 

(1) Assessment of fire alarm 

effectiveness, time required to notify and 

assemble fire brigade, and selection, 

placement and use of equipment, and fire 

fighting strategies. 

(2) Assessment of each brigade 

member's knowledge of his or her role in 

the fire fighting strategy for the area 

assumed to contain the fire. Assessment of 

the brigade member's conformance with 

established plant fire fighting procedures 

and use of fire fighting equipment, including 

self-contained emergency breathing 

apparatus, communication equipment, and 

ventilation equipment, to the extent 

practicable. 

(3) The simulated use of fire fighting 

equipment required to cope with the 

situation and type of fire selected for the 

drill. The area and type of fire chosen for the 

drill should differ from those used in the 

previous drill so that brigade members are 

trained in fighting fires in various plant 

areas. The situation selected should 

simulate the size and arrangement of a fire 

that could reasonably occur in the area 

selected, allowing for fire development due 

to the time required to respond, to obtain 

equipment, and organize for the fire, 

assuming loss of automatic suppression 

capability. 

(4) Assessment of brigade leader's 

direction of the fire fighting effort as to 

thoroughness, accuracy, and effectiveness. 

4. Records 

Individual records of training provided to 

each fire brigade member, including drill 

critiques, shall be maintained for at least 3 

years to ensure that each member receives 

training in all parts of the training program. 

These records of training shall be available 

for NRC review. Retraining or broadened 

training for fire fighting within buildings shall 

be scheduled for all those brigade members 

whose performance records show 
E-11 

deficiencies. 

J. Emergency lighting. Emergency 

lighting units with at least an 8-hour battery 

power supply shall be provided in all areas 

needed for operation of safe shutdown 

equipment and in access and egress routes 

thereto. 

K. Administrative controls. 

Administrative controls shall be established 

to minimize fire hazards in areas containing 

structures, systems, and components 

important to safety. These controls shall 

establish procedures to: 

1. Govern the handling and limitation of 

the use of ordinary combustible materials, 

combustible and flammable gases and 

liquids, high efficiency particulate air and 

charcoal filters, dry ion exchange resins, or 

other combustible supplies in safety-related 

areas. 

2. Prohibit the storage of combustibles 

in safety-related areas or establish 

designated storage areas with appropriate 

fire protection. 

3. Govern the handling of and limit 

transient fire loads such as combustible and 

flammable liquids, wood and plastic 

products, or other combustible materials in 

buildings containing safety-related systems 

or equipment during all phases of operating, 

and especially during maintenance, 

modification, or refueling operations. 

4. Designate the onsite staff member 

responsible for the inplant fire protection 

review of proposed work activities to identify 

potential transient fire hazards and specify 

required additional fire protection in the 

work activity procedure. 

5. Govern the use of ignition sources by 

use of a flame permit system to control 

welding, flame cutting, brazing, or soldering 

operations. A separate permit shall be 

issued for each area where work is to be 

done. If work continues over more than one 

shift, the permit shall be valid for not more 

than 24 hours when the plant is operating or 

for the duration of a particular job during 

plant shutdown. 

6. Control the removal from the area of 

all waste, debris, scrap, oil spills, or other 

combustibles resulting from the work activity 

immediately following completion of the 

activity, or at the end of each work shift, 

whichever comes first. 

7. Maintain the periodic housekeeping 

inspections to ensure continued compliance 

with these administrative controls. 

8. Control the use of specific 

combustibles in safety-related areas. All 

wood used in safety-related areas during 

maintenance, modification, or refueling 

operations (such as lay-down blocks or 

scaffolding) shall be treated with a flame 

retardant. Equipment or supplies (such as 

new fuel) shipped in untreated combustible 

packing containers may be unpacked in 

safety-related areas if required for valid 

operating reasons. However, all 

combustible materials shall be removed 

from the area immediately following the 

unpacking. Such transient combustible 

material, unless stored in approved 

containers, shall not be left unattended 

during lunch breaks, shift changes, or other 

similar periods. Loose combustible packing 

material such as wood or paper excelsior, or 

polyethylene sheeting shall be placed in 

metal containers with tight-fitting self-closing 

metal covers. 

9. Control actions to be taken by an 

individual discovering a fire, for example, 

notification of control room, attempt to 

extinguish fire, and actuation of local fire 

suppression systems. 

10. Control actions to be taken by the 

control room operator to determine the need 

for brigade assistance upon report of a fire 

or receipt of alarm on control room 

annunciator panel, for example, announcing 

location of fire over PA system, sounding 
E-12 

fire alarms, and notifying the shift supervisor 

and the fire brigade leader of the type, size, 

and location of the fire. 

11. Control actions to be taken by the 

fire brigade after notification by the control 

room operator of a fire, for example, 

assembling in a designated location, 

receiving directions from the fire brigade 

leader, and discharging specific fire fighting 

responsibilities including selection and 

transportation of fire fighting equipment to 

fire location, selection of protective 

equipment, operating instructions for use of 

fire suppression systems, and use of 

preplanned strategies for fighting fires in 

specific areas. 

12. Define the strategies for fighting fires 

in all safety-related areas and areas 

presenting a hazard to safety-related 

equipment. These strategies shall 

designate: 

a. Fire hazards in each area covered by 

the specific prefire plans. 

b. Fire extinguishants best suited for 

controlling the fires associated with the fire 

hazards in that area and the nearest 

location of these extinguishants. 

c. Most favorable direction from which to 

attack a fire in each area in view of the 

ventilation direction, access hallways, stairs, 

and doors that are most likely to be free of 

fire, and the best station or elevation for 

fighting the fire. All access and egress 

routes that involve locked doors should be 

specifically identified in the procedure with 

the appropriate precautions and methods 

for access specified. 

d. Plant systems that should be 

managed to reduce the damage potential 

during a local fire and the location of local 

and remote controls for such management 

(e.g., any hydraulic or electrical systems in 

the zone covered by the specific fire fighting 

procedure that could increase the hazards 

in the area because of overpressurization or 

electrical hazards). 

e. Vital heat-sensitive system 

components that need to be kept cool while 

fighting a local fire. Particularly hazardous 

combustibles that need cooling should be 

designated. 

f. Organization of fire fighting brigades 

and the assignment of special duties 

according to job title so that all fire fighting 

functions are covered by any complete shift 

personnel complement. These duties 

include command control of the brigade, 

transporting fire suppression and support 

equipment to the fire scenes, applying the 

extinguishant to the fire, communication 

with the control room, and coordination with 

outside fire departments. 

g. Potential radiological and toxic 

hazards in fire zones. 

h. Ventilation system operation that 

ensures desired plant air distribution when 

the ventilation flow is modified for fire 

containment or smoke clearing operations. 

i. Operations requiring control room and 

shift engineer coordination or authorization. 

j. Instructions for plant operators and 

general plant personnel during fire. 

L. Alternative and dedicated shutdown 

capability. 1. Alternative or dedicated 

shutdown capability provided for a specific 

fire area shall be able to (a) achieve and 

maintain subcritical reactivity conditions in 

the reactor; (b) maintain reactor coolant 

inventory; (c) achieve and maintain hot 

standby2 conditions for a PWR (hot 

shutdown2 for a BWR); (d) achieve cold 

shutdown conditions within 72 hours; and 

(e) maintain cold shutdown conditions 

thereafter. During the postfire shutdown, the 

reactor coolant system process variables 

shall be maintained within those predicted 

for a loss of normal a.c. power, and the 

fission product boundary integrity shall not 

be affected; i.e., there shall be no fuel clad 
E-13 

damage, rupture of any primary coolant 

boundary, of rupture of the containment 

boundary. 

2. The performance goals for the 

shutdown functions shall be: 

a. The reactivity control function shall be 

capable of achieving and maintaining cold 

shutdown reactivity conditions. 

b. The reactor coolant makeup function 

shall be capable of maintaining the reactor 

coolant level above the top of the core for 

BWRs and be within the level indication in 

the pressurizer for PWRs. 

c. The reactor heat removal function 

shall be capable of achieving and 

maintaining decay heat removal. 

d. The process monitoring function shall 

be capable of providing direct readings of 

the process variables necessary to perform 

and control the above functions. 

e. The supporting functions shall be 

capable of providing the process cooling, 

lubrication, etc., necessary to permit the 

operation of the equipment used for safe 

shutdown functions. 

3. The shutdown capability for specific 

fire areas may be unique for each such 

area, or it may be one unique combination 

of systems for all such areas. In either case, 

the alternative shutdown capability shall be 

independent of the specific fire area(s) and 

shall accommodate postfire conditions 

where offsite power is available and where 

offsite power is not available for 72 hours. 

Procedures shall be in effect to implement 

this capability. 

4. If the capability to achieve and 

maintain cold shutdown will not be available 

because of fire damage, the equipment and 

systems comprising the means to achieve 

and maintain the hot standby or hot 

shutdown condition shall be capable of 

maintaining such conditions until cold 

shutdown can be achieved. If such 

equipment and systems will not be capable 

of being powered by both onsite and offsite 

electric power systems because of fire 

damage, an independent onsite power 

system shall be provided. The number of 

operating shift personnel, exclusive of fire 

brigade members, required to operate such 

equipment and systems shall be on site at 

all times. 

5. Equipment and systems comprising 

the means to achieve and maintain cold 

shutdown conditions shall not be damaged 

by fire; or the fire damage to such 

equipment and systems shall be limited so 

that the systems can be made operable and 

cold shutdown can be achieved within 72 

hours. Materials for such repairs shall be 

readily available on site and procedures 

shall be in effect to implement such repairs. 

If such equipment and systems used prior to 

72 hours after the fire will not be capable of 

being powered by both onsite and offsite 

electric power systems because of fire 

damage, an independent onsite power 

system shall be provided. Equipment and 

systems used after 72 hours may be 

powered by offsite power only. 

6. Shutdown systems installed to ensure 

postfire shutdown capability need not be 

designed to meet seismic Category I 

criteria, single failure criteria, or other 

design basis accident criteria, except where 

required for other reasons, e.g., because of 

interface with or impact on existing safety 

systems, or because of adverse valve 

actions due to fire damage. 

7. The safe shutdown equipment and 

systems for each fire area shall be known to 

be isolated from associated non-safety 

circuits in the fire area so that hot shorts, 

open circuits, or shorts to ground in the 

associated circuits will not prevent operation 

of the safe shutdown equipment. The 

separation and barriers between trays and 

conduits containing associated circuits of 

one safe shutdown division and trays and 

conduits containing associated circuits or 
E-14 

safe shutdown cables from the redundant 

division, or the isolation of these associated 

circuits from the safe shutdown equipment, 

shall be such that a postulated fire involving 

associated circuits will not prevent safe 

shutdown.3 

M. Fire barrier cable penetration seal 

qualification. Penetration seal designs must 

be qualified by tests that are comparable to 

tests used to rate fire barriers. The 

acceptance criteria for the test must include 

the following: 

1. The cable fire barrier penetration seal 

has withstood the fire endurance test 

without passage of flame or ignition of 

cables on the unexposed side for a period 

of time equivalent to the fire resistance 

rating required of the barrier; 

2. The temperature levels recorded for 

the unexposed side are analyzed and 

demonstrate that the maximum temperature 

is sufficiently below the cable insulation 

ignition temperature; and 

3. The fire barrier penetration seal 

remains intact and does not allow projection 

of water beyond the unexposed surface 

during the hose stream test. 

N. Fire doors. Fire doors shall be selfclosing or provided with closing 

mechanisms and shall be inspected 

semiannually to verify that automatic holdopen, release, and closing mechanisms and 

latches are operable. 

One of the following measures shall be 

provided to ensure they will protect the 

opening as required in case of fire: 

1. Fire doors shall be kept closed and 

electrically supervised at a continuously 

manned location; 

2. Fire doors shall be locked closed and 

inspected weekly to verify that the doors are 

in the closed position; 

3. Fire doors shall be provided with 

automatic hold-open and release 

mechanisms and inspected daily to verify 

that doorways are free of obstructions; or 

4. Fire doors shall be kept closed and 

inspected daily to verify that they are in the 

closed position. 

The fire brigade leader shall have ready 

access to keys for any locked fire doors. 

Areas protected by automatic total 

flooding gas suppression systems shall 

have electrically supervised self-closing fire 

doors or shall satisfy option 1 above. 

O. Oil collection system for reactor 

coolant pump. The reactor coolant pump 

shall be equipped with an oil collection 

system if the containment is not inerted 

during normal operation. The oil collection 

system shall be so designed, engineered, 

and installed that failure will not lead to fire 

during normal or design basis accident 

conditions and that there is reasonable 

assurance that the system will withstand the 

Safe Shutdown Earthquake.4 

Such collection systems shall be 

capable of collecting lube oil from all 

potential pressurized and unpressurized 

leakage sites in the reactor coolant pump 

lube oil systems. Leakage shall be collected 

and drained to a vented closed container 

that can hold the entire lube oil system 

inventory. A flame arrester is required in the 

vent if the flash point characteristics of the 

oil present the hazard of fire flashback. 

Leakage points to be protected shall include 

lift pump and piping, overflow lines, lube oil 

cooler, oil fill and drain lines and plugs, 

flanged connections on oil lines, and lube oil 

reservoirs where such features exist on the 

reactor coolant pumps. The drain line shall 

be large enough to accommodate the 

largest potential oil leak. 

(45 FR 76611, Nov. 19, 1980; 46 FR 

44735, Sept. 8, 1981, as amended at 53 FR 

19251, May 27, 1988; 65 FR 38191, June 
E-15 

20, 2000) 

1 Alternative shutdown capability is 

provided by rerouting, relocating, or 

modifying existing systems; dedicated 

shutdown capability is provided by installing 

new structures and systems for the function 

of post-fire shutdown. 

2 As defined in the Standard Technical 

Specifications. 

3 An acceptable method of complying 

with this alternative would be to meet 

Regulatory Guide 1.75 position 4 related to 

associated circuits and IEEE Std 384-1974 

(Section 4.5) where trays from redundant 

safety divisions are so protected that 

postulated fires affect trays from only one 

safety division. 

4 See Regulatory Guide 1.29--"Seismic 

Design Classification" paragraph C.2. 
E-16 

This page intentionally left blank. 
F-1 

Appendix F Summary of GL 06-03 Responses 

Compiled Listing of ERFBS used in NPP as of December 21, 2007 

The following list has been compiled from feedback obtained through GL 06-03. This list differs from the table p

beginning on page 1-2 of this report. Table 1.1. is based on docketed information for licensees and feedback recomment. Table F.1 has been generated from docketed responses to GL 06-03. Both tables should be used foonly and do not constitute licensing bases. 

Table F.1. Summary of GL 06-03 Responses 

Plant Name 

ADAMS Accession No. 

Type(s) of 

Licensee 

Response NRC Closeout 

Arkansas Nuclear One Units, 1 and 2 ML061720459 ML062620115 Hemyc, Thermo-Lag, VeBeaver Valley Power Station, Units 1 and 2 

ML061710429 ML070370315 ML070680131 Thermo-Lag, 3M Interam

Braidwood Station, Units, 1 and 2 

ML061640343 ML071520085 ML071700766 3M Interam 

Browns Ferry Nuclear Plant 

Units, 1, 2, and 3 ML061600208 ML070250411 Thermo-Lag 

Brunswick Steam Electric Plant 

Units, 1 and 2 ML061640386 ML071580106 3M Interam 

Byron Station, Units, 1 and 2 ML061640343 ML071000347 Darmatt Callaway Plant, Unit 1 

ML061570382 ML062060383 ML062680005 Darmatt 

Calvert Cliffs Nuclear Power Plant 

Units, 1 and 2 ML061650026 ML070880103 None 

Catawba Nuclear Station, Units, 1 and 2 ML061640310 ML071430127 Hemyc 
F-2 

Table F.1. Summary of GL 06-03 Responses (Continued) 

Plant Name 

ADAMS Accession No. 

Type(s) of 

Licensee 

Response NRC Closeout 

Clinton Power Station, Unit 1 

ML061640343 ML071520085 ML071700766 Thermo-Lag, 3M Interam 

Columbia Generating Station ML061710470 ML062850088 3M Interam, Darmatt Comanche Peak Steam Electric Station, 

Units, 1 and 2 ML061660092 ML071230006 Hemyc, Thermo-Lag 

Cooper Nuclear Station ML061530275 ML061650200 None Crystal River Unit 3 Nuclear Generating 

Plant ML061570390 ML071580594 Thermo-Lag, Mecatiss 

Davis Besse Nuclear Power Station, 

Unit 1 

ML061710429 ML070370315 ML070680131 3M Interam 

Diablo Canyon Nuclear Power Plant, 

Units, 1 and 2 ML061720079 ML063390066 3M Interam, Pyrocrete 

Donald C. Cook Nuclear Power Plant Units, 1 and 2 

 ML061600213 ML070180221 Thermo-Lag, Darmatt, M

Dresden Nuclear Power Station, 

Units, 2 and 3 ML061640343 

ML063000065 ML071360223 3M Interam 

Duane Arnold Energy Center ML061640269 ML070860462 Darmatt Edwin I. Hatch Nuclear Plant 

ML061600376 ML063330230 ML071280045 3M Interam, Promat 

Fermi-2 

ML061660087 ML070580135 ML070860419 3M Interam 

James A. Fitzpatrick Nuclear Power Plant ML061650025 ML062960164 Hemyc, FP-60 
F-3 

Table F.1. Summary of GL 06-03 Responses (Continued) 

Plant Name 

ADAMS Accession No. 

Type(s) of 

Licensee 

Response NRC Closeout 

Fort Calhoun Station, Unit 1 

ML061530476 ML070850193 ML071060295 3M Interam, Pyrocrete, 

R. E Ginna Nuclear Power Plant ML061650026 ML070940337 Hemyc, MT Grand Gulf Nuclear Station ML061570135 ML061650383 Thermo-Lag, 3M Interam Shearon Harris Nuclear Power Plant, Unit 1 

ML061240052 ML061710062 ML062900541 Hemyc, MT, Thermo-La

Edwin I. Hatch Nuclear Plant 

ML061600376 ML072060088 ML072180188 Promat 

Hope Creek Generating Station ML061660080 ML061810011 None Indian Point Nuclear Generating, 

Units, 2 and 3 ML061720091 ML073320029 Hemyc, 3M Interam 

Kewaunee Power Station 

ML061590505 ML071520515 ML072500079 3M Interam 

LaSalle County Station, Unit 1 ML061640343 

ML062300114 ML071360223 Darmatt, Kaowool 

LaSalle County Station, Unit 2 ML061640343 

ML062300114 ML071360223 Darmatt, Kaowool 

Limerick Generating Station, Units, 1 and 2 ML061640343 ML071000347 Thermo-Lag, Darmatt McGuire Nuclear Station, Units, 1 and 2 ML061640310 ML071430162 Hemyc Millstone Power Station, Units, 2 and 3 

ML061590505 ML071520515 ML073060163 None 

Monticello Nuclear Generating Plant, 

Unit 1 ML061600209 ML061810437 None 
F-4 

Table F.1. Summary of GL 06-03 Responses (Continued) 

Plant Name 

ADAMS Accession No. 

Type(s) of 

Licensee 

Response NRC Closeout 

Nine Mile Point Nuclear Station, 

Units, 1 and 2 ML061650026 ML070880123 None 

North Anna Power Station, Units, 1 and 2 

ML061590505 ML071520515 ML071910366 3M Interam 

Oconee Nuclear Station, Units, 1, 2, and 3 ML061640310 ML061650421 None Oyster Creek Nuclear Generating Station ML061640343 ML071000347 Thermo-Lag, Mecatiss Palisades Nuclear Plant ML061600209 ML070660064 Concrete Palo Verde Nuclear Generating Station, 

Units, 1, 2, and 3 ML061650261 ML063540027 Thermo-Lag 

Peach Bottom Atomic Power Station, 

Units, 2 and 3 ML061640343 ML071000347 Thermo-Lag, Darmatt 

Perry Nuclear Power Plant, Unit 1 

ML061710429 ML070370315 ML070680131 3M Interam 

Pilgrim Nuclear Power Station ML061640132 ML063620110 3M Interam, Mecatiss Point Beach Nuclear Plant, Units, 1 and 2 

ML061600209 ML062550167 ML061640009 3M Interam 

Prairie Island Nuclear Generating Plant, 

Units, 1 and 2 ML061600209 ML062050077 3M Interam, Darmatt 

Quad Cities Nuclear Power Station, 

Units, 1 and 2 

ML061640343 ML071630310 ML071700766 3M Interam, Darmatt, Ve

River Bend Station, Unit 1 

ML061570394 ML061670210 ML061650386 Thermo-Lag 

H. B. Robinson Steam Electric Plant, Unit 2 

ML061640136 ML072250063 ML071070583 3M Interam 
F-5 

Table F.1. Summary of GL 06-03 Responses (Continued) 

Plant Name 

ADAMS Accession No. 

Type(s) of 

Licensee 

Response NRC Closeout 

St. Lucie Plant, Units, 1 and 2 

ML061640269 ML062680162 ML063070029 Hemyc, Thermo-Lag, M

Salem Nuclear Generating Station, 

Units, 1 and 2 ML061660091 ML061810077 3M Interam 

San Onofre Nuclear Generating Station, 

Units, 2 and 3 

ML061590310 ML071710548 

ML071920538 ML072770906 3M Interam, Cerablanke

Seabrook Station, Unit 1 

ML061640269 ML071990101 ML072010149 3M Interam 

Sequoyah Nuclear Plant, Units, 1 and 2 ML061600208 ML070250184 Thermo-Lag South Texas Project, Units, 1 and 2 ML061510352 ML071130024 Thermo-Lag Virgil C. Summer Nuclear Station, Unit 1 

ML061590311 ML062220348 ML061660200 3M Interam, Kaowool 

Surry Power Station, Units, 1 and 2 

ML061590505 ML071520515 ML071910366 Pyrocrete 

Susquehanna Steam Electric Station, 

Units 1 and 2 ML061660076 ML062160010 Thermo-Lag, Darmatt 

Three Mile Island Nuclear Station, Unit 1 ML061640343 ML061810093 Thermo-Lag, Mecatiss Turkey Point Nuclear Generating, 

Units, 3 and 4 ML061640269 ML062910197 Thermo-Lag 

Vermont Yankee Nuclear Power Station ML061630231 ML063620129 3M Interam Vogtle Electric Generating Plant, 

Units, 1 and 2 ML061600376 ML063490324 3M Interam, Cementitiou

Waterford Steam Electric Station, Unit 3 ML061600210 ML062300315 Hemyc, 3M Interam Watts Bar Nuclear Plant, Unit 1 ML061600208 ML070250345 Thermo-Lag 
F-6 

Table F.1. Summary of GL 06-03 Responses (Continued) 

Plant Name 

ADAMS Accession No. 

Type(s) of 

Licensee 

Response NRC Closeout 

Wolf Creek Generating Station, Unit 1 ML061570375 ML061650179 Thermo-Lag, Darmatt 
G-1 

Appendix G Additional Information on ERFBS Acceptance Criteria 

G.1 UL Subject 1724 

UL Subject 1724, “Outline of Investigations for Fire Tests for Electrical Circuit Protective 

Systems,” is an acceptable method of qualifying ERFBS provided the cable qualification testing 

of UL 1724 Appendix B and Generic Letter 86-10 Supplement 1 is performed. 

Appendix B to UL Subject 1724 provides a method acceptable to NRC to determine circuit 

integrity of insulated electrical cables protected with ERFBS. This method evaluates the circuit 

integrity independent of use of an ERFBS. The method consists of exposing unprotected cable 

samples to elevated temperatures in a circulating air oven. The exposure temperatures are 

based on fire endurance test temperature data collected on a bare # 8 American Wire Gauge 

(AWG) conductor protected in a raceway by an ERFBS (data from separate test). 

The cables under evaluation are arranged in a cable raceway (i.e., conduit or ladder-backed or 

solid cable tray) along with a bare #8 AWG conductor that is used to monitor and control the air 

oven temperature. All conductors are energized and monitored for electrical circuit faults 

(1) between individual conductors in a multiconductor cable, (2) between adjacent individual 

conductors (cables), and (3) between the electrical conductors and ground or raceway. The air 

oven exposes the cables to the thermal environment experienced within an ERFBS. The testing 

is conducted until the air oven temperature reaches the maximum interior ERFBS endurance 

test temperature or when a circuit fault occurs. 

During the test, the cables are under constant compression loading to simulate the maximum 

allowable fill of insulated electrical cable. In addition, the test assembly is subjected to an 

impact test representative of the impact force and frequency of impacts that could be 

encountered by the raceway from falling material (e.g., ceiling) during a fire. Circuit integrity is 

monitored during these impact tests. 

Appendix B is typically used when the ERFBS fire endurance testing temperature rise 

acceptance criteria were not met. UL Subject 1724 provides one method to demonstrate the 

functionality of the electrical cables protected with an ERFBS exposed to elevated 

temperatures. 

G.2 NRC Acceptance Criteria 

Supplement 1 to GL 86-10, “Fire Endurance Test Acceptance Criteria for Fire Barrier Systems 

Used to Separate Redundant Safety Shutdown Trains within the Same Fire Area,” and RG 

1.189, “Fire Protection for NPPs,” provide guidance related to the criteria found acceptable to 

NRC for qualifying ERFBSs. It should be understood that these guidance documents only 

provide one particular method that is acceptable to NRC; however, other acceptable methods 

exist such as those used by TVA to license Watts Bar Unit 1 in 1995. 

 
G-2 

Based on past reviews, NRC staff acceptance is based on the barriers performance in the 

following areas: 

 Fire Endurance 

o Test Specimen Construction 

o Hose Stream Test 

o Cable Functionality 

 Combustibility 

 Ampacity Derating 

 Seismic Qualification 

G.2.1 Acceptance Criteria – ERFBS Fire Endurance Test 

NRC considers the fire endurance qualification test for fire barrier materials applied directly to a 

raceway or component to be successful when exposed to a standard time-temperature fire 

endurance exposure if the following conditions are met: 

 The average unexposed side temperature of the fire barrier system, as measured on the 

exterior surface of the raceway or component, did not exceed 139°C (250°F) above its initial 

temperature. 

 Irrespective of the unexposed side temperature rise during the fire test, a visual inspection 

should be performed if cables or components are included in the fire barrier test specimen. 

Cables should not show signs of degraded conditions resulting from the thermal affects of 

the fire exposure. 

 The cable tray, raceway, or component fire barrier system remained intact during the fire 

exposure and water hose stream test without developing any openings through which the 

cable tray, raceway, or component (e.g., cables) is visible. 

NFPA 251 and ASTM E-119 allow the temperature criteria to be determined by averaging 

thermocouple temperature readings. For the purposes of the first criterion, thermocouple 

averaging can be used provided similar series of thermocouples (e.g., cable tray side rail) are 

averaged together to determine temperature performance of the raceway fire barrier system. 

In addition, conditions of acceptance are placed on the temperatures measured by a single 

thermocouple. If any single thermocouple exceeds 30 percent of the maximum allowable 

temperature rise (i.e., 139°C + 42°C = 181°C (250°F + 75°F = 325°F)), the test exceeded the 

temperature criteria limit. This is a single point failure and often indicates a joint failure in an 

otherwise acceptable ERFBS. 

Because of the poor thermal conductivity of cable jacket and insulation material, measuring 

cable temperatures is not considered a reliable means for determining excessive temperature 

conditions that may occur at any point along the length of the cable during the fire test. In lieu of 

measuring the unexposed surface temperature of the fire barrier test specimen, methods that 

will adequately measure the surface temperature of the raceway (e.g., exterior of the conduit, 

side rails of cable trays, bottom and top of cable tray surfaces, junction box external surfaces) 

can be considered as equivalent if the raceway components used to construct the fire test 

specimen represent plant-specific components and configuration. The metal surfaces of the 

raceway, under fire test conditions, exhibit good thermal conductivity properties. Temperatures 
G-3 

measured on these surfaces provide a reliable indication of the actual temperature rise within 

the fire barrier system. 

The basic premise of NRC fire resistance criteria is that fire barriers that do not exceed the 

maximum allowable temperature rise and pass the hose stream test to provide adequate 

assurance that the shutdown capability is protected without further analyses. If the temperature 

criteria are exceeded, sufficient additional information is needed to perform an engineering 

evaluation to demonstrate that the shutdown capability is protected. 

The following are acceptable placement of thermocouple for determining the thermal 

performance of raceway or cable tray fire barrier systems that contain cables during the fire 

exposure: 

 Conduits – Unexposed surface of the fire barrier system should be measured by placing 

thermocouples every 152 mm (6-in) on the exterior conduit surface underneath the fire 

barrier material. The thermocouples should be attached to the exterior conduit surface 

located opposite the test deck and closest to the furnace fire source. Thermocouples should 

also be placed immediately adjacent to all structural members, supports, and barrier 

penetrations. 

 Cable Trays – The temperature rise on the unexposed surface of a fire barrier system 

installed on a cable tray should be measured by placing the thermocouples on the exterior 

surface of the tray side rails between the cable tray side rail and the fire barrier material. In 

addition to placing thermocouples on the side rails, thermocouples should be attached to two 

AWG 8 stranded bare copper conductors. The first copper conductor should be installed on 

the bottom of the cable tray rungs along the entire length and down the longitudinal center of 

the cable tray run. The second conductor should be installed along the outer top surface of 

the cables closest to the top and toward the center of the fire barrier. The bare copper wire is 

more responsive than cable jackets to temperature rise within the fire barrier enclosure. The 

temperature changes measured along the bare copper conductors provide indication of joint 

failure or material burn through conditions. Thermocouples should be placed every 152 mm 

(6-in) down the longitudinal center along the outside surface of the cable tray side rails and 

along the bare copper conductors. Thermocouples also should be placed immediately 

adjacent to all structural members, supports, and barrier penetrations. 

 Junction Boxes – The temperature rise on the unexposed surface of a fire barrier system 

installed on junction boxes should be measured by placing thermocouples on either the 

inside or the outside of each junction box (JB) surface. Each JB surface or face should have 

a minimum of one thermocouple located at its geometric center. In addition, one 

thermocouple should be installed for every 1 square foot of JB surface area. These 

thermocouples should be located at the geometric centers of the 1-square-foot areas. 

At least one thermocouple should also be placed within 25 mm (1-in) of each penetration 

connector/interface. 

 Airdrops – The internal airdrop temperatures should be measured by thermocouples placed 

every 305 mm (12-in) on the cables routed within the air drop and by a stranded AWG 8 bare 

copper conductor routed inside and along the entire length of the airdrop system with 

thermocouples installed every 152 mm (6-in) along the length of the copper conductor. 

The copper conductor should be in close proximity with the unexposed surface of the fire 

barrier material. Thermocouples also should be placed immediately adjacent to all supports 

and barrier penetrations. 
G-4 

With the exception of airdrops, the installation of thermocouples on cables is optional and is left 

to the discretion of the licensee, test sponsor, or test laboratory. Cable thermocouples are to be 

used for engineering purposes only. Cable thermocouples alone are not acceptable for the 

demonstration of fire barrier performance. However, cable thermocouples may support fire 

barrier deviation conditions. 

Regarding the second criteria, examples of thermal cable degradation include: 

 Jacket swelling, 

 Splitting, 

 Cracking, 

 Blistering, 

 Melting, or discoloration, 

 Exposed shield, 

 Jacket hardening; 

 Exposed conductor insulation, degraded, or discolored; and 

 Exposed bare copper conductor. 

For those cases where signs of thermal degradation are present, the fire barrier did not perform 

its intended fire-resistive function. For these barriers, a deviation based on demonstrating that 

the functionality of thermally degraded cables or component was maintained and that the cables 

or component would have adequately performed their intended function during and after a 

postulated fire exposure may be acceptable. Refer to Section G.2.4 for more information on 

cable functionality testing. 

When evaluating the test results to configurations installed in the plant, the installed ERFBS 

configuration can be considered to be bounded by a tested ERFBS configuration only if the 

physical configuration (dimensions of the raceway, number of layers, interfering items, 

protection of supports, etc.) are the same as the tested configuration and the weight of the 

raceway, including cables, equals or exceeds the weight of the tested configuration. For 

example, a 4-inch conduit with a raceway total mass (including conduit and cables) of 16.5 

pounds (7.5 kilograms) would bound a 4-inch conduit with a raceway total mass of 9.1 kilograms 

(20 pounds). However, 4-inch conduit with a total raceway of 6.8 kilograms (15 pounds) would 

be considered indeterminate when using this test data. Explained differently, for a plant 

configuration to be bounded by a qualified test configuration, the plant configuration must be of 

the same physical construction and have a thermal mass equivalent or greater than the tested 

configuration. 

G.2.2 Acceptance Criteria – Test Specimen Construction 

In addition to the above criteria, GL 86-10 Supplement 1 provides guidance on acceptable 

methods for conducting the fire endurance test, including: 

 Raceway fire barrier system construction should be representative of the end use 

o (i.e., if raceway supports are not protected in actual plant applications, then they should 

not be protected in test), 

 Test program should encompass or bound raceway sizes and the various configurations for 

those fire barrier systems installed in the plant, and 

 Tests should be conducted without cables. 
G-5 

Supplement 1 to GL 86-10 also provides guidance on acceptable placement of thermocouples, 

which includes placing a bare single conductor 8 AWG cable, instrumented every 152 mm (6-in) 

with thermocouples. The bare copper wire is more responsive than cable jackets to 

temperature rise within the fire barrier enclosure. Where exact replication of a tested 

configuration cannot be achieved, the field installation should meet all of the following criteria: 

 The continuity of the fire barrier material is maintained. 

 The thickness of the barrier is maintained. 

 The nature of the support assemblies is unchanged from the tested configuration. 

 The application or “end use” of the fire barrier is unchanged from the tested configuration. 

For example, the use of cable tray barriers to protect a cable tray which differs in 

configuration from those that were tested would be acceptable. However, the use of 

structural steel fire proofing to protect a cable tray assembly may not be acceptable. 

 The configuration has been reviewed by a qualified fire protection engineer and found to 

provide an equivalent level of protection. 

Although cables may be placed within the raceway, NRC has determined that measuring cable 

temperature is not a reliable means for determining excessive temperature conditions that may 

occur at any point along the length of the cable during the fire test. Monitoring cable 

temperature as the primary method of determining cable tray or raceway fire barrier 

performance is a nonconservative approach. The additional thermal mass added by the cables 

may cause the internal fire barrier temperature rise conditions to be masked. As stated in the 

acceptance criteria above, temperature monitored on the exterior surface of the raceway 

provides a more representative indication of fire barrier performance. The metal surfaces of the 

raceway, under fire test conditions, exhibit good thermal conductivity properties. As such, 

temperatures measured on these surfaces provide an indication of the actual temperature rise 

within the fire barrier system. The following provides a technical basis for the effects of cable 

mass on ERFBS thermal performance, based on an evaluation of Thermo-Lag fire test results. 

G.2.2.1 Effects of Cable Mass in the Thermal Performance of ERFBS 

As a part of the TVA Thermo-Lag 330-1 ERFBS program, Salley and Brown investigated the 

effects of cable fill on the thermal performance of the ERFBS. The following is their description 

of the cable tray testing and resultant relationships. 

The first three Phase II fire tests of the joint TVA/TSI program were dedicated to cable tray 

configurations. TVA test 6.1.7 "Fire Endurance Test of Thermo-Lag 330-1 Fire Protective 

Envelopes (Three 18 in. Cable Trays and a 3 in. Conduit)" (41) consisted of three 18-inch wide, 

ladder back, steel cable trays with identical upgraded ERFBS and varying cable fill. The left tray 

in the test deck represented a maximum filled tray (i.e., 289 4/C #16 AWG (69.36 lbs. 

cable/linear ft)). The center tray in the test deck was filled with a single layer of cables (i.e., 26 

4/C #16 AWG (6.24 Lbs. cable/linear ft)). The protected cable trays were constructed by the 

same installers and subjected to the same test fire to reduce as many variables as possible. 

The right tray in the test deck represented an empty tray i.e., no cables). The results of the fire 

test are shown in Figure G-1. 
G-6 

Figure G-1. Effects of Cable Mass on Cable Tray ERFBS Performance 

(M.H. Salley Thesis UMd 2000) 

At the end of the test, the only thermocouples to exceed the acceptance temperature were 

those on the instrumented bare #8 AWG copper cable inside the empty tray. This occurred at 56 

minutes into the 1-hour test. The ambient temperature at the start of the test was 28 °C (83 °F) 

which dictated a maximum average temperature of 167 °C (333 °F) at 60 minutes (ambient 

temperature plus 121 °C (250 °F) allowable rise). By plotting the weight of each cable tray 

system (i.e., the weight of the tray and cables and not including the weight of the Thermo-Lag 

330-1 ERFBS that was about approximately the same for each tray) versus its temperature at 

60 minutes, an expression for the effects of cable mass can be developed (lumped heat 

formation). 

t q A mC T p    " (Equation G-1) 

mCp

q A

t

T "  



( ) " mC t

q A T T

p

   

( ) " mC t

q A T T p

    (Equation G-2) 

 where: 

 m = mass of raceway (mr) + mass of cable (mc) 

 q"= rate of heat transfer 

 A = area 
G-7 

 Cp = specific heat 

The correlation of the curves could be further defined as follows: 

t q A m C m C T r p r c p c     " ( ) , ,  (Equation G-3) 

m C m C t

q A T T r p r c p c ( ) "

,  ,

    (Equation G-4) 

The test laboratory, OPL, developed an exact equation using a computer model based on a 

"best fit" curve approach with a logarithmic relationship from the data shown in Figure G-2 (i.e., 

results of linear regression, method of least squares).20

Figure G-2. Cable Tray System Weight vs. Endpoint Temperatures - Test 1 

(M.H. Salley Thesis UMd 2000) 

The equation is: 

 Final Temp = 387.9 – 86.75*Log (Weight) (Equation G-5) 

 where: 

 Final Temp. = Degrees Fahrenheit21

 

20 The constants developed for these equations were originally based on the British Units and no 

International System of Units (SI) conversions were performed. 

21 The ambient starting temperature of 83 °F must be used for the equation to be valid. The figure has 
G-8 

 Weight = Lbs/ft of cable tray and cables 

This equation is valid for 18-inch-wide cable trays protected with the TVA-designed Thermo-Lag 

330-1 ERFBS having cable fills ranging from 6.24 lbs/ft up thru 69.36 lbs/ft. Further review was 

performed on the results of the single-layer-filled cable tray (6.24 lbs/ft of cable) and the empty 

cable tray (0.0 lbs/ft of cable). This was determined to be necessary because the effects of 

adding cables over the first layer becomes less important because of the cable insulation 

slowing the heat transfer to the copper conductors. Figure G-3 shows this data. 

Figure G-3. Cable Tray System Weight vs. Endpoint Temperatures - Test 2 

(M.H. Salley Thesis UMd 2000) 

Conservatively, a plot was constructed of the temperatures for the empty cable tray (0.0 lbs/ft of 

cable) and the single-layer cable tray (6.24 lbs/ft of cable). The resulting linear equation given 

below conservatively predicts the system's thermal response at low cable fills (i.e., less than 

6.24 lbs/ft of cable). 

 Final Temp. = 385.10 – 9.7756 * (w) (Equation G-6)22

 where: 

 Final Temp. = Degree Fahrenheit23

 

been simplified (i.e., the ambient temperature subtracted) to graphically show the allowable temperature 

rise (i.e., ∆T=250°F). 22 The constants developed for these equations were originally based on the British Units and no 

International System of Units (SI) conversions were performed. 
G-9 

 w = total weight of cable tray and cables (Lbs/ft) 

Solving this linear equation in the range of acceptable temperatures indicates that a cable tray 

system with a weight of 5.33 lbs/ft would maintain acceptable temperatures for 60 minutes. 

Subtracting the weight of the cable tray (4.00 lbs/ft) from the system yields a cable loading of 

1.33 lbs/ft. Based on the cables used in the test (4C #16 AWG = 0.24 lbs/ft), a minimum of six 

cables are needed to produce acceptable temperatures (i.e., AT < 250 °F). 

The TVA has also performed similar tests on Thermo-Lag 330-1 ERFBS for aluminum conduits 

as installed at SQN (42). The testing consisted of three, 76.2 mm (3 in.) diameter aluminum 

conduits with identical minimum 12.7 mm (1/2 in.) thick Thermo-Lag 330-1 ERFBS. Conduit "B" 

had no cable fill, conduit "C" had five 7/C #16 AWG (0.85 Lb/linear ft) cables installed, and "D" 

had 16 7/C #16 AWG (2.70 Lbs./linear ft) cables installed. Figure G-4 shows the plot of the 

system weight vs. endpoint data for the surface of the conduit while Figure G-5 shows the plot 

of the system weight vs. endpoint data for the bare copper conductor located inside the conduit. 

Figure G-4. Conduit System Weight vs. Endpoint Temperatures - Measured on the 

Conduit (M.H. Salley Thesis UMd 2000) 

 

23 The ambient starting temperature of 83 °F must be used for the equation to be valid. The figure has 

been simplified (i.e., the ambient temperature subtracted) to graphically show the allowable temperature 

rise (i.e., ∆T = 250 °F). 
G-10 

Figure G-5. Conduit System Weight vs. Endpoint Temperatures 

Measured on the Bare Copper Conductor Inside the Raceway 

(M.H. Salley Thesis UMd 2000) 

Table G-1 shows the temperatures recorded at the end of the 1-hour ASTM E 119 

fire exposure. 

Table G-1. Effects of Cable Mass on ERFBS Thermal Performance 

Conduit 

(Number of Cables) 

Average External conduit 

Temperature °C (°F) 

Average Internal Conduit 

Temperature °C (°F) 

B 

(0) 

138 

(280) 

156 

(313) 

C 

(5) 

105 

(221) 

141 

(286) 

D 

(16) 

81 

(177) 

129 

(264) 

Reviewing the temperature profiles, the plots demonstrated that the rate of temperature rise was 

inversely proportional to the cable mass. Performing a linear regression, method of least 

squares, OPL developed the following relationships to predict the end point temperature based 

on cable mass: 

External Conduit Temperature (°F) = 366.37 – 147.23*Log(w+2.41) (Equation G-7) 

Internal Conduit Temperature (°F) = 390.96 – 308.60*Log(w+2.41) (Equation G-8) 
G-11 

 where: 

Temperature = final temperature in °F at 60 minutes of exposure with 

an assumed starting temperature of 65°°F 

w = weight in pounds of cable per linear foot (Lbs/ft) 

Another noteworthy observation is the average external surface temperature of the aluminum 

conduit compared to the average internal temperature as shown in Table G-2. The cable fill not 

only reduces the external temperature rise of the raceway as shown by the values in Table G-2, 

but an even greater temperature reduction occurs inside the raceway. 

 Table G-2. ERFBS Protected Conduit - External Raceway Surface vs. Internal 

 Area Temperature Differential as a Function of Cable Mass 

 (M.H. Salley Thesis UMd 2000) 

Conduit 

(Number of Cables) 

External vs. Internal Temperature 

Difference as a Function of Cable Fill 

°C (°F) 

B 

(0) 

18 

(64) 

C 

(5) 

36 

(97) 

D 

(16) 

48 

(118) 

In summary, the TVA research demonstrated that properly designed and installed Thermo-Lag 

330-1 provides an effective ERFBS. The TVA research also provides insight to the effects of 

thermal mass inside a protected electrical raceway, and the temperature gradients across the 

assembly. 

G.2.3 Acceptance Criteria – Hose Stream Test 

The purpose of the hose stream test is to evaluate the cooling, impact and erosion aspects of 

the ERFBS. NRC identified that the hose stream application specified in NFPA 251 an 

acceptable method of application for safe-shutdown-related fire barrier systems that have been 

exposed to the fire endurance exposure. NFPA 251 required that as a condition of acceptance 

a hose stream test be conducted on a duplicate specimen subjected to a fire exposure test of 

one-half the duration of the resistance period but no more than 1 hour, followed by a hose 

stream impact test. The standard provided specifics on hose stream equipment and water 

pressures varied by resistance. 

As an alternative to the procedure specified in NFPA 251, NRC also found it acceptable to 

perform the hose stream immediately after the completion of the full fire endurance test period 

on a single specimen, provided that one of the following applications methods are used. 

 The stream applied at random to all exposed surfaces of the test specimen through a 6.4 cm 

(2.5 inch) national standard playpipe with a 2.9 cm (1.1 inch) orifice at a pressure of 

207 kiloPascals (30 lbs per in2

) at a distance of 6.1 m (20 feet) from the specimen. (Duration 

of the hose stream application - 1 minute for a 1-hour barrier and 2 minutes for a 3-hour 

barrier); or 
G-12 

 The stream applied at random to all exposed surfaces of the test specimen through a 3.8-cm 

(1.5-inch) fog nozzle set at a discharge angle of 30 degrees with a nozzle pressure of 517 

kiloPascals (75 lbs per in2

) and a minimum discharge of 284 liters per minute (75 gallons per 

minute) with the tip of the nozzle at a maximum of 1.5 m (5 ft) from the test specimen. 

(Duration of the hose stream application 5 minutes for both 1-hour and 3-hour barriers); or 

 The stream applied at random to all exposed surfaces of the test specimen through 3.8-cm 

(1.5-inch) fog nozzle set at a discharge angle of 15 degrees with a nozzle pressure of 517 

kiloPascals (75 lbs per in2

) and a minimum discharge of 284 liters per minute (75 gallons per 

minute) with the tip of the nozzle at a maximum of 3 m (10 ft) from the test specimen. 

(Duration of the hose stream application - 5 minutes for both 1-hour and 3-hour barriers.) 

To perform this during actual testing, the test specimen (assembly deck) is typically removed 

from the test furnace, raised 1.2 to 2.4 m (4.0 to 8.0 ft) off of the ground and slowly turned 

(nominally 6 revolutions to 8 revolutions per minute) while being exposed to the impact erosion 

and cooling effects of a hose stream directed perpendicularly at the exposed surface of the test 

specimen. Figure G-6 shows the performance of a hose stream test following the fire 

endurance portion of testing. 

Figure G-6. Post-Fire Exposure – Hose Stream Test 

 (NRC Hemyc Tests 2005) 

G.2.4 Acceptance Criteria – Cable Functionality 

When the ERFBS doesn’t pass the endurance testing criteria specified above, a deviation 

based on demonstrating that the functionality of thermally degraded cables or component was 

maintained and that the cables or component would have adequately performed their intended 

function during and after a postulated fire exposure may be acceptable. Enclosure 2 to GL 86-

10, Supplement 1, provides NRC staff guidance on acceptable methods to perform the cable 

functionality testing and engineering determination (often called an “engineering evaluation”). 

These methods include evaluation of equipment qualification tests, cable insulation tests, and 
G-13 

air oven tests. The remainder of this section will describe these methods. However, it should 

be noted that Enclosure 2 also stated that circuit integrity monitoring, as specified in the ANI 

standard, is not acceptable to NRC staff for determination of cable integrity. 

The American Nuclear Insurers (ANI) testing standard provided the first method available to 

perform cable integrity testing (for insurance purposes only). As was mentioned above, this ANI 

method used low voltages that would not typically be used in nuclear power plants for 

safety-related equipment important to safe shutdown. NRC and licensees felt that the use of 

this low-voltage testing would only indicate a dead short or open circuit fault. Realistic circuits’ 

loss-of-cable insulation conditions can exist during the fire tests without a dead short occurring. 

As a result of this determination, the use of circuit-integrity monitoring during the fire-endurance 

test is not a valid method for demonstrating that the protected shutdown circuits are capable of 

performing their required function during and after the test fire exposure. Therefore, 

circuit-integrity monitoring is not required to satisfy NRC acceptance criteria for fire barrier 

qualification. 

The purpose of the functionality test is to justify observed deviations in fire barrier performance. 

For those fire barrier test specimens that are tested without cables, an engineering analysis 

justifying internal fire barrier temperature conditions greater than allowed can be based on a 

comparison of the fire barrier internal temperature profile measured during the fire-endurance 

test to existing cable-specific performance data such as environmental qualification (EQ) tests. 

Comparison of the fire barrier internal time-temperature profile measured during the 

fire-endurance test to existing cable performance data, such as data from the EQ tests, could be 

submitted to the NRC staff as a method for demonstrating cable functionality. The EQ testing 

was performed to rigorous conditions, including rated voltage and current. Correlating the EQ 

test time-temperature curve to that of the ERFBS fire endurance test would provide a viable 

mechanism to ensure cable functionality. In addition, the large volume of EQ test data presents 

a cost-effective approach to addressing cable functionality for fire testes for those cases where 

the 163°C (325°F) limit is exceeded. 

Cable insulation testing can be used as an acceptable method for demonstrating cable 

functionality. Supplement 1 to GL 86-10, provides one method acceptable to NRC for 

demonstrating cable functionality through the use of cable insulation testing. Table G-3 

summarizes the acceptable cable insulation testing approach. This approach uses a megom to 

test conductors for any insulation damage (often referred to as megger testing). The megom 

applies a direct current (dc) voltage between the two conductive planes being tested and 

outputs the resistance of the insulation between the two conductive planes. The Megger test 

provides a nondestructive method to evaluate cable performance. 

 
G-14 

Table G-3: Summary of Acceptable Cable Insulation Testing Approach 

Type 

Operating 

Voltage 

Megger Test 

Voltage 

High Potential 

Test Voltage 

Power ≥ 1000 V ac 2500 V dc 60% x 80 V/mil (ac) 

60% x 240 V/mil (dc) 

Power < 1000 V ac 1500 V dc* None 

Instrument 

and 

Control 

≤ 250 V dc 

≤ 120 V ac 500 V dc 

* A Megger test voltage of 1000 V dc is acceptable provided a Hi-Pot test 

is performed after the Megger test for power cables rated at less than 

1000 V ac. 

To provide reasonable assurance that the cables would have functioned during and after the fire 

exposure, Megger tests need to be performed before the fire tests, at multiple time intervals 

during the test (for instrument cable only), and immediately after the fire test before the hose 

stream test. Megger testing should be done immediately after the fire test such that the cable 

insulation does not reset after the cables are removed from elevated temperatures. As a result 

of cable insulation tendency to reset, Megger tests of insulated cables after the fire endurance 

test and after the cables have cooled may not detect degradation in the insulation resistance. In 

addition, Megger testing should be done conductor-to-conductor for multiconductor cables and 

conductor-to-ground for all cables. The minimum acceptable insulation resistance (IR) value, 

using the test voltage shown above in Table G-3, is determined by using the following 

expression: 

 IR (Mega-ohms) ≥ { (K+1 Mega-ohm ) * 1000 (ft) } (Equation G-9) 

 Length (ft) 

When the ERFBS test specimen is tested without cables and doesn’t pass the endurance 

testing on internal temperature rise, then an Air Oven test may be used to evaluate the 

functionality of cables. This testing method consists of exposing insulated wires and cables at 

rated voltage to elevated temperatures. The Air Oven temperature profile will be the 

temperature measured by the # 8 AWG bare copper conductor during the fire exposure of those 

ERFBS test specimen that were tested without cables. NRC staff determined that the test 

method described by UL Subject 1724, “Outline of Investigations of Fire Tests for Electrical 

Circuit Protective Systems,” Issue Number 2, August 1991, Appendix B, “Qualification Test for 

Circuit Integrity of Insulated Electrical Wires and Cables in Electrical Circuit Protection 

Systems,” was acceptable with the following modifications: 

 During the air oven test, the cables should be energized at rated voltage. The cables should 

to be monitored for conductor-to-conductor faults in multi-conductor cables and conductor-toground in all cables. 

 The cables being evaluated should be subjected to the Megger and high-potential tests. 
G-15 

 The impact force test, which simulated the force of impact imposed on the raceway by the 

solid stream test, described in UL 1724, Appendix B, Paragraph B3.16, is not required to be 

performed. 

The last acceptable method for determining cable functionality, as presented in Supplement 1, 

involves the comparison of cable operating temperature within the ERFBS at the time of failure 

along with the cable thermal exposure threshold (TET). The difference between the cable TET 

and internal ERFBS cable operation temperature presents the maximum temperature rise 

allowed within the ERFBS. The cable TET limits in conjunction with a post test visual cable 

inspection and the Hi-Pot test should demonstrate the functionality of the cable circuit during 

and after a fire. 

G.2.5 Acceptance Criteria – Combustibility of the ERFBS 

NRC’s fire protection guidelines and requirements establish the need for each nuclear power 

plant to perform a plant-specific fire hazard analysis. The fire hazard analysis should consider 

the potential for in situ and transient fire hazards and combustibles. With respect to building 

materials (e.g., cable insulation and jackets, plastics, thermal insulation, fire barrier materials), 

the combustibility, ease of ignition, and flame spread over the surface of a material should be 

considered by the fire hazards analysis. This is especially important when licensee’s have 

installed ERFBS inside containment as “Radiant Energy Shields” that are required to be 

noncombustible per Appendix R to 10 CFR Part 50, which states: 

III.G.2 

Inside noninerted containments one of the fire protection means specified above or 

one of the following fire protection means shall be provided: 

d. Separation of cables and equipment and associated non-safety circuits of 

redundant trains by a horizontal distance of more than 20 feet with no intervening 

combustibles or fire hazards; 

e. Installation of fire detectors and an automatic fire suppression system in the fire 

area; or 

f. Separation of cables and equipment and associated non-safety circuits of 

redundant trains by a noncombustible radiant energy shield. 

A radiant energy shield is a shield designed to provide protection from redundant essential 

raceways or fire safe shutdown equipment against the radiant energy from an exposure fire. 

Radiant energy shields are typically installed within containment. Numerous ERFBS have been 

used to construct these shields and, in some cases, licensees have had to replace or modify the 

shields because they were later determined to be combustible. 

In Branch Technical Position (BTP) CMEB 9.5-1, “Guidelines for Fire Protection for NPPs,” 

dated July 1981, noncombustible materials are defined as: 

a. A material which in the form in which it is used and under the conditions anticipated, will 

not ignite, burn, support combustion, or release flammable vapors when subjected to fire 

or heat. 
G-16 

b. Material having a structural base of noncombustible material, as defined in a., above, 

with a surface not over 0.318 cm (0.125 inch) thick that has a flame spread rating not 

higher than 50 when measured using ASTM E-84. 

Per the guidance in BTP CMEB 9.5-1, an acceptable method to test a materials 

combustibility/flame spread characteristic is to subject it to the ASTM E-84, “Standard Test 

Method for Surface Burning Characteristics of Building Materials.” If the testing results in a 

flame spread not higher than 50, then the material is considered noncombustible. Ease of 

ignition can be determined by the flashover ignition temperature derived by ASTM-D1929, 

“Standard Test Method for Determining Ignition Temperature of Plastics.” 

In addition, Supplement 1 to Generic Letter 86-10 accepted ASTM E-136, “Standard Test 

Method for Behavior of Materials in a Vertical Tube Furnace at 750°C (1382°F),” as an 

acceptable method for determining the combustibility of a fire barrier material. The criteria for 

passing the ASTM E-136 test for classifying a material as noncombustible are that three of the 

four test specimens must meet the following conditions: (1) the increase in the recorded 

temperatures of internal and external thermocouples may not exceed 30°C (86°F), (2) no 

flaming occurs from the test specimen after the first 30 seconds, and (3) if the weight loss of the 

specimen exceeds 50 percent, then the increase in the recorded temperatures of the internal 

and external thermocouples may not exceed the furnace temperature at the beginning of the 

test and the specimen may not flame. 

G.2.6 Acceptance Criteria – Ampacity Derating 

Title 10 of the Code of Federal Regulations, Part 50, Appendix A, General Design Criterion 

(GDC) 17, "Electric power systems," if applicable, requires that onsite and offsite electric power 

systems be provided to permit the functioning of structures, systems, and components important 

to safety. The safety function of either electrical power system (assuming the other system is 

not functioning) is to provide sufficient capacity and capability to ensure that vital functions are 

maintained. Cables routed in electrical raceways are derated to ensure that systems have 

sufficient capacity and capability to perform their intended safety functions. Other factors that 

affect ampacity derating include cable fill, cable loading, cable type, raceway construction, and 

ambient temperature. 

NRC requires that cable derating due to the use of fire retardant coatings be considered by 

utilities during plant design or when design changes are made to existing electrical system 

configurations. The utility is responsible for evaluating the ampacity derating effect of ERFBS 

and applying those factors when designing the current carrying capacity of individual cables. 

Cable derating calculations that are based on inaccurate or non-conservative derating factors 

could result in the installation of undersized cables or overfilling of raceways. Either of these 

conditions could cause operating temperatures to exceed design limits within the raceways, 

thereby reducing the expected design life of the cables. The National Electrical Code, Insulated 

Cable Engineers Association publications, and other industry standards provide general 

ampacity derating factors for open-air installations but do not include derating factors for fire 

barrier systems. The Insulated Conductors Committee of the Institute of Electrical and 

Electronics Engineers (IEEE) Power Engineering Society, Task Force 12-45, has developed 

IEEE Standard Procedure 848, "Procedure for the Determination of the Ampacity Derating of 

Fire Protected Cables," for use as an industry standard. 
G-17 

Appendix A provides a detailed description of ampacity derating. 

G.2.7 Acceptance Criteria – Seismic Qualification 

The regulations that address the need for fire protection at nuclear power plants (i.e., 10 CFR 

Section 50.48; Part 50, Appendix A, General Design Criterion 3; and Part 50 Appendix R) do not 

explicitly require fire barriers to be seismically qualified (i.e., to maintain their functionality after 

postulated seismic events). However, provision C.2 of Regulatory Guide (RG) 1.29, “Seismic 

Design Classification,” addresses the issue of seismic Category II versus seismic Category I. 

In that context, fire barriers are considered a seismic Category II component. Based on these 

provisions, the fire barriers are allowed to undergo damage during the postulated seismic 

events. However, the fire barriers may not lose its position and potentially fall on Class 1E 

equipment. This requirement for position retention is a requirement where Category II 

commodities are located above safety related equipment. 

G.2.8 Test Assembly 

ERFBS fire endurance testing often involves an elaborate test assembly consisting of several 

raceway configurations (e.g., conduit, cable tray, junction box, raceway supports, raceway 

bends, etc.). A typical test deck has a steel framework that provides the structural support for 

raceways and junction boxes. Either a sheet of steel with an insulation fiber blanket or a 

concrete slab is used to provide a continuous enclosure surface to the test deck. The test deck 

has predetermined holes that provide penetration points for the raceways. At the raceway 

penetration point the edges of the raceway are completely filled with a suitable fire stop 

material-usually cement grout, ceramic fiber packed tightly or silicon foam. The penetration 

seal is considered a part of the support system and is not in itself being evaluated by the test. 

Figure G-7 shows a 90° angled test assembly deck with protected raceways installed as test 

specimens. 
G-18 

Figure G-7: Thermo-Lag 90 Degree Test Assembly (TVA Thermo-Lag Test Report) 

Some utilities testing used the 90*-degree test assembly shown in Figure G-7, while others used 

a horizontal test assembly. The horizontal test configurations resulted in the raceways 

penetrating the ceiling of the test deck vertically, extending a few feet into the oven space 

before making a 90-degree bend, then traveling several m horizontally followed by another 90-

degree bend back up through the test deck. Figure G-8 and G-9 depict a typical horizontal test 

deck and associated test oven, respectively. In either case, the test decks provided the mobility 

to allow the installers easy access to the raceways and immediately following the fire endurance 

portion of the test, the test assembly could be hoisted to a location suitable for hose stream 

application. Though the horizontal test configuration was commonly used, several other test 

assembly configurations were used. 

 
G-19 

Figure G-8. Isometric View of Typical Base Horizontal Test Assembly Prior to ERFBS 

 Installation (NRC Hemyc Report by OPL) 

Figure G-9. 12’ x 18’ Horizontal Furnace (Top View) (NRC Hemyc Tests) 
G-20 

G.3 TVA Position 

TVA position of fire testing criteria for fire barrier systems used to protect electrical cabling 

required for 10 CFR 50 appendix r compliance 

BACKGROUND 

There is considerable discussion between NRC, nuclear utilities and manufacturers of fire 

barrier systems on the appropriate test method and acceptance criteria for electrical fire barrier 

systems. NRC has based its methodology and criteria on National Fire Protection Association 

(NFPA) 251, “Standard Method of Fire Tests of Building Construction and Materials,” Chapter 7, 

“Tests of Nonbearing Walls and Partitions.”1 Thermal Science, Inc. (TSI), the manufacturer of 

Thermo Lag, and most nuclear utilities, have based their methodology and criteria on American 

Nuclear Insurers (ANI) “Standard Fire Endurance Test Method to Qualify a Protective Envelope 

for Class 1E Electrical Circuits.”2

 Other manufacturers of fire barrier systems, such as 3M and 

Thermal Ceramics, Inc., have typically used Underwriters Laboratory (UL) test methods and 

acceptance criteria such as UL Subject 1724, “Outline of Investigation for Fire Tests for 

Electrical Circuit Protective Systems.”3 The American Society for Testing and Materials (ASTM) 

has recognized the need to develop a unique test method and acceptance criteria for electrical 

fire barrier systems. They have been working for approximately the last five years on this issue 

but have not issued a standard. 

DISCUSSION 

The Code of Federal Regulations (CFR), Title 10 Part 50 Domestic Licensing of Production and 

Utilization Facilities, Appendix R, Fire Protection Program for Nuclear Power Facilities Operating 

Prior to January 1, 1979, paragraph III.G.2 provides the requirements for fire protection and safe 

shutdown capability. If redundant trains are located in the same fire area and a licensee does 

not provide alternative or dedicated shutdown systems for the redundant equipment in that fire 

area, the three acceptable methods of ensuring that one of the trains is free from fire damage 

are: 

a.) Separation of cables and equipment and associated non-safety circuits of 

 redundant trains by a fire barrier having 3-hour rating. Structural steel forming a 

 part of or supporting such fire barriers shall be protected to provide fire 

resistance equivalent to that required of the barrier; 

b.) Separation of cables and equipment and associated non-safety circuits of 

 redundant trains by a horizontal distance of more than 20 feet with no intervening 

 combustible or fire hazards. In addition, fire detectors and an automatic fire 

 suppression system shall be installed in the fire area; or 

c.) Enclosure of cable and equipment and associated non-safety circuits of one 

 redundant train in a fire barrier having 1-hour rating. In addition, fire detectors 

 and an automatic fire suppression system shall be installed in the fire area.4

 

A fire wall design that has passed on appropriate test method (e.g., NFPA 251) is considered a 

“rated” barrier. Components which penetrate fire walls, such as mechanical and electrical 

penetrations, fire doors, and HVAC fire dampers, are presently not generally accepted test 

method and acceptance criteria specifically applicable to fire barrier enclosures applied to 

electrical cable systems. Existing methods intended for other purposes have been utilized to 
G-21 

test such barrier systems, but none of these standards are fully appropriate to this unique 

application of fire barrier materials. In an attempt to define a test method for electrical circuit 

protection, American Nuclear Insurers (ANI) prepared “Guidelines for Fire Stop and Wrap 

Systems at Nuclear Facilities”. However, this test method was intended to be used “for 

insurance purposes only”.2

 The method and acceptance criteria in the ANI document are not 

definitive. 

POSITION 

The fire test methodology and acceptance criteria for electrical cable systems should be unique 

to these systems. Underwriters Laboratory currently has an appropriate test method (Subject 

1724), which addresses the uniqueness of electrical cable fire barrier systems. This test 

method was developed by UL specifically to address issues such as Appendix R electrical fire 

barrier rating requirements. The scope of the test method is: 

a.) Measurement of temperature changes within the electrical circuit protective 

 system caused by the heat transfer through the electrical circuit protective 

 system to the electrical conductor or raceway, or both, during the external fire 

 exposure test. 

b.) Determination of the integrity of the electrical circuit protective system during the 

 external fire exposure and water hose stream test. 

c.) Determination of the ability of insulated electrical conductors to maintain 

 electrical circuit integrity at the temperature conditions present within the 

 electrical circuit protective system during the external fire exposure test and 

 during the water hose stream test.3

 

Details such as thermocouple types and placements are discussed in this test method. The test 

follows the standard time-temperature curve specified in ASTM E-119, as used in other fire 

endurance tests (e.g., NFPA 251). The test allows the use of the actual installed cables or a 

No. 8 AWG (3.38 mm2

) bare copper conductor to simulate the electrical circuits. With the bare 

conductor method the thermocouple measurements can be correlated to actual cable 

qualification tests as described in Appendix B of UL Subject 1724. 

TVA considers that UL Subject 1724 is the most appropriate test method currently available for 

determining the fire resistance rating of electrical fire barrier systems. TVA will use UL Subject 

1724 with the following clarifications to perform tests of Thermo-Lag 330 electrical circuit 

protective systems intended for use at Watts Bar: 

a.) The exterior surface temperature of the electrical raceway will be recorded (cold 

 side of the barrier). If the average temperature recorded by the exterior 

 thermocouples is less than 250oF (121oC) above their initial temperature and no 

 individual thermocouple is in excess of 325oF (163oC) above its initial 

 temperature, the fire barrier will be considered acceptable for use with any type 

 cable.5

 

b.) Section 6, Internal Fire Exposure Test, will not be used. TVA considers that this 

 portion of the testing is not necessary, since an internally generated cable tray 

 fire would be extremely unlikely. Circuits are protected with a fuse or breaker 

 that will actuate prior to the jacket of a faulted cable reaching its auto-ignition 
G-22 

 temperature (for existing designs) or reaching its insulation damage temperature 

 (for new designs) for all credible low impedance and bolted faults.6

 No other 

 ignition sources exist within the protective barrier. 

c.) Section 5, Hose Stream Test. TVA will follow the criteria for hose stream testing 

 described in NUREG-0800 using one and on-half inch fog nozzle set at a 

 discharge angle of 15o with a nozzle pressure of 75 psi and a minimum discharge 

 of 75 gpm.7

 TVA considers that this would accurately represent the mechanical 

 impact, erosion and cooling effects that would exist in TVA’s nuclear power plant 

 environment. The hose stream test shall be performed within ten minutes of the 

 completion of the fire test. The duration and application will follow the 

 requirements of UL 1724 Table 5.1. The nozzle will be located a maximum of ten 

 feet measured horizontally from the outside edge of the testing assembly. 

 Acceptance shall be based on the fire barrier system remaining intact with 

 minimal material flaking. (The alternative test called for by the UL document, 

 involving a one and 1-eighth inch solid bore National Standard Playpipe 

 operating at 30 psi, is not a realistic simulation of the challenge to barrier 

 systems as installed in a nuclear power plant). 

Appendix G References

M.H. Salley, “An Examination of the Methods and Data Used to Determine Functionality of 

Electrical Cables When Exposed to Elevated Temperatures as a Results of a Fire in a Nuclear 

Power Plant,” University of Maryland Masters of Science Thesis, 2000, U.S. NRC (ADAMS 

Accession No. ML051450082). 

OPL Report for NRC sponsored Hemyc Tests, 2005, ML051190026 

TVA Thermo-Lag Test Report, 1994, (NUDOCS Accession No. ML9501120204) 

Supplement 1 to GL 86-10, “Fire Endurance Test Acceptance Criteria for Fire Barrier Systems 

Used to Separate Redundant Safety Shutdown Trains within the Same Fire Area” 

RG 1.189, “Fire Protection for NPPs,” 

UL Subject 1724, “Outline of investigation for fire tests for electrical circuit protective systems” 

IEEE Standard 848-1996, “Standard Procedure for the Determination of the Ampacity Derating 

of Fire Protected Cables,” The Institute of Electrical and Electronics Engineers, Inc., 345 East 

47th Street, New York, NY 10017-2394, USA. 
NRC FORM 335 

(9-2004) 

NRCMD3.7

 U.S. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER 

(Assigned by NRC, Add Vol., Supp., Rev., 

 and Addendum Numbers, if anv.) 

NUREG-1924 

BIBLIOGRAPHIC DATA SHEET 

 (See instructions on the reverse) 

2. TITLE AND SUBTITLE 

Electric Raceway Fire Barrier Systems in U.S. Nuclear Power Plants 

3. DATE REPORT PUBLISHED 

MONTH YEAR 

May 2010

4. FIN OR GRANT NUMBER 

 

5. AUTHOR(S) 

Gabriel J. Taylor and Mark Henry Salley 

6. TYPE OF REPORT 

Technical

7. PERIOD COVERED (Inclusive Dates) 

10/1/2008 – 6/1/2009

8. PERFORMING ORGANIZATION – NAME AND ADDRESS (If NRC, provide Division, Office or Region, U.S. Nuclear Regulatory Commission, and mailing address: if contractor, provide 

name and mailing address.) 

Division of Risk Analysis 

Office of Nuclear Regulatory Research 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001

9. SPONSORING ORGANIZATION – NAME AND ADDRESS (If NRC, type “Same as above”, if contractor, provide NRC Division, Office or Region, U.S. Nuclear Regulatory Commission, and 

mailing address.) 

Division of Risk Analysis 

Office of Nuclear Reactor Regulation 

U.S. Nuclear Regulatory Commission 

Washington, DC 20555-0001

10. SUPPLEMENTARY NOTES

 

11. ABSTRACT (200 words or less) 

On March 22, 1975, the Tennessee Valley Authority (TVA) Browns Ferry Nuclear Plant (BFN) experienced a 

serious fire in their cable spreading room (CSR) and Unit 1 reactor building. The fire lasted over seven hours and 

damaged over 1,600 electrical cables, rendering all Unit 1 Emergency Core Cooling Systems inoperable. This near 

miss accident illustrated the vulnerability of essential electric cables to fire damage. In response to this fire, the 

United States Nuclear Regulatory Commission (NRC) issued Appendix R to Title 10 of the Code of Federal 

Regulations Part 50 (10 CFR 50) as a backfit to operating reactors and similar requirements implemented on 

reactors under construction. In order to comply with this new requirement, most operating United States (US) 

NPPs (NPPs) installed 1- or 3-hour Electrical Raceway Fire Barrier Systems (ERFBS) to protect electrical cables 

essential to Post-Fire Safe-Shutdown. At the time of initial installation, there were no definitive test standards for 

the ERFBS qualification. This resulted in most NPPs using the ERFBS to re-qualify/upgrade/change out their 

barriers. This report traces this history and how US NPPs returned their ERFBS to compliance. 

10.5.1 12. KEY WORDS/DESCRIPTORS (List words or phrases that will assist researchers in locating the report.) 

Electric Raceway, Fire Barrier, ERFBS, Thermo-Lag, Hemyc, MT, Mecatiss, Darmatt, 

Versawrap, 3M Interam, Kaowool, Cerablanket, FP-60, Pabco, Promat, cables, fire, cable 

failure, fire risk, fire PRA, post-fire safe shutdown analysis.

13. AVAILABILITY STATEMENT 

unlimited 

14. SECURITY CLASSIFICATION 

(this page) 

unclassified 

this report) 

unclassified

15. NUMBER OF PAGES 

 

16. PRICE 

 

NRC FORM 335 (9-2004)