POLICY ISSUE

(Information)

March 24, 2006 SECY-06-0068

FOR: The Commissioners

FROM: Luis A. Reyes

Executive Director for Operations /RA/

SUBJECT: ISSUANCE OF GENERIC LETTER 2006-XX, “POTENTIALLY

NONCONFORMING HEMYC AND MT FIRE BARRIER

CONFIGURATIONS”

PURPOSE:

To inform the Commission that the staff intends to issue the subject generic letter (GL). This

paper does not address any new commitments or resource implications.

BACKGROUND:

In 1981, the NRC issued Section 50.48 of Title 10 of the Code of Federal Regulations 

(10 CFR), the fire protection rule. The rule requires protection of safe shutdown capabilities in

the event of a fire. One means of complying with this requirement is to separate one safe

shutdown train from its redundant trains using rated fire barriers. Consequently, a number of

licensees installed Hemyc and MT fire barrier systems in U.S. nuclear power plants (NPPs) to

protect circuits and other electrical and instrumentation components and/or systems in

accordance with regulatory requirements and plant-specific commitments. 

In 1989, fire barrier performance became an issue with the failure of Thermo-Lag fire barriers to

pass performance tests. The NRC issued several generic communications relating to 

nonconforming fire barrier configurations, and, based on these communications, licensees

committed to take corrective actions. The staff also developed an action plan to resolve the

Thermo-Lag issue. The action plan included implementation of a fire protection functional

inspection program. 

CONTACT: Daniel Frumkin, DRA/NRR

 (301) 415-2280
The Commissioners -2-

In 1999, plant-specific fire protection inspection findings raised concerns about the performance

of Hemyc and MT fire barriers. The NRC regional offices and the Office of Nuclear Reactor

Regulation (NRR) established a task interface agreement to address the concerns. The NRC

concluded that existing testing was likely insufficient to properly qualify either Hemyc or MT as

rated fire barriers. 

In 2005, the NRC completed the confirmatory fire endurance test program for Hemyc and MT

fire barriers, which began in 2001. These tests were based on National Fire Protection

Association (NFPA) Standard 251, “Standard Methods of Fire Tests of Building Construction

and Materials” (essentially equivalent to American Society for Testing and Materials (ASTM)

Standard E-119, “Fire Test of Building Construction Materials”). The configurations tested

modeled typical Hemyc and MT configurations used in nuclear power plants and were based on

industry input. For thermocouple arrangement and spacing, the staff also applied guidance

from GL 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.”

The NRC test results conducted in March and April 2005 indicated that the NRC tested Hemyc

fire barriers did not meet the NFPA thermal acceptance criteria for a 1-hour fire rating for

Hemyc, and the NRC tested MT fire barriers did not meet the criteria for a 3-hour rating. In

April 2005, the NRC issued Information Notice 2005-07, “Results of Hemyc Electrical Raceway

Fire Barrier System Full Scale Fire Testing,” notifying licensees of the test findings. Hemyc and

MT installed in configurations that are not capable of providing the designed level of protection

are considered nonconforming installations. However, NRC recognized that plant-specific

assessments are needed to determine compliance with existing regulatory requirements for any

plant that relies on Hemyc and/or MT for compliance. Therefore, the staff concluded that the

information notice should be followed up with a GL.

DISCUSSION:

In the GL, the staff of the U.S. Nuclear Regulatory Commission (NRC) asks licensees of lightwater nuclear power reactors to inform the NRC whether they use Hemyc or MT fire barrier

systems at their facilities. The staff requests that licensees who use Hemyc or MT inform the

NRC whether they continue to conform with the plant’s licensing basis, in light of the recent test

results, the compensatory measures adopted for nonconforming conditions, and the planned

corrective actions. In addition, the staff requests that all licensees provide a description of the

controls that were used to ensure that other fire barrier types relied on for separation of

redundant trains of safe shutdown equipment located in a single fire area are capable of

providing the necessary level of protection. A copy of the proposed GL is provided as

Enclosure 1. The staff dispositioned public comments (Enclosure 2) on the draft GL published

in the Federal Register on July 25, 2005. 

If licensees identify nonconforming conditions, they have several options. A licensee may make

plant modifications, for example, replacing the Hemyc or MT fire barriers with an appropriately

rated fire barrier material, upgrading the Hemyc or MT to a rated barrier, or rerouting cables or

instrumentation lines through another fire area. Alternatively, licensees may voluntarily commit

to 10 CFR 50.48(c), the NFPA 805 standard, follow the process in the rule and the NFPA 805

standard, and establish compliance through the application of technical evaluations that

consider potential adverse effects, risk, defense-in-depth (DID), and safety margins. 
The Commissioners -3-

Since the Hemyc and MT tests revealed that the fire barrier systems did not meet the

acceptance criteria, the staff concluded that performance of other fire barrier systems may also

be suspect. Therefore, the GL also requests a description of controls that were used to ensure

the adequacy of other fire barrier types. This request is consistent with the earlier GL 92-08,

which conveyed the staff’s expectation that fire barrier systems other than Thermo-Lag be

assessed in light of the findings on Thermo-Lag. This is a change from the draft GL that the

staff issued for public comment, but the staff’s position is that nonconforming conditions may

exist with other fire barriers providing separation for redundant trains in a single fire area. This

staff position is based on historical issues identified with various other fire barriers and the

staff’s position that fire barrier issues may stem from a generic problem with licensees installing

fire barriers improperly. Additionally, the staff simplified some of the discussion in the GL and

clarified the requested information.

The staff has assessed whether immediate regulatory action is necessary while licensees

respond to the subject GL, and has determined that continued operation is justified for several

reasons. As a 1-hour rated fire barrier, Hemyc is installed only in fire areas where fire detection

and automatic fire suppression systems are present or the licensee has previously obtained an

approved exemption to the automatic fire suppression requirement because such suppression

was deemed unnecessary (for example, there is negligible fire potential). The Hemyc fire

barrier systems used at the plant are, therefore, just one of several layers of DID (fire detection,

manual suppression, and automatic suppression are other layers of DID). 

In addition, the ASTM-E119 standard fire test performed by the NRC exposed the Hemyc

material to higher temperatures and more rapid rises in temperature than are expected to occur

due to a fire in fire areas where Hemyc fire barrier systems are installed. The NRC considers

the safety margins between the test and actual conditions to be wide enough that the integrity

of installed Hemyc fire barrier systems is unlikely to be challenged. 

For MT (which consists of several layers of materials, the outermost being Hemyc), the staff

also concluded that the risk was low because, in NRC confirmatory testing, MT provided nearly

an hour of protection in every test run, providing sufficient time for fire suppression by a fire

brigade before cable damage is expected to occur. 

During the December 8, 2005, public meeting of the Advisory Committee on Reactor

Safeguards (ACRS) on the subject GL, a Nuclear Energy Institute (NEI) representative

commented that the information request for a description of programmatic controls in place to

ensure the adequacy of other fire barrier types is a backfit. The NEI representative also said

this was “another example” of how the staff misuses GLs to backfit the industry. 

The staff disagrees with NEI because the GL is a request for information. Furthermore, the GL

addresses some of the same issues communicated in GL 92-08, that fire barrier systems other

than Thermo-Lag be assessed for potential degradation in light of the findings on Thermo-Lag. 

GL 92-08 did not require any response from addressees regarding barriers other than 

Thermo-Lag. The industry failed to identify the inadequacy of Hemyc and MT. The staff has,

therefore, concluded that a written response is necessary to assure the ability of fire barrier

systems to perform their intended safety function. 
The Commissioners -4-

On January 20, 2006, the Director of the Office of Nuclear Reactor Regulation (NRR) published

a notice in the Federal Register (71 FR 3344) announcing the issuance of a Director's Decision

granting in part a 10 CFR 2.206 petition filed by the Nuclear Information and Research Service

(NIRS). The petition requested, among other things, that the NRC determine the extent of

condition of the inoperable fire barriers through the use of a generic communication, and

require sites that use these fire barriers to provide justification for operation in their response to

the generic communication. The Director of NRR granted these requested actions in the

petition and will use the generic communication process to perform the requested actions. 

Issuance of this GL constitutes the regulatory action referred to in the Director's Decision.

COORDINATION:

The Committee To Review Generic Requirements (CRGR) reviewed the GL on November 29,

2005, and endorsed it after the staff incorporated the CRGR comments. The ACRS reviewed

the GL on December 8, 2005, and recommended that it be issued. The Office of the General

Counsel reviewed the GL and had no legal objection to its content. The Office of the Chief

Financial Officer reviewed the GL and had no objections based on budget or financial

management concerns or potential resource impacts.

The subject GL is not a major “rule” under the Small Business Regulatory Enforcement

Fairness Act of 1996, and the Office of Management and Budget has confirmed this

determination.

/RA/

Luis A. Reyes

Executive Director 

 for Operations

Enclosures:

1. Generic Letter 2006-XX

2. Resolution of Public Comments Table
The Commissioners -5-

On January 20, 2006, the Director of the Office of Nuclear Reactor Regulation (NRR) published

a notice in the Federal Register (71 FR 3344) announcing the issuance of a Director's Decision

granting in part a 10 CFR 2.206 petition filed by the Nuclear Information and Research Service

(NIRS). The petition requested, among other things, that the NRC determine the extent of

condition of the inoperable fire barriers through the use of a generic communication, and

require sites that use these fire barriers to provide justification for operation in their response to

the generic communication. The Director of NRR granted these requested actions in the

petition and will use the generic communication process to perform the requested actions. 

Issuance of this GL constitutes the regulatory action referred to in the Director's Decision.

COORDINATION:

The Committee To Review Generic Requirements (CRGR) reviewed the GL on November 29,

2005, and endorsed it after the staff incorporated the CRGR comments. The ACRS reviewed

the GL on December 8, 2005, and recommended that it be issued. The Office of the General

Counsel reviewed the GL and had no legal objection to its content. The Office of the Chief

Financial Officer reviewed the GL and had no objections based on budget or financial

management concerns or potential resource impacts.

The subject GL is not a major “rule” under the Small Business Regulatory Enforcement

Fairness Act of 1996, and the Office of Management and Budget has confirmed this

determination.

/RA/

Luis A. Reyes

Executive Director 

 for Operations

Enclosures:

1. Generic Letter 2006-XX

2. Resolution of Public Comments Table

Commission Paper Accession Number: ML053620138

OFFICE AFPB:DRA AFPB:DRA Tech Editor BC:AFPB:DRA D:DRA BC:DORL

NAME ALavretta

/RA/ DFrumkin for

DFrumkin PKleene SWeerakkody JLyons MMarshall

DATE 01/05/06 01/05/06 01/05/06 01/05/06 01/09/06 01/17 /06

OFFICE D:DORL OGC (NLO) OGC (SBREFA) OIS PGCB:LA

NAME CHaney STreby DReddick (NLO) BJShelton CHawes

DATE 01/20/06 02/02/06 01/12 /06 01/23/06 03/07/06

OFFICE PGCB:DPR BC:PGCB:DPR D:DPR D:NRR EDO

NAME AMarkley CJackson CGrimes JDyer (GHolahan for) LReyes

DATE 03/10/06 03/08/06 03/10/06 03/15/06 03 /24 /06

 OFFICIAL RECORD COPY
1

Hemyc and MT are commonly-used names for the fire barrier types discussed in this GL. The references to Hemyc

and MT in this GL apply to any fire barriers using the materials and configuration described on pages 4 and 5 of this GL.

2

American Society for Testing and Materials E-119, “Fire Test of Building Construction Materials,” and NFPA 251 are

essentially equivalent.

ENCLOSURE 1

OMB Clearance No.: 3150-0011

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001

NRC GENERIC LETTER 2006-XX: POTENTIALLY NONCONFORMING HEMYC AND MT

FIRE BARRIER CONFIGURATIONS

ADDRESSEES 

All holders of operating licenses for light-water nuclear power reactors, except those who have

ceased operations and have certified that fuel has been permanently removed from the reactor

vessel.

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this generic letter (GL) to:

(2) Request that addressees evaluate their facilities to confirm compliance with the existing

applicable regulatory requirements in light of the information provided in this GL and, if

appropriate, take additional actions. Specifically, although Hemyc and MT1

 fire barriers

in nuclear power plants (NPPs) may be relied on to protect electrical and

instrumentation cables and equipment that provide safe shutdown capability during a

fire, 2005 NRC testing has revealed that both materials failed to provide the protective

function intended for compliance with existing regulations, for the configurations tested

using the thermal acceptance criteria from the National Fire Protection Association

(NFPA) Standard 251, “Standard Methods of Fire Tests of Building Construction and

Materials.”2

 The NRC staff applied the supplemental guidance in GL 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” for the test

details of thermocouple number and location, and 

(3) Require that addressees submit a written response to the NRC in accordance with 

NRC regulations in Title 10 of the Code of Federal Regulations (10 CFR)

Section 50.54(f). 
GL 2006-xx

Page 2 of 13

BACKGROUND

The NRC’s concern with the performance of fire barriers at NPPs began with the failure of

Thermo-Lag to pass performance tests in October 1989 at Southwest Research Institute. The

tests were done for the Gulf States Utilities Company after visual observations of degradation of

Thermo-Lag at River Bend Station. In June and August 1992, two sets of 

full-scale fire endurance tests on Thermo-Lag were conducted at Omega Point Laboratories in

San Antonio, Texas, by Texas Utilities Electric Company for Comanche Peak Steam Electric

Station, with similar results. In July 1992, the NRC sponsored a series of small-scale fire

endurance tests at the National Institute of Standards and Technology. Again, 1-hour and 

3-hour rated Thermo-Lag barrier material failed to consistently provide its intended protective

function.

On August 6, 1991, the NRC issued Information Notice (IN) 91-47, “Failure of Thermo-Lag Fire

Barrier Material to Pass Fire Endurance Test,” the first in a series of INs issued between 1991

and 1995 on performance test failures and installation deficiencies related to Thermo-Lag 330

fire barrier systems. 

Because of questions about the ability of 1-hour and 3-hour rated Thermo-Lag fire barrier

material to perform its specified function, and because of the widespread use of Thermo-Lag in

the nuclear industry, the NRC issued the following generic communications to inform licensees

of the Thermo-Lag test results and to request that licensees implement appropriate

compensatory measures and develop plans to resolve any noncompliances with 10 CFR 50.48: 

• Bulletin 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, 

• Bulletin 92-01, Supplement 1, “Failure of Thermo-Lag 330 Fire Barrier System To

Perform its Specified Fire Endurance Function,” August 28, 1992, 

• GL 92-08, “Thermo-Lag 330-1 Fire Barriers,” December 17, 1992, and

• 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,” March 25, 1994.

GL 92-08 included the NRC staff expectation that licensees review other fire barrier materials

and systems credited for 10 CFR 50.48 compliance and consider actions to avoid problems

similar to those identified with Thermo-Lag. 

In response, the licensees reviewed their fire protection safe shutdown plans to determine if

corrective actions were needed. Some licensees had made conservative commitments and

installed Thermo-Lag in locations where it was not needed to satisfy NRC requirements;

therefore, no corrective actions were required. Where fire barrier materials were required,

licensees took one or a combination of the following corrective actions: 

• Rerouted cables through other fire areas so that redundant safe shutdown trains were

not located in the same fire area, 
GL 2006-xx

Page 3 of 13

• Replaced Thermo-Lag, or the affected material, with an alternative rated fire barrier

material,

• Upgraded the installed fire barriers to a rated configuration, and

• Concluded that certain Thermo-Lag barriers were no longer required.

Subsequently, deficiencies were also identified in other fire barrier materials. In 1993, for

example, Kaowool® installed as a 1-hour rated fire barrier was found to be unable to pass circuit

integrity tests. In response, the NRC staff reassessed previous reviews of Kaowool® fire

barriers and informed the industry and the Commission of the potential failure of Kaowool® to

perform as intended and suggested additional testing of Kaowool® (SECY-99-204; Agencywide

Documents Access and Management System (ADAMS) Accession No. ML992810028). To

resolve the issue, the industry took voluntary corrective actions.

In August 1993, the Nuclear Energy Institute (NEI) formed a Fire Barrier Review Ad Hoc

Advisory Committee to address the adequacy of fire barrier materials other than Thermo-Lag. 

The Committee performed reviews of the original testing of the fire barrier material Hemyc in

the early 1980s in Spain, and concluded that Hemyc was differently constructed than

Thermo-Lag 330-1 and was not subject to the same failure modes as Thermo-Lag 330-1. In

May 1994, this review was documented in the NEI report, “Documentation of the Adequacy of

Fire Barrier Materials in Raceway Applications Vis-á-vis Failure Characteristics Inherent to the

Thermo-Lag 330-1.” 

In September 1993, the NRC staff conducted pilot-scale fire endurance tests at the National

Institute of Standards and Technology to investigate the performance characteristics of fire

barrier materials. Because simplified and small-scale assembly models were used, the NRC

staff intended to apply the test results for screening purposes only. The test results indicated

unacceptable performance in approximately one-third of the assemblies tested. Although

Hemyc was tested, the result was inconclusive because the configuration tested was

inconsistent with the installation configuration recommended by the manufacturer. Details of

these tests are documented in a March 1994 report (ADAMS Accession No. ML9610170283). 

In September 1995, after assessing the scope of licensees’ corrective actions, the NRC staff

informed the Commission that a broader scope of inspections was needed to close out the

Thermo-Lag action plan due to the broad range of corrective action options submitted by

licensees. Rather than the stand-alone Thermo-Lag fire barrier inspection program proposed in

the original action plan (submitted to the Commission in 1992), the NRC staff recommended a

Fire Protection Functional Inspection (FPFI) program. SECY-96-267 (ADAMS Accession No.

ML9701080067) provides details of the proposed FPFI, and includes a review of safe shutdown

design and licensing bases. The NRC staff developed and implemented the FPFI program

following issuance of the Commission’s staff requirements memorandum in February 1997. 

Beginning in late 1999, three plant-specific findings by the NRC staff raised concerns about the

performance of Hemyc and MT fire barriers.

• In November 1999, during an inspection at Shearon Harris Nuclear Power Plant 

(IR 50-400/99-13, ADAMS Accession No. ML003685341), the inspection team noted

that the acceptance of the Hemyc and MT fire barrier materials used was based on
GL 2006-xx

Page 4 of 13

American Nuclear Insurers (ANI) Bulletin No. 5 test acceptance criteria, even though the

ANI test methodology clearly stated that the tests were for insurance purposes only and

were not the equivalent of fire barrier endurance tests for fire barrier ratings. 

• In October and November 2000, during an inspection at McGuire, Units 1 and 2 

(IR 50-369/00-09, 50-370/00-09, ADAMS Accession No. ML003778709), the inspection

team noted that the licensee was unable to provide documentation demonstrating

protection by Hemyc fire barrier material used to separate safe shutdown functions for

two trains within a single fire area. 

• In September 2000, during an inspection at Waterford 3 (IR 50-382/00-07, ADAMS

Accession No. ML003773900), the inspectors noted that the Hemyc materials were

installed in configurations which were usually not bounded by the existing tests.

In June 2001, the NRC initiated confirmatory fire tests in response to Task Interface 

Agreement 99-028 (ADAMS Accession No. ML003736721), after concluding that existing

testing was likely insufficient to qualify Hemyc or MT as rated fire barriers. The NRC tests were

based on ASTM E-119 standard time-temperature conditions, for typical Hemyc and MT

installations used in U.S. NPPs. Thermocouple placement was based on the current NRC

guidance in GL 86-10, Supplement 1. The test results indicated that Hemyc and MT fire

barriers did not pass the criteria to achieve a 1-hour fire rating for Hemyc or a 3-hour fire rating

for MT for the configuration tested.

On April 1, 2005, the NRC issued IN 2005-07, “Results of Hemyc Electrical Raceway Fire

Barrier System Full Scale Fire Testing.” This IN describes the results of the NRC-sponsored

confirmatory testing of Hemyc. However, the NRC staff recognized that additional evaluations

would be needed to determine whether regulatory compliance exists in light of the concerns

identified in IN 05-07. 

On April 29, 2005, the NRC staff held a public meeting with licensees and interested members

of the public to discuss the Hemyc and MT test results and the NRC staff’s intention to take

additional regulatory action to ensure that appropriate measures were under way for

compliance with 10 CFR 50.48 requirements at affected plants. This GL is the follow-on to

IN 05-07.

On January 20, 2006, the Director of the Office of Nuclear Reactor Regulation (NRR) published

a notice in the Federal Register (71 FR 3344) announcing the issuance of a Director's Decision

granting in part a 10 CFR 2.206 petition filed by the Nuclear Information and Research Service. 

The petition requested, among other things, that the NRC determine the extent of condition of

the inoperable fire barrier through the use of a generic communication, and require sites that

use these fire barriers to provide justification for operation in their response to the generic

communication. The Director of NRR granted these requested actions in the petition and will

use this generic communication to perform the requested actions. Issuance of this GL

constitutes the regulatory action referred to in the Director's Decision.
GL 2006-xx

Page 5 of 13

3

Refrasil® was used during NRC tests. Siltemp® and Refrasil® were tested by the NRC and determined to be essentially

equivalent (ADAMS Accession No. ML051190055).

The NRC has established a Web page to keep the public informed of the status of the 

Hemyc/MT fire barrier issue at http://www.nrc.gov/reactors/operating/ops-experience/

fire-protection/fire-barriers.html. This page provides links to information on related fire

protection issues, along with documentation of NRC interactions with industry (including generic

communications, industry submittals, meeting notices, presentation materials, and meeting

summaries). The NRC will continue to update this Web page as new information becomes

available.

Hemyc Construction—Hemyc fire barrier material consists of mats of 2 inch Kaowool® ceramic

fiber insulation inside an outer covering of Refrasil®3 high-temperature fabric. The mats are

custom-sized for the electrical raceway, junction box, or other intended application, and

machine-stitched to produce the factory mats. Hemyc mats, which are installed over a metal

frame to embody the 2 inch air gap design, are identical except that 11⁄2 inch Kaowool® is used

instead of 2 inch material.

MT Construction—MT is usually used with conduits and has four layers. The first layer, closest

to the conduit or other intended application, is 1 inch of Kaowool® ceramic fiber blanket

wrapped in a fiberglass fabric. The second layer is a 2 mil sheet of stainless steel. The third

layer is a hydrate packet. This packet is made by stitching together packets of aluminum

trihydrate in a fiberglass-coated fabric. The fourth and outermost layer is a 11⁄2 inch Kaowool®

blanket wrapped in Refrasil®. The configuration is slightly different for air drops and structural

supports. Air drops use a 3-inch blanket of Kaowool® as the inner layer. Structural supports do

not have the hydrating packet layer or the stainless steel sheet.

DISCUSSION

Hemyc and MT fire barrier systems were installed at NPPs to protect circuits and other

electrical and instrumentation features in order to meet regulatory requirements and in

accordance with plant-specific commitments. The NRC conducted confirmatory testing of

Hemyc and MT materials at the Omega Point Laboratories in San Antonio, Texas. The tests

indicated that when tested to NFPA 251 thermal acceptance criteria, with thermocouples placed

in accordance with the guidance in GL 86-10, Supplement 1, neither the Hemyc nor the MT fire

barrier system could provide its rated fire barrier protection. Fire barriers installed in

configurations that are not capable of providing the designed level of protection are considered

nonconforming installations.

The NRC staff noted at least two failure modes in the limited test program. One failure mode

resulted from shrinkage of the outer covering, exposing the interior surfaces or layers to the

fire. The second failure mode resulted from failure to adequately protect steel structural

supports intruding into the fire barrier. The standard used by some utilities required protection

of 3 inches of intruding steel for the Hemyc 1-hour fire barrier and 18 inches of intruding steel

for the MT 3-hour fire barrier. The test results indicated that additional protection of intruding

steel was required to achieve a 1-hour or 3-hour fire rating. 
GL 2006-xx

Page 6 of 13

Based on these test results, the NRC is concerned that the Hemyc and MT fire barriers may not

provide the level of fire endurance intended by licensees, and that licensees that use Hemyc or

MT may not be conforming with their licensing basis. 10 CFR 50.48 requires that each

operating NPP have a fire protection plan that satisfies 10 CFR Part 50, Appendix A, General

Design Criterion (GDC) 3, “Fire Protection.” GDC 3 requires that structures, systems, and

components important to safety be designed and located to minimize, in a manner consistent

with other requirements, the probability and effect of fires and explosions. Fire protection

features required to satisfy 10 CFR 50.48 include features to limit fire damage to structures,

systems, or components important to safety so that the capability to shut down the plant safely

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

train from its redundant train with rated fire barriers. The duration of fire resistance required of

the barriers, usually 1 hour or 3 hours, depends on the other fire protection features in the fire

area. The NRC issued guidance on acceptable methods of satisfying GDC 3 in the branch

technical positions (BTPs) and GLs identified in the “Applicable Regulatory Guidance” section

of this GL. 

The NRC staff requests licensees to review their fire protection programs in light of information

in IN 05-07 and this GL and implement appropriate compensatory measures and develop plans

to resolve any nonconformances. 

NRC Inspection Manual, Part 9900, Technical Guidance, “Operability Determinations &

Functionality Assessments for Resolution of Degraded or Nonconforming Conditions

Adverse to Quality or Safety,” dated September 26, 2005, provides guidance on acceptable

treatment of nonconformances. Licensees are also encouraged to review Regulatory Issue

Summary 2005-07, “Compensatory Measures to Satisfy the Fire Protection Program

Requirements,” in determining the appropriate compensatory measures to meet fire protection

program requirements for nonconforming fire barrier installations. All licensees should consider

the impact of fire barrier functionality on affected equipment and assess the impact on plant

safety.

If licensees identify nonconforming conditions, they have several options. A licensee may make

plant modifications, for example, replacing the Hemyc or MT fire barriers with an appropriately

rated fire barrier material, upgrading the Hemyc or MT to a rated barrier, or rerouting cables or

instrumentation lines through another fire area. Alternatively, licensees may voluntarily commit

to 10 CFR 50.48(c), NFPA 805 Standard, and by following the process in the rule and the

NFPA 805 standard, establish compliance through the application of technical evaluations that

consider potential adverse effects, risk, defense-in-depth (DID), and safety margins. 

APPLICABLE REGULATORY REQUIREMENTS

NRC regulations in 10 CFR 50.48 and 10 CFR Part 50, Appendix A, GDC 3, require each

operating NPP to have a fire protection plan providing post-fire safe shutdown. That is, a 

means must be provided to limit fire damage to structures, systems, or components important

to safety so that the capability to shut down the plant safely is ensured. 
GL 2006-xx

Page 7 of 13

APPLICABLE REGULATORY GUIDANCE

The NRC issued guidance on acceptable methods of satisfying the regulatory requirements of

GDC 3 in Auxiliary and Power Conversion Systems Branch (APCSB) BTP 9.5-1, “Guidelines for

Fire Protection for Nuclear Power Plants,” May 1, 1976; Appendix A to APCSB BTP 9.5-1,

February 24, 1977; and Chemical Engineering Branch BTP 9.5-1, “Fire Protection for Nuclear

Power Plants,” July 1981. In response to licensees’ questions, the NRC staff provided

additional guidance on fire barriers in GL 86-10, “Implementation of Fire Protection

Requirements.” 

In the BTPs and in GL 86-10, the NRC staff stated that the fire resistance ratings of fire barriers

should be established in accordance with NFPA 251, by subjecting a test specimen that

represents the materials, workmanship, method of assembly, dimensions, and configuration for

which a fire rating is desired to a “standard fire exposure.” Supplement 1 to GL 86-10 provides

additional guidance for testing fire barrier endurance and for evaluating deviations from tested

configurations. This guidance is repeated in RG 1.189, “Fire Protection for Operating Nuclear

Power Plants.”

REQUESTED ACTIONS

Within 60 days of the date of this letter, all addressees are requested 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. In addition, licensees are

asked to describe controls that were used to ensure the adequacy of other fire barrier types,

consistent with the assessment requested in GL 92-08.

Addressees that credit Hemyc or MT for compliance are requested to provide information

regarding the extent of the installation, whether the material complies with regulatory

requirements, and any compensatory actions in place to provide equivalent protection and

maintain the safe shutdown function of affected areas of the plant in light of the recent findings

associated with Hemyc and MT. Licensees are requested to provide evaluations to support

conclusions that they are in compliance with regulatory requirements for the Hemyc and MT

applications. Licensees that cannot justify their continued reliance on Hemyc or MT are

requested to provide a description of corrective actions taken or planned and a schedule for

milestones, including when full compliance will be achieved. 

Compensatory and corrective actions must be implemented in accordance with existing

regulations commensurate with the safety significance of the nonconforming condition. The

NRC expects all licensees to fully restore compliance with 10 CFR 50.48 and submit the

required documentation to the NRC by December 1, 2007. 

REQUESTED INFORMATION

All addressees are requested to provide the following information:

2. Within 60 days of the date of this GL, provide the following: 
GL 2006-xx

Page 8 of 13

a. A statement on whether Hemyc or MT fire barrier material is used at their NPPs

and whether it is relied upon for separation and/or safe shutdown purposes in

accordance with the licensing basis, including whether Hemyc or MT is credited in

other analyses (e.g., exemptions, license amendments, GL 86-10 analyses).

b. A description of the controls that were used to ensure that other fire barrier types

relied on for separation of redundant trains located in a single fire area are capable

of providing the necessary level of protection. Addressees may reference their

responses to GL 92-08 to the extent that the responses address this specific issue. 

3. Within 60 days of the date of this GL, for those addressees that have installed Hemyc or

MT fire barrier materials, discuss the following in detail: 

a. The extent of the installation (e.g., linear feet of wrap, areas installed, systems

protected), 

b. Whether the Hemyc and/or MT installed in their plants is conforming with their

licensing basis in light of recent findings, and if these recent findings do not apply,

why not,

c. The compensatory measures that have been implemented to provide protection

and maintain the safe shutdown function of affected areas of the plant in light of the

recent findings associated with Hemyc and MT installations, including evaluations to

support the addressees’ conclusions, and 

d. A description of, and implementation schedules for, corrective actions, including a

description of any licensing actions or exemption requests needed to support

changes to the plant licensing basis. 

4. No later than December 1, 2007, addressees that identified in 1.a. Hemyc and/or MT

configurations are requested to provide a description of actions taken to resolve the

nonconforming conditions described in 2.d.

REQUIRED RESPONSE

In accordance with 10 CFR 50.54(f), an addressee is required to respond as described below

so that the NRC can determine whether a facility license should be modified, suspended, or

revoked, or whether other action should be taken. 

Within 30 days of the date of this GL, addressees are required to submit a written response if

they are unable to provide the information or it cannot meet the requested completion date. 

Addressees are requested to address any alternative course of action that they propose to

take, including the basis for the acceptability of the proposed alternative course of action.

The required written response should be addressed to the U.S. Nuclear Regulatory

Commission, ATTN: Document Control Desk, 11555 Rockville Pike, Rockville, Maryland 
GL 2006-xx

Page 9 of 13

20852, under oath or affirmation under the provisions of Section 182a of the Atomic Energy Act

of 1954, as amended, and 10 CFR 50.54(f). In addition, a copy of the response should be

submitted to the appropriate regional administrator.

REASON FOR INFORMATION REQUEST

The recent confirmatory testing of the Hemyc and MT fire barriers revealed that similar barriers

installed at NPPs may not perform their intended protective function during a fire. The NRC

staff will review the responses to this GL and will notify addressees if concerns are identified

regarding compliance with NRC regulations. The NRC staff may also conduct inspections to

determine addressees’ effectiveness in addressing the GL. 

RELATED GENERIC COMMUNICATIONS

5. Regulatory Issue Summary 05-07, “Compensatory Measures To Satisfy the Fire

Protection Program Requirements,” April 19, 2005.

6. IN 05-07, “Results of Hemyc Electrical Raceway Fire Barrier System Full Scale Fire

Testing,” April 1, 2005.

7. IN 99-17, “Problems Associated with Post-Fire Safe-Shutdown Circuit Analysis,” June 3,

1999.

8. IN 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.

9. IN 95-49, Supplement 1, “Seismic Adequacy of Thermo-Lag Panels,” December 10,

1997.

10. RIS 2005-20, Revision to Guidance Formerly Contained in NRC Generic Letter 91-18,

“Information to Licensees Regarding Two NRC Inspection Manual Sections on

Resolution of Degraded and Nonconforming Conditions and on Operability,” 

September 26, 2005.

11. IN 97-70, “Potential Problems With Fire Barrier Penetration Seals,” September 19,

1997.

12. IN 97-59, “Fire Endurance Test Results of Versawrap Fire Barriers,” August 1, 1997. 

13. IN 94-86, Supplement 1, “Legal Actions Against Thermal Science, Inc., Manufacturer of

Thermo-Lag,” November 15, 1995.

14. IN 95-52, “Fire Endurance Test Results for Electrical Raceway Fire Barrier Systems

Constructed from 3M Company Interam Fire Barrier Materials,” November 14, 1995.

15. IN 95-49, “Seismic Adequacy of Thermo-Lag Panels,” October 27, 1995.
GL 2006-xx

Page 10 of 13

16. IN 95-32, “Thermo-Lag 330-1 Flame Spread Test Results,” 

August 10, 1995.

17. IN 95-27, “NRC Review of Nuclear Energy Institute, “Thermo-Lag 330-1 Combustibility

Evaluation Methodology Plant Screening Guide,” May 31, 1995. 

18. IN 94-86, “Legal Actions Against Thermal Science, Inc., Manufacturer of Thermo-Lag,”

December 22, 1994.

19. IN 94-34, “Thermo-Lag 330-660 Flexi-Blanket Ampacity Derating Concerns,” May 13,

1994.

20. IN 94-28, “Potential Problems With Fire Barrier Penetration Seals,” 

April 5, 1994.

21. GL 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.

22. IN 94-22, “Fire Endurance and Ampacity Derating Test Results for 

3-Hour Fire-Rated Thermo-Lag 330-1 Fire Barriers,” March 16, 1994.

23. 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,” May 28, 1993.

24. IN 93-40, “Fire Endurance Test Results for Thermal Ceramics FP-60 Fire Barrier

Material,” May 26, 1993.

25. GL 92-08, “Thermo-Lag 330-1 Fire Barriers,” December 17, 1992.

26. IN 92-82, “Results of Thermo-Lag 330-1 Combustibility Testing,” December 15, 1992.

27. Bulletin 92-01, Supplement 1, “Failure of Thermo-Lag 330 Fire Barrier System to

Perform its Specified Fired Endurance Function,” August 28, 1992.

28. IN 92-55, “Current Fire Endurance Test Results for Thermo-Lag Fire Barrier Material,”

July 27, 1992.

29. Bulletin 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.

30. IN 92-46, “Thermo-Lag Fire Barrier Material Special Review Team Final Report

Findings, Current Fire Endurance Tests, and Ampacity Calculation Error,” 

June 23, 1992. 

31. IN 91-79, “Deficiencies in the Procedures for Installing Thermo-Lag Fire Barrier

Materials,” December 6, 1991.

32. IN 91-47, “Failure of Thermo-Lag Fire Barrier Material To Pass Fire Endurance Test,”
GL 2006-xx

Page 11 of 13

August 6, 1991. 

33. IN 88-56, “Potential Problems With Silicone Foam Fire Barrier Penetration Seals,”

August 4, 1988.

34. GL 88-12, “Removal of Fire Protection Requirements From Technical Specifications,”

August 2, 1988.

35. GL 86-10, “Implementation of Fire Protection Requirements,” April 26, 1986.

36. GL 83-33, “NRC Position on Certain Requirements of Appendix R to 10 CFR Part 50,”

October 19, 1983.

37. GL 81-12, “Fire Protection Rule (45 FR 76602, November 19, 1980),” February 20,

1981.

BACKFIT DISCUSSION

Under the provisions of Section 182.a of the Atomic Energy Act of 1954, as amended, and

10 CFR 50.54(f), this GL asks addressees to evaluate their facilities to confirm compliance with

the existing applicable regulatory requirements discussed in this GL. Specifically, although

Hemyc and MT fire barriers in NPPs may be relied on to protect electrical and instrumentation

cables and equipment that provides safe shutdown capability during a fire, 2005 NRC testing

revealed that these materials may not provide the protective function intended for compliance

with existing regulations. The NRC staff performed these tests using the fire barrier thermal

acceptance criteria from NFPA 251; the test details of thermocouple spacing and arrangement

were applied in accordance with the guidance in GL 86-10, Supplement 1. 

This GL is an information request in accordance with 10 CFR 50.54(f). Information requests are

not considered by the NRC to be subject to the Backfit Rule, 10 CFR 50.109. Furthermore, this

GL is based on current regulations and guidance and does not constitute a change in NRC staff

position. Accordingly, the NRR staff's interpretations of current fire protection requirements in

this GL do not constitute backfitting as defined in 10 CFR 50.109(a)(i). 

The NRC staff has determined, in accordance with 10 CFR 50.54(f), that the information sought

in this GL is necessary to verify licensee compliance with current licensing basis for each

facility. If licensees identify nonconforming conditions, they have several options. A licensee

may make plant modifications, for example, replacing the Hemyc or MT fire barriers with an

appropriately rated fire barrier material, upgrading the Hemyc or MT to a rated barrier, or

rerouting cables or instrumentation lines through another fire area. Alternatively, licensees may

voluntarily commit to 10 CFR 50.48(c), NFPA 805 Standard, and by following the process in the

rule and the NFPA 805 Standard, establish compliance through the application of technical

evaluations that consider potential adverse effects, DID, and safety margins. 
GL 2006-xx

Page 12 of 13

FEDERAL REGISTER NOTIFICATION

A notice of opportunity for public comment on this GL was published in the

Federal Register (70 FR 42596) on July 25, 2005. 

SMALL BUSINESS REGULATORY ENFORCEMENT FAIRNESS ACT

In accordance with the Small Business Regulatory Enforcement Fairness Act of 1996, the NRC

has determined that this GL is not a major rule and the Office of Information and Regulatory

Affairs of the Office of Management and Budget (OMB) has confirmed this determination.

PAPERWORK REDUCTION ACT STATEMENT

This GL contains information collection requirements that are subject to the Paperwork

Reduction Act of 1995 (44 U.S.C. 3501 et seq.). These information collections were approved

by OMB, clearance no. 3150-0011, which expires February 28, 2007. 

The burden to the public for these mandatory information collections is estimated to average

120 hours per response, including the time for reviewing instructions, searching existing data

sources, gathering and maintaining the data needed, and completing and reviewing the

information collection. Send comments on any aspect of these information collections,

including suggestions for reducing the burden, to the Records and FOIA/Privacy Services

Branch (T5-F52), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by

Internet electronic mail to INFOCOLLECTS@NRC.GOV; and to the Desk Officer, Office of

Information and Regulatory Affairs, NEOB-10202 (3150-0011), Office of Management and

Budget, Washington, DC 20503. 

Public Protection Notification

The NRC may not conduct or sponsor, and a person is not required to respond to, an

information collection, unless the requesting document displays a currently valid OMB control

number.
GL 2006-xx

Page 13 of 13

CONTACT

Please direct any questions about this matter to the technical contacts or the Lead Project

Manager listed below, or to the appropriate NRR project manager. 

Christopher I. Grimes, Director

Division of Policy and Rulemaking

Office of Nuclear Reactor Regulation

Technical Contacts: Daniel Frumkin, DRA/NRR Angie Lavretta, DRA/NRR

 (301) 415-2280 (301) 415-3285

 E-mail: dxf1@nrc.gov E-mail: axl3@nrc.gov

Lead Project Manager: Quynh T. Nguyen, PGCB/NRR

 301-415-8123

 E-mail: qtn@nrc.gov

Note: NRC generic communications may be found on the NRC public Web site,

http://www.nrc.gov, under Electronic Reading Room/Document Collections. 
GL 2006-XX

Page 13 of 13

CONTACT

Please direct any questions about this matter to the technical contacts or the Lead Project

Manager listed below, or to the appropriate NRR project manager. 

Christopher I. Grimes, Director

Division of Policy and Rulemaking

Office of Nuclear Reactor Regulation

Technical Contacts: Daniel Frumkin, DRA/NRR Angie Lavretta, DRA/NRR

 (301) 415-2280 (301) 415-3285

 E-mail: dxf1@nrc.gov E-mail: axl3@nrc.gov

Lead Project Manager: Quynh T. Nguyen, PGCB/NRR

 301-415-8123

 E-mail: qtn@nrc.gov

Note: NRC generic communications may be found on the NRC public Web site,

http://www.nrc.gov, under Electronic Reading Room/Document Collections. 

DISTRIBUTION:

GL File

ADAMS ACCESSION NUMBER: ML052840185 

OFFICE SPLB:DSSA SPLB:DSSA SC:SPLB:DSSA Tech Editor C:SPLB:DSSA D:DSSA

NAME APLavretta DMFrumkin SDWeerakody PKleene JNHannon JELyons

DATE 10/11/2005 10/12/2005 10/11/2005 10/12/2005 10/13/2005 10/24/2005

OFFICE PM:DLPM LP:DLPM D:DLPM OE OGC(SBREFA) OGC(NLO)

NAME CPPatel MMarshall LMarsh MJohnson DReddick STreby

DATE 10/17/2005 10/24/2005 10/27/2005 10/30/2005 10/31/2005 11/02/2005

OFFICE PMAS OIS PGCB:LA PGCB:DPR C:PGCB:DPR D:DPR

NAME VGladhill BShelton CHawes AWMarkley CJackson CIGrimes

DATE 11/07/2005 10/28/2005 02/13/2006 / /2006 / /2006 / /2006

OFFICIAL RECORD COPY
ENCLOSURE 2

U.S. Nuclear Regulatory Commission (NRC) Staff Resolution of Public Comments 

on the Draft Generic Letter (GL) on Potentially Non-Compliant Hemyc/MT Fire Barriers 

(by category and bin number)

Table 1. Key for Resolution of Comments

Source of Comments

(ADAMS Accession Number)

Comment Designator Remarks

PCI Promatec (ML052420492) P Received 8-23-05

Progress Energy (ML052660204) E Received 9-22-05

Duke Power (ML052860138) D Received 9-23-05 

Nuclear Energy Institute (NEI)

(ML052860142)

N Received 9-26-05 

Strategic Teaming and Resource Sharing

(STARS) (ML052790367)

S Received 10-5-05

Exelon/AmeriGen (ML052780386) X Received 10-4-05

Table 2. Key to Categories of Comments

Bin No. Description

1 Comments on backfit determinations and justifications

2 Comments on schedule

3 Comments on Hemyc testing

4 Comments on use of risk-informed methods

5 Miscellaneous comments

6 Comments on wording and specific references in GL text 

7 Comments on the burden estimate
-2-

BIN 1 - COMMENTS ON BACKFIT DETERMINATION AND JUSTIFICATIONS

Comment:

Duke Power Comment (D-1), Nuclear Energy Institute (NEI) Comment (N-1a),

and Exelon/AmeriGen Comment (X-1) - The criteria of GL 86-10 Supplement 1

are not applicable to Hemyc installations that were previously accepted.

Application of GL 86-10, Supplement 1 to previously accepted configurations

should be evaluated under the backfit rule, 10 CFR 50.109. The application of

GL 86-10, Supplement 1 is a new regulatory position. 

Staff Response:

NRC staff agrees with these comments - The NRC has clarified that this GL is

requesting licensees to describe their plant’s compliance with their approved licensing basis,

and does not require licensees to apply the methodology contained in GL 86-10, supplement 1,

to previously accepted fire barrier installations. Licensees are requested to show that, based

on the information gathered during the NRC testing, the assumptions used in the licensee’s and

NRC’s acceptance of the existing configurations are still valid. GL 86-10, supplement 1, does

not contain criteria for acceptance of fire barriers, acceptance criteria are contained in the rules

and license commitments. 

Comment:

Duke Power Comment (D-2) - The proposed GL does not accurately convey the

McGuire Nuclear Station Hemyc qualification. Also, the excerpts from the above

referenced inspection report do not completely describe the conclusions from the

inspection report.

Staff Response:

NRC staff does not agree with this comment - The NRC is using the discussion of the

McGuire inspection in the Background section of the GL to illustrate that the staff began to raise

concerns regarding Hemyc after 1999. No conclusions regarding the acceptance of the

McGuire specific configurations are being made in this GL, only restating portions of the

inspection report to show that Hemyc concerns had been raised. 

Comment:

Duke Power Comment (D-3) - Duke asks that the NRC provide clarification on

the acceptance of ‘86-10 evaluations’ that meet the same qualitative standards

used in the past.

Staff Response:

NRC staff agrees in part with this comment - GL 86-10 evaluations that are not based

on risk analysis are still applicable and acceptable for post-79 plants. See Bin 4 for more

discussion on evaluations.
-3-

BIN 2 - COMMENTS ON SCHEDULE

Comment:

Progress Energy Comment (E-2), Strategic Teaming and Resource Sharing

(STARS) Comment (S-12), and NEI Comment (N-4) - Some plants have

significant amounts of Hemyc making the December 1, 2007, date for restoring

compliance is unduly burdensome. NEI suggests the date be changed to

December 1, 2008, would be needed to support additional testing as well.

Staff Response:

NRC staff does not agree with these comments – The NRC staff expects all licensees to

fully restore compliance by December 1, 2007. This date was selected to allow at least one

outage so work may not have to be performed in the vicinity of safety-related equipment during

power operations. However, the NRC staff will consider extension requests to accommodate

plant-specific needs related to design modifications and outage schedules. The NRC does not

expect additional testing to be needed due to the recent NRC and industry testing that has been

completed.

Comment:

Progress Energy (E-3) - Flexibility for compliance schedule is requested for

those plants committed to NFPA 805 (10 CFR 50.48(c) - voluntary rule).

Staff Response:

NRC staff agrees with this comment - NFPA 805 discretion applies to the Hemyc/MT

issue for those licensees that properly adopt 10 CFR 50.48(c). Licensees should propose their

approach to resolving the Hemyc/MT issue, with the proposed schedule for resolution including

reference to their letter of intent, in their response to the GL. 

Comment:

Strategic Teaming and Resource Sharing (STARS) Comment (S-11) -

‘Requested Actions’ and ‘Requested Information’ – the 60-day time period for the

initial response is arbitrary, and it may not allow sufficient time for licensees who

are affected by this issue to adequately respond and provide the requested

information. STARS recommends extending the initial response period to 90

days at a minimum so that an adequate and complete response can be

developed by the licensee. 

Staff Response:

NRC staff does not agree with this comment - With the public release of this draft GL

and publication of Information Notice (IN) 05-07 in April 2005, licensees have had time to

evaluations and corrective actions. Therefore, the NRC staff considers a 60-day response time

from the issuance of the GL sufficient. 

BIN 3 - COMMENTS ON HEMYC TESTING 

Comment:

Progress Energy (E-1) - The NRC should review the Hemyc users' group test

that was performed in August 2005. The results of that testing could have an

impact on the application of some or all of the GL.
-4-

Staff Response:

NRC staff agrees with this comment - The NRC has considered the results of the recent

industry testing in this generic letter. After carefully reviewing the industry tests, the NRC staff

concludes that concerns about Hemyc performance have been confirmed by these test results. 

Therefore, the NRC staff intends to maintain the current course of action. 

Comment:

Duke Power Comment (D-5) and NEI Comment (N-2) - Hemyc as used primarily

throughout nuclear plants has an outer covering made of either Siltemp or a twopart blanket with Siltemp and Klevers. The GL should therefore note the original

construction in this description section and note the material used in the NRC

test to be a modified construction.

Staff Response:

NRC staff does not agree with this comment - The NRC confirmatory test results are

consistent with the industry test results and with the installation procedure, the NRC staff

considers the noted difference in construction insignificant and intends to maintain the current

course of action. The details of the NRC tests are provided in IN 05-07 and on the NRC public

Web site. The GL is intended not to replicate those details, but to focus on the implications and

application of the test results.

Comment:

STARS Comment (S-2) - The NRC fire tests were performed in accordance with

Generic Letter 86-10, Supplement 1. GL 86-10, Supplement 1 contains

standards that are much more restrictive that those that were required for the

initial testing and qualification of these fire barrier systems. The proposed

generic communication should clearly indicate that the fire tests performed by

the NRC did not duplicate the original fire tests that were performed to originally

certify the HEMYC and MT fire barrier system product line.

Staff Response:

NRC staff does not agree with this comment - The NRC testing was based on a 1 or 

3-hour fire rating, and using a fire that follows the NFPA 251 time-temperature curve. This is

the same as was used during the original fire testing. The NRC requires the cables to remain

free of fire damage. The test used a temperature threshold to demonstrate cable functionality. 

Other methods are available and discussed in NRC guidance documents.

Comment:

STARS Comment (S-5) - What configuration standard was used during the tests

for protection of intruding steel, and consider limiting the discussion to the tested

configuration.

Staff Response:

NRC staff does not agree with this comment - NRC tests did not include support

structures or the barrier configurations within the furnace. Supports for the assemblies were

located outside the furnace due to the concern that fire barrier penetration by supports inside

the furnace might cause premature failure of the fire barrier system, with a resulting loss of 
-5-

data. Supporting steel configurations were tested separately and did not affect the Hemyc and

MT test results. Data can be taken from the supporting steel configurations that were tested

and applied to plant specific configurations.

Comment:

STARS Comment (S-6) - It is inappropriate to declare the entire product line of

Hemyc and MT fire barrier systems deficient based on limited samples.

Staff Response:

NRC staff agrees with this comment - The GL has been modified to consistently state

that the NRC test results apply “for the configurations tested.”

BIN 4 – COMMENTS ON RISK INFORMED METHODS

Comment:

Duke Power Comment (D-3), NEI Comment (N-3) and STARS Comment (S-9) -

The NRC should accept a risk assessment approach for making changes to the

approved fire protection program using a licensee’s standard license condition

without need for a license amendment. Also does the NRC intend to require a

license amendment for risk-informed approaches that are applied to NFPA 805

transition?

Staff Response:

NRC staff does not agree with this comment - Currently the NRC has not approved risk

assessment approaches for fire protection, therefore applications of these approaches should

be submitted as part of a license amendment or exemption request as appropriate. As

reflected in other risk-informed rules, such as 10 CFR 50.69, the NRC staff obtains assurance

that licensees possess appropriate PRA capabilities before allowing licensees to use riskinformed methods without prior NRC approval. NRC staff encourages the use of risk insights in

all regulatory matters, but using risk methods exclusively for self-approval of fire protection

changes using the standard license condition is not considered acceptable by the staff at this

time based on the reason previously stated.

Regarding application to NFPA 805 transition, this information has not yet been

finalized, the NRC will publish this information as part of the planned regulatory guide for

implementation of 10 CFR 50.48(c). 

BIN 5 – MISCELLANEOUS COMMENTS

Comment:

NEI Comment (N-1b) - The utilities that use this system for compliance with NRC

regulatory requirements have implemented compensatory and corrective actions

in accordance with existing regulations commensurate with the safety

significance of this issue, and plan to fully address this issue while maintaining

defense-in-depth and the safety margins associated with currently approved fire

protection programs.
-6-

Staff Response:

NRC staff agrees with this comment – This comment is consistent with the points

included in the NRC’s information request. 

Comment:

NEI Comment (N-6) – A public meeting is requested with the licensees that use

the Hemyc/MT fire barrier system to discuss specific compensatory and

corrective actions, and schedules for resolution of NRC concerns. 

Staff Response:

NRC staff agrees with this comment - The NRC staff held a public meeting 

September 29, 2005, following the September 23, 2005, closure of the public comment period. 

During that meeting NEI indicated that the September 29, 2005, meeting was sufficient and no

additional meeting was needed. 

Comment:

STARS Comment (S-1) A limited number of licensees use Hemyc or MT,

therefore the proposed generic communication distribution should be limited to

only those licensees that use these fire barrier systems, and that the draft

generic letter should be revised accordingly to minimize the impact on those

licensees that are not impacted by this issue. 

Staff Response:

NRC staff does not agree with this comment - The NRC staff is concerned that other

licensees unknown to NEI and the manufacturer may have installed these materials, due to the

material’s specifications being publicly available and based on the barriers reliance on generally

available construction materials. 

Also, the NRC staff is requesting information from all plants to ensure that other fire

barriers have adequate programmatic controls in place to demonstrate compliance with

applicable requirements. In GL 92-08, the NRC expected licensees to resolve all fire barrier

issues. New issues identified with Hemyc and MT suggest to the NRC that a complete

resolution had not been performed.

BIN 6 – COMMENTS ON WORDING AND SPECIFIC REFERENCES IN GL TEXT

Comment:

Duke Comment (D-4), Exelon Comment (X-2), and NEI Comment (N-5) – The

GL is requesting a description of the existing programmatic controls that will

insure that other fire barrier types will be assessed for potential degradation and

resultant adverse effects. This request is too broad, instead the GL should

specifically state that the licensee should describe the evaluation of other

electrical raceway fire barrier systems (ERFBS) that may be subject to similar

deficiencies. Also, more clearly define what is meant by ‘programmatic controls.’

Staff Response:

NRC staff does not agree with these comments - GL 92-08 requested the evaluation of

other fire barrier systems. The recent NRC tests revealed that these fire barriers may not

function as intended, therefore the performance of other fire barrier systems may also be
-7-

suspect, since the same evaluation that missed potential problems with Hemyc and MT may

have been applied to the other barrier materials. 

A programmatic control is a program (plan or procedure) in place to ensure that all fire barriers

will perform as intended, especially in light of new information that could affect their

performance. Programmatic controls use some means of checking, testing, or verifying by

evidence or experiments. For these reasons, the NRC staff did not include a description of the

existing programmatic controls.

Comment:

STARS Comment (S-3) – The paragraph on Hemyc Construction is confusing. It

appears that two different fire barrier configurations are being discussed. Please

clarify, and provide additional information regarding the use and configuration of

the second fire barrier.

Staff Response:

NRC staff does not agree with this comment - The paragraph in question discusses two

configurations of Hemyc—i.e., the 2-inch mat used for direct wrap conduit and the 11⁄2-inch mat

used in the air gap design.

Comment:

STARS Comment (S-4) – The GL discusses ‘three failure modes’ of the fire

barriers, but it implies only two ‘types’ of failures, i.e., shrinkage of the outer

material, and inadequate protection of intruding steel members. Please provide

additional information regarding the ‘three failure modes,’ or clarify that only two

‘types’ of failures were observed.

Staff Response:

The NRC staff agrees with this comment – The draft GL has been corrected to reflect

two failure modes rather than three. 

Comment:

STARS Comment (S-7) – The paragraph, beginning with ‘NRC regulations’

appears to be misplaced, and its meaning is unclear. Is the intent to state that

an exemption or license amendment is an acceptable approach to resolving this

issue?

Staff Response:

NRC does not agree with this comment - The intent is to state that properly justified

exemptions or amendment requests, prepared in accordance with the plant-specific licensing

basis, are acceptable approaches.

Comment:

STARS Comment (S-8) – In the paragraph beginning with ‘NRC regulations,’

should the word ‘ratings’ more appropriately be ‘barriers’ at the end of

paragraph. 
-8-

Staff Response:

The NRC staff agrees with this comment – The existing wording has been replaced with

the wording proposed in the draft GL.

Comment:

STARS Comment (S-10) – In the Applicable Regulatory Guidance section, first

paragraph, first reference to “GL 86-10” – The reference to ‘GL 86-10’ is

incomplete, it should read “Generic Letter (GL) 86-10, ‘Implementation of Fire

Protection Requirements.’”

Staff Response:

NRC staff agrees with this comment - The suggested change has been made. 

Comment:

PCI Promatec Comment (P-1) – Regarding the GL reference to the Hemyc

manufacturer, Promatec Inc.; clarification is requested specifying that Peak

Seals, Inc. purchased the assets of the manufacturer in 1997; but that Peak

Seals, Inc. (now known as PCI Promatec) never marketed the Hemyc and MT

technologies. 

Staff Response:

NRC staff agrees with this comment - The GL reference to the manufacturer has been

removed from the draft document because the NRC staff could not assure that Promatec, Inc

manufactured all Hemyc materials installed in plants. 

BIN 7 – COMMENTS ON BURDEN ESTIMATE

None