Compensatory and Alternative 

Regulatory MEasures for 

Nuclear Power Plant FIRE

Protection (CARMEN-FIRE)

Draft Report for Comment

Office of Nuclear Regulatory Research

NUREG/CR-7135
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Compensatory and Alternative 

Regulatory MEasures for 

Nuclear Power Plant FIRE

Protection (CARMEN-FIRE)

Draft Report for Comment

Draft Manuscript Completed: February 2013

Date Published: June 2013

Prepared by: 

K. Sullivan

Brookhaven National Laboratory

Nuclear Science and Technology Department

P.O. Box 5000

Upton, NY 11973

F. Gonzalez, NRC Project Manager

NRC Job N6760

Office of Nuclear Regulatory Research

NUREG/CR-7135
COMMENTS ON DRAFT REPORT

Any interested party may submit comments on this report for consideration by the NRC staff. 

Comments may be accompanied by additional relevant information or supporting data. Please 

specify the report number NUREG/CR-7135 in your comments, and send them by the end of 

the comment period specified in the Federal Register notice announcing the availability of this 

report. 

Addresses: You may submit comments by any one of the following methods. Please include 

Docket ID NRC-2013-0103 in the subject line of your comments. Comments submitted in 

writing or in electronic form will be posted on the NRC website and on the Federal rulemaking 

website http://www.regulations.gov. 

Federal Rulemaking Website: Go to http://www.regulations.gov and search for documents 

filed under Docket ID NRC-2013-0103. Address questions about NRC dockets to Carol 

Gallagher at 301-492-3668 or by e-mail at Carol.Gallagher@nrc.gov. 

Mail comments to: Cindy Bladey, Chief, Rules, Announcements, and Directives Branch 

(RADB), Division of Administrative Services, Office of Administration, Mail Stop: 

TWB-05-B01M, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001. Faxes 

may be sent to RADB at 301-492-3446. 

For any questions about the material in this report, please contact: Felix Gonzalez, Reliability 

and Risk Engineer, and 301-251-7596 or by e-mail at felix.gonzalez@nrc.gov. 

Please be aware that any comments that you submit to the NRC will be considered a public 

record and entered into the Agencywide Documents Access and Management System 

(ADAMS). Do not provide information you would not want to be publicly available. 
Draft for Comment 

iii 

ABSTRACT 

Each commercial nuclear power plant operating in the United States has a comprehensive Fire 

Protection Program (FPP) that has been reviewed and approved by the U.S. Nuclear 

Regulatory Commission (NRC). 1 The purpose of the FPP is to prevent the occurrence of fire 

and minimize radioactive releases to the environment in the unlikely event a significant fire were 

to occur. To achieve these objectives, the FPP integrates a number of plant designs and 

operating features (i.e., systems, components, personnel and administrative controls) needed to 

provide defense-in-depth protection of the public health and safety. This means that the FPP 

includes measures that are directed at reducing the likelihood of fires and explosions; rapidly 

detecting and suppressing those fires that may occur, and ensuring the capability to achieve 

and maintain safe shutdown conditions in the event of a significant fire. 

Over the life of a plant, certain elements of the FPP may be found to be incapable of performing 

their intended function (i.e., become impaired). Ensuring appropriate actions are promptly taken 

to mitigate the effect of such impairments until permanent corrective actions can be completed 

is a key element of the FPP. Such actions are called “compensatory measures.” 

For most impairments, appropriate measures are specified in the approved FPP. However, 

since it is not possible to address all conceivable plant conditions, the actions specified in the 

FPP may not be appropriate in all cases. In such instances, an alternate compensatory 

measure is identified by the licensee on a case-by-case basis. The selection of a specific type 

of compensatory measure for a given impairment should be based on its ability to offset the 

degradation in defense-in-depth created by the inoperable, degraded, or nonconforming 

condition. Thus, appropriate alternate measure(s) may consist of wide range of options; from 

enhancing the measure specified in the FPP (e.g., placing additional controls over combustible 

materials) to the use of technologically advanced fire protection systems that were not available 

at the time the FPP was approved. 

Employing compensatory measures, on a short-term basis, is an integral part of NRC-approved 

fire protection programs. However, compensatory measures are not expected to be in place for 

an extended period of time. The NRC staff expects that the corrective action(s) will be 

completed, and reliance on the compensatory measure eliminated, at the first available 

opportunity, typically the first refueling outage. Thus, a compensatory measure that is in place 

beyond the next refueling outage (typically 18 – 24 months) is considered to be a “long-term 

compensatory measure.”

This report is intended to serve as a reference guide for agency staff responsible for evaluating 

the acceptability of interim compensatory measures provided to offset the degradation in fire 

safety caused by impaired fire protection features at nuclear power plants. The report 

documents the history of compensatory measures and details the regulatory framework 

established by NRC to ensure they are appropriately implemented and maintained. This report 

 

1

 As defined in Generic Letter 81-12, an approved Fire Protection Program includes the fire protection and 

post-fire safe shutdown systems necessary to satisfy NRC guidelines and requirements; administrative 

and technical controls; the fire brigade and fire protection related technical staff; and other related plant 

features which have been described by the licensee in the FSAR, fire hazards analysis, responses to staff 

requests for additional information, comparisons of plant designs to applicable NRC fire protection 

guidelines and requirements, and descriptions of the methodology for assuring safe plant shutdown 

following a fire. 
Draft for Comment 

iv 

also explores technologies that did not exist when the current plants were licensed such as 

video-based detection, temporary penetration seals and portable suppression systems which 

under certain conditions may provide an effective alternative to traditional measures specified in 

a plant’s approved fire protection program. 
Draft for Comment 

v 

TABLE OF CONTENTS 

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

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

LIST OF TABLES ......................................................................................................................... ix

EXECUTIVE SUMMARY ............................................................................................................. xi

ACKNOWLEDGEMENTS ........................................................................................................... xv

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

1. INTRODUCTION ..................................................................................................................... 1

1.1 Background ......................................................................................................................... 1

1.2 Objective ............................................................................................................................. 2

1.3 Scope .................................................................................................................................. 3

2. DISCUSSION ........................................................................................................................... 5

2.1 Historical Overview ......................................................................................................... 5

2.2 Purpose of Report .......................................................................................................... 7

2.3 Scope of Report .............................................................................................................. 8

3. REGULATORY FRAMEWORK ............................................................................................... 9

3.1 Historical Overview of Fire Protection Technical Specifications ................................... 15

3.2 Fire Protection Program ............................................................................................... 17

3.2.1 Design Features .................................................................................................... 17

3.2.2 Administrative Controls ......................................................................................... 18

3.2.3 Quality Assurance ................................................................................................. 18

4. IMPAIRMENTS AND COMPENSATORY MEASURES ......................................................... 21

4.1 Fire Protection Impairments ......................................................................................... 21

4.2 Compensatory Measures ............................................................................................. 23

4.2.1 Types of Compensatory Measures ....................................................................... 24

4.2.2 Selecting Appropriate Compensatory Measures ................................................... 28

4.2.3 Alternate Compensatory Measures ....................................................................... 32

4.3 Use of New Technologies ............................................................................................. 33

5. EXAMPLE ASSESSMENT .................................................................................................... 35

5.1 Scenario ....................................................................................................................... 35

5.2 Assessment .................................................................................................................. 37

5.2.1 Evaluation of Defense-in-Depth Element 1 – Fire Prevention ............................... 37

5.2.2 Evaluation of Defense-in-Depth Element 2 – Detection, Suppression, and 

Mitigation ............................................................................................................... 38

5.2.3 Evaluation of Defense-in-Depth Element 3 – Protecting SSCs Important to 

Safety .................................................................................................................... 39
Draft for Comment 

vi 

5.3 Evaluation of Compensatory Measures ........................................................................ 39

6. REFERENCES ...................................................................................................................... 41

7. GLOSSARY ........................................................................................................................... 47

APPENDIX A: COMPARISON OF ACTIONS SPECIFIED IN STANDARDIZED TECHNICAL 

SPECIFICATIONS TO COMPENSATORY MEASURES IDENTIFIED IN 

APPROVED FIRE PROTECTION PROGRAMS ............................................. A-1

APPENDIX B: ADVANCED TECHNOLOGIES ........................................................................ B-1

B.1 Advanced Detection Technologies ............................................................................. B-1

B.1.1 Aspirating (Air Sampling) Smoke Detectors ........................................................ B-3

B.1.2 Laser-Based Spot-Type Smoke Detectors .......................................................... B-7

B.1.3 Video Image Detection ........................................................................................ B-8

B.1.4 Thermal Imaging Cameras ................................................................................ B-10

B.2 Advanced Suppression Technologies ...................................................................... B-12

B.2.1 Solid Propellant Gas Generators ....................................................................... B-12

B.2.2 Transportable Automatic Suppression Systems ............................................... B-16

B.2.3 Pre-packaged Portable Water Mist Systems ..................................................... B-16

B.3 Temporary Fire Barrier Penetration Seals ................................................................ B-17

B.3.1 Intumescent Pillows and Blocks ........................................................................ B-19

B.3.2 Reusable Firestop Plugs and Putty ................................................................... B-21
Draft for Comment 

vii 

LIST OF FIGURES 

Figure Page

Figure 3-1. Major Documents and Milestones of FP and Compensatory Measures in the 

Nuclear Industry ....................................................................................................... 14

Figure 5-1. Fire Area SW-1A ..................................................................................................... 36

Figure B-1. Qualitative relationship between time and damage for different speeds of fire 

development and average detection, reaction and fire-fighting times (Ref. 

NUREG/CR-2409) ................................................................................................. B-2

Table B-2. Detector Sensitivity Comparison (Ref. Brazzell, 2009) ......................................... B-3

Figure B-2. Cloud Chamber ..................................................................................................... B-4

Figure B-3. Light Scatter Aspirating Smoke Detector .............................................................. B-5

Figure B-4. Laser Aspirating Smoke Detector ......................................................................... B-6

Figure B-5. Spot-Type Laser Detector ..................................................................................... B-8

Figure B-6. Video Image Detection ........................................................................................ B-10

Figure B-7. Condensed Aerosol Generator ........................................................................... B-14

Figure B-8. N2 Gas Generator ............................................................................................... B-15

Figure B-9. Transportable Suppression System Applications ................................................ B-16

Figure B-10. Skid-mounted Water Mist System ..................................................................... B-17

Figure B-11. Diagram of Intumescent Pillows in a cable tray penetration ............................. B-20

Figure B-12. Diagram of fire stop plug in a cable penetration ................................................ B-21

Figure B-13. Diagram of fire stop putty in a cable penetration ............................................... B-22

Figure B-14. Possible Applications of Advanced Technologies ............................................ B-23

Draft for Comment 

ix 

LIST OF TABLES 

Table Page

Table 4-1. Examples of Fire Protection Impairments ................................................................. 21

Table 4-2. Common Types of Compensatory Measures ........................................................... 24

Table A-1. Comparison of Technical Specification Compensatory Actions to Current FPP 

Measures ............................................................................................................... A-2

Table B-2. Detector Sensitivity Comparison (Ref. Brazzell, 2009) ......................................... B-3

Draft for Comment 

xi 

EXECUTIVE SUMMARY 

During the initial development of the U.S. commercial nuclear power program, the level of fire 

protection adopted by a nuclear power plant (NPP) was generally found to be acceptable if it 

complied with applicable national and local fire codes, as evidenced by an acceptable rating 

from its fire insurance underwriter. Consequently, the fire protection features at NPPs were very 

similar to those of conventional, fossil-fueled, power generating stations. Fire protection 

continued to be evaluated on this basis until a major fire at the Browns Ferry Nuclear Power 

Plant on March 22, 1975 prompted significant changes in the NRC’s fire-safety regulatory 

framework. 

A key recommendation of a Special Review Group (SRG) tasked by the Commission to 

investigate the Browns Ferry fire, was the need for each operating plant to establish a 

comprehensive fire protection program (FPP) that integrates the multiple levels of protection 

established by the time-honored safety concept known as “defense-in-depth.” The incorporation 

of this recommendation into the NRC’s regulatory framework required each operating plant to 

establish a FPP that integrates the structures, systems, components, procedures, and 

personnel needed to: (1) Prevent fires from starting; (2) Detect rapidly, control, and extinguish 

those fires that do occur; and, (3) Ensure that fire will not prevent the performance of necessary 

safe shutdown functions, and will not significantly increase the risk of radioactive releases to the 

environment. The aim is to achieve a suitable balance between each layer of protection. 

Increased strength, redundancy, performance, or reliability of one layer of protection can 

compensate in some measure for deficiencies in the others. 

Consistent with the defense-in-depth safety concept, the SRG also recommended that an 

adequate level of fire safety be maintained when a fire protection feature is degraded or 

disabled. The Commission addressed this recommendation by allowing licensees, through their 

approved fire protection program2

, to implement temporary corrective actions called 

“compensatory measures” or “interim compensatory measures” until the functionality of 

degraded or disabled equipment is restored. The objective of these measures is to temporarily 

offset the reduction in fire safety caused by the impairment. 

The incorporation of SRG recommendations into the NRC’s regulatory framework resulted in a 

comprehensive FPP at each plant that integrates design features needed to provide an 

appropriate balance between each element of defense-in-depth and administrative controls 

(e.g., policies and procedures) to govern all fire protection activities, including the establishment 

of interim compensatory measures that are appropriate for the specific hazards, compatible with 

plant operations, and are properly implemented and maintained. 

To assure that fire protection systems and features are available and in proper working 

condition, the Commission initially imposed Technical Specifications (TS) for certain fire 

 

2

 The NRC-approved Fire Protection Program includes the fire protection and post-fire safe shutdown 

systems necessary to satisfy NRC guidelines and requirements; administrative and technical controls; the 

fire brigade and fire protection related technical staff; and other related plant features which have been 

described by the licensee in the FSAR, fire hazards analysis, responses to staff requests for additional 

information, comparisons of plant designs to applicable NRC fire protection guidelines and requirements, 

and descriptions of the methodology for assuring safe plant shutdown following a fire. 
Draft for Comment 

xii 

protection systems. The incorporation of the fire protection system, including impairments and 

their associated compensatory measures, into the TS was deemed necessary to assure that: 

 Prompt compensatory measures would be taken, 

 An appropriate alternate means of protection is provided, and 

 Appropriate organizations are notified to counter the effects of systems/equipment being 

out-of-service. 

In 1986, the Commission provided an approach for licensees to remove unnecessary fire 

protection Technical Specifications (TS). (GL 86-10). Under this guidance, most TS 

requirements for fire protection system operability (and associated compensatory measures) 

were relocated from the technical specifications to documents referred to in the FSAR, such as 

a technical requirements manual (TRM). Specific FPP elements that remained in the TSs 

include: (a) specifications associated with safe-shutdown equipment; and, (b) administrative 

controls which ensure that the NRC-approved FPP is appropriately established, implemented, 

and maintained in accordance with the current license basis (CLB). A review of several FPPs 

found that that relocating fire protection features from the TS to licensee controlled documents 

referenced in the FSAR did not result in a significant change to the operability requirements for 

fire protection features or their associated compensatory measures. 

For most impairments, compensatory measures are specified in the NRC-approved FPP. The 

most common type of compensatory measure is a fire watch, which is a person trained to look 

for fire hazards, detect early signs of fire, and initiate alarms. For unique impairments not 

addressed by the FPP or where the compensatory measure specified in the FPP does not 

provide an appropriate level of protection for the specific circumstances, an alternate approach 

may be determined by the licensee in accordance with NRC guidance (RIS 2005-07). The 

evaluation should consider the impact of the proposed alternate compensatory measure to the 

FPP and its adequacy compared to the compensatory measure required by the FPP. In 

addition, the evaluation must demonstrate that the alternate compensatory measure would not 

adversely affect the ability to achieve and maintain safe shutdown in the event of a fire. For 

example, if an evaluation of the specific hazards in the area finds that sole reliance on a fire 

watch would not be sufficient to assure the ability to achieve and maintain safe shutdown 

conditions in the event of fire, a licensee would be expected to implement an alternate measure. 

Depending on the specific circumstances, alternate compensatory measures may be limited to 

enhancements of the compensatory measure specified in the FPP, such as additional 

administrative controls, operator briefings, temporary procedures, and interim shutdown 

strategies; or they may be more comprehensive such as procedures which specify actions to be 

taken by operators outside the control room in the event of fire, installing temporary fire barrier 

penetration sealing materials such as intumescent pillows and blocks and the use advanced fire 

protection technologies. 

Compensatory measures are expected to temporary. They are not intended to be in place for 

extended periods of time or used as a technique to avoid the completion of activities required to 

achieve full compliance with regulatory requirements. Nevertheless, some NPPs have been 

found to rely on compensatory measures for extended periods of time (in some cases years). In 

2005 the NRC informed licensees that it expects corrective action(s) will be completed, and 

reliance on the compensatory measure eliminated, at the first available opportunity, typically the 

first refueling outage (RIS 2005-20) . More recently, in a March 30, 2012 letter report 

(ML120900777), NRC defines a “long term compensatory measure” as one that has been in 
Draft for Comment 

xiii 

place for longer than 18 months. This means that the functionality3

 of impaired fire protection 

feature(s) is expected to be restored no later than 18 months from the date of discovery. 

This report consolidates a number of NRC communications and technical documents related to 

the use of fire protection compensatory measures at commercial NPPs. In addition to providing 

an historical overview, the report details the current regulatory framework for compensatory 

measures and illustrates how methods different from those specified in a plant’s approved fire 

protection program may be used to provide an effective alternative when unique circumstances 

are encountered. As such, the document is primarily intended to serve as a knowledge base for 

members of the NRC staff. However, NPP operators may also find it to serve as a useful 

reference. 

 

3 To be considered operable, a fire protection system or component that is not controlled by the plant’s TS, does not 

have to be “fully qualified” in terms of its design and licensing bases as long as the licensee can demonstrate 

functionality. This definition does not apply to systems or components controlled by the plant’s TS (Ref.51). 

Draft for Comment 

xv 

ACKNOWLEDGEMENTS 

The author would like to thank the individuals who contributed their time and expertise in 

providing input and reviewing drafts of this report. In particular, Mr. Felix Gonzalez and Mr. 

Mark H. Salley of the Office of Nuclear Regulatory Research, and Mr. Phillip M. Qualls of the 

Office of Nuclear Reactor Regulation. Also, I greatly appreciate the comments and suggestions 

received from Mr. Dan Frumkin and Mr. Brian Metzger of the NRC Office of Nuclear Reactor 

Regulation; Mr. Patrick Finney, Mr. Keith Young, and Mr. John Rogge of NRC Region I; Mr. 

Gerald Wiseman of NRC Region II; and Mr. Robert Krsek and Mr. Dariusz Szwarc of NRC 

Region III. I would also like to express my gratitude for the assistance provided by my 

colleagues, Mr. Randy Weidner and Mr. Jim Higgins of BNL. 

Finally, I would like to acknowledge the excellent assistance offered by Ms. Maryann Julian and 

Ms. Maria Anzaldi of BNL in preparing the document and Eric Goss of NRC’s Graphics 

Department in preparing some of the Figures. 

This report was issued for 45 day public comment on TBD, 2013 (FR XXXX). I would also like 

to acknowledge the following public comments: 

xvii 

ACRONYMS AND ABBREVIATIONS 

ALARA As Low As is Reasonably Achievable 

AOP Abnormal operating procedure 

APCSB Auxiliary Power Conversion Systems Branch 

ASD Alternate Shutdown or Aspirating Smoke Detection, depending on usage. 

BNL Brookhaven National Laboratory 

BTP Branch Technical Position 

CFR Code of Federal Regulations 

CLB Current Licensing Basis 

CO2 Carbon Dioxide 

DID Defense-In-Depth 

EGM Enforcement Guidance Memorandum 

EPRI Electric Power Research Institute 

ERFBS Electrical Raceway Fire Barrier Systems 

FAQ Frequently Asked Question 

FHA Fire Hazards Analysis 

FPP Fire Protection Program 

FR Federal Register 

FSAR Final Safety Analysis Report 

GDC General Design Criteria 

GL Generic Letter 

HVAC Heating, Ventilation and Air Conditioning 

IEEE Institute of Electrical and Electronics Engineers 

IN Information Notice 

IP Internet Protocol 

LCIE License Condition Impact Evaluation 

LCO Limiting Condition of Operation 

LED Light-emitting diode 

LER Licensee Event Report 

NEI Nuclear Energy Institute 

NFPA National Fire Protection Association 

NPP Nuclear Power Plant 

NRC Nuclear Regulatory Commission 

NRR Office of Nuclear Reactor Regulation (at NRC) 

NUMARC Nuclear Management and Resources Council 

OE Office of Enforcement 
xviii 

OMA Operator Manual Action 

PRA Probabilistic Risk Assessment 

QA Quality Assurance 

RES Office of Nuclear Regulatory Research (at NRC) 

RG Regulatory Guide 

RIS Regulatory Issue Summary 

SCBA Self-contained breathing apparatus 

SDP Significance Determination Process 

SER Safety Evaluation Report 

SRG Special Review Group 

SRM Staff Requirements Memorandum 

SRP Standard Review Plan 

SSA Safe Shutdown Analysis 

SSD Safe Shutdown 

SSC Structures, Systems and Components 

STS Standard Technical Specifications 

TS Technical Specification 

UFSAR Updated Final Safety Analysis Report 

VEWFD Very Early Warning Fire Detection 

VID Video Image Detection 
1 

1. INTRODUCTION 

1.1 Background 

A fire which occurred at the Browns Ferry Nuclear Power Plant on March 22, 1975 led to 

significant changes in the fire protection regulatory framework for commercial nuclear power 

plants (NPP). As part of the Commissions response to the fire, the Executive Director for 

Operations of the NRC established a Special Review Group (SRG) to identify lessons learned 

and make recommendations for improving the level of fire safety at commercial NPPs. In its 

report, NUREG-0050, "Recommendations Related to the Browns Ferry Fire: Report by Special 

Review Group" [Ref. NUREG-0050], the SRG noted that when fire protection features are 

disabled temporary measures must be provided for fire protection in areas covered by the 

disabled equipment. This recommendation has been incorporated into current fire protection 

programs by requiring licensees to implement temporary actions, called “interim compensatory 

measures,” (or “compensatory measures”) to offset the reduction in fire safety caused by the 

impaired4

 fire protection feature until corrective actions are completed. Examples of common 

impairments include damaged or degraded fire barriers, inoperable smoke detectors, fire 

protection components taken out-of-service to facilitate maintenance, and broken hardware on 

fire-rated doors. 

Based on recommendations contained in the SRG’s report, Subsequent to the SRG report, in 

1976, the NRC issued Branch Technical Position Auxiliary and Power Conversion Systems 

Branch 9.5-1 (BTP APCSB 9.5-1), "Guidelines for Fire Protection for Nuclear Power Plants," to 

describe acceptable methods for implementing General Design Criterion 3, “Fire Protection” of 

Appendix A to 10 CFR Part 50, “General Design Criteria for Nuclear Power Plants” (GDC 3)5

. 

A key objective of the BTP and its Appendix A, was for every NPP to establish a fire protection 

program (FPP) that is based on the defense-in-depth safety concept of using multiple, 

independent, layers of protection to assure the health and safety of the public. The BTP further 

specified that administrative procedures be provided to ensure impaired fire protection systems 

are reviewed by appropriate levels of management and appropriate actions and procedures are 

implemented to assure adequate fire protection and reactor safety until the impairment is 

permanently corrected. 

Integrating the defense-in-depth concept into fire protection resulted in the establishment of 

comprehensive FPPs at each plant that are designed to achieve an adequate balance among 

each of the following fire safety objectives: 

 

4

 When a fire protection feature or system cannot perform its intended function, it is said to be “impaired” 

(Ref. RG1.189). 

5

 BTP APCSB 9.5-1 did not apply to plants already in operation (i.e., docketed) at the time it was issued. 

Guidance for operating plants was provided later in Appendix A to BTP APCSB 9.5-1, “ Guidelines for 

Fire Protection for Nuclear Power Plants Docketed Prior to July 1, 1976,” which, to the extent practicable, 

relies on BTP APCSB 9.5-1. 
2 

1. Preventing fires from starting. 

2. Detecting and extinguishing quickly fires that may start and limiting their damage. 

3. Designing the plant to minimize the effect of fires on essential safety functions so the 

ability to achieve and maintain safe shutdown conditions will be preserved. 

Impairments cause the overall level of fire protection defense-in-depth to be degraded. 

Therefore, their associated compensatory measures should 

 be promptly implemented, 

 provide an appropriate level of compensation, and 

 be temporary; Reliance on the compensatory measure should be eliminated by the end 

of first available refueling outage 

Examples of common compensatory measures include: 

 fire watches 

 enhanced controls over combustible materials and/or ignition sources, 

 temporary repairs or modifications, 

 temporary procedures 

 operations crew briefings (e.g., Control Room Night Orders), 

 staging temporary backup fire suppression equipment 

As discussed in Regulatory Guide 1.189, “Fire Protection for Nuclear Power Plants” [RG 1.189] 

and Regulatory Information Summary (RIS) 2005-07: “Compensatory Measures To Satisfy The 

Fire Protection Program Requirements” [RIS 2005-07], implementing only those measures 

specified in the approved FPP may not be sufficient to mitigate fire risk in all circumstances. For 

example, if an evaluation of the specific hazards in the area finds that sole reliance on a fire 

watch would not be sufficient to assure the ability to achieve and maintain safe shutdown 

conditions in the event of fire, a licensee would be expected to implement an alternate measure 

or combination of measures. Depending on the specific circumstances, alternate compensatory 

measures may be limited to enhancements of the compensatory measure specified in the FPP, 

such as additional administrative controls, operator briefings, temporary procedures, and interim 

shutdown strategies; or they may be more comprehensive such as procedures which specify 

actions to be taken by operators outside the control room in the event of fire, installing 

temporary fire barrier penetration sealing materials such as intumescent pillows and blocks and 

/ or the use advanced fire protection technologies. A licensee may implement alternate 

compensatory measures without prior approval of the NRC provided they are evaluated in 

accordance with the guidance provided by the staff in RIS 2005-07. However, changes to 

compensatory measures defined in the plant’s Technical Specifications (TS) would require a 

license amendment. 

1.2 Objective 

During the development of the current fire protection regulatory framework, the NRC foresaw 

cases in which fire protection features would be inoperable, and allowed licensees to 

implement, in accordance with their approved fire protection program, interim measures to 
3 

compensate for the impaired condition or component until permanent corrective actions were 

implemented. More recently, several generic communications have been issued by NRC staff 

to address various issues related to the application of compensatory measures for fire 

protection programs. For example, in 1997, NRC issued Information Notice (IN) 97-48 to alert 

addressees to potential problems associated with the implementation of interim compensatory 

measures. In Regulatory Issue Summary (RIS) 2005-07 (ML042360547) the staff describes 

how licensees may use alternate approaches, when the measures specified in the approved 

FPP do not provide an appropriate level of safety for the specific circumstances. Both IN 97-48 

and RIS 2005-07 cite cases where compensatory measures specified in approved FPPs may 

not be appropriate for unique circumstances, such as degraded or inoperable components and 

fire protection features associated with the plant’s post-fire safe-shutdown capability. 

In 2009, the NRC Office of Nuclear Reactor Regulation (NRR) Fire Protection Branch Chief, 

recommended that longstanding concerns about compensatory measures be addressed and 

requested the Office of Nuclear Regulatory Research (RES) to prepare a document 

consolidating documentation regarding compensatory measures usage. Subsequently, RES 

contracted Brookhaven National Laboratory (BNL) to develop a reference guide for agency staff 

who evaluate the acceptability of interim compensatory measures when degraded or 

nonconforming conditions are identified in fire protection features at nuclear power plants. 

1.3 Scope 

BNL was requested to assist the NRC staff in the development of a NUREG series report which: 

 provides an historical background of compensatory measures for fire protection; 

 describes the fire protection regulatory framework concerning compensatory measures, 

including the relationship between compensatory measures and defense-in-depth. 

 consolidates and clarifies existing NRC staff positions, interpretations, and guidance 

regarding compensatory measures 

 describes the types of compensatory measures typically included in fire protection 

programs approved by the staff; 

 identifies alternate approaches such as new fire protection technologies that may be 

used in lieu of, or as a supplement to, the originally approved compensatory measures; 

and, 

 provides an illustrative example of how the use of new technologies may provide a more 

appropriate method of compensation than methods specified in the approved FPP when 

unique conditions exist. 

This report is primarily intended to serve as a knowledge base for members of the NRC staff. It 

consolidates a number of NRC generic communications and technical documents related to the 

use of fire protection compensatory measures at commercial NPPs. However, it should be used 

as a compliment to, not a substitute for, requirements, inspection procedures, and standard 

review plans. Users are encouraged to review the references cited in the document to gain an 

in-depth understanding of compensatory measures. 

Draft for Comment 

5 

2. DISCUSSION 

2.1 Historical Overview 

During the initial development of the U.S. nuclear reactor program in the early 1970s, fire 

protection requirements for commercial nuclear power plants were limited to the broad 

performance objectives of Appendix A to 10 CFR Part 50, “General Design Criteria for Nuclear 

Power Plants.” Specifically, General Design Criteria 3, (GDC 3) specified that “structures, 

systems, and components important to safety be designed and located to minimize the 

probability, and adverse effects of fires and explosions, that noncombustible and heat- resistant 

material be used wherever practical, and that fire detection and suppression systems be 

provided to minimize the effect of fire on structures, systems, and components important to 

safety.” Because of a lack of detailed implementation guidance, the level of fire protection 

adopted by a facility was generally found to be acceptable if it complied with local and industrial 

fire codes and received an acceptable rating from its fire insurance underwriter. Thus, the fire 

protection features at commercial NPPs were very similar to those of conventional, fossil-fueled, 

power generating stations. 

A major fire at the Browns Ferry Nuclear Power Plant on March 22, 1975 underscored the need 

for more detailed criteria and guidance for satisfying GDC 3 (Ref. NUREG-0298). The revised 

regulatory framework which followed was largely based on recommendations made by a 

“Special Review Group” (SRG) appointed by the NRC Executive Director for Operations to 

identify lessons learned and make recommendations for improving fire safety. The main 

objective of the SRG was to (a) review the circumstances, origins and consequence of the fire 

and (b) propose improvements in NRC policies, procedures and technical requirements (Ref: 

NUREG-0050). 

In its report (Ref. NUREG-0050), the SRG recognized the importance of providing temporary 

enhancements when fire protection features are disabled or taken out-of-service. Specifically, 

in its discussion of disabling fire protection systems for maintenance the SRG states: “temporary 

measures” must be established for fire protection in areas covered by the disabled equipment.” 

This recommendation is reflected in the current fire protection program, which requires 

licensees to implement temporary actions, called “compensatory measures” (Ref. RG 1.189) to 

offset the reduction in fire safety caused by the impaired fire protection systems and features 

until corrective actions are completed and the component or system is capable of performing its 

specified design functions, as specified in the plant’s current license basis (i.e., functionality6

 is 

restored). 

Based on the SRG recommendations, the NRC staff developed comprehensive guidelines for 

satisfying GDC 3; they are documented in the following Branch Technical Positions (BTP): 

 

6

 To be considered operable, a non-TS system or component does not have to be “fully qualified” in terms 

of its design and licensing bases as long as the licensee can demonstrate functionality. This definition 

does not apply to systems or components controlled by the plant’s TS (Ref.51). 
Draft for Comment 

6 

1. BTP Auxiliary Power Conversion Systems Branch (APCSB) 9.5-1, “Guidelines for Fire 

Protection for Nuclear Power Plants.” BTP 9.5-1 was issued in May 1976 but was only 

applicable to plants which filed an application for construction after July 1, 1979, 

2. Appendix A to BTP APCSB 9.5-1. Frequently identified as “Appendix A to the BTP,”

these guidelines were issued in September 1976 for currently operating NPPs to offer 

acceptable alternatives in areas where strict compliance with BTP 9-5-1 would require 

significant modifications. 

At the time these documents were issued, there was a wide variation in plant design, operating 

status and construction phase. Some plants had been operating for some time or in the final 

stages of construction, while others were in the early stages of design or construction. Many 

newer plants incorporated physical separation of safety systems into their designs. However, 

older plants, like Browns Ferry, had significantly less inherent separation. Thus, two separate 

guidance documents were deemed necessary to provide a balanced approach in the application 

of the SRG recommendations to specific facilities. 

Following their promulgation, licensees were requested to evaluate their fire protection program 

against the appropriate guidelines. Toward the end of 1978, the NRC found that fifteen fire 

protection issues remained unresolved, with certain licensees refusing to adopt some of the 

recommendations in the new guidance. Even though only a few plants might contest a given 

issue, the Commission concluded that rulemaking was the appropriate vehicle for implementing 

their fire protection policy. Accordingly, in 1980, five years after the Browns Ferry fire, the 

Commission proposed a new fire protection rule to resolve the contested issues. In a letter 

dated November 24, 1980 (Ref. GL 80-100), the Commission informed all power-reactor 

licensees with plants licensed before January 1, 1979, of the new fire protection regulations in 

Section 10 CFR 50.48 ,"Fire Protection," and Appendix R to 10 CFR 50 "Fire Protection 

Program for Nuclear Power Plants Operating Prior to January 1, 1979”. Plants licensed to 

operate after this date were required to satisfy similar criteria, as specified by the provisions of 

their operating license. 

Because it was not deemed possible at the time (1980) to accurately predict the manner in 

which a fire would start and propagate, the new fire protection requirements employed a 

“deterministic” approach which considers a set of challenges to fire safety and then determines 

how they should be mitigated. The key assumptions of this approach are: 

 An exposure fire7

 occurs in any single fire area; and, 

 Structures, Systems, and Components (SSCs) not conforming to the specified protection 

criteria cannot perform their intended function. 

One example of a deterministic criterion is the requirement that electrical raceway fire barrier 

systems (ERFBS) relied upon to protect post-fire safe shutdown related cables have a fire rating 

of either 1- or 3-hours depending on the availability of other fire protection features (Ref. RG 

1.189). Due to deficiencies identified in the early 1990s with a widely used ERFBS 

manufactured by Thermal Science, Inc. (Thermo-lag 330-1), the staff requested that interim 

compensatory measures (i.e. fire watches), be implemented and remain in place until the 

licensee can declare the fire barriers operable (Ref. NRC Bulletin No. 92-01). In certain 

 

7

 An exposure fire is a fire that involves either in situ or transient combustibles in a given fire area, and is external to any structures, 

systems, or components located in or adjacent to that same area. 
Draft for Comment 

7 

instances, these interim compensatory measures remained in place for extended periods, in 

some cases years. 

Recently, there have been significant advances in applying probabilistic risk assessment (PRA) 

techniques for fire protection at commercial NPPs. In 1998, the staff informed the Commission 

of its plans to work with the National Fire Protection Association (NFPA) and the nuclear power 

industry to develop a risk-informed, performance-based, fire protection consensus standard for 

NPPs (Ref. SECY-98-0058). In 2000, the staff received Commission’s approval to proceed with 

rulemaking to permit reactor licensees to adopt NFPA 8058

 as a voluntary alternative to existing 

requirements (Ref. SECY 00-0009) On July 16, 2004, 10 CFR 50.48 “Fire Protection” was 

amended to add a new subsection, 10 CFR 50.48 (c) (Ref. 69 FR 33536) allowing licensees to 

adopt NFPA 805 on a voluntary basis. Hence, a licensee may choose risk-informed and 

performance-based fire protection requirements as an alternative to the deterministic 

requirements of 10 CFR 50.48(a) and Appendix R to 10 CFR 50. At present, approximately half 

of the operating NPPs have submitted letters of intent to transition to a risk-informed approach 

under 10 CFR 50.48(c). 

Regardless of the selected approach, the goal of minimizing both the likelihood of occurrence 

and the consequences of fire in nuclear power plants remains the same. In both approaches, 

the requisite level of safety is assured through a “defense-in-depth” (DID) concept which 

incorporates multiple protective barriers to prevent the occurrence of fire, and features to 

mitigate its consequences should one occur. The aim is to provide a suitable balance between 

each layer of protection. Increased strength, redundancy, performance, or reliability of one 

layer can compensate in some measure for deficiencies in the others (Ref. NUREG 0050). 

2.2 Purpose of Report 

In 2008, the Commission directed the staff to formulate a closure plan for stabilizing the fire 

protection regulatory infrastructure (Ref. SRM-M080717). In response, the staff identified eight 

specific tasks for improving the regulatory stability of fire protection (Ref. SECY 08-0171). In a 

July 2009 Memo (Ref. Klein, 2009) the Chief of the Fire Protection Branch of NRR identifies 

Task 7 to consolidate regulatory documentation on compensatory measures and to identify 

available new technologies that potentially could be used in lieu of, or as a supplement to 

traditional measures specified in approved FPPs. 

To address this issue, the NRC Office of Nuclear Regulatory Research (RES) contracted 

Brookhaven National Laboratory to assist them to prepare a NUREG series report that (a) 

provides a comprehensive “knowledge base” of regulatory and technical information about 

assessing compensatory measures for impaired fire protection elements; (b) describes the 

types of compensatory measures included in approved fire protection programs; and, (c) 

identifies new technologies that may offer a viable alternative to those delineated in approved 

fire protection programs. 

RES envisioned that this NUREG report would be used by agency staff (inspectors and 

reviewers) who evaluates the acceptability of alternative compensatory measures after impaired 

conditions are identified in fire protection features at nuclear power plants. Therefore, the 

 

8

 NFPA 805 is discussed for historical purposes only. Discussions on compensatory measures do not 

apply to NFPA 805 unless stated otherwise. 
Draft for Comment 

8 

report’s overall objective is to serve as a consolidated source of regulatory and technical 

information for the NRC staff responsible for assessing the appropriateness of fire-safety 

compensatory measures at commercial NPPs. 

2.3 Scope of Report 

This report provides guidance to assist the NRC staff in determining whether a compensatory 

measure is appropriate for a given impairment. It discusses the criteria and guidance upon 

which the approved fire protection program is based, and, to the extent practical, describes 

unique aspects of compensatory measures, such as the potential for advanced technologies to 

be implemented as an alternative to the “traditional” compensatory measures specified in the 

approved fire protection program. It should be noted that NFPA 805 is discussed for historical 

purposes only and discussions on compensatory measures do not apply to NFPA 805 unless 

stated otherwise. 
Draft for Comment 

9 

3. REGULATORY FRAMEWORK 

General Design Criterion 3 (GDC 3), Fire Protection, of Appendix A to 10 CFR Part 50 

establishes the fundamental performance objectives for fire protection at NPPs. In response to 

the fire at the Browns Ferry NPP, the NRC codified criteria for satisfying GDC 3 in Title 10 of the 

Code of Federal Regulations, Part 50, Section 48, “Fire Protection” (10 CFR 50.48). Paragraph 

(a) of 10 CFR 50.48 (50.48(a)) requires, in part, that each operating nuclear power plant have a

fire protection plan that describes the overall fire protection program, and specific features 

necessary to implement the program. In July 2004, the NRC amended 10 CFR Part 50.48 

adding a new subsection, 10 CFR 50.48(c) to allow licensees to adopt, on a voluntary basis, a 

risk informed approach described in the 2001 Edition of National Fire Protection Association 

(NFPA) Standard 8059

, “Performance-Based Standard for Fire Protection for Light Water 

Reactor Electric Generating Plants.” Regardless of the selected approach, all plants must 

develop and maintain a fire protection program (FPP) which provides assurance, through a 

defense-in-depth approach, that the Commission’s fire protection objectives are satisfied. 

These objectives are: 

1. Minimize the potential for fires and explosions to occur; 

2. Rapidly detect, control, and extinguish fires that do occur; and, 

3. Ensure that fire will not prevent the performance of necessary safe shutdown 

functions, and will not significantly increase the risk of radioactive releases to the 

environment (Ref. NUREG 0800). 

The specific features (i.e., personnel, structures, systems, components, analyses, procedures 

and policies) which collectively form the FPP are described in licensee controlled documents, 

such as: 

 Fire Hazards Analysis (FHA) 

 Safe Shutdown Analysis (SSA) 

 Plant operating procedures 

 Surveillance, maintenance and test procedures 

 Fire brigade response procedures and pre-fire plans 

Since the Browns Ferry fire in 1975, the NRC has provided additional information on a number 

of fire protection issues. Guidance related to use of compensatory measures is principally 

contained in the following: 

1. Appendix A to BTP APCSB 9.5-1, "Guidelines for Fire Protection for Nuclear Power 

Plants Docketed Prior to July 1, 1976 

Specifies that licensees should establish administrative controls for the impairment of fire 

detection and suppression systems and special actions and procedures, such as fire 

watches or temporary fire barriers put in place to ensure adequate fire protection and 

reactor safety. 

 

9

 NFPA 805 is discussed for historical purposes only. Discussions on compensatory measures do not 

apply to NFPA 805 unless stated otherwise. 
Draft for Comment 

10 

2. Generic Letter 81-12, “Fire Protection Rule,” February 20, 1981 

In addition to defining safe-shutdown objectives, reactor performance goals, safeshutdown systems and components, and Requested licensee’s to develop TS’s 

surveillance requirements and limiting conditions for operation (LCO) for safe shutdown 

equipment that was not addressed in the plant’s existing TS. 

3. Generic Letter 86-10, “Implementation of Fire Protection Requirements”, April 24, 1986 

This Letter recommends that each licensee place its fire protection program and major 

commitments into its FSAR and, encourages licensees to: 

 replace current license conditions regarding fire protection and adopt the Standard 

Fire Protection License Condition provided in the GL 

 add administrative controls to TS consistent with those for other programs 

implemented by the license condition 

 remove most fire protection requirements from the TS 

The GL also clarifies that temporary changes to specific fire protection features which 

may be necessary to accomplish maintenance or modifications are acceptable provided 

appropriate interim compensatory measures are implemented. 

4. Generic Letter 88-12, “Removal of Fire Protection Requirements from Technical 

Specifications,” August 2, 1988. 

Contains supplemental guidance for licensees preparing a license amendment request 

that conforms to GL 86-10. It identifies four major areas where the fire protection 

requirements should be relocated from the TS to the Fire Protection Program, and 

clarifies that the technical specifications associated with safe shutdown (SSD) 

equipment and the administrative controls related to fire protection audits were to be 

retained. As described in the GL, a conforming amendment would remove the fire 

protection requirements from the TS in four major areas: 

1. Fire detection systems, 

2. Fire suppression systems, 

3. Fire barriers, and 

4. Fire brigade staffing requirements. 

5. Generic Letter 91-18. Revision 1, "Information to Licensees Regarding NRC Inspection 

Manual Section On Resolution of Degraded and Nonconforming Conditions," October 8, 

1997. 

This Letter addresses licensee activities in resolving degraded and nonconforming 

conditions for plants that are at power and for those that will resume operations from any 

shutdown. Attachment 1, Inspection Manual, Part 9900 (IM 9900) Technical Guidance, 

"Resolution of Degraded and Nonconforming Conditions," identifies compensatory 

measures as an item to be considered in licensee assessments of reasonable 

assurance of safety for SSCs that are not expressly subject to TSs. In addition, IM 9900 

provided guidance for evaluating compensatory measures as an interim step until final 

corrective actions were completed. 
Draft for Comment 

11 

Note: As indicated in item 9 below, GL 91-18 was replaced by RIS 2005-20 and a 

09/26/05 September 26, 2005 revision to NRC IM 9900, " Technical Guidance: 

Operability Determinations and Functionality Assessments for Resolution of Degraded 

and Nonconforming Conditions Adverse to Quality or Safety." 

6. Information Notice 97-48, “Inadequate or Inappropriate Interim Fire Protection 

Compensatory Measures,” July 9, 1997. 

This Notice was issued to alert licensees to potential problems associated with the 

implementation of interim compensatory measures for degraded or inoperable plant fire 

protection features or conditions associated with post-fire safe shutdown capability. 

7. Response to Region IV Task Interface Agreement (TIA) (96TIA008) - Evaluation of 

Definition of Continuous Fire Watch, August 17, 1998. 

This Memorandum Documents the staff’s evaluation of a fire protection inspection issue 

concerning the definition of a continuous fire watch. Specifically, the licensee’s FPP 

defined a continuous fire watch as a fire watch that patrolled the fire area(s) of concern 

at least once every 15 minutes. Based on its evaluation, the staff disagreed, and 

concluded that a continuous fire watch is to remain in the affected fire area at all times. 

The TIA also notes that in addition to a fire watch, enhanced compensatory measures 

may be warranted to fully address potential safety issues presented by the 

nonconformance. Specific examples cited in the staff evaluation include enhancing 

controls over combustible materials and hot work, briefing operators and fire brigade 

members on the nonconformance condition, implementing temporary operating 

procedures, pre-staging manual firefighting equipment, and installing temporary fire 

protection features. 

8. NRC Regulatory Issue Summary (RIS) 2005-07 – “Compensatory Measures to Satisfy 

the Fire Protection Program Requirements,” April 19, 2005 

Informs addressees that under certain circumstances, compensatory measures other 

than those delineated in the approved fire protection program may be used to 

compensate for degraded or inoperable fire protection features. In addition, it provides 

specific guidance on how a licensee, with the GL 86-10 standard license condition for 

fire protection, may change the approved FPP to employ such alternate measures. 

9. NRC Inspection Manual Part 9900, "Technical Guidance: Operability Determinations 

and Functionality Assessments for Resolution of Degraded and Nonconforming 

Conditions Adverse to Quality or Safety" September 26, 2005. 

This guidance was developed to assist NRC inspectors in their review of licensee 

determinations of operability and resolution of degraded or nonconforming conditions. 

This manual covers fire protection systems, structures, and components (SSCs) within 

the scope of the guidance for reviewing licensee actions for degraded and 

nonconforming conditions. . This version of IM 9900 supersedes guidance set out in 

Revision 1 of GL 91-18, “Information to Licensees Regarding Two NRC Inspection 

Manual Sections on Resolution of Degraded and Nonconforming Conditions and on 

Operability,” dated October 8, 1997. 
Draft for Comment 

12 

10. RIS 2006-10, “Regulatory Expectations with Appendix R Paragraph III.G.2 Operator 

Manual Actions,” June 30, 2006: 

RIS 2006-10 discusses the use of operator manual actions as a means of satisfying 

Section III.G of Appendix R to 10 CFR 50. Specifically, the RIS notes that some 

licensees relied on operator manual actions to compensate for degraded or missing fire 

barriers in lieu of providing one of the protective features specified in paragraph III.G.2 or 

requesting an exemption under 10 CFR Part 50.12, “Specific Exemptions.”10 With 

regard to compensatory measures for missing or degraded fire barriers, Section 2.5 

“Compensatory Measures and Corrective Actions” states that for missing or degraded 

fire barriers, the following should occur: 

 compensatory measures for missing or degraded fire barriers should be 

implemented, as required, in accordance with the licensees’ approved fire protection 

program, 

 missing or degraded fire barriers should be reported in accordance with the 

requirements of 10 CFR 50.72(b) (3) (ii) and 50.73(a) (2) (ii), and the guidance in 

NUREG-1022, “Event Reporting Guidelines 10 CFR 50.72 and 10 CFR 50.73, ” 

 missing or degraded fire barriers should be documented in accordance with their 

corrective action program including a detailed description of the affected structures, 

systems, or components (e.g., circuits) 

 Corrective actions should be completed in accord with the guidance in 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.” 

11. Regulatory Guide 1.189, “Fire Protection For Nuclear Power Plants,” Revision 2, 

October 2009 

This Regulatory Guide contains comprehensive fire protection guidance and specific 

criteria for defining an acceptable FPP at NPPs. Section 1.5 details the regulatory 

position on compensatory measures for degraded and nonconforming conditions. 

12. NFPA 805 “Performance-Based Standard for Fire Protection for Light Water Reactor 

Electric Generating Plants” 2001 

Compensatory measures are termed “compensatory actions” and defined as: 

“Actions taken if an impairment to a required system, feature, or component 

prevents that system, feature, or component from performing its intended 

function. These actions are a temporary alternative means of providing 

reasonable assurance that the necessary function will be compensated for during 

the impairment, or an act to mitigate the consequence of a fire. Compensatory 

 

10 Plants licensed to operate on or after January 1, 1979 (post-1979 licensees), are not required to meet 

the requirements of paragraph III.G.2. Therefore, for this group of plants, a staff decision in an SER that 

approves the use of manual operator actions does not require exemption under 10 CFR 50.12. However, 

Post-1979 licensees may be requested to demonstrate, as part of the NRC Reactor Oversight Process, 

that the use of an operator manual action would not adversely affect the ability to achieve and maintain 

safe shutdown in the event of a fire consistent with their license. 
Draft for Comment 

13 

measures include but are not limited to actions such as fire watches, 

administrative controls, temporary systems, and features of components.” 

NFPA 805 requires the development of procedures for compensatory actions to be 

implemented when fire protection systems and other systems credited by the fire 

protection program and this standard cannot perform their intended function and limit the 

duration of impairment. In addition, NFPA 805 specifies that compensatory actions 

should be appropriate with the level of risk created by the unavailable equipment, and 

that plant procedures should ensure that compensatory actions are not a substitute for 

promptly restoring the impaired system. 
14 

Figure 3-1. Major Documents and Milestones of FP and Compensatory Measures in the Nuclear Industry 
Draft for Comment 

15 

3.1 Historical Overview of Fire Protection Technical Specifications 

Technical specifications (TS) define the limits and conditions necessary to assure that the plant 

is operated in a manner consistent with the analyses and evaluations in the plant's Safety 

Analysis Report (Ref. 10 CFR 50.36). Specifically, the TS establish the following: 

 Limiting Conditions For Operation (LCO) that constitute the lowest functional capability 

or performance levels of equipment required to safely operate the facility; 

 Surveillances (e.g., tests or measurements) needed to confirm the operability of 

structures systems and components (SSCs) identified in the TS. 

One of the first actions taken by the Commission in response to the Browns Ferry fire was to 

impose TSs for fire protection systems. During the 1976-1977 timeframe, each operating plant 

was provided a sample of recommended standard TS for fire protection and was requested to 

do the following: 

a) Compare TS for existing fire protection systems against that sample; and, 

b) Provide proposed fire protection TS for staff review. 

The incorporation fire protection systems including impairments and their associated 

compensatory measures into the TS, was deemed necessary to assure that: 

 Prompt compensatory measures would be taken, 

 Appropriate temporary protection features would be provided, and 

 Appropriate organizations are notified to counter the effects of systems/equipment being 

out-of-service. 

FP systems, and features typically included in the scope of the TS include: 

 Fire Protection Water Supply System 

 Detection Systems 

 Sprinkler / Spray Systems 

 Fire Hose Stations 

 Halon Systems 

 CO2 Systems 

 Fire Barriers Penetration Seals 

 Fire Brigade Staffing 

 Rated fire barriers and their components (Fire doors, fire dampers, etc.) 

This list subsequently was expanded by Generic Letter 81-12 to cover TS for safe shutdown 

equipment that was not already included in the plant’s existing TSs. 

On October 26, 1984, a fire protection policy steering committee (SC) recommended bringing 

together the existing fire protection guidance together in one generic letter and improving the 

consistency of information provided in the Standard Review Plan, TS, and operating licenses. 

Specifically, the SC recommended that the staff: 

1. Develop and implement a standard fire protection license condition requiring compliance 

with the provisions of the Fire Protection Program, as described in the FSAR. 
Draft for Comment 

16 

2. Revise the Standard Review Plan (SRP) to assure that Appendix R is fully covered 

3. Revise the Standard Technical Specifications (STS) in a manner which assures 

functioning of fire protection features but which requires only those activities which are 

commensurate with other TS items in terms of their importance to safety (Ref. FP Policy 

Steering Committee Memo, 1984). 

In GL 86-10 the Commission recommended that licensees apply for an amendment to their 

operating licenses to remove unnecessary fire protection Technical Specifications (TS). 

Additional guidance for the preparation of a license amendment request to implement Generic 

Letter 86-10 was provided on August 2, 1988 via Generic Letter 88-12, “Removal of Fire 

Protection Requirements from Technical Specifications.” As discussed in GL 88-12, such an 

amendment (1) institutes the standard license condition for a Fire Protection Program. (2) 

removes requirements for fire protection systems from Technical Specifications (TS), (3) 

removes fire brigade staffing requirements from TS, and (4) adds administrative controls to TS 

that are consistent with those for other programs implemented by license condition. 

By making fire protection program systems and features consistent with other plant features 

described in the FSAR, adoption of the “standard license condition” specified in GL 86-10, 

provides licensees greater flexibility in managing their fire protection programs. clarified To 

balance GL 88-12 further specified that the Administrative Controls section of the TS be 

augmented to support the Fire Protection Program by adding two specifications to the TS: 

1. The Unit Review Group (Onsite Review Group) shall be given responsibility for reviewing 

the Fire Protection Program and implementing procedures, and for submitting 

recommended changes to the Company Nuclear Review and Audit Group (Offsite or 

Corporate Review Group). 

2. The implementation of the Fire Protection Program implementation shall be added to the 

list of elements for which written procedures shall be established, implemented, and 

maintained. 

In 1999 the Commission determined that the requirement to have the onsite review group (or a 

similar committee) review all changes to the fire protection program could place an 

unnecessary burden on licensees and, issued Regulatory Issue Summary (RIS) 99-002 

“Relaxation of the Technical Specification Requirements for PORC Review of Fire Protection 

Program Changes” to allow a licensee to request a license amendment to remove the TS 

requirement provided it can be demonstrated that adequate controls are in place to ensure the 

maintenance of the effectiveness of their fire protection program. 

Under the guidelines of GL 86-10 and 88-12, the requirements for fire protection operability and 

their associated compensatory measures were relocated from the TS to documents referred to 

in the FSAR (e.g., administrative procedures and / or technical requirements manual). 

Consequently, the operability requirements of most fire protection features that formally were 

included the plant’s TS currently are governed by licensee controlled procedures referenced in 

the NRC-approved fire protection program. Specific FPP elements that remain in the scope of 

current TSs include: (a) specifications associated with safe-shutdown equipment; and, (b) 

administrative controls which ensure that the NRC-approved FPP is appropriately established, 

implemented, and maintained in accordance with the current license basis (CLB). 

Based on a review of a sample of approved FPPs, the relocation of fire protection features from 

the TS to documents/procedures referenced in the CLB, does not appear to have had a 
Draft for Comment 

17 

significant impact on either the operability requirements for fire protection features or their 

associated compensatory measures. Appendix A summarizes the results of this review. 

3.2 Fire Protection Program

The NRC-approved Fire Protection Program includes the fire protection and post-fire safe 

shutdown systems necessary to satisfy NRC guidelines and requirements; administrative and 

technical controls; the fire brigade and fire protection related technical staff; and other related 

plant features which have been described by the licensee in the FSAR, fire hazards analysis, 

responses to staff requests for additional information, comparisons of plant designs to 

applicable NRC fire protection guidelines and requirements, and descriptions of the 

methodology for assuring safe plant shutdown following a fire. (GL 88-12) 

3.2.1 Design Features 

Implementation of the defense-in-depth safety concept required each NPP to employ a wide 

array of plant design features that are directed at: (a) detecting, containing, and rapidly 

suppressing fires that may occur (in spite of fire prevention efforts) and (b) preventing fire from 

damaging SSCs important to safety. Common fire protection design features include: 

 Structural fire barriers (e.g., fire-rated doors, fire-rated HVAC dampers, fire walls and 

cable penetrations) 

 Electrical raceway fire barrier systems (e.g., ERFBS) 

 Fire detection and alarm systems 

 Fire suppression systems and equipment, including: 

 Fire water supply systems 

 Deluge water spray systems 

 Wet pipe sprinkler systems 

 Pre-action sprinkler systems 

 Dry pipe sprinkler systems 

 Carbon dioxide systems 

 Halon 1301 systems 

 Dry chemical suppression systems 

 Foam suppression systems 

 Manual firefighting equipment 

 Post-fire safe shutdown capability, including: 

 SSCs required to perform essential shutdown functions (e.g., reactivity control, 

reactor coolant makeup, reactor pressure control, and decay heat removal) 

 Alternate Shutdown Panels 

 Emergency lighting and communications 

The design of fire protection systems and equipment should satisfy criteria specified in the 

plant’s fire protection license basis documents, such as: 

 Final Safety Analysis Report (FSAR) 
Draft for Comment 

18 

 Various Institute Of Electrical And Electronics Engineers(IEEE) Standards, such as IEEE 

Standard 634 -1978 "Standard Cable Penetration Fire Stop Qualification Test" 

 Various National Fire Protection Association Codes, such as NFPA 13 - "Standard for 

the Installation of Sprinkler Systems" 

 American Society for Testing and Materials (ASTM) E119-1976 "Fire Test of Building 

Construction and Materials" 

3.2.2 Administrative Controls 

In addition to design features needed to provide the requisite high level of fire safety, the 

defense-in-depth approach requires appropriate administrative controls be established to 

ensure the integrity of the FPP and equipment is maintained over the life of the plant. In 

addition, the Administrative Controls section of the plant’s technical specifications typically 

requires the FPP to be established, implemented, and maintained in accordance with written 

procedures and administrative policies. With regard to compensatory measures, procedures 

should be established to identify and control fire protection system impairments and ensure 

appropriate remedial actions are taken. Additional examples of administratively controlled 

elements of the FPP include: 

 The fire protection organization, including staffing requirements and responsibilities 

 Transient combustible control 

 Ignition source control 

 Review and control of modifications to ensure that fixed fire loadings are not increased 

beyond those accounted for in the fire hazards analysis, or, if increased, that suitable 

protection is provided and the fire hazards analysis is revised accordingly. 

 Review and control of temporary modifications and maintenance. 

 Installation and use of temporary electrical power services 

 Periodic testing and inspection of fire protection features 

Additional specific guidance on administrative controls is provided in Section 2 of RG 1.189. 

3.2.3 Quality Assurance 

The quality assurance (QA) program for fire protection ensures that inspection, surveillance, 

and tests that govern the FPP are prescribed by documented instructions, procedures, and 

drawings. The QA program also ensures that testing is performed to demonstrate conformance 

with design and system readiness requirements. Thus, the QA program provides assurance 

that the fire protection systems and features are designed, fabricated, erected, tested, 

maintained, and operated so that they function as intended when needed. 

Since fire detection and suppression systems are not safety-related they are generally not 

included within the scope of 10 CFR Part 50, Appendix B, “Quality Assurance Criteria for 

Nuclear Power Plants and Fuel Reprocessing Plants,” unless the licensee has committed to 

include these systems under the plant’s Appendix B program. Licensees that have not 

committed to include fire protection systems within the scope of their Appendix B program must 

provide a description of the fire protection QA program and the measures for implementing it for 

the NRC’s review. For plants licensed after January 1, 1979, this review is conducted in 

accordance with the guidance provided in Regulatory Guide 1.189, “Fire Protection For Nuclear 

Power Plants,” Revision 2, (RG 1.189). The QA program for fire protection at plants licensed 

before January 1, 1979, is reviewed against similar guidance contained in Appendix A to 
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19 

APCSB 9.5-1 and Generic Letter 77-02, “Nuclear Plant Fire Protection Functional 

Responsibilities, Administrative Controls and Quality Assurance,” (GL 77-02). 

 

Examples of fire protection QA program features related to compensatory measures include: 

 Procedures which control plant activities affecting fire protection equipment important to 

safety. 

 Reporting, tracking, and ensuring restoration of fire protection equipment or features 

which have become inoperable 

 Ensuring that inspections and tests of fire protection equipment and features are 

performed in accordance with documented instructions, procedures, and drawings. 

 Periodic inspections of materials subject to degradation, such as fire barriers, stops, 

seals, and fire retardant-coatings to ensure these items have not deteriorated or been 

damaged. 

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21 

4. IMPAIRMENTS AND COMPENSATORY MEASURES 

4.1 Fire Protection Impairments11

As discussed above, the fire protection program is composed of a number of individual 

elements (e.g., plant design features, administrative controls, trained personnel, and 

engineering analyses) that reduce the likelihood of fires and explosions, rapidly detect and 

suppress those fires that may occur, and ensure the capability to achieve and maintain safe 

shutdown conditions in the event of a significant fire. When one element of the FPP can not 

perform its intended function, the overall level of defense-in-depth is reduced and, therefore, the 

potential for loss from fire is increased.. Although FPP features are well designed and highly 

reliable, it is expected that the performance of certain features will degrade over the life of the 

plant. If a fire protection feature is not capable of performing its specified function, it is 

considered to be impaired. Examples of common impairments are shown in Table 4-1 below. 

Table 4-1. Examples of Fire Protection Impairments 

Fire Suppression Water Supply Systems 

Inoperable fire pump 

Water supply volume is less than system requirements. 

Inadequate Flow Path (e.g., inoperable valve or pipe necessary to supply fixed suppression 

systems or hose station hydrants, automatic valves in the flow path do not actuate to their 

correct positions on a simulated actuation signal). 

Sprinkler, Spray and Deluge Systems 

Inoperable or degraded / impaired sprinkler heads. 

Inoperable fire detection actuation system (If fire detection that automatically initiates a fire 

suppression system is inoperable, the fire suppression system is also considered to be 

inoperable). 

SSCs that that interfere with the ability of fire suppression systems to perform their 

intended function (e.g., scaffolds, work platforms, temporary equipment, etc.). 

Gaseous Fire Suppression Systems (CO2 and Halon)

Opening in a suppression system containment boundary (e.g., fire barrier wall). 

Underweight or under-pressure halon cylinder / banks. 

Area ventilation dampers fail to close upon receipt of a simulated actuation signal. 

System isolation to support maintenance activities. 

 

11 As used in this document, phrases such as “fire protection impairment,” “fire protection element” or “fire 

protection feature” are intended to include any component or feature identified NRC approved fire 

protection program documents (e.g., FSAR, FHA, SSA, TRM etc.). Thus, the phrases include 

impairments to both classic fire protection features (e.g., sprinkler systems, hose stations, etc.) and 

features provided to ensure post-fire safe shutdown capability (e.g., electrical raceway fire barrier wraps, 

alternate shutdown panel, etc.). 
Draft for Comment 

22 

Table 4-1. Examples of Fire Protection Impairments 

Fire Hose Stations 

One or more of the fire hose stations inoperable. 

SSCs that (e.g., scaffolds, work platforms, temporary equipment, etc.) that impede access 

to a fire hose station. 

Degraded or missing gaskets in fire hose couplings. 

Failed hose hydrostatic test. 

Yard Fire Hydrants and Hydrant Hose Houses 

One or more of the yard fire hydrants or associated hydrant hose houses are inoperable 

and are the primary means of fire suppression. 

Fire Rated Assemblies (Electrical Raceway Fire Barrier Systems, Structural Fire 

Barriers and Penetration Seals) 

One or more of the required barriers non-functional. 

A breach of a fire rated assembly/barrier that forms the compartmentalization (e.g., fire 

areas, fire zones) boundary. 

A breach of a fire rated assembly/barrier that provides fire proofing for structural steel that 

supports fire barriers. 

 As-installed fire barrier penetration seal differs from the as-designed condition (e.g., 

unsealed penetrations, gaps greater than acceptance criteria). 

Fire Detection 

The number of operable fire detection instruments is less than the minimum required. 

False / spurious alarms. 

Safe (III.G.2) and Alternative (III.L) Shutdown 

A required component is inoperable or has been removed from service 

A required support system (e.g., electrical power sources, remote control circuits, room 

cooling etc.) is impaired or inoperable (. 

One or more designated Emergency Lighting units impaired (e.g., lamps fail to illuminate 

on loss of ac power, ELU not in correct position to illuminate intended target(s)). 

Fire Doors 

Door hardware loose or damaged (e.g., loose hinges, missing /damaged door handle, 

door latch stuck in retracted position). 

Door or frame structurally damaged. 

Fire door propped / blocked open to support maintenance or prevented from fully closing 

by equipment (e.g. running a temporary cable under the door to facilitate maintenance). 

Fire Dampers 

Damper or frame structurally damaged. 

Operation of damper impaired by rust, corrosion, paint, dirt, etc. 

Damaged or missing parts on damper release mechanism. 
Draft for Comment 

23 

4.2 Compensatory Measures 

When an impairment is identified, either an operability determination or functionality assessment

is performed.12 In general, a determination of operability is required when an SSC described in 

the plant’s TSs cannot perform the safety function specified in the plant’s design basis. For nonTS SSCs that are risk significant and/or perform functions specified in the plant’s current 

licensing basis (CLB), a functionality assessment is appropriate. Functionality assessments are 

performed to ensure that the availability and reliability of SSCs are maintained. Implicit in this 

definition is the assumption of the full capability of all necessary attendant instrumentation, 

controls, normal and emergency electrical power sources, cooling or seal water, lubrication or 

other auxiliary equipment required for the performance of the system, subsystem, train, 

component, or device to complete their related support function(s). Under the guidance of GL 

86-10 and GL 88-12, technical specifications of fire protection program elements other than 

those related to the capability for safe shutdown following a fire, were relocated from the TS to 

documents referenced in the approved FPP (e.g., UFSAR, FHA, and Technical Requirements 

Manual). Therefore, the majority of fire protection impairments are evaluated for functionality. 

Functionality is normally assessed and documented through the corrective action process. 

When a fire protection feature is not capable of performing the function(s) specified in the FPP, 

appropriate compensatory measures should be promptly implemented to restore, in some 

measure, the reduction in defense-in-depth created by the degraded, inoperable, or 

nonconforming condition. Employing compensatory measures, on a short-term basis, is an 

integral part of NRC-approved fire protection programs. However, compensatory measures are 

not expected to be in place for an extended period of time. As discussed in RIS 2005-20 (Ref. 

RIS 2005-20), the NRC staff expects that the corrective action(s) will be completed, and reliance 

on the compensatory measure eliminated, at the first available opportunity, typically the first 

refueling outage. More recently, in a March 30, 2012 letter report (ML120900777), NRC 

defines a “long term compensatory measure” as one that has been in place for longer than 18 

months. This means that the functionality13 of impaired fire protection feature(s) is expected to 

be restored no later than 18 months from the date of discovery. Thus, a “long-term 

compensatory measure” is considered as one that is in place for more than 18 months. As 

discussed in RIS 2005-20, the NRC staff may approve the use of compensatory measures for 

longer periods if appropriately justified. In making its determination, the NRC staff considers 

safety significance, the effects on operability, the significance of the degradation, and what is 

necessary to implement the corrective action. They also may consider the time needed for 

designing, reviewing, approving, or procuring the repair or modification; the availability of 

specialized equipment for the repair or modification; and, whether the plant must be in hot or 

cold shutdown to implement the actions. If the licensee does not resolve the degraded or 

 

12 Detailed guidance on operability, functionality, and resolution of degraded and nonconforming 

conditions are provided in NRC Regulatory Issue Summary 2005-20, Revision 1, “Revision to NRC 

Inspection Manual (IMC) Part 9900 Technical Guidance, Operability Determinations & Functionality 

Assessments for Resolution of Degraded or Nonconforming Conditions Adverse to Quality or Safety” 

(Ref. RIS 2005-20). 

13 To be considered operable, a fire protection system or component that is not controlled by the plant’s TS, does not 

have to be “fully qualified” in terms of its design and licensing bases as long as the licensee can demonstrate 

functionality. This definition does not apply to systems or components controlled by the plant’s TS (Ref.51). 
Draft for Comment 

24 

nonconforming condition at the first available opportunity, or does not appropriately justify a 

longer completion schedule, the staff would conclude that corrective action was not timely and 

would consider taking enforcement action. 

4.2.1 Types of Compensatory Measures 

For typical fire protection system impairments (e.g., inoperable fire detection or suppression 

systems) the appropriate compensatory measure(s) to be implemented are specified the plant 

procedures or other documents referenced in the approved FPP. Examples of common 

compensatory measures are shown below in Table 4-2. Occasionally, unique circumstances 

may be encountered that were not considered in the approved FPP. When such instances 

arise, licensee’s are expected to determine appropriate compensatory measures on a case-bycase basis. The selected measures should be appropriate for the equipment or issue for which 

they were meant to compensate, and be consistent with the plant’s license basis. 

Table 4-2. Common Types of Compensatory Measures 

Compensatory 

Measure Description 

Continuous Fire 

Watch 

A continuous fire watch is an individual the serves as an uninterrupted fire 

watch in a single fire area. If all parts of the single fire area are not in the 

line of sight from a fixed watch station (e.g., line-of-sight vision is 

obstructed by equipment), the fire watch is to maintain watch over the 

entire area by patrolling the assigned fire area. 

Hourly Fire Watch An hourly (roving) fire watch is an individual assigned to observe posted 

area(s) 24 times in 24 hours, at 60 minute intervals. A roving once-pershift fire watch patrol assigned to tour specific fire areas once every eight 

hours has been approved by the staff for certain specific circumstances 

such as impairments located inside containment. 

Backup 

Suppression 

A backup means of suppression that is provided to compensate for an 

impaired fire suppression system. Examples include backup pumping 

capability, supplemental water source(s), and additional lengths of fire 

hose. 

Standard Video 

Monitoring 

Use of standard closed-circuit television (CCTV) systems such as those 

used for plant security to enhance the level of fire protection provided by 

a roving fire watch when unique conditions exist. 

Temporary 

Repairs 

A short-term, temporary plant change to restore the functional capability 

of an impaired FPP feature. Examples include installing temporary fire 

barriers, penetration seal materials, and i emergency lighting units. 

Enhanced 

Combustible 

Controls 

Placing additional limits on the amount and/or type of combustible 

material materials in the area(s) of concern. 

Enhanced Ignition 

Source Controls 

Placing additional limits on the amount and/or type of ignition sources in 

the area(s) of concern. 
Draft for Comment 

25 

Fire Watch 

A properly trained fire watch strengthens the first element of fire protection defense-in-depth 

(fire prevention) by looking for fire hazards and other conditions that could lead to a fire. In 

addition, it offers detection capability and, depending upon plant-specific protocols14, may 

initiate manual fire suppression activities. These actions all strengthen the second principle of 

fire protection defense-in-depth (rapid fire detection and suppression). 

Fire watches typically are assigned when one of the following conditions exists: 

1. Fire hazards involving burning, welding, or similar operations that can initiate fires or 

explosions (hot work).

2. When FPP systems or features are no longer capable of performing their intended 

function, as specified in the plant’s fire protection license basis. 

Specific fire watch training should provide appropriate instruction on fire watch duties, 

responsibilities, and required actions for the different types of fire watches, such as continuous, 

hot-work, and roving fire watch patrols. If applicable, fire watch qualifications should include 

hands-on training on a practice fire with the extinguishing equipment to be used while on fire 

watch. If fire watches are to be used as compensatory actions, the training should include 

recordkeeping requirements (Ref. RG1.189). 

Personnel required to perform fire watch duties for degraded FPP features typically receive 

training in the following topics: 

 Purpose and responsibilities of a fire watch 

 Types and classification of fires 

 Selection and use of portable fire extinguishers 

 Actions to be taken upon discovering a possible fire 

 Types of combustibles and potential ignition sources 

 Conduct of plant rounds 

 Maintaining complete, accurate logs and records 

Fire watches provided for hot-work15 duties have the authority to stop these operations if unsafe 

conditions develop; these personnel typically are trained in the following: 

 The inherent hazards of the work site, and of the hot work. 

 Ensuring that safe conditions are maintained during hot work operations. 

 

14 Whether or not a fire watch engages in manual fire fighting activities is determined by the individual 

licensees’. 

15 Additional guidance for the use of hot work fire watches is provided in NFPA 51B, “Standard for Fire 

Prevention During Welding, Cutting, and Other Hot Work.” 
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26 

 Using fire-extinguishing equipment 

 Procedures for sounding an alarm if there is a fire. 

The hot-work fire watch is not a replacement for proper planning to prevent conditions that allow 

a fire to develop, regardless of the fire-fighting equipment available and the capabilities of the 

individuals involved (Ref. NFPA 51B, 2009). 

In general, fire watches are responsible for the following: 

 Knowing the location of the nearest in-plant communications device (e.g. GAI-TRONICS 

Box) in relation to the fire watch post. 

 Being in the assigned watch area as required. 

 Maintaining alertness during the assigned fire watch. 

 Ensuring the completeness and accuracy of fire watch records 

 Knowing how to properly report a fire to the Main Control Room (MCR). 

 Having a clear understanding of the Fire Watch duties and post assignment. 

A fire watch is currently the most common type of compensatory measure. The physical 

presence of a fire watch enhances fire prevention through prompt recognition and disposition of 

fire hazards. In the event a fire were to occur, the fire watch helps to assure that it would be 

detected and extinguished during its early stages. 

The benefits of a fire watch have been described by the NRC’s Office of Nuclear Reactor 

Regulation (NRR) as follows: 

A fire watch provides more than simply a detection function. Personnel assigned to fire 

watches are trained by the licensee to inspect for the control of ignition sources, fire 

hazards, and combustible materials; to look for signs of incipient fires; to provide prompt 

notification of fire hazards and fires; and to take appropriate action to begin fire 

suppression activities. Fire watch personnel are capable of determining the size, the 

actual location, the source, and the type of fire—valuable information that cannot be 

provided by an automatic fire detection system. (Ref. 61FR16011) 

A roving fire watch patrol is typically assigned to observe posted area(s) 24 times in 24 hours, at 

60 minute intervals. The patrol does not have to begin on the hour, but it must be completed 

within 60 minutes. However, a once-per-shift roving patrol that tours assigned areas once every 

eight hours has been approved by the staff for certain specific circumstances such as 

impairments located inside containment. In most cases, an hourly fire watch can effectively 

patrol multiple fire areas within the time available to complete each fire watch tour (i.e., 60 

minutes). In some cases, however, the licensee may need to strategically to post several fire 

watches to assure the tours will be successfully completed in the allotted time-frame. Whether 

or not a single patrol can cover multiple fire areas varies with plant-specific conditions such as 

the size and complexity of the fire areas to be patrolled and their accessibility. 

As its name implies, a continuous fire watch provides an uninterrupted watch of a single fire 

area. Task Interface Agreement (TIA) (Ref. NRR 96TIA0008, 1998)A procedure that does not 

require the fire watch to remain within the specified “fire area” at all times is not acceptable. 
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27 

A continuous fire watch may, however, be assigned to monitor several fire zones or rooms that 

are located within a single fire area, provided that the zones or rooms are readily accessible and 

easily viewed by a single fire watch at a frequency of about every fifteen minutes, with a margin 

of five minutes. This approach is acceptable because the “fire area” would be continuously 

monitored. As described by the staff in a 1998 Task Interface Agreement (TIA) (Ref. NRR 

96TIA0008), a continuous fire watch is defined as follows: 

Continuous Fire Watch – A fire watch who performs a continuous watch over an 

assigned area(s), room(s), or object(s). All parts of the area may not be in the line of 

sight from a fixed watch station due to location of equipment, therefore the fire watch is 

to maintain watch over the entire area by patrolling the assigned area. The continuous 

fire watch can be assigned to watch more than one room as long as the rooms are in the 

same general area; the fire watch remains in the same general area; welding, grinding or 

burning is not in progress within the area; and the assigned patrol is made every 15 

minutes.

Personnel assigned to a continuous fire watch should have no additional assigned duties that 

would require their leaving the post. In addition, a continuous fire watch should not leave the 

assigned post unless it is terminated by operations (typically the shift supervisor); this includes 

drills and emergencies, unless plant conditions are too hazardous to remain. 

Although a fire watch is the most common, in certain cases it may not provide a sufficiently 

effective type of compensatory measure. For example, NRC inspectors conducting a fire 

protection inspection in the mid-1990s, (Ref. IR50-458/97-201) identified a licensee that had 

established an hourly roving fire watch as the only compensatory measure for its removal major 

sections of electrical raceway fire barrier systems (ERFBS) used to separate redundant trains of 

shutdown cables. Because the licensee considered the complete removal of the ERFBS as 

being equivalent to a degraded barrier, an hourly fire watch was deemed an acceptable 

compensatory measure. However, as noted by the inspection team, the complete removal of 

ERFBS is not the same as a degraded ERFBS that might have cracks or does not meet its 

specified fire-resistance rating. Had degraded ERFBS remained in place, the fire damage 

would have likely been delayed long enough to permit the fire brigade to respond and extinguish 

the fire. The sole use of a fire watch for a safe shutdown function which is not adequately 

protected against fire damage is an inappropriate application of a compensatory measure. As 

discussed by the staff in Information Notice (IN) 97-48, reliance on a fire watch without alerting 

operators of the deficient post-fire safe shutdown equipment, or providing interim shutdown 

strategies, could force them to undertake complex trouble-shooting and repair activities to 

compensate for the post-fire, safe-shutdown-design deficiencies. A Fire watch enhances the 

level of protection afforded by degraded fire barriers; it was never intended to serve as a 

replacement for a fire barrier. 

Temporary Repairs and Modifications 

In certain cases, a minor modification can restore the functional capability of an impaired FPP 

feature. For example, the functionality of a breached structural fire barrier may be temporarily 

restored by plugging the gap with intumescent pillows or blocks such as those shown in 

Appendix B. Other examples include: 

 Temporary emergency lighting, such as portable lighting units having an 8-hour capacity. 
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28 

 staging backup suppression equipment, such as fire extinguishers, backup fire pumps, 

or additional lengths of fire hose 

 temporary procedure changes, such as revising abnormal operating procedures (AOPs) 

to temporarily direct operators to use of feasible and reliable manual actions in the 

event of fire in areas where the impaired electrical raceway fire barriers are located 

 use of portable (temporary) detection systems or cameras 

 temporary modifications to hardware, such as removing motive and control power to 

preclude a fire-induced spurious operation of equipment 

Temporary modifications such as these have been shown to provide an effective compensatory 

measure. As with all such measures, their selection, preparation, installation, and maintenance 

should be governed by established procedures which ensure that they are appropriate for the 

particular impairment and properly installed and maintained. However, as stated previously, a 

compensatory measure is not a permanent replacement for a regulatory requirement. 

4.2.2 Selecting Appropriate Compensatory Measures 

The selection of a specific type of compensatory measure for a given impairment should be 

based on its ability to offset the degradation in defense-in-depth created by the inoperable, 

degraded, or nonconforming condition (Ref. NRR 96TIA0008, 1998). Depending on the plantspecific circumstances, certain impairments may have a greater impact on defense-in-depth 

than others. For example, because it impacts both the detection and mitigation elements of 

defense-in-depth, fire detectors used to actuate fire suppression systems typically represent a 

more critically important component of a plant's fire protection program than detectors installed 

solely for early fire warning and notification. Therefore, the appropriateness of a proposed 

compensatory measure should be evaluated by a qualified fire protection engineer. . In certain 

cases, this assessment may determine that additional enhancements are needed to supplement 

the measure specified in the FPP (Ref. NRR, 96TIA0008, 1998). Some examples include: 

 creating temporary “combustible free zones” 

 temporarily prohibiting hot-work in the affected fire area 

 adjusting work planning to minimize the introduction of combustibles or ignition sources 

that could increase the likelihood and severity of a fire 

 installing closed circuit television (CCTV) capability in high radiation areas 

 installing temporary detection and alarm systems 

 informing fire brigade members of nonconforming suppression systems so appropriate 

pre-fire strategies can be developed 

 pre-staging manual firefighting equipment 

 briefing operators on potential impacts to safe shutdown capability 

 temporary procedure changes 

The evaluation also should consider the effects of the compensatory measure on other aspects 

of the facility. As an example, a licensee may plan to close a valve as a compensatory measure 
Draft for Comment 

29 

to temporarily isolate a leak. While this action may resolve the degraded condition from a fire 

protection perspective, it may also affect flow distribution to other components or systems, 

complicate operator responses to normal or off-normal conditions, or have other effects that 

should be reviewed (Ref. RG 1.189). 

4.2.2.1 Examples of Inappropriate Compensatory Measures 

Compensatory measures are routinely evaluated by the NRC as part of its inspection program. 

The majority of these reviews have found compensatory measures to be appropriate for the 

given impairment. . As discussed in the following examples, however, certain methods have not 

been found to provide an appropriate level of compensation. These examples are provided to 

illustrate the influence ineffective compensatory measures may have on defense-in-depth. 

Sole Reliance on Fire Watches for Impaired Post-fire Safe Shutdown Functions 

In 1996 an NRC inspection found that a licensee had relied solely on roving, hourly, fire watches 

as a compensatory measure for a number of post-fire safe-shutdown design deficiencies while 

long-term corrective actions were being evaluated (Ref.: Inspection Report 50-255/ 96-004, 

Accession No. 9605290105). Although the design issues could impact the operators ability to 

achieve and maintain safe shutdown in the event of fire, the roving fire watches were not 

supplemented by any additional measures, such as alerting the operators to deficient conditions 

or providing them with interim shutdown strategies for successfully dealing with fire damage to 

safe-shutdown components. As a result, placing and maintaining the plant in a safe shutdown 

condition following a fire in the affected fire areas would have required operators to perform a 

significant number of trouble-shooting, and repair activities to compensate for the design 

deficiencies. As noted by the Commission in its Notice of Violation (Ref. Significant Enforcement 

Action EA-96-131), reliance on roving one-hour fire patrols as interim compensatory measures 

for several safety significant design deficiencies indicated a lack of sensitivity to implementing 

immediate corrective actions commensurate with the safety significance of the deficiencies. . 

Improper Definition of a Continuous Fire Watch 

A continuous fire watch is an uninterrupted fire watch that is posted in a single fire area (Ref.: 

US NRC, 96TIA0008, 1998). Where there is no installed automatic fire detection system, the 

continuous presence of a fire watch is typically required to adequately compensate for the 

degraded, inoperable, or nonconforming condition. Depending on the size of the fire area and 

the specific hazards involved, it may be necessary to strategically post several continuous fire 

watches in single fire area to effectively maintain confidence that potential fire conditions will be 

promptly detected and reported. 

An inspection conducted by NRC Region IV in 1995, found a licensee had revised its fire watch 

procedure to allow a single continuous fire watch to patrol multiple fire areas. Since the 

previous version of the procedure specified that a continuous fire watch was restricted to a 

single fire area, NRC Region IV asked the Office of Nuclear Reactor Regulation (NRR) staff to 

review the adequacy of the licensee’s revised criteria. In its response (Ref. NRR 96TIA0008, 

1998), the staff concluded the following: 

 The definition of a continuous fire watch used by the licensee is not consistent with the 

intent of the continuous fire watch (to remain in the affected fire area at all times). 
Draft for Comment 

30 

 The licensee did not provide sufficient technical justification for redefining the criteria for 

a continuous fire watch or for extending the frequency of the fire watch patrols and did 

not establish that the newly defined fire watch is equivalent to the previously defined fire 

watch. 

 To the extent that other licensees have adopted similar definitions for continuous fire 

watches without adequate technical justification, our conclusions would be the same. 

Inappropriate Elimination of a Compensatory Measure (Fire Watch) 

In October of 2009, NRC Region IV inspectors observed maintenance personnel performing 

weld preparation work on essential service water piping using an abrasive flapper wheel grinder. 

Sparks were observed to extend four to five feet from the work area. However, there was no 

fire watch posted. When the inspectors questioned the maintenance personnel about this 

omission, they stated that since they were using a flapper wheel a fire watch was not required. 

From a subsequent review of applicable procedures, the inspectors determined that a prior 

(December 2003) procedure revision inappropriately eliminated the need to post a fire watch 

when using wire brushes, flapper wheels, polishing devices, or buffing pads mounted on power 

grinder motor drives or air tools. The inspectors determined that the revised procedure 

adversely affected the fire safety in the affected area. This decision was based on the 

recognition that the ability of the fire watch was not limited to identifying fires in a timely manner, 

but also on mitigation actions that an established fire watch could take in the event of fires. 

These actions could include the ability to close doors limiting fire exposure to adjacent areas, 

and providing more timely capability of detecting fires in certain cases. The inspectors 

concluded that the lack of a posted fire watch could adversely affect the ability to achieve and 

maintain safe shutdown in the event of a severe fire in the affected area (Ref. IR 

05000482/200905). 

Removal of Fire Protection Features without Compensatory Measures 

In October 2002, NRC Region II inspectors found that a licensee made changes to the 

approved FPP which decreased the effectiveness of the program without prior Commission 

approval (Ref.: IR 05000260/2003007 and 05000296/2003007). Specifically, the licensee 

inappropriately used the License Condition Impact Evaluation (LCIE) change process to revise 

the FPP to allow the removal of fire suppression systems and/or fire-rated barrier assemblies 

installed to satisfy the separation and suppression requirements of 10 CFR 50, Appendix R, 

Sections III.G.2 and III.G.3, from service without implementing compensatory measures (i.e., 

fire watches). Before making this change, the licensee’s NRC-approved FPP required that 

either a continuous or a one-hour compensatory fire watch patrol (with backup suppression 

equipment) be posted whenever a required fire suppression system and/or fire rated barrier 

assembly was inoperable. The LCIE concluded that the assignment and presence of fire watch 

personnel for the purpose of detecting and reporting fires with operable fire detection equipment 

was unnecessary and provided minimal additional fire protection safety margins. However, the 

evaluation did not include a technical basis for these conclusions. 

In this case, the inspectors concluded that the licensee inappropriately used the fire protection 

program change process to revise the FPP to permit removing fire suppression systems and/or 

fire rated barrier assemblies from service without enhancing the other defense-in-depth 

elements as a compensatory measure. The change adversely affected the ability to achieve 

and maintain safe shutdown in the event of a fire, in that the licensee went from full compliance 

with the fire protection safe shutdown system separation and suppression criteria to less than 
Draft for Comment 

31 

full compliance without implementing temporary measures to compensate for weakness in this 

defense-in-depth element. This was contrary to the safety objectives of the FPP and constituted 

a change from the approved program that required NRC approval prior to implementation. 

Use of Operator Rounds to Compensate for Potential Circuit Vulnerabilities 

The 1975 fire at Browns Ferry revealed the inadequacy of electrical isolation and physical 

separation practices in effect at that time. Failing to adequately identify circuits required to 

achieve and maintain safe shutdown and protect them from the effects of fire damage, could 

result in; 

1) redundant trains of systems needed to achieve and maintain safe shutdown being 

damaged by fire; and, 

2) the ability to safely shutdown the plant and maintain it in a safe shutdown condition 

being impaired. 

In the mid-1990s, the NRC staff identified a regulatory concern about the potential impact of 

multiple spurious operations (MSO) that may occur as a result of fire damage to unprotected 

cables and circuits. These circuit analysis non compliances were judged to stem, in part, from a 

misunderstanding of the regulatory requirements and inappropriate reliance on a 1992 

recommendation from the Nuclear Management and Resources Council (NUMARC now NEI) 

which was not endorsed by the NRC, and may have caused confusion during licensee 

evaluations (Ref. NUREG/BR-0195 Rev 2). 

Based on the apparent widespread misunderstanding of regulatory requirements, enforcement 

discretion was deemed appropriate until the circuit analysis issue was resolved. On March 2, 

1998, the NRC Office of Enforcement (OE) issued Enforcement Guidance Memorandum (EGM) 

98-002 to temporarily defer formal enforcement actions to allow the industry time to develop 

positions that the NRC could endorse. During this time, licensees were to implement 

reasonable compensatory actions for identified circuit vulnerabilities. This initial guidance 

revised in July 1999 and February 2000. 

On September 11, 2006, the staff proposed that the Commission issue a generic letter to clarify 

the fire-induced circuit failures. However, the staff’s proposal was not approved by the 

Commission. Specifically, in SRM-SECY-06-0196, the Commission: 

1) disapproved the proposed generic letter, 

2) directed the staff to develop a clearly defined method of compliance to resolve fireinduced circuit failures for licensees who choose not to utilize the risk-informed approach 

in 10 CFR 50.48(c), and, 

3) directed the staff to engage industry stakeholders to discuss the clarification of 

regulatory expectations to ensure a common understanding of the path to closure for this 

issue. 

Subsequently, on June 30, 2008, the staff published SECY-08-0093, “Resolution of Issues 

Related to Fire Induced Circuit Failures.” This SECY proposed a technical path forward to 

resolve multiple fire-induced circuit faults, including changes to enforcement guidance. On 

September 3, 2008, the Commission published SRM-SECY-08-0093 approving the staff’s 
Draft for Comment 

32 

changes to the enforcement discretion for such circuit faults. Accordingly, on May 14, 2009, the 

NRC issued Enforcement Guidance Memorandum (EGM) 99-02 (Ref. Enforcement Guidance 

Memo 09-002) to provide a period of enforcement discretion for analyzing the effects of multiple 

fire-induced circuit faults. Specifically, EGM 99-02 permitted licensees to have until November 

2, 2012, (3 years from the date of the issuance of Regulatory Guide (RG) 1.189, Revision 2, 

“Fire Protection for Nuclear Power Plants”16) to complete the corrective actions associated with 

the noncompliant multiple fire-induced circuit faults. Under EGM 99-02, licensees were 

expected to complete the following activities by November 2, 2012: 

 identify noncompliance related to multiple fire-induced circuit faults 

 implement adequate compensatory measures for these noncompliance, 

 place the noncompliance in the corrective-action program, and, 

 complete all corrective actions or submit a request for exemption or license 

amendment request for NRC review (Ref. Memorandum to NRC Region 

Administrators, 2010). 

On May 13, 2010, the NRC staff held a public meeting with industry stakeholders to 

discuss, in part, industry’s approach to compensatory measures for the multiple 

spurious-operation (MSO) non-compliances described in EGM 09-002. During the 

meeting, industry representatives described the use of existing, once-per-shift, operator 

rounds as a generic compensatory measure to satisfy EGM 09-002 requirements. In a 

subsequent, June 9, 2010, meeting summary (Ref. NRC Public Meeting Summary, 

ML101590181), the staff stated that sole reliance existing operator plant rounds that take 

place once per shift (i.e., every 8 or 12 hours depending on the shift’s duration) is not an 

appropriate compensatory measure. The staff stated that MSOs that could affect safe 

shutdown are considered equivalent to a lack of a fire barrier and licensees should 

implement appropriate compensatory measures in accordance with their approved fire 

protection program. 

During a subsequent meeting between the NRC Fire Protection Steering Committee and 

industry stakeholders on August 23, 2010 (Ref. NRC Public Meeting Summary, 

ML101590181), the staff again discussed the industry’s use of enhanced operator 

rounds as a compensatory measure for MSO issues, and reiterated its position that 

using this approach is considered a noncompliance and licensees should implement 

compensatory measures consistent with the approved fire protection program. 

4.2.3 Alternate Compensatory Measures 

In certain instances, an approach different from the one specified in the approved FPP 

may be needed to provide an effective method of compensation. For example, properly 

analyzed Operator Manual Actions17 (OMA) may be demonstrated to provide a more 

 

16 RG 1.189, Revision 2, issuance date was November 2, 2009 (74 FR 56673) 

17 In this context, “properly analyzed” means that the OMAs are appropriately justified by an evaluation. 

Criteria guidance acceptable to the staff for performing this evaluation is provided in Triennial Fire 

Protection Inspection Procedure IP 71111.05T. 
Draft for Comment 

33 

effective compensatory measure for a degraded fire barrier than the hourly fire watch 

typically specified in an approved FPP. Similarly, a licensee may prefer to use new 

technologies, such those described in Appendix B, in lieu of or in conjunction with the 

measures specified in the approved FPP. For plants that have adopted the GL 86-10 

Standard License Condition, the licensee may modify its FPP to allow their use of 

measures other than those specifically defined in the approved fire protection program, 

provided they would not adversely affect the ability to achieve and maintain safe 

shutdown in the event of a fire. This criterion is typically satisfied if the licensee can 

demonstrate that the alternate measure adequately offsets the degradation in defensein-depth created by the inoperable, degraded, or nonconforming condition. In general, 

the evaluation should incorporate risk insights regarding: 

 the location, quantity, and type of combustible material in the fire area, 

 the presence of ignition sources and their likelihood of occurrence, 

 the automatic fire suppression and fire detection capability in the fire area, 

 the manual fire suppression capability in the fire area, and 

 the human error probability where applicable. 

The NRC staff has provided detailed information on the proper method for changing the 

approved fire protection program (FPP) to use an alternate compensatory in RIS 2005-07, 

“Compensatory Measures To Satisfy The Fire Protection Program Requirements” (Ref. RIS 

2005-07). 

4.3 Use of New Technologies 

Many compensatory measures remain virtually unchanged from those that were put in place 

over 30 years ago in response to the Browns Ferry fire. In certain instances, these traditional 

measures may not be practical to implement, or may not provide an appropriate level of 

compensation for the degradation in defense-in-depth caused by the impairment. For example, 

the compensatory measure typically specified for a degraded fire barrier is an hourly fire watch. 

If, due to the specific hazards in the area, it is determined that sole reliance on a fire watch 

would not be sufficient to assure the ability to achieve and maintain safe shutdown conditions in 

the event of fire, a licensee would be expected to implement an alternate measure or 

combination of measures. Depending on the specific circumstances, such alternate 

compensatory measures may only involve additional enhancements to the compensatory 

measure specified in the FPP, such as operator briefings and interim shutdown strategies; or 

they may be more comprehensive such as installing temporary seals in fire barrier penetrations. 

In recent years, advances in fire technology have become available that, depending on the 

plant-specific conditions, may offer an effective alternate to or supplement for compensatory 

measures specified in the approved FPP. Several examples of new technologies that could 

potentially be used are illustrated in Appendix B. 

Draft for Comment 

35 

5. EXAMPLE ASSESSMENT 

As discussed previously, each operating plant has an approved FPP that integrates plant design 

features, personnel and administrative controls necessary to achieve an appropriate balance 

between each of the following elements of the defense-in-depth safety concept: 

(1) prevent fires from starting; 

(2) rapidly detect, control, and extinguish those fires that do occur; and 

(3) protect 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 protection that are established by the defense-in-depth concept, offer 

reasonable assurance that deficiencies in one layer will not present an undue risk to public 

health and safety. Inherent in the DID safety concept is the need to ensure an appropriate level 

of fire safety is maintained when a fire protection feature is impaired or disabled. To achieve this 

objective, the FPP is designed to ensure appropriate compensatory measures are implemented 

whenever FPP features are degraded or impaired. The selection of a specific type of 

compensatory measure for a given impairment should be based on its ability to appropriately 

offset the degradation in DID created by the inoperable, degraded, or nonconforming condition. 

Compensatory measures specified in a plant’s approved FPP, are designed to provide an 

appropriate level of compensation for common impairments, such as those identified in Table 4-

1 above. However, in certain unique cases, an appropriate compensatory measure may not be 

specified in the FPP. NRC Information Notice (IN) 97-48, “Inadequate or Inappropriate Interim 

Fire Protection Compensatory Measures,” (Ref. US NRC, IN 97-48) notes that when unique 

cases are identified, appropriate compensatory measures should be determined by the licensee 

and tailored to the particular circumstances on a case-by-case basis. The selected measures 

should be consistent with the plant’s license basis and demonstrated to be appropriate for the 

equipment or issue for which they were meant to compensate. 

The hypothetical example provided in the following paragraphs is intended to illustrate how 

methods other than those specified in a plant’s approved may be used to provide an effective 

alternative when unique circumstances are encountered. 

5.1 Scenario 

As illustrated in Figure 5-1, Fire Area SW-1A primarily contains equipment and cables 

associated with Shutdown Train A (shown in green). Thus, in the event of fire in this area, Train 

B (shown in red) systems and equipment would be relied on to achieve and maintain safe 

shutdown conditions. With the exception of control cables associated with a Train B motoroperated valve (MOV), one train of systems necessary to achieve hot shutdown is independent 

of the fire area. The cable trays containing this cable are protected throughout the area by an 

electrical raceway fire barrier system (i.e., fire wrap) having a 1-hour rating. In addition, the fire 

area is provided with area-wide ionization detectors and automatic sprinklers. However, 

consistent with the plant’s fire protection licensing basis, sprinkler coverage limited a portion of 

the fire area that contains a high concentration of stacked cable trays. As shown in Figure 5-1, 

the automatic suppression system protects the Train B cable tray with the exception of a small 

segment that is routed near the 480V MCCs. 
Draft for Comment 

36 

Figure 5-1. Fire Area SW-1A 

Recently, the fire barrier covering the portion of the cable tray that is routed near the MCCs has 

been found have several significant through-cracks along its length. While not equivalent to a 

missing fire barrier, the degradation is considered to be sufficient to reduce the amount of time 

available for the fire brigade to manually extinguish a fire prior to cable damage. The specific 

“target” cable of concern is a multi-conductor PVC-insulated, control cable which transfers 

“open” and “close,” position signals between the control room and a normally open MOV located 

in the suction line of a required pump. A fire-induced short circuit between two conductors in 

this cable would have the same effect as placing the MOV control switch to the “close” position. 

This would be unacceptable since this MOV must remain open to prevent pump damage due to 

loss of suction. 

Because the fire area is provided with area-wide detection, the compensatory measure 

specified in the approved FPP is an hourly, roving, fire watch. However, due to the unique 

circumstances in this case (degraded protection of SSD capability), it is necessary to determine 

if the compensatory measure specified in the FPP (hourly fire watch) would provide a sufficiently 

effective means of compensation. 

Train A 480V MCCs Area Covered by 

Auto Sprinklers 

Train B MOV Control Cables 
Draft for Comment 

37 

Scenario Summary 

Degraded / Impaired FPP Feature: Electrical Raceway Fire Barrier System (ERFBS) 

DID Element Impacted: 3 (protect SSCs important to safety so that a fire 

that is not promptly extinguished will not prevent 

the safe shutdown of the plant) 

FPP Compensatory Measure: Hourly Fire Watch 

5.2 Assessment 

For this hypothetical scenario, the affected DID element is Element 3, (protect SSCs important 

to safety so that a fire that is not promptly extinguished will not prevent the safe shutdown of the 

plant). Therefore, the first step of the process is to determine the overall effectiveness of DID 

elements 1 and 2. For this example the following ranking scale will be used: 

H = Highly Degraded, 

M = Moderately Degraded, or 

L = Low or no degradation – (Normal Operating State) 

5.2.1 Evaluation of Defense-in-Depth Element 1 – Fire Prevention 

The first element of DID is directed at preventing fires from starting. This is typically 

accomplished by controlling transient combustibles and ignition sources and preventing, to the 

extent practical, in situ ignition sources and combustible materials from causing self-sustaining 

fires. Examples of fire prevention activities include: 

 Storing, handling, and using of flammable materials. 

 Storage, control, and use of combustible materials relative to locations of flammable 

materials and ignition sources. 

 Use and control of open flames and other ignition sources 

 Housekeeping 

Evaluation 

Transient and fixed combustibles and ignition sources are found to be well controlled by 

established procedures in accordance with the plant’s approved fire protection program.  Thus, 

the Fire Prevention element of DID (DID Element 1) is judged to have a low degradation 

(Normal Operating State). 

Fire Prevention Feature Degradation Ranking 

Transient Combustible Controls: L 

Transient Ignition Source Controls: L 
Draft for Comment 

38 

5.2.2 Evaluation of Defense-in-Depth Element 2 – Detection, Suppression, and Mitigation 

The second element of DID is directed at rapidly detecting, controlling, and extinguishing fires 

that may occur in spite of the fire prevention efforts. This DID element is provided various 

types of fire protection features, such as: Heat and smoke detectors; fire alarm systems; Halon 

1301, carbon dioxide (CO2), and dry chemical fire suppression systems; automatic sprinkler, 

foam, and water spray systems; portable fire extinguishers; hose stations, fire hydrants, and 

water supply systems; and the fire brigades. 

For the specific scenario under evaluation, DID element 2 is provided by the following systems: 

 area-wide ionization detection system 

 partial area automatic fire suppression 

 manual suppression by fire brigade 

Evaluation 

Consistent with license basis requirements, area wide, ceiling mounted, spot-type detectors are 

installed and maintained to meet the NFPA code of record. In addition, partial sprinkler 

coverage is provided where a high concentration of cable trays are located. However, since the 

automatic suppression system does not provide coverage for the cable tray where the degraded 

fire barrier is located, it is judged to be moderately degraded. 

As discussed in NRC Inspection Manual Chapter 609, Appendix F, (Ref. US NRC, IMC 609 App 

F Att. 3), cables protected by a fire barrier system with a 1-hour fire rating are subject to fireinduced failure if the fire barrier is degraded. Thus, a fire in FA SW-1A is expected to damage 

the cable of concern. Once the cable is damaged by fire, the type of fault needed to cause the 

MOV to spuriously change position (i.e., a conductor-to-conductor short in a multi-conductor 

cable) is expected to occur fairly quickly, prior to suppression by the plant fire brigade. 

Therefore the effectiveness of the fire brigade in preventing fire damage is also judged to be 

moderately degraded. Thus, although the area wide detection system will provide a prompt 

notification of fire, the impaired suppression capability causes DID Element 2 to be moderately 

degraded (M). 

Fire Mitigation Feature Degradation Ranking 

Detection: L – Normal Operating State 

Automatic Sprinkler: Moderately degraded with respect 

to the specific impairment 

Manual Suppression: 

Moderately degraded – with 

respect to the fire brigade’s ability 

to extinguish a fire prior to cable 

damage. 
Draft for Comment 

39 

5.2.3 Evaluation of Defense-in-Depth Element 3 – Protecting SSCs Important to Safety 

The purpose of the third and final element of DID is to ensure that in the unlikely event that both 

DID elements 1 and 2 were to fail, the capability to achieve and maintain safe shutdown 

conditions would still be assured. Thus, this element of DID includes plant systems and design 

features that prevent fire from significantly damaging the SSCs required to achieve and maintain 

safe shutdown conditions. Examples include: 

 Electrical Raceway Fire Barrier Systems (e.g., fire-resistant cable tray and conduit 

wraps) 

 Fire Barriers (e.g., fire rated walls, floors, and ceilings) 

 Electrical Isolation Devices (e.g., Isolation / Transfer Switches) 

 Remote / Alternate Shutdown Equipment (e.g., Alternate Shutdown Panels) 

In this example scenario, DID element 3 is primarily provided by the fire barrier wrap. However, 

the effectiveness of the barrier is degraded by several significant through-cracks. As discussed 

above for DID Element 2, cables protected by a fire barrier system with a 1-hour fire rating are 

considered to be subject to fire-induced failure if the fire barrier is degraded. Therefore, the 

target cable of concern can be expected to experience fire-induced faults as a result of fire in 

Fire Area SW-1A. Since fire damage that causes a short between two conductors of the target 

cable is sufficient to cause the MOV to move to an undesired (closed) position, spurious 

operation could occur prior to extinguishment by the plant fire brigade. Because pump damage 

on loss of suction is expected to occur fairly quickly, operators would not have sufficient time to 

restore operability of the affected pump. 

Summary of DID Element 3 

Due to the degraded ERFBS, a fire in Fire Are SW-1A would damage the target cable and, 

thereby, cause a normally open MOV to spuriously close. Due to its location in the flow path, 

unintended closing of this MOV would result in the loss of a makeup pump that is relied on to 

accomplish a hot shutdown function. 

DID element 3 is judged to be Highly degraded. 

5.3 Evaluation of Compensatory Measures 

The licensee’s FPP specifies that an hourly roving fire watch be implemented whenever an 

ERFBS is impaired and there is an operable detection system. However sole reliance on a fire 

watch as a compensatory measure for a safe shutdown function that is not adequately protected 

against fire damage may not be appropriate. As illustrated in this hypothetical scenario, the 

shutdown capability could be significantly affected if a fire were to occur during the time that the 

hourly fire watch is not in the area. To provide a more effective compensatory measure, the 

licensee has decided to enhance the level of protection provided by the hourly fire watch 

Capability to prevent cable damage (given a fire): H 

Capability to prevent spurious MOV actuation, given 

cable damage: H 

Capability of operators to recover H 
Draft for Comment 

40 

through the addition of advanced detection technologies capable of detecting fire in the incipient 

stages and operator guidance on actions necessary to prevent pump damage in the unlikely 

event a fire were to occur. 
Draft for Comment 

41 

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Draft for Comment 

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Draft for Comment 

44 

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Draft for Comment 

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Nuclear Plant Fire.” 

Draft for Comment 

47 

7. GLOSSARY 

Below are key terms or phrases whose definitions and associated context, for purposes of this 

document, are as shown. 

Administrative 

Controls 

Policies, procedures, and other elements that relate to the FPP. 

Administrative controls include but are not limited to inspection, testing, 

and maintenance of fire protection systems and features; compensatory 

measures for fire protection impairments; review of the impact of plant 

modifications on the FPP; fire prevention activities; fire protection staffing; 

control of combustible/flammable materials; and control of ignition 

sources. (RG 1.189 R2) 

Air Sampling 

Detector 

A detector that consists of a piping or tubing distribution network that runs 

from the detector to the area(s) to be protected. An aspiration fan in the 

detector housing draws air from the protected area back to the detector 

through air sampling ports, piping, or tubing. At the detector, the air is 

analyzed for fire products. (NFPA 72 2007) 

Alternate 

Compensatory 

Measure 

Alternate compensatory measures are those which differ from measures 

identified in the approved fire protection program. For example, if the 

approved FPP identifies a fire watch as the only appropriate 

compensatory measure for a degraded fire barrier, the use of a video 

image smoke detection system in lieu of a fire watch would be considered 

an “alternate compensatory measure.” Ref.: RIS 2005-07, 

“Compensatory Measures To Satisfy The Fire Protection Program 

Requirements.” 

Alternate Shutdown The capability to shut down the reactor that is required when it is not 

feasible to provide the required protection for redundant safe-shutdown 

trains in one or more fire areas or where fire suppression activities, 

including inadvertent operation or rupture of a suppression system, could 

prevent safe shutdown. Appendix R to 10 CFR Part 50 allows an existing 

plant system to be rerouted, relocated, or modified (at the time the need 

for an alternative means of shutdown is identified but not during or after 

the fire) such that it can perform the required safe-shutdown function that 

the redundant system damaged by fire or damaged by suppression 

system discharge would normally perform. (RG 1.189 R2) 

Approved Tested and accepted for a specific purpose or application by a 

recognized testing laboratory or reviewed and specifically approved by 

the NRC in accordance with the appropriate regulatory process. (RG 

1.189 R2) 

Automatic Self-acting, operating by its own mechanism when actuated by some 

monitored parameter such as a change in current, pressure, temperature, 

or mechanical configuration. (RG 1.189 R2) 
Draft for Comment 

48 

Compensatory 

Actions 

Actions taken if an impairment to a required system, feature, or 

component prevents that system, feature, or component from performing 

its intended function. These actions are a temporary alternative means of 

providing reasonable assurance that the necessary function will be 

compensated for during the impairment, or an act to mitigate the 

consequence of a fire. Compensatory measures include but are not 

limited to actions such as firewatches, administrative controls, temporary 

systems, and features of components. (NFPA 805) (NFPA Glossary 

2008) 

Configuration 

Management 

Configuration management is an integrated management process used 

to ensure that the licensee maintains the plant’s physical and functional 

characteristics in conformance with its design and licensing basis; that 

operating, training, modification, and maintenance processes are 

consistent with the conditions prescribed by the design and current 

licensing basis; and that the licensee operates and maintains the plant 

within these conditions (NUREG-1913) 

Current License 

Basis 

The current licensing basis (CLB) is the set of NRC requirements 

applicable to a specific plant and a licensee’s written commitments for 

ensuring compliance with and operation within applicable NRC 

requirements and the plant-specific design basis (including all 

modifications and additions to such commitments over the life of the 

license) that are docketed and in effect. The CLB includes: 

 NRC regulations contained in 10 CFR Parts 2, 19, 20, 21, 26, 

30, 40, 50, 51, 54, 55, 70, 72, 73, 100, and appendices 

thereto; 

 Commission orders; 

 License Conditions; 

 Exemptions; 

 Technical Specifications. 

 Plant specific design-basis information defined in 10 CFR 50.2 

as documented in the most recent FSAR, as required by 10 

CFR 50.71 

 Licensee’s commitments remaining in effect that were made in 

docketed licensing correspondence such as licensee 

responses to NRC bulletins, generic letters, and enforcement 

actions, 

 Licensee commitments documented in NRC safety 

evaluations or licensee event reports (LERs). (10 CFR 

54.3(a)) 
Draft for Comment 

49 

Defense-in-Depth Fire protection for nuclear power plants uses the concept of defense-indepth to achieve the required degree of reactor safety. This concept 

entails the use of echelons of administrative controls, fire protection 

systems and features, and safe-shutdown capability to achieve the 

following objectives: 

 Prevent fires from starting. 

 Detect rapidly, control, and extinguish promptly those fires that do 

occur. 

 Protect SSCs 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. (RG 1.189 R2) 

Defense-in-depth is an element of the NRC’s Safety Philosophy that 

employs multiple layers or echelons of protection to prevent accidents or 

mitigate damage if a malfunction, accident, or naturally-caused event 

occurs at a nuclear facility. The defense-in-depth philosophy ensures 

that safety will not be wholly dependent on any single element of the 

design, construction, maintenance, or operation of a nuclear facility. As 

stated in NUREG 0050, "Recommendations Related to the Browns Ferry 

Fire." the goal is to provide a suitable balance of these multiple layers or 

echelons of protection. Increased strength, redundancy, performance, or 

reliability of one echelon can compensate in some measure for 

deficiencies in the others. 

Degraded 

Condition 

A condition of an SSC in which there has been any loss of quality or 

functional capability. (GL 91-18) 

A degraded condition is one in which the qualification of an SSC or its 

functional capability is reduced. Examples of degraded conditions are 

failures, malfunctions, deficiencies, deviations, and defective material and 

equipment. Examples of conditions that can reduce the capability of a 

system are aging, erosion, corrosion, improper operation, and 

maintenance. (NUREG 1913) 

Design Basis Design bases means that information which identifies the specific 

functions to be performed by a structure, system, or component of a 

facility, and the specific values or ranges of values chosen for controlling 

parameters as reference bounds for design. These values may be (1) 

restraints derived from generally accepted "state of the art" practices for 

achieving functional goals, or (2) requirements derived from analysis 

(based on calculation and/or experiments) of the effects of a postulated 

accident for which a structure, system, or component must meet its 

functional goals (10 CFR 50.2) 

Design basis is that body of plant-specific design bases information 

defined by 10 CFR 50.2 (GL 91-18). 

Electrical Raceway 

Fire Barrier System 

(ERFBS) 

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 R2) 
Draft for Comment 

50 

Fire A rapid oxidation process, which is a chemical reaction resulting in the 

evolution of light and heat in varying intensities. (NFPA Glossary 2008) 

Fire Alarm System A system or portion of a combination system that consists of components 

and circuits arranged to monitor and annunciate the status of fire alarm or 

supervisory signal-initiating devices and to initiate the appropriate 

response to those signals. (NFPA 1 2012) 

Fire Area The portion of a building or plant that is separated from other areas by 

rated fire barriers adequate for the fire hazard. (RG 1.189 R2) 

Fire Barrier 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 that are used to prevent the spread of fire. (RG 1.189 R2) 

A continuous membrane or a membrane with discontinuities created by 

protected openings with a specified fire protection rating, where such 

membrane is designed and constructed with a specified fire resistance 

rating to limit the spread of fire, that also restricts the movement of 

smoke. (NFPA 101 2003) 

In nuclear facilities, a continuous assembly designed and constructed to 

limit the spread of heat and fire and to restrict the movement of smoke. 

(NFPA 805) 

Fire Brigade A team of onsite plant personnel that is qualified and equipped to perform 

manual fire suppression activities. (RG 1.189 R2) 

Fire Damage The total damage to a building, structure, vehicle, natural vegetation 

cover, or outside property resulting from a fire and the act of controlling 

that fire. (NFPA Glossary 2008) 

Fire Hazards Conditions that involve the necessary elements to initiate and support 

combustion, including in situ or transient combustible materials, ignition 

sources (e.g., heat, sparks, open flames), and an oxygen environment. 

(RG 1.189 R2) 

Fire Hazards 

Analysis 

An analysis used to evaluate the capability of a nuclear power plant to 

perform safe-shutdown functions and minimize radioactive releases to 

the environment in the event of a fire. The analysis includes the following 

features: 

 identification of fixed and transient fire hazards 

 identification and evaluation of fire prevention and protection 

measures relative to the identified hazards 

 evaluation of the impact of fire in any plant area on the ability to 

safely shut down the reactor and maintain shutdown conditions, 

as well as to minimize and control the release of radioactive 

material (RG 1.189 R2) 

An analysis to evaluate potential fire hazards and appropriate fire 

protection systems and features used to mitigate the effects of fire in any 

plant location. (NFPA 805) 
Draft for Comment 

51 

Fire Protection 

Feature 

Administrative controls, emergency lighting, fire barriers, fire detection 

and suppression systems, fire brigade personnel, and other features 

provided for fire protection purposes. (RG 1.189 R2) 

Administrative controls, fire barriers, means of egress, industrial fire 

brigade personnel, and other features provided for fire protection 

purposes. (NFPA 805) 

Fire Protection Plan 10 CFR 50.48(a) requires licensees to have a fire protection plan that 

meets General Design Criterion (GDC) 3 of Appendix A to 10 CFR Part 

50. In accordance with 10 CFR 50.48, the fire protection plan must do 

the following: 

 Describe the overall Fire Protection Program for the facility. 

 Identify the various positions within the licensee’s organization 

that are responsible for the program. 

 State the authorities that are delegated to each of these positions 

to implement those responsibilities. 

 Outline the plans for fire protection, fire detection and 

suppression, and limitation of fire damage. 

 Describe the administrative controls and personnel requirements 

for fire protection and manual fire suppression activities. 

 Describe the automatic and manually operated fire detection and 

suppression systems. 

 Describe the means to limit fire damage to SSCs important to 

safety to ensure the ability to shut down the plant safely. 

Fire Protection 

Program 

The integrated effort involving components, procedures, analyses, and 

personnel utilized in defining and carrying out all activities of fire 

protection. It includes system and facility design, fire prevention, fire 

detection, annunciation, confinement, suppression, administrative 

controls, fire brigade organization, inspection and maintenance, training, 

quality assurance, and testing. (RG 1.189 R2) 

Fire Protection 

Program Attribute 

Fire Protection Program Attributes are characteristics of the fundamental 

FPP elements and may vary based on the plant licensing basis (SECY04-0050) 

Fire Protection 

Program Elements 

Fire Protection Program Elements are the fundamental features or 

components of the approved fire protection program (SECY-04-0050) 

Fire Protection 

System 

Fire detection, notification, and suppression systems designed, installed, 

and maintained in accordance with the applicable nationally recognized 

codes and standards endorsed by the NRC. (RG 1.189 R2) 

Any fire alarm device or system or fire extinguishing device or system, or 

combination thereof, that is designed and installed for detecting, 

controlling, or extinguishing a fire or otherwise alerting occupants, or the 

fire department, or both, that a fire has occurred. (NFPA 1) 

Fire detection, notification, and fire suppression systems designed, 

installed, and maintained in accordance with the applicable NFPA codes 

and standards. (NFPA 805) 
Draft for Comment 

52 

Fire Scenario A set of conditions that defines the development of fire, the spread of 

combustion products throughout a building or portion of a building, the 

reactions of people to fire, and the effects of combustion products. 

(NFPA 101 2012) 

Fire Suppression Control and extinguishing of fires (firefighting). Manual fire suppression is 

the use of hoses, portable extinguishers, or manually actuated fixed 

systems by plant personnel. Automatic fire suppression is the use of 

automatically actuated fixed systems such as water, Halon, or CO2 

systems. (RG 1.189 R2) 

Fire Watch Individuals responsible for providing additional (e.g., during hot work) or 

compensatory (e.g., for system impairments) coverage of plant activities 

or areas for the purposes of detecting fires or for identifying activities and 

conditions that present a potential fire hazard. The individuals should be 

trained in identifying conditions or activities that present potential fire 

hazards, as well as the use of fire extinguishers and the proper fire 

notification procedures. (RG 1.189 R2) 

The assignment of a person or persons to an area for the express 

purpose of notifying the fire department, the building occupants, or both 

of an emergency; preventing a fire from occurring; extinguishing small 

fires; or protecting the public from fire or life safety dangers. (NFPA 1 

2012) 

Fire Zones Fire zones are subdivisions of fire areas. (RG 1.189 R2) (NUREG-1805) 

A subdivision of a fire area not necessarily bounded by fire-rated 

assemblies. Fire zone can also refer to the area subdivisions of a fire 

detection or suppression system, which provide alarm indications at the 

central alarm panel. (NFPA 805) 

Fire zones are subdivisions of fire areas defined in the context of the fire 

protection program. A fire zone is not necessarily bounded by fire 

barriers. Zone divisions are often defined based on the fire suppression 

and/or detection systems designed to combat particular types of fires. A 

fire zone may contain one or more rooms. A fire compartment may 

contain one or more fire zones. (NUREG/CR 6850) 

 

Functional / 

Functionality 

Functionality is an attribute of SSCs that is not controlled by TSs. An 

SSC is functional or has functionality when it is capable of performing its 

specified function, as set forth in the CLB. Functionality does not apply to 

specified safety functions, but does apply to the ability of non-TS SSCs to 

perform other specified functions that have a necessary support function. 

To be considered operable, a non-TS SSC does not have to be “fully 

qualified” in terms of its design and licensing bases as long as the 

licensee can demonstrate functionality. For example, if a fire protection 

SSC that was removed from the TS in accordance with GL 86-10 is 

determined to be nonfunctional, a functionality assessment should be 

performed to determine if it is capable of performing the function specified 

in the plant’s current licensing basis. (RIS 2005-20) 

 
Draft for Comment 

53 

Heat Detector A fire detector that detects either abnormally high temperature or rate of 

temperature rise, or both. (NFPA 72, 2010) 

Hot Work Activities that involve the use of heat, sparks, or open flame such as 

cutting, welding, and grinding. (RG 1.189 R2) 

Impairment The degradation of a fire protection system or feature that adversely 

affects the ability of the system or feature to perform its intended function. 

(RG 1.189 R2) 

Impairment exists if a fire protection feature (both active and passive) is 

no longer capable of performing the function(s) specified in the current 

fire protection licensing basis. 

 

Incipient Stage Fire A fire which is in the initial or beginning stage and which can be 

controlled or extinguished by portable fire extinguishers or small hose 

systems without the need for protective clothing or breathing apparatus. 

(NFPA Glossary 2008) 

In situ 

Combustibles 

Combustible materials that constitute part of the construction, fabrication, 

or installation of plant SSCs and as such are fixed in place. (RG 1.189 

R2) 

Combustible materials that are permanently located in a room or an area 

(e.g., cable insulation, lubricating oil in pumps). (NFPA 805) 

Interim 

Compensatory 

Measures 

Actions taken if an impairment to a required system, feature, or 

component prevents that system, feature, or component from performing 

its intended function. These actions are a temporary alternative means of 

providing reasonable assurance that the necessary function will be 

compensated for during the impairment, or an act to mitigate the 

consequence of a fire. Compensatory measures include but are not 

limited to actions such as fire watches, administrative controls, temporary 

systems, and features of components. (NFPA 805) (NFPA Glossary 

2008). See Compensatory Measures 

Limiting Condition 

for Operation 

The section of Technical Specifications that identifies the lowest 

functional capability or performance level of equipment required for safe 

operation of the facility. 

Mitigate Perform an action that stops the progression of or reduces the severity of 

an unwanted condition. With respect to nuclear plant fire protection, 

mitigation generally refers to operator actions inside or outside the main 

control room to restore the capability to achieve and maintain safe 

shutdown where a fire has degraded that capability. (RG 1.189 R2) 

Activities taken to eliminate or reduce the degree of risk to life and 

property from hazards, either prior to or following a disaster/emergency. 

(NFPA Glossary 2003) 
Draft for Comment 

54 

Noncombustible 

Material 

(a) Material that, in the form in which it is used and under conditions 

anticipated, will not ignite, burn, support combustion, or release 

flammable vapors when subjected to fire or heat, or (b) material having 

a structural base of noncombustible material, with a surfacing not over 3 

mm (c inch) thick that has a flame spread rating not higher than 50 when 

measured in accordance with ASTM E-84, “Standard Test Method for 

Surface Burning Characteristics of Building Materials” (RG 1.189 R2) 

A substance that will not ignite and burn when subjected to a fire. (NFPA 

Glossary 2008) 

Nonconforming 

Condition 

A condition of an SSC in which there is failure to meet requirements or 

licensee commitments (GL 91-18). 

Some examples of nonconforming conditions include the following: 

 There is failure to conform to one or more applicable codes or 

standards specified in the FSAR. 

 As-built equipment, or as-modified equipment, does not meet 

FSAR descriptions. 

 Operating experience or engineering reviews demonstrate a 

design inadequacy. 

 Documentation required by NRC requirements such as 10 CFR 

50.49 is not available or deficient. 

NRC NRC means the Nuclear Regulatory Commission, the agency established 

by title II of the Energy Reorganization Act of 1974, as amended, 

comprising the members of the Commission and all offices, employees, 

and representatives authorized to act in any case or matter (see also 

Commission). 

Onsite As defined in the site specific UFSAR (usually refers to the ownercontrolled area or real estate over which the licensee has the legal right 

to control access.). 

Operable A system, subsystem, train, component, or device is considered operable 

or have operability when it is capable of performing its specified safety 

function(s) This includes adequate performance of any support 

instrumentation, controls, electrical power, cooling or seal water, 

lubrication or auxiliary equipment. (NUREG 1913) 

Note: Operable applies to SSCs identified in the TS. Existing plantspecific TSs contain several variations on this basic definition. In all 

cases, a licensee’s plant-specific TS definition of Operable/Operability 

governs. (IMC 9900, Operability Determination Process 9/26/05). 

Functionality applies to non-TS SSCs. 

Operator Manual 

Action (OMA) 

Actions performed by operators to manipulate components and 

equipment from outside the main control room not including “repairs.” 

(RG 1.189 R2) 

Those actions performed by operators to manipulate components and 

equipment from outside the main control room to achieve and maintain 

postfire hot shutdown, but not including “repairs.” Operator manual 

actions comprise an integrated set of actions needed to help ensure that 

hot shutdown can be accomplished, given that a fire has occurred in a 

particular plant area. (NUREG-1852) 
Draft for Comment 

55 

Passive Fire 

Protection Feature 

A fire protection feature that provides a means of controlling a fire without 

a distinct change of state. Fire barriers, cable tray fire wrap, and 

penetration seals are examples of passive fire protection features. 

Protection measures that prolong the fire resistance of an installation 

before an eventual fire occurrence from the effects of smoke, flames, and 

combustion gases. These can consist of insulation (fireproofing) of a 

structure, choice of noncombustible materials of construction, use of fireresistant partitions, and compartmentation to resist the passage of fire. It 

includes coatings, claddings, or free-standing systems that provide 

thermal protection in the event of fire and that require no manual, 

mechanical, or other means of initiation, replenishment, or sustainment 

for their performance during a fire incident. (NUREG-1805) 

Penetration An opening for penetrations that pass through both sides of a vertical or 

horizontal fire resistance–rated assembly. (NFPA 5000 2012) 

PerformanceBased Approach A performance-based approach relies upon measurable (or calculable) 

outcomes (i.e., performance results) to be met but provides more 

flexibility as to the means of meeting those outcomes. A performancebased approach is one that establishes performance and results as the 

primary basis for decision-making and incorporates the following 

attributes: (1) Measurable or calculable parameters exist to monitor the 

system, including facility performance; (2) Objective criteria to assess 

performance are established based on risk insights, deterministic 

analyses, and/ or performance history; (3) Plant operators have the 

flexibility to determine how to meet established performance criteria in 

ways that will encourage and reward improved outcomes; and (4) A 

framework exists in which the failure to meet a performance criteria, while 

undesirable, will not in and of itself constitute or result in an immediate 

safety concern. (NFPA 805) 

Post-Fire SafeShutdown Analysis A process or method of identifying and evaluating the capability of SSCs 

necessary to accomplish and maintain safe-shutdown conditions in the 

event of a fire. (RG 1.189 R2) 

Post-Fire SafeShutdown 

System/Equipment 

Systems and equipment that perform functions needed to achieve and 

maintain safe shutdown during and following a fire (regardless of whether 

the system or equipment is part of the success path for safe shutdown). 

This includes systems and equipment of which fire-induced spurious 

actuation could prevent safe shutdown. (RG 1.189 R2) 

Pre-Fire (Incident) 

Plans 

Documentation that describes the facility layout, access, contents, 

construction, hazards, hazardous materials, types and locations of fire 

protection systems, and other information important to the formulation 

and planning of emergency fire response. (RG 1.189 R2) 

A written document resulting from the gathering of general and detailed 

data to be used by responding personnel for determining the resources 

and actions necessary to mitigate anticipated emergencies at a specific 

facility. (NFPA Glossary 2008) 
Draft for Comment 

56 

Quality Assurance "Quality assurance" comprises all those planned and systematic actions 

necessary to provide adequate confidence that a structure, system, or 

component will perform satisfactorily in service. Quality assurance 

includes quality control, which comprises those quality assurance actions 

related to the physical characteristics of a material, structure, component, 

or system which provide a means to control the quality of the material, 

structure, component, or system to predetermined requirements. (10 

CFR 50, Appendix B—Quality Assurance Criteria for Nuclear Power 

Plants and Fuel Reprocessing Plants) 

Attributes of a QA program include programs that preserve quality 

through procedures, recordkeeping, inspections, corrective actions, and 

audits. NUREG-1913) 

Redundancy Redundancy refers to the provision of multiple independent methods of 

equivalent capacity to perform a specified function. 

Redundant train or 

system 

One of two or more similar trains of equivalent capacity in the same 

system powered by separate electrical divisions or one of two or more 

separate systems that each perform the same post-fire safe-shutdown 

function as its design function. With respect to fire protection regulatory 

requirements and guidance, a redundant train or system is distinct from 

an alternative or dedicated shutdown train or system. (RG 1.189 R2) 

Risk The set of probabilities and consequences for all possible accident 

scenarios associated with a given plant or process. (NFPA 805) 

Risk Informed 

Approach 

A philosophy whereby risk insights are considered together with other 

factors to establish performance requirements that better focus attention 

on design and operational issues commensurate with their importance to 

public health and safety. (NFPA 805) 

Safe-Shutdown 

Analysis 

A process or method of identifying and evaluating the capability of SSCs 

necessary to accomplish and maintain safe-shutdown conditions in the 

event of a fire. (RG 1.189 R2) 

Safety-Related 

Function 

A safety-related function applies to the SSCs, procedures, and controls of 

a facility or process that must remain functional during and following 

design-basis events to ensure the integrity of the facility’s reactor coolant 

pressure boundary, the facility’s capability to shut down the reactor and 

maintain it in a safe shutdown condition, or the facility’s capability to 

prevent or mitigate the consequences of accidents that could result in 

potential offsite exposure comparable to the guidelines in 10 CFR 

50.34(a)(1), 10 CFR 50.67(b)(2), or 10 CFR 100.11, “Determination of 

Exclusion Area, Low Population Zone, and Population Center Distance.” 

An example of a safety related function is a facility’s capability to shut 

down a nuclear reactor and maintain it in a safe shutdown condition. 

(NUREG-1913) 

Smoke Detector A device that detects visible or invisible particles of combustion. (NFPA 

72 2010) 
Draft for Comment 

57 

Spot-Type Detector A device in which the detecting element is concentrated at a particular 

location. Typical examples are bimetallic detectors, fusible alloy 

detectors, certain pneumatic rate-of-rise detectors, certain smoke 

detectors, and thermoelectric detectors. (NFPA 72 2010) 

Standards (Code) 

of Record 

The specific editions of the nationally recognized codes and standards 

accepted by the NRC that constitute the licensing and design basis for 

the plant. (see Code of Record) 

Standard Technical 

Specifications 

NRC staff guidance on model technical specifications for an operating 

license. (NRC Online Glossary) 

Standard Technical Specifications (STS) are published for each of the 

five reactor types as a NUREG-series publication. Plants are required to 

operate within these specifications. (NRC Technical Specifications web 

page) 

Standpipe and 

Hose Systems 

An arrangement of piping, valves, hose connections, and allied 

equipment installed in a building or structure, with the hose connections 

located in such a manner that water can be discharged in streams or 

spray patterns through attached hose and nozzles, for the purpose of 

extinguishing a fire, thereby protecting a building or structure and its 

contents in addition to protecting the occupants. (NFPA 14 2010) 

The provision of piping, riser pipes, valves, firewater hose connections, 

and associated devices for the purpose of providing or supplying 

firewater hose applications in a building or structure by the occupants or 

fire department personnel. (NUREG-1805) 

Technical 

Specification (TS) 

Part of an NRC license authorizing the operation of a nuclear production 

or utilization facility. A Technical Specification establishes requirements 

for items such as safety limits, limiting safety system settings, limiting 

control settings, limiting conditions for operation, surveillance 

requirements, design features, and administrative controls. (NRC Online 

Glossary) 

Transient 

Combustibles 

Combustible materials that are not fixed in place or not an integral part of 

an operating system or component. (RG 1.189 R2) 

 
 
Draft for Comment 

A-1 

APPENDIX A: COMPARISON OF ACTIONS SPECIFIED IN 

STANDARDIZED TECHNICAL SPECIFICATIONS TO COMPENSATORY 

MEASURES IDENTIFIED IN APPROVED FIRE PROTECTION 

PROGRAMS 

This section provides a comparison of compensatory measures specified in Historical 

Standardized Technical Specifications (prior to GL 86-10) to those specified in a sample 

of approved Fire Protection Programs. 

 
Draft for Comment 

A-2 

Table A-1. Comparison of Technical Specification Compensatory Actions to Current FPP 

Measures 

Affected 

System or 

Feature 

Impairment Original STS Action18 Current FPP Actions 19

Plant Action 

Fire 

Suppression 

Water Supply 

System 

One fire pump 

and/or one water 

supply inoperable 

Restore to operable 

status within 7 days A 

Restore the water supply system to 

operable station within 7 days or provide 

an alternate backup pump or supply 

B 

Restore the inoperable equipment to 

OPERBLE status within 7 days. 

C 

Restore the inoperable equipment to 

operable status within 7 days. 

D 

Establish hourly fire watch in fire areas 

where design flow requirements for 

required spray/sprinkler systems are not 

met using the electric motor-driven 

pump(s). Provide alternate pumping 

capability, OR Provide backup pumping 

capability and maintain fire watch 

E 

Restore the inoperable pump and/or 

water supply to operable status within 7 

days, OR provide an alternate backup 

pump and/or water supply. 

F 

Restore on additional pump to 

operable/functional status OR provide 

an alternate pump within 7 days. 

G 

Restore pump to operable status or 

provide a backup fire pump in 14 Days 

Fire 

Suppression 

Water Supply 

System 

Both fire pumps 

and/or both water 

supplies 

inoperable

Establish backup fire 

suppression within 24 

hours A 

Establish a backup fire protection water 

system within 24 hours OR within one 

hour initiate action to place the plant in 

Hot Shutdown within the following 6 

hours, and Cold Shutdown within the 

subsequent 24 hours. 

 

18 Based on NRC/RES review of the Standard Technical Specifications. Fire Protection was added to the 

STS in Revision 1 of each of the NSSS Vendor STS (NUREG-0103, 0123, 0212 and 0452). 

19 As specified in available revisions of plant specific TRMs and / or FPP implementing procedures 

developed in response to GL 86-10 
Draft for Comment 

A-3 

Table A-1. Comparison of Technical Specification Compensatory Actions to Current FPP 

Measures 

Affected 

System or 

Feature 

Impairment Original STS Action18 Current FPP Actions 19

Plant Action 

B 

Establish a backup fire suppression 

water system within 24 hours, OR Be in 

at least Hot Shutdown within the next 12 

hours and in Cold Shutdown within the 

following 24 hours. 

C 

Establish a backup fire suppression 

water system within 24 hours or place 

the reactor in Hot Standby within the 

next six (6) hours and in Cold Shutdown 

within the following 30 hours. 

D 

Provide a backup supply within 24 hours 

And Establish hourly fire watch in fire 

areas where design flow requirements 

for required / specified spray/sprinkler 

systems are not met 

E Establish a backup fire suppression 

water system within 24 hours. 

F 

Restore at least one water supply 

source OR establish an alternate fire 

water supply within 24 hours. 

G 

Provide a backup fire pump within 24 

hours. If completion times are not met 

Be in Mode 3 within 7 hours AND Be in 

Mode 4 in 13 hours AND Be in Mode 5 

in 37 hours. 

Spray and/or 

Sprinkler 

Systems 

one or more of 

the required 

spray/sprinkler 

systems 

inoperable in 

areas containing 

redundant trains 

of shutdown 

equipment, 

Outside 

Containment 

Continuous fire watch 

with back up fire 

suppression 

A Continuous fire watch with backup fire 

suppression equipment 

B Continuous fire watch with backup fire 

suppression equipment 

C Continuous fire watch with backup fire 

suppression equipment 

D Continuous fire watch with backup fire 

suppression equipment 

E Continuous fire watch with backup fire 

suppression equipment 
Draft for Comment 

A-4 

Table A-1. Comparison of Technical Specification Compensatory Actions to Current FPP 

Measures 

Affected 

System or 

Feature 

Impairment Original STS Action18 Current FPP Actions 19

Plant Action 

F Continuous fire watch with backup fire 

suppression equipment 

G Continuous fire watch with backup fire 

suppression equipment 

Fire 

Suppression 

Sprinkler / 

Spray 

Systems 

One or more 

spray / sprinklers 

inoperable in 

areas NOT 

containing 

redundant trains 

of shutdown 

equipment 

(Outside 

Containment) 

Hourly Fire Watch 

A Hourly fire watch 

B Hourly fire watch 

C Hourly fire watch 

D Hourly fire watch 

E Hourly fire watch 

F Hourly fire watch 

G Hourly fire watch 

Fire 

Suppression 

CO2 Systems 

(TS Rev 2: 

Combines LP 

and HP 

Systems in the 

same section) 

One or more of 

the required LP 

CO2 systems 

inoperable 

Establish a continuous 

fire watch with back up 

fire suppression 

equipment for the 

unprotected areas 

within 1 hour 

STS Rev 2 changed 

this to fire watch with 

fire suppression 

equipment for those 

areas redundant 

systems or components 

and for other areas an 

hourly fire watch patrol. 

A 

(Non-essential): Issue a Fire Protection 

System Impairment (FPSI) permit. 

Evaluate the potential impact on the 

impairment and implement appropriate 

compensatory actions. 

B 

Establish a continuous fire watch and 

backup fire suppression equipment for 

the unprotected re(s) within 1 hour AND 

restore the system to OPERABLE status 

within 14 days AND Place signs at the 

backup fire suppression equipment to 

identify the proper hose to be used. 

C Not Applicable. 

D Not Applicable. 
Draft for Comment 

A-5 

Table A-1. Comparison of Technical Specification Compensatory Actions to Current FPP 

Measures 

Affected 

System or 

Feature 

Impairment Original STS Action18 Current FPP Actions 19

Plant Action 

E 

Establish a continuous fire watch with 

backup fire suppression equipment for 

those areas in which redundant systems 

or components could be damaged within 

1 hour OR for those areas not having 

redundant systems or components 

establish a roving watch. 

F Not Applicable. 

G Not Applicable. 

Fire 

Suppression 

Halon Systems 

One or more 

Halon systems 

inoperable 

With one or more of the 

required Halon systems 

inoperable, establish a 

continuous fire watch 

with back up fire 

suppression equipment 

for the unprotected 

areas within 1 hour 

STS Rev 2 changed 

this to fire watch with 

fire suppression 

equipment for those 

areas redundant 

systems or components 

and for other areas an 

hourly fire watch patrol. 

A 

Issue an Fire Protection System 

Impairment (FPSI) permit for the 

inoperable system. A fire tour is not 

required in the Min Control Room since 

it is continually manned. 

B 

(DG Building Basement): Establish an 

hourly fire watch with backup fire 

suppression within one hour AND 

restore the system to OPERABLE status 

within 14 days 

C 

Establish a continuous fire watch with 

backup fire suppression equipment in 

the area protected within 1 hour AND 

Restore the system operable status 

within 14 days or generate a Condition 

Report to document the event in 

accordance with SO-R-2. 

D Not Applicable. 

E 

Establish a continuous fire watch for 

those areas in which redundant systems 

or components could be damaged within 

1 hour OR for those areas not having 

redundant systems or components 

establish roving fire watch patrol within 1 

hour. 
Draft for Comment 

A-6 

Table A-1. Comparison of Technical Specification Compensatory Actions to Current FPP 

Measures 

Affected 

System or 

Feature 

Impairment Original STS Action18 Current FPP Actions 19

Plant Action 

F 

Establish a continuous fire watch with 

backup suppression equipment within 1 

hour 

G 

Establish a continuous fire watch with 

backup fire suppression capability for 

those areas containing redundant 

systems or components within 1 hour; 

For those areas not having redundant 

systems or components establish an 

hourly fire watch patrol within 1 hour. IF 

Required Action and associated 

Completion Times not met then initiate a 

Condition Report immediately. 

Fire Hose 

Stations 

One or more of 

the fire hose 

stations 

inoperable

Route additional 

equivalent capacity to 

fire hose to the 

unprotected areas from 

an OPERABLE hose 

station within 1 hour. 

STS Rev 2: route 

additional equivalent 

capacity within one 

hour if the inoperable 

fire hose is the primary 

mean of fire 

suppression; otherwise 

route additional hose 

within 24 hours. 

STS Rev 4: Changed 

wording to: With one or 

more of the fire hose 

stations inoperable, 

provide gated wye(s) on 

the nearest operable 

hose station. One 

outlet of the wye shall 

be connected to the 

standard length of hose 

provided at the station. 

The second outlet shall 

be connected to a 

length of hose sufficient 

to provide coverage for 

A 

Issue an Fire Protection System 

Impairment (FPSI) permit and within one 

hour: provide gated wye(s) on the 

nearest operable hose station(s) (one 

for the hose station and one to sufficient 

hose for the unprotected area); Post 

signs to indicate that the station is 

inoperable and which station is providing 

coverage; Post signs at the operable 

station indicating which hose is now 

providing coverage to the furthest area. 

B 

Provide an alternate means of fire 

suppression for the unprotected areas 

within one hour, AND/OR Route and 

additional equivalent capacity fire hose 

to the unprotected area(s) from an 

OPERABLE hose station located in 

another fire zone using a gated wye off 

that operable station. Place signs at the 

backup fire suppression equipment to 

identify the proper hose to be used. 

C 

Stage a hose of equivalent capacity 

which can service the unprotected areas 

from an operable hose station within one 

(1) hour from the time that the hose 

station is determined to be inoperable, if 

the inoperable hose station is the 

primary means of fire suppression; 

otherwise, stage the additional hose 

within 24 hours. 
Draft for Comment 

A-7 

Table A-1. Comparison of Technical Specification Compensatory Actions to Current FPP 

Measures 

Affected 

System or 

Feature 

Impairment Original STS Action18 Current FPP Actions 19

Plant Action 

the area left 

unprotected. Where it 

can be demonstrated 

that the physical routing 

of the fire hose would 

result in a recognizable 

hazard to operating 

technicians, plant 

equipment, or the hose 

itself, the fire hose shall 

be stored in a roll at the 

outlet of the 

OPERABLE hose 

stations. Signs shall be 

mounted above the 

gated wye(s) to identify 

the proper hose to use. 

The above action shall 

be accomplished within 

1 hour if the inoperable 

hose is the primary 

means of fire 

suppression; otherwise 

within 24 hours. 

D 

Route fire hose to provide equivalent 

nozzle flow capacity to the unprotected 

area(s) from the OPERABLE hose 

station or alternate water supply within 1 

hour. (Required to run hose if operable 

water supply is not within 250’ or area 

protected by the inoperable spray and/or 

sprinkler system) 

E 

(ONE) If identified as being the primary 

means of fire suppression within one 

hour: provide gated wye(s) on the 

nearest operable hose station(s) (one 

for the hose station and one to sufficient 

hose for the unprotected area); Post 

signs to indicate that the station is 

inoperable and which station is providing 

coverage; Post signs at the operable 

and inoperable stations indicating which 

hose is now providing coverage to the 

furthest area; If not the primary means 

then actions to be completed within 24 

hours. (ALL) Immediately notify the 

affected unit CRS/Shift Manager to 

suspend all hot work within the area 

affected until adequate compensatory 

measures have been established. 

F 

Issue an Fire Protection System 

Impairment (FPSI) permit and within one 

hour: provide gated wye(s) on the 

nearest operable hose station(s) (one 

for the hose station and one to sufficient 

hose for the unprotected area); Post 

signs to indicate that the station is 

inoperable and which station is providing 

coverage; Post signs at the operable 

station indicating which hose is now 

providing coverage to the furthest area. 
Draft for Comment 

A-8 

Table A-1. Comparison of Technical Specification Compensatory Actions to Current FPP 

Measures 

Affected 

System or 

Feature 

Impairment Original STS Action18 Current FPP Actions 19

Plant Action 

G 

Provide an alternate means of fire 

suppression for the unprotected areas 

within one hour, AND/OR Route and 

additional equivalent capacity fire hose 

to the unprotected area(s) from an 

OPERABLE hose station located in 

another fire zone using a gated wye off 

that operable station. Place signs at the 

backup fire suppression equipment to 

identify the proper hose to be used. 

STS Rev 2: 

Added the 

Section: 

Yard Fire 

Hydrants and 

Hydrant Hose 

Houses 

One or more of 

the yard fire 

hydrants or 

associated 

hydrant hose 

houses are 

inoperable and 

are the primary 

means of fire 

suppression 

Route sufficient 

additional lengths of 

2.5" diameter hose 

located in an adjacent 

operable hydrant hose 

house to provide 

service to unprotected 

area(s) within 1 hours if 

it is the primary means 

of fire suppression; 

otherwise within 24 

hours 

A 

Within 24 hr. attach sufficient additional 

lengths of 2.5 in. diameter hose located 

in an adjacent operable hydrant hose 

house to provide service to the 

unprotected area(s). 

B 

NA - Two fire carts provided in lieu of 

hydrant hose houses, and contain fire 

fighting equipment necessary to support 

the fire brigade in response to a fire. 

C 

Stage a hose of equivalent capacity 

which can service the unprotected areas 

from an operable hose station within one 

(1) hour from the time that a hose 

station is determined to be inoperable if 

the inoperable fire hose station is the 

primary means of fire suppression; 

otherwise, stage the additional hose 

within 24 hours. 

D 

Establish backup suppression or verify 

available backup suppression on fire 

apparatus. 

E 

Within 24 hours, verify sufficient 

additional lengths of adequate hose is 

available on an emergency response 

vehicle to provide service to the 

Protected Area. 

F 

Provide sufficient additional lengths of 2 

1/2” fire hose to provide service to the 

affected structure (Hydrant / Structures 

identified in the procedure) 

G 

Stage adequate fire hose lines at the 

nearest operable hose station to ensure 

equivalent capacity backup hose 

protection to the unprotected area 
Draft for Comment 

A-9 

Table A-1. Comparison of Technical Specification Compensatory Actions to Current FPP 

Measures 

Affected 

System or 

Feature 

Impairment Original STS Action18 Current FPP Actions 19

Plant Action 

Fire Rated 

Assemblies 

(Fire Barrier) 

One or more of 

the required 

barriers nonfunctional 

With one or more of the 

required barriers nonfunctional, establish a 

continuous fire watch 

on at least one side of 

the affected penetration 

within 1 hour. 

STS Rev 2 added or 

verify the operability of 

fire detectors on at 

least one side of the 

non-functional fire 

barrier and establish an 

hourly fire watch patrol.

A 

Hourly fire watch patrol –IF detectors or 

auto suppression on one side of the 

non-functional fire barrier – Otherwise 

Continuous Fire Watch 

B 

Hourly fire watch patrol –IF detectors or 

auto suppression on one side of the 

non-functional fire barrier – Otherwise 

Continuous Fire Watch 

C 

Hourly fire watch patrol –IF detectors or 

auto suppression on one side of the 

non-functional fire barrier – Otherwise 

Continuous Fire Watch 

D 

Hourly fire watch patrol –IF detectors or 

auto suppression on one side of the 

non-functional fire barrier – Otherwise 

Continuous Fire Watch 

E 

Hourly fire watch patrol –IF detectors or 

auto suppression on one side of the 

non-functional fire barrier – Otherwise 

Continuous Fire Watch 

F 

Hourly fire watch patrol –IF detectors or 

auto suppression on one side of the 

non-functional fire barrier – Otherwise 

Continuous Fire Watch 

G 

If Detection is operable in the room 

where the barrier is located establish 

Hourly Fire Watch, otherwise a 

Continuous Fire Watch is required 

Draft for Comment 

B-1 

APPENDIX B: ADVANCED TECHNOLOGIES 

In recent years, significant technological advances in fire technology have emerged which 

warrant consideration as possible alternatives to compensatory measures identified in the 

approved FPP. Depending on the plant-specific circumstances, these technologies may be 

found to provide an adequate level of compensation when used alone or in conjunction with the 

traditional measures specified in the approved FPP. 

The following examples are only provided to illustrate advanced detection and suppression 

technologies that are currently available. Inclusion in this Appendix does not constitute an 

endorsement by NRC. In addition, depending on plant-specific circumstances (e.g., license 

basis requirements, fire hazards, physical construction, operating practices, etc.), the 

technologies may not be cost-effective, may be difficult to implement or may not provide an 

appropriate method of compensation. 

B.1 Advanced Detection Technologies 

Early detection is a key factor in preventing fire damage. The earlier a fire is detected, the 

sooner it can be controlled and extinguished. The initiation of combustion requires the 

conversion of fuel into a gaseous state by heating. The chemical decomposition of a solid 

substance by heat is called pyrolysis. During this phase, microscopic combustion particles are 

emitted that are often too small to actuate conventional ionization and photoelectric smoke 

detectors. While certain standard photoelectric and ionization detectors may be set to very high 

sensitivities, increasing sensitivity beyond the normal range typically results in a high number of 

nuisance alarms. 

Recent advances in sensor types and signal processing technologies have led to the 

development of fire detection systems that are capable of detecting particles emitted during the 

pyrolysis or “incipient” 20 stage of fire growth. As shown in Figure B-1 below, detector actuation 

during the incipient stage may prevent fire damage by allowing early intervention; frequently 

before suppression is necessary. 

 

20 The National Fire Protection Association (NFPA) defines an incipient stage fire is a fire that is in the 

initial or beginning stage and which can be controlled or extinguished by portable fire extinguishers or 

small hose systems without the need for protective clothing or breathing apparatus. (Ref. 25) 
Draft for Comment 

B-2 

Figure B-1. Qualitative relationship between time and damage for different speeds of fire 

development and average detection, reaction and fire-fighting times (Ref. NUREG/CR2409) 

Systems that are able to detect products of combustion during pyrolysis are referred to as Very 

Early Warning Fire Detection (VEWFD) Systems. For a fire detection system to be considered 

a VEWFD system, it must meet the following sensitivity criteria specified in NFPA 76, “Standard 

for the Fire Protection of Telecommunication Facilities”: 

1. It must be set up to provide Alert thresholds of at least 0.2 percent per foot obscuration 

(effective sensitivity at each port), and, 

2. Alarm thresholds of at least 1 percent per foot of obscuration (effective sensitivity at 

each port). 

Detection technologies capable of satisfying the criteria in NFPA 76 for classification as a 

VEWFD system are available, and have been used extensively in the telecommunications 

industry for several years to guard against service disruptions caused by fire. It should be 
Draft for Comment 

B-3 

noted, that conventional spot type detectors installed to meet the requirements of NFPA 72 may 

be described as being able to detect incipient fires. However, to obtain the credit as a VEWFD 

system, the detection system must be capable of meeting the more stringent requirements in 

NFPA 76. Currently, the two primary types of VEWFD systems available are aspirated (air 

sampling) smoke detectors, and laser-based, spot-type, smoke detectors. 

B.1.1 Aspirating (Air Sampling) Smoke Detectors 

Thermal decomposition (pyrolysis) takes place causing solid materials to generate microscopic 

particles. Aspirating smoke detectors (ASDs) are capable of detecting these particles that 

evolve during pyrolysis which occurs well before the appearance of visible smoke. As 

discussed below, there are variations between specific designs. However, all ASD designs 

operate by actively and continuously sampling the air in a protected space. An aspirator (aka 

fan) draws air through a series of small holes in a piping network to an optical measuring 

chamber. Inside the chamber a light source (e.g. high energy light source, laser or light-emitting 

diode [LED]) and optical sensor develop a signal that is proportional to concentration of smoke 

particles in the sampled air. 

Obscuration, or the effect that smoke has on reducing visibility, is a unit of measurement which 

defines smoke detector sensitivity. A detector that requires higher concentrations of smoke to 

alarm will have a higher obscuration level (lower sensitivity). Systems used for very early 

warning of smoke and fire must be capable of sensing extremely low smoke levels, with 

obscuration values of 0.03% per foot or less. As shown in Table B-2 below, ASDs are capable 

of providing a much earlier warning of an impending fire than the traditional, spot-type 

ionization and photoelectric detectors. 

Table B-2. Detector Sensitivity Comparison (Ref. Brazzell, 2009) 

Detector Type Sensitivity (Obscuration per Meter) 

 

Ionization 2.6–5.0% obs/m (0.8-1.6 % obs/ft) 

Photoelectric 6.5–13.0% obs/m (2.0-4.2 % obs/ft) 

Aspiration (ASD) 0.005–20.5% obs/m (.002-6.8 % obs/ft) 

Over the past decade or so, several plants have installed aspirating smoke detectors in various 

plant locations. In addition, the use of aspirating smoke detectors has been found to provide a 

suitable approach under 10 CFR 50.48 (c) for assisting in the prevention of multiple spurious 

actuations that may occur as a result of fire within electrical cabinets and preventing fires within 

the cabinets from progressing to the point where a hot gas layer (HGL) would be developed in 

the room. (Ref.: Shearon Harris Nuclear Power Plant, Unit 1 – Issuance Of Amendment 

Regarding Adoption Of National Fire Protection Association Standard 805, “Performance-Based 

Standard For Fire Protection For Light Water Reactor Electric Generating Plants,” 

ML101750602). Guidance on modeling the use of incipient fire detection systems in fire 

probabilistic risk assessment (PRA) applications at plants transitioning to a risk-informed 

approach under 10 CFR 50.48 (c) has been provided by the staff in its response to Frequently 

Asked Question (FAQ) 08-0046 (ML093220426). 

Currently, there are three basic ASD sensor technologies: Cloud Chamber; Light Scattering and 

Laser Particle Counter. As illustrated in the following paragraphs, all aspirating smoke detectors 
Draft for Comment 

B-4 

use an aspirator (fan) to draw a sample of air from a series of pipes or tubes into a detection 

chamber. What differs is the technology used to measure the amount of smoke in the sampled 

air. 

B.1.1.1 Cloud Chamber ASD 

As shown in Figure B-2, in a cloud chamber smoke detector, a sample of air is drawn into a high 

humidity chamber. After the air sample is raised to a high humidity, the pressure is slightly 

reduced. If smoke particles are in the air, the moisture in the air condenses on them, forming a 

cloud in the chamber. The light obscuration of the cloud is a measure of the number of particles 

in the air sample (number density). The detector responds when the inferred number density is 

greater than a preset level. The cloud chamber system typically uses a valve and switching 

arrangement to sample from several detection zones. 

Figure B-2. Cloud Chamber 
Draft for Comment 

B-5 

B.1.1.2 Light Scattering ASD 

A stream of sampled air is continually passed through a detection chamber in which a highenergy light source is pulsed. Unlike the cloud chamber which senses light obscuration, the 

photosensitive device is not in the light beam path. As smoke particles enter the sensing 

chamber, light is reflected (scattered) from the smoke particles onto the photosensitive device 

causing the detector to respond. As illustrated in Figure B-3, an arrangement of light emitters, 

screening disk and receivers inside the measuring chamber keep emitted light signals from 

hitting the optical receiver cell during normal (no fire) conditions. Should smoke enter inside the 

box through the inlet apertures the floating smoke particles will scatter the light signal. Those 

scattered light rays will hit the optical cell and be transformed into an electric signal. The 

intensity of scattered light at a particular angular range is measured by a solid-state light 

receiver, and is proportional to the smoke concentration for a fixed smoke particle size 

distribution. The analyzer circuit triggers an alarm if a threshold value is exceeded for a 

predetermined number of consecutive pulses. 

Figure B-3. Light Scatter Aspirating Smoke Detector 

B.1.1.3 Laser Particle Counter ASD 

Similar to the Cloud Chamber and Light Scattering technologies air is drawn into a detection 

chamber through a network of sampling pipes by an aspirator (Fan). Inside the chamber the 

laser particle ASD count the number of “flashes” caused by microscopic particles emitted but 
Draft for Comment 

B-6 

with much greater sensitivity. This measurement is typically used in conjunction with light 

scattering measurements to improve false alarm immunity. 

Figure B-4. Laser Aspirating Smoke Detector 

ASD systems typically incorporate multiple alarm levels that are generally configurable. 

Therefore, an ASD system can provide very early warning of an event, prompting investigation 

at the earliest pyrolysis/smoldering stage of a fire when it is more easily extinguished. Other 

alarm levels may be configured to provide alarm inputs to fire protection systems, as well as 

activation of suppression systems. ASD alarm sensitivities are configurable and can be 

programmed to levels ranging from thousands of times more sensitive than a conventional 

detector, to much less sensitive level. 

Key Benefits 

 They are capable of providing indications of the earliest pyrolysis/smoldering stage of a 

fire allowing corrective actions to be taken before an extinguishing action is needed, 

 Since the detector can be physically located outside the area to be protected, the system 

can be used in areas of high air flows, or harsh environments (e.g. vibration, humidity 

and temperature), 

 They can provide early warning, irrespective of the level of stratification (air sampling 

ports can be sited at various horizontal and vertical positions), 

 The ability to keep monitoring smoke levels after they set off an alarm may provide 

valuable data to emergency personnel, and, 

 They afford ease of access for maintenance ( compared to ceiling mounted detectors) 

 Could contribute to the effort to maintain exposures to ionizing radiation “as low as is 

reasonably achievable” (ALARA) in high radiation areas. 
Draft for Comment 

B-7 

Potential Limitations 

 ASD may not be suitable for use in areas where a large fire may rapidly occur, such as 

those containing high concentrations of volatile combustibles, or in high voltage cabinets 

susceptible to energetic (arcing) faults, 

 Sensor pipe flow degradations / obstructions may occur and could be difficult to locate, 

 Dust may be a problem if the filtration of sample air is not adequate. 

B.1.2 Laser-Based Spot-Type Smoke Detectors 

Spot-type detectors, similar in appearance to traditional ceiling mounted detectors, are available 

that meet NFPA 76 criteria for application as a VEWDS. The principles of laser detection are 

similar to those of light-scattering photoelectric technology. In a photoelectric smoke detector, 

an LED emits light into a sensing chamber that is designed to keep out ambient light while 

allowing smoke to enter. Any particles of smoke (or dust) entering the chamber will scatter the 

light and trigger the photodiode sensor. Rather than a light-emitting diode (LED), laser spot 

detectors use a laser diode coupled to a lens, such that it creates a narrow but very intense light 

beam which provides up to 100x greater sensitivity than a standard photoelectric detector. If a 

particle of smoke enters the chamber, light from the laser is scattered and sensed by a photo 

detector. Algorithms built into the detector check the nature of the scattered light to determine 

whether the source is dust or smoke. If a determination of smoke is made, the alarm is 

signaled. 

Laser-based detectors also provide multiple alarm set-points that generally are configurable In 

one design, users can select from nine different sensitivities in the range of 0.02–2% per foot 

obscuration for either pre-alarm or alarm settings. 

Key Benefits 

 Laser-based detectors can be mixed with standard photoelectric or ionization detectors 

on the same loop or system, 

 An addressable system allows identification of the exact location of fire, 

 They can detect both fast-flaming and slow-smoldering fires. 

Potential Limitations 

 Laser-based detectors may not be suitable for use in areas containing large 

concentrations of dust or areas because they potentially might give false alarms in areas 

where welding or other processes are undertaken that generate combustion particles. 
Draft for Comment 

B-8 

Figure B-5. Spot-Type Laser Detector 

B.1.3 Video Image Detection 

Recent improvements in video camera capabilities, computer processing, and image analysis, 

combined with a desire for real time monitoring capabilities have driven the development of 

advanced video image detection (VID) systems similar to the one illustrated in Figure B-6. 

Advanced VID systems should not be confused with standard closed-circuit television (CCTV) 

systems such as those used for plant security which only provide an image. While VID systems 

may use the same cameras, in a VID system, the video image from the camera is processed by 

proprietary software to determine if smoke or flame from a fire can be identified in the video 

image. The detection algorithms identify the flame and smoke characteristics based on 

spectral, spatial or time-based properties such as changes in brightness, contrast, edge content, 

motion, dynamic frequencies, and pattern and color matching. Unlike conventional fire 

detectors, VID is not governed by a single physical principle, such as temperature or optical 

obscuration. Instead, several software algorithms detect features in the video that correspond 

to one or more visible characteristics of fire. 

The National Fire Alarm and Signaling Code, NFPA 72, covers the application, installation, 

location, performance and maintenance of fire alarm systems and their components. The use of 

VID systems for flame and smoke detection was first recognized in the 2007 edition of the 

National Fire Alarm Code21. 

Multiple environmental and system variables must be considered in designing and using a VID 

system, including obstructions, changing light levels, ventilation, lens contamination, and 

camera settings. Depending on the particulars of an application, the installation goals and 

performance criteria could vary significantly. Consequently, NFPA 72 specifies a performance-

 

21 As part of the 2010 revision, the title was changed from “National Fire Alarm Code” to “National Fire 

Alarm and Signaling Code.” 
Draft for Comment 

B-9 

based design approach in the form of an engineering evaluation. This means that VID systems 

should be designed to achieve a specified goal for a specified use or application. 

Key Benefits 

 VID systems have the ability to protect a large area, while achieving fast detection. 

They can detect smoke or flame anywhere within the field of view of the camera, 

whereas conventional smoke detectors require smoke to migrate to the detector. 

 They can be used for outdoor applications. 

 Digitized video and/or audio streams can be sent to any location via a wired and/or 

wireless IP network, enabling video monitoring and recording from anywhere with 

network access. 

 They can use the system’s basic hardware (i.e., the cameras and wiring) for multiple 

purposes (e.g., fire, flood, security, equipment monitoring). 

 They improve the operator’s response and positive event verification. 

 Video archiving of events supports future investigations of fire. 

 They can operate in environments where spot detectors may not be effective. 

 Instant situational awareness reduces the operator’s and fire brigades’ response time. 

 Could contribute to the effort to maintain exposures to ionizing radiation “as low as 

reasonably achievable possible” (ALARA) in high radiation areas. 

Potential Limitations 

 VID systems require a certain minimum amount of light for effective detection and most 

will not work in the dark. 

 Depending on the software algorithms, nuisance alarms may be generated by events 

other than fires, such as steam from vents or exhaust from vehicles. It should be noted 

that the potential for nuisance sources is highly dependent on the specific VID 

technology. Some systems have the abilities to ignore areas of the field of view that 

may have potential nuisance sources, to adjust sensitivity, and to adjust the persistence 

time of the event before an alarm signal is issued. Manufacturers also have developed 

specific alarm algorithms to avoid signaling common nuisance events. 

 VID systems should not be expected to perform in the environments outside the normal 

operating space of general CCTV installations (e.g., pointing a camera where the sun 

can be in field of view). 

 Video images may be degraded by environmental contaminants or hardware 

adjustments that change the image’s focus and brightness. Self-diagnostic capability 

typically is required to determine video image quality for proper detection performance. 

 Because VID is a line-of-sight device, it typically requires an unobstructed view of the 

area to be protected. 

 
Draft for Comment 

B-10 

Figure B-6. Video Image Detection 

B.1.4 Thermal Imaging Cameras 

One tool currently available to identify possible fire initiators is the thermal imaging camera. The 

advantage of this device is its ability to rapidly display areas of varying temperatures without 

contact. This allows for the identification of specific equipment elements that are operating at 

higher temperatures than adjacent elements. 

Thermal imaging instrument measures radiated infrared (IR) energy and convert the data to 

corresponding maps of temperatures. With thermal imaging technology, cameras capture this 

energy. Once captured, the camera’s processor software reads the infrared signals and 

translates them into an image that we can easily see, providing an early warning of hot spots 

that are detected. Because thermal imaging cameras use the heat emitted from an object to 

produce images, they are able to work in the dark. Using this technology, it is possible to “see” 

the surface temperature of any object. A true thermal image is a gray scale image with the hot 

items shown in white and the cold items in black. Temperatures between the two extremes are 

shown as gradients of gray. Some thermal imagers enhance operator performance by adding 

color which is artificially generated by the camera's electronics in response to the thermal 

attributes seen by the camera. 
Draft for Comment 

B-11 

Infrared (IR) spot measurements also are obtainable using a simple IR point radiometer 

(sensor) that measures the object’s emitted IR energy and converts it into a digital temperature 

readout. However, a point radiometer does not provide an image of the object and, thus, it is 

difficult to find what or where the problem is precisely located without actually scanning the 

entire object or surface. 

Thermography may serve as an alternative or complementary approach to conventional fire 

detection technologies provided the system includes some basic features such as the ability to 

 detect and clearly visualize emerging hot spots 

 measure and indicate temperature 

 raise an alarm when a temperature threshold is exceeded. 

Often, deterioration, such as high contact resistance in a circuit breaker contact, or loose 

electrical connections produce warning signs that can be identified by a thermal imaging device 

before the device fails. Using a hand-held infrared camera, potential precursors to fire ignition 

can be quickly identified for evaluation. In many cases, precursors can be detected well before 

an actual failure. Many NPP fire brigades currently use this technology as hand-held thermal 

imaging cameras (TICs) to aid in locating and evaluating fire conditions. Other applications 

include locating potential ignition sources prior to fire, such as loose electrical connections, 

failing/overheated transformers, and, overloaded motors or pumps. 

Advantages 

 These cameras allow monitoring of locations that are difficult to reach due to extreme 

environmental conditions. 

 They provide early identification of potential ignition sources, such as hot spots in 

electrical switchgear enclosures or transformers. 

 They can significantly enhance the capabilities of a roving fire watch and may justify less 

frequent tours of certain areas. 

 They offer a warning before an actual fire event. 

 Could contribute to the effort to maintain exposures to ionizing radiation “as low as is 

reasonably achievable” (ALARA) in high radiation areas. 

Potential Challenges 

 Conditions that cause the camera's thermal detector to become saturated, or in which 

the range of temperatures detected becomes too wide for the optics and/or electronics to 

operate at the highest resolution. 

 Thermal images may be difficult to interpret. Reflections and low surface emissivity can 

produce false indications – training is required.

 
Draft for Comment 

B-12 

B.2 Advanced Suppression Technologies 

Research into the development of Halon alternatives has resulted new fire extinguishing agents 

which have been incorporated into the design of completely self-contained fire suppression 

systems and devices. The systems typically use clean agents that are non-conductive and 

leave no residue. Clean Agents are particularly useful for hazards where: 

 An electrically non-conductive agent is required 

 Cleanup of other agents presents a problem 

 Hazard obstructions require the use of a gaseous agent 

 The hazard is normally occupied and requires a non-toxic agent 

Types of hazards typically protected with clean agents include: 

 Computer rooms 

 Control rooms 

 Telecommunications facilities 

 Electric switchgear 

Although clean agents are most common, the systems are generally compatible with most 

commercially available fire suppression agents. The suppression of fires by clean agents is 

covered by the NFPA 2001, Standard on Clean Agent Fire Suppression Systems. . The selfcontained design of the examples illustrated in the following paragraphs enables them to 

provide a standalone, transportable, fire suppression system.. Depending on the plant-specific 

circumstances, they may provide an effective alternative to compensatory measures specified 

in the FPP. . 

B.2.1 Solid Propellant Gas Generators 

Based on automotive airbag technology, gas generators have been developed for fire 

suppression applications. Gas generators can produce a large quantity of gases (mainly N2, 

CO2 and water vapor) by combustion of solid propellants. 

. Solid propellant gas generators typically consist of solid propellant tablets which rapidly 

generate a gas when ignited. Two common types of solid propellant gas generators are 

condensed aerosol extinguisher which produces a powdered aerosol and a nitrogen generator 

that produces inert nitrogen gas. 

B.2.1.1 Condensed Aerosol Generators 

In a condensed system the aerosols are produced by exothermic chemical reaction (i.e., 

pyrotechnically) using a solid compound. When the system is activated the aerosol is introduced 

into a space through a delivery system similar to that used for gaseous agents. Condensed 

aerosol generators are completely self-contained and suitable for nearly all types of plant fire 

hazards. 

The condensed aerosol generator can be activated manually, thermally (by the fire) or 

electrically from a suitable detection device. Different-sized generators are available to protect 

different volumes. In addition, several generators can be strung together to provide additional 

coverage. The design, installation, operation, testing, and maintenance of condensed aerosol 

fire-extinguishing systems are governed by NFPA 2010, Standard for Fixed Aerosol FireExtinguishing Systems. 
Draft for Comment 

B-13 

As illustrated in Figure B-7 a condensed aerosol generator is completely self-contained within a 

heavy duty aluminum canister that can be easily installed as needed. Storing the extinguishing 

agent in a dense solid form until activated, permits the condensed aerosol generators to be 

fairly small. As a result, the canisters may be hung from walls, ceilings or mounted within an 

enclosure. 

Key Benefits 

 Compact 

 Lightweight 

 No pipework required 

 Environmentally friendly 

 Ease of installation 

 Long service life 

 High extinguishing efficiency 

Possible Limitations 

 Reduced visibility in protected space following discharge 

 The temperature of the expelled aerosol near the generator surface may be as high as 

200 °C (392°F). 

 Are effective only in closed spaces. May not be suitable for ventilated enclosures 

 Should not be used in normally manned enclosures. 
Draft for Comment 

B-14 

Figure B-7. Condensed Aerosol Generator 

B.2.1.2 Nitrogen Gas Generators 

As shown in Figure B-8, Nitrogen (N2) generators are physically similar to condensed aerosol 

generators. Like the condensed aerosol generator, the N2 generator does not need highpressure gas storage cylinders and associated piping networks. Nitrogen generators produce 

an inert N2 gas, which reduces the concentration of oxygen in a room below the level that will 

sustain combustion. However, the oxygen concentration is maintained at a sufficient level to 

meet the requirements of NFPA 2001 for clean agent Halon 1301 alternatives in normally 

occupied areas. 

N2 gas generation is initiated in response to an electrical signal that is generated by a fire 

detector, fire control panel or manual pull station. The electrical signal actuates a pyrotechnic 

device (squib) which ignites the solid N2 fuel. Suppression coverage varies with the size of the 

generator canister. One manufacturer states that a single 6” x 12” generator will cover up to 

200 cubic feet. Individual generators can be installed under floors, on ceilings or inside cabinets 

and multiple generators can be daisy-chained together to provide a total room flooding 

capability. N2 systems should conform to NFPA 2010 Standard On Aerosol Fire-Extinguishing 

Systems - Edition 1 and UL 2775 - Fixed Condensed Aerosol Extinguishing System Units - 

Edition 1. 

Key Benefits 

 Long (up to 25 year) service-free shelf life 

 Rechargeable on site 
Draft for Comment 

B-15 

 Compact 

 No piping or nozzles 

 Releases harmless, inert, N2 gas - maintains oxygen levels that are safe for occupied 

spaces 

 No residue or cleanup 

Potential Limitations 

 enclosure must be capable of holding the gas and be able to withstand the pressure 

produced during discharge 

Figure B-8. N2 Gas Generator 

 
Draft for Comment 

B-16 

B.2.2 Transportable Automatic Suppression Systems 

Several self-contained, transportable, fire suppression systems are commercially available that 

are capable of detecting and extinguishing fire inside equipment, cabinets or enclosed spaces r 

up to 250 cu ft. As illustrated in Figure B-9, these systems incorporate flexible, polymer tubing 

that acts as both a fire detector and suppressant dispersion nozzle. When exposed to the heat 

of fire (typically 100°C) the tubing ruptures to dispense the suppression agent. A key advantage 

of these systems is that the flexible polymer tubing can be routed to provide protection in many 

different types of enclosures, including cable trays. In addition to being highly transportable 

these systems do not require any type of outside electrical source or detection system and will 

remain totally operational during power outages. 

 

Figure B-9. Transportable Suppression System Applications 

B.2.3 Pre-packaged Portable Water Mist Systems 

Water has several favorable properties for fire suppression. When applied in a fine mist, its 

effectiveness is further improved by the increased surface area of water that is available for heat 

absorption and evaporation. Water mist systems have been demonstrated to extinguish a wide 

variety of fires, including fires in electrical and electronic equipment cabinets. In addition, 

evacuation of the compartment may not be necessary and the electronic equipment can 

continuously be operated during the discharge of a water mist especially if a zoned system is 

used (Ref. Liu, 2001). 

NFPA 750, Standard on Water Mist Fire Protection Systems, contains the minimum 

requirements for the design, installation, testing, and maintenance of such systems. Prepackaged, self-contained, portable water mist systems are of particular interest for their possible 

use as an alternate compensatory measure. As illustrated in Figure B-10, a completely selfcontained system is commercially available that is pre-packaged on steel plate skid. The water 

cylinder is bolted to the skid and the nitrogen cylinder(s) are mounted to the water cylinder with 

straps. The skid is designed so it can be easily transported with a fork lift. According to one 
Draft for Comment 

B-17 

manufacturer, this system has successfully demonstrated fire extinguishment in Factory Mutual 

fire tests for machinery spaces22 up to 9,175 ft3

 (260 m3). 

Figure B-10. Skid-mounted Water Mist System 

B.3 Temporary Fire Barrier Penetration Seals 

To limit fire damage and prevent the spread of toxic products of combustion (e.g. smoke, hot 

gases and fumes) NPPs are divided by fire-rated structural barriers into separate fire areas. 

The fire-rated walls, floors and ceiling assemblies (structural fire barriers) have sufficient fire 

resistance to withstand the fire hazards associated with the area and to protect important 

equipment located in the area from a fire that occurs outside the area. These structural fire 

barriers may contain a number of penetrations or openings to allow such services as piping, 

electrical conduits, cable trays; and ventilation ducts to pass from one fire area to another. To 

maintain the fire-resistive integrity of the barriers and provide reasonable assurance that a fire 

will be confined to the area in which it started, openings and voids in structural fire barriers are 

closed with penetration seal assemblies (also known as firestops) that have been tested and 

qualified to ensure the fire resistance rating of the barrier is maintained. 

According to NUREG-1552, (Ref. US NRC, NUREG-1552), each NPP has an average of 3,000 

penetration seals. However, a single NPP may have as many as 10,000. The fire at the 

Browns Ferry NPP in 1975 illustrated how improper penetration seal materials can contribute to 

the spread of fire. Today, penetration seal materials are available that, if properly installed and 

 

22 A machinery space is defined as areas that contain flammable liquid processing hazards with Class 1, 

2, or 3 flammable liquids as specified in NFPA 325 and incidental Class A combustibles 
Draft for Comment 

B-18 

maintained, will maintain the fire-resistive integrity of the fire barriers in which they are installed. 

A fire barrier penetration seal is a system that includes the fire-rated wall or floor, the opening, 

the cable or conduit that passes through the opening, and the material used to seal the opening. 

The performance of a penetration seal is dependent upon the specific assembly of materials 

tested including the number, type, and size of penetrations and the floors or walls in which it is 

installed. Achieving an effective penetration seal requires taking all of the components present 

into consideration when selecting the material that is best suited for that application. 

Fire barrier penetration seals are intended for use in openings in fire-resistive walls, floors, and 

ceilings that have been evaluated in accordance with ASTM E119, "Standard Test Methods for 

Fire Tests of Building Construction and Materials."23 ASTM E119 assigns ratings based on “T” 

(temperature rise) and “F” (time for flame spread). The T-rating is a measure of the thermal 

conductivity of a firestop system and can be considered a temperature rating. This is the time 

required for various points on the unexposed side of the test assembly to rise 325 degrees over 

the starting (ambient) temperature. As a result, penetrating items which conduct heat readily, 

such as metallic pipes and conduits, would significantly hinder the ability to achieve a 

acceptable T-rating when tested under ASTM E119. To address this and other concerns, 

ASTM E814-11a, “ Standard Test Method for Fire Tests of Penetration Firestop Systems” and 

IEEE Std. 634, “IEEE Standard for Cable-Penetration Fire Stop Qualification Test” have been 

developed to test the unique fire resistance of penetration firestops. In these standards the Trating is intended to provide engineering information relative to how hot penetrants might 

become in a fire exposure. A T-rating of a specified duration establishes that the fire stop 

effectively maintained unexposed side temperatures at or below 325°F above initial temperature 

for a general acceptance test or the auto ignition temperature of the cable type tested for a 

cable-specific qualification. Conformance to either ASTM E814-11 or IEEE Std. 634 a provides 

assurance that the penetration seal (firestop) meets its design objective of ensuring that the 

penetrated fire barrier will be capable of withstanding the fire hazards located within the area of 

concern and will adequately protect important equipment located in the area from a fire that 

occurs outside the area. 

All fire barriers and fire barrier penetration seals do not have the same level of safety 

significance. The importance of a specific fire barrier depends on many factors, such as the 

importance of the equipment in the fire area (and adjacent areas); the configuration and location 

of combustible materials and other fire hazards, if any, in the areas; the potential for fire growth 

in the areas; the other fire protection features installed in the areas; and the accessibility of the 

areas to the plant fire brigade. Similarly, the importance of a specific fire barrier penetration 

seal depends on these factors and on such other factors as its size, location or position in the 

fire barrier, and the number and sizes of the other seals in the barrier. 

In Generic Letter 86-10 (Ref. US NRC, GL88-10) the staff established that certain penetration 

seals need not have the same fire rating as the barrier in which they are installed and that 

certain fire barrier penetrations may not need to be sealed at all provided they are considered in 

the plant in its evaluation of the effectiveness of the overall barrier. Specifically, Interpretation 4, 

"Fire Area Boundaries," states, in part: 

The term "fire area" as used in Appendix R means an area sufficiently bounded to 

withstand the [fire] hazards associated with the area and, as necessary, to protect 

important equipment within the area from a fire outside the area. In order to meet the 

regulation, fire area boundaries need not be completely sealed floor-to-ceiling, wall-to-

 

23 NRC classically has used NFPA 251 rather than E119 although they are the same. 
Draft for Comment 

B-19 

wall boundaries. However, all unsealed openings should be identified and considered 

[in] evaluating the effectiveness of the overall barrier. Where fire area boundaries are 

not wall-to-wall, floor-to-ceiling boundaries with all penetrations sealed to the fire rating 

required of the boundaries, licensees must perform an evaluation to assess the 

adequacy of fire boundaries in their plants to determine if the boundaries will withstand 

all [fire] hazards associated with the area. 

Thus, for penetration seals that cannot be demonstrated to meet ASTM E814-11a, an 

engineering evaluation may be used to determine the expected fire resistance rating. Licensees 

evaluate such seals on a case-by-case basis. The engineering evaluations performed to 

assess the effectiveness of the penetration seals are based on the expected fire resistive 

performance of the seal and on the fire hazards and fire protection features in the fire area. 

These analyses may use computer simulation and mathematical fire modeling, 

thermodynamics, heat-flow analysis, and materials science to predict the fire performance of the 

penetration seal assembly. Deviations from NRC requirements or accepted industry standards 

for fire barrier penetration seals should be technically substantiated as part of the review and 

approval of the fire protection plan or in other separate formal correspondence. 

Like other plant features, it is expected that over the life of the plant, instances of degraded fire 

barrier penetration seals will be found. It is also expected that penetrations will be opened to 

allow for plant modifications, maintenance and upgrades. When such conditions are identified, 

NRC approved fire protection programs typically specify that fire watches be posted to maintain 

an appropriate level of defense in depth to assure the deficiency will not pose an undue risk to 

public health and safety. In general, if fire detection is not available on either side of the barrier, 

the FPP will specify the establishment of a continuous fire watch. Typically, in cases where 

automatic detection systems protect the affected components, an hourly fire watch patrol is 

specified. Although posting a fire watch is the most common compensatory measure, 

depending on the plant-specific conditions and nature of the deficiency, a number of products 

are currently available that may provide a more effective compensatory measure. Two specific 

examples are described below. 

B.3.1 Intumescent Pillows and Blocks 

An intumescent substance expands or swells when exposed to heat. This phenomenon is the 

working principle behind many fire barrier penetration seal products: they expand when exposed 

to the heat of fire thereby closing any small voids or gaps that may remain after installation or 

formed during a fire by melted components. 

Intumescent pillows and blocks are two examples of temporary fire-rated materials that are 

available to seal medium to large openings in structural fire barriers. The pillows and blocks 

may be used to temporarily fill openings that are entirely blank or around penetrating items such 

as pipes, conduits, cable trays and HVAC ducts. This capability could be especially useful 

when a fire barrier is removed or breached during plant modifications. If a fire does not occur, 

they may be readily removed and stored for reuse. However, should a fire occur, the bags or 

blocks will expand, tightly closing any small spaces between cables, trays and masonry to 

create a fire-rated seal that is capable of withstanding mechanical damage caused by falling 

debris or a hose stream from fire fighters. 
Draft for Comment 

B-20 

Figure B-11. Diagram of Intumescent Pillows in a cable tray penetration 

Key Benefits 

 Expand and seal into place when exposed to high temperatures 

 Can provide up to 4-hours of fire resistance (F-rating) when tested in accordance with 

ASTM E 814 

 Relatively easy to install, remove, and replace 

 Useful for sealing difficult configurations such as where access is restricted to one side 

of the assembly 

 Can be reused 

 Pillows may be used to temporarily protect cable trays during cutting and welding 

 Long shelf life 

Potential Challenges 

 May be subject to damage during use and un-intentional or unauthorized removal - 

periodic inspection is necessary 

 Some configurations may require the installation of wire mesh. 

 Excessive handling or abuse may permanently compress the pillows. 
Draft for Comment 

B-21 

B.3.2 Reusable Firestop Plugs and Putty 

For small to medium sized fire barrier penetrations and openings various plugs and putties are 

available which may provide an effective temporary seal. Empty conduit penetrations created 

during plant maintenance or cable routing modifications may be quickly sealed by firestop plugs. 

Plugs having a three-hour fire rating are available and are easily removed for penetration 

access. The plugs are typically prefabricated to fit standard conduit /pipe sleeve sizes. 

However, custom sizes are available. 

Figure B-12. Diagram of fire stop plug in a cable penetration 

For sealing small diameter conduits or openings around metallic pipes, fire stop putty, may 

provide an effective temporary seal. Fire stop putty is a ready-to-use fire stop product that is 

hand pressed into place. During normal use the putty remains soft and pliable. However, in 

response to high temperatures caused by fire, the putty will expand within the opening, forming 

a solid char that helps prevent through penetration of the fire. Since no drying or curing is 

required, the putty is fully functional as soon as it is installed. 
Draft for Comment 

B-22 

Figure B-13. Diagram of fire stop putty in a cable penetration 

Key Benefits 

 Can provide up to 3-hour F-ratings of fire resistance when tested in accordance with 

ASTM E 814 

 Reusable 

 Smoke and gas tight 

 Weather resistant 

 Long shelf life 

 Quick and easy installation: no special tools required 

 Does not require cable de-rating 

 No curing or drying time: provides an immediate firestop 

 Intumescent 

 Easily re-penetrated 

Potential Challenges 

 May be subject to damage during use and un-intentional or unauthorized removal. 

Therefore, periodic inspection is necessary 

 Putties contain oils which may be absorbed into porous surfaces. Sleeves are 

recommended 

 Only high-tack putties should be chosen. Less tacky products may not stay in place 
Draft for Comment 

B-23 

Figure B-14. Possible Applications of Advanced Technologies 




UNITED STATES 

NUCLEAR REGULATORY COMMISSION

WASHINGTON, DC 20555-0001

--------------------

OFFICIAL BUSINESS
NUREG/CR

-7135

Draft

Compensatory and Alternative Regulatory MEasures for 

Nuclear Power Plant FIRE Protection (CARMEN-FIRE)