ML20045G912
| ML20045G912 | |
| Person / Time | |
|---|---|
| Issue date: | 07/16/1993 |
| From: | Marcus G Office of Nuclear Reactor Regulation |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-86-10, NUDOCS 9307160137 | |
| Download: ML20045G912 (53) | |
Text
_
!(paaugjo UNITED STATES g
NUCLEAR REGULATORY COMMISSION n
h WASHINGTON. D. C. 20555 July 16, 1993 MEMORANDUM FOR: Document Control Desk Document Management Branch Division of Information Support Services Office of Information Resources Management FROM:
Gail H. Marcus, Chief Generic Communications Branch Division of Operating Reactor Support Office of Nuclear Reactor Regulation
SUBJECT:
DOCUMENTS ASSOCIATED WITH THE PROPOSED SUPPLEMENT 1 TO GENERIC LETTER 86-10, " FIRE ENDURANCE ACCEPTANCE CRITERIA FOR FIRE BARRIER SYSTEMS USED TO SEPARATE REDUNDANT SAFE SHUTDOWN TRAINS WITHIN THE SAME FIRE AREA" The Plant Systems Branch has prepared the subject generic letter supplement.
The Committee to Review Generic Requirements (CRGR) has reviewed and endorsed this draft generic communication. The Generic Communications Branch is preparing to publish the draft generic communication in the Federal Reaister for public comment.
This memorandum provides a compilation of the background material relevant to the subject generic communication that should be made available to the public.
By copy of this memorandum we are providing the enclosed documents to the Public Document Room. The enclosures are (1) the draft generic letter supplement as endorsed by CRGR, (2) the CRGR Review Package and Generic Backfit Requirements Reporting Form, and (3) a summary of the public comments previously received on the staff's position on fire endurance test acceptance criteria for fire barrier systems used to separate redundant safe shutdown trains within the same fire area.
4 We request that you provide us with the Nuclear Documents System accession number for this memorandum.
This information can be provided to the listed contact by telephone or by E-Mail.
cus Gail H. Marcus, Chief Generic Communications Branch
{
Division of Operating Reactor Support i
Office of Nuclear Reactor Regulation i
Enclosures:
As Stated CONTACT:
Richard J. Kiessel, NRR 504-2840 150006 9307160137 930716
's PDR ORG NRRB r
nl PDR y
(
July 16, 1993 MEMORANDUM FOR: Document Control-Desk Document Management Branch Division of Information Support Services Office of Information Resources Management FROM:
Gail H. Marcus, Chief Generic Communications Branch Division of Operating Reactor Support Office of Nuclear Reactor Regulation
SUBJECT:
DOCUMENTS ASSOCIATED WITH THE PROPOSED SUPPLEMENT 1 TO GENERIC LETTER 86-10, " FIRE ENDURANCE ACCEPTANCE CRITERIA FOR FIRE BARRIER SYSTEMS USED TO SEPARATE REDUNDANT SAFE SHUTDOWN TRAINS WITHIN THE SAME FIRE AREA" The Plant Systems Branch has prepared the subject generic letter supplement.
The Committee to Review Generic Requirements (CRGR) has reviewed and endorsed.
this draft generic communication.
The Generic Communications Branch is-preparing to publish the draft generic communication in the Federal Reaister for public comment.
This memorandum provides a compilation of the background material relevant to the subject generic communication that should be made available to the public.
By copy of this memorandum we are providing the enclosed documents to the Public Document Room. The enclosures ~ are (1) the draft generic letter supplement as endorsed by CRGR, (2) the CRGR Review Package and Generic Backfit Requirements Reporting Form, and.(3) a summary of the public comments previously received on the staff's position on fire endurance-test acceptance criteria for fire barrier systems used to separate redundant safe shutdown trains within the same fire area.
We request that you provide us with the Nuclear Documents System accession number for this memorandum.
This information can be provided to the listed contact by telephone or by E-Mail.
Crigiral highed tv:
0111 II. !&trotis Gail H. Marcus, Chief Generic Communications Branch Division of Operating Reactor Support Office of Nuclear Reactor Regulation
Enclosures:
As Stated CONTACT:
Richard J. Kiessel, NRR 504-2840 Distribution w/ enclosures:
RJKiessel, NRR OGCB r/f Central ; Files PDR JHConran, AE0D Distribution w/o Enclosures _:
BKGrimes, NRR GHMarcus, NRR AEChaffee, NRR CIGrimes, NRR SHWeiss, NRR WMDean, NRR PMMadden, NRR DORS r/f RJKiessel r/f ACThadani, NRR CEMcCracken, NRR KSWest, NRR 0GCB, DORS,NRR,j C/0GCB, DORS,NRR RJKiesselgf GHMarcu 77/f/93 f//t /93 DOCUMENT NAME: MEMO.361
4 4
T0:
ALL HOLDERS OF OPERATING LICENSES OR CONSTRUCTION PERMITS FOR NUCLEAR POWER REACTORS
SUBJECT:
FIRE ENDURANCE TEST ALCEPTANCE CRITERIA FOR FIRE BARRIER SYSTEMS USED TO SEPARATE REDUNL?NT SAFE SHUTDOWN TRAINS WITHIN THE SAME FIRE AREA (SUPPLEMENT 1 TO GEtJRIC LETTER 86-10, "IMPLEMEgTfTION OF FIRE PROTECTION REQUIREMENTS")
PURPOSE The U.S. Nuclear Regulatory Commission (NRC) is issuing this supplement to Generic Letter (GL) 86-10, " Implementation of Fire Protection Requirements,"
of April 24, 1986, to disseminate review guidance contained in Enclosure A,
" Fire Endurance Test Acceptance Criteria for Fire Barriers Used to Seoarate Redundant Safe Shutdown Trains Located Within the Same Fire Area".
This guidance will be used by the staff for review and evaluation of the adequacy of fire endurance tests and fire barrier systems that may be pr oposed by licensees or applicants in the future to satisfy NRC fire protection rules and regulations.
This guidance refines and clarifies the fire barrier testing acceptance criteria specified by GL 86-10, for application in that specific (future review) context.
BACKGROUND On April 24, 1986, the NRC issued GL 86-10 in order to give the industryThe additional guidance on implementing NRC fire protection requirements.
guidance in GL 86-10 did not change the requirement to separate one safe shutdown train from its redundant train with either a 1-hour or a 3-hour fire rated barrier.
In Enclosure 2 to GL 86-10, the NRC staff responded to industry questions.
Question 3.2.1 of the enclosure provided the staff position on fire endurance test acceptance criteria for fire barrier cable In its response, the staff referenced Chapter 7, " Tests of tray wraps.
Nonbearing Walls and Partitions," of National Fire Protection Association (NFPA) Standard 2S1
" Standard Methods of Fire Tests of Building Construction," as being applicable to cable-tray fire wraps.
On July 30, 1991, the NRC established a special review team to identify and evaluate technical issues related to the Thermo-Lag 330-1 fire barrier system.
On August 6. 1991, the NRC issued Information Notice (IN) 91-47, " Failure of Thermo-Lag Fire Barrier Material to Pass fire Endurance Test." This IN gave licensees information on the fire endurance test performed by Gulf States Utilities Company on a Thermo-Lag 330-1 fire barrier installed on a wide aluminum cable tray and the associated fire test failure.
On December 6, 1991, the NRC issued IN 91-79, " Deficiencies in the Procedures for Installing Thermo-Lag Fire Barrier Material," which gave information on deficiencies in procedures that the Thermo-Lag vendor (Thermal Science, In Incorporated) provided for constructing Thermo-Lag 330-1 fire barriers.
response to concerns about the indeterminate qualifications of Thermo-Lag 330-1 fire barriers, on June 23, 1992, the NRC issued IN 92-46,
6 4
e Generic Letter 86-10, Supp. 1.
September XX, 1993 "Thermo-Lag Fire Barrier Material Special Review Team Findings, Current Fire Endurance Tests, and Ampacity Calculation Errors." The staff found the following problems with Thermo-Lag 330-1 fire _ barriers:
incomplete or indeterminate fire test results, questionable ampacity derating test results and a wide range of documented ampacity derating factors, some barrier installations that were not constructed in accordance with vendor-recommended installation procedures, incomplete installation procedures, and as-built fire barrier configurations that may not have been qualified by val.14,f, ire endurance tests or evaluated in accordance with the guidance that the staff issued in GL 86-10.
After reviewing ins 91-47 and 91-79, Texas Utilities. (TU) Electric instituted a fire endurance test program to qualify its Thermo-Lag electrical raceway fire barrier systems for its Comanche Peak Steam Electric Station.
Under this program, TV Electric performed its initial fire barrier test series during the weeks of June 15 and 22, and August 19, 1992. Notwithstanding the fire test acceptance criteria guidance specified in GL 86-10, TU Electric followed the guidance of American Nuclear Insurers (ANI) as described in ANI Information Bulletin No. 5 (79), "AN1/MAERP Standard Fire Endurance Test Method to Qualify a Protective Envelope for class IE Electrical Circuits," July 1979.
As result of NRC interaction with TV Electric regarding its fire tests, the NRC concluded that there was uncertainty on the part of licensees as to whether or not the ANI test method established a level of fire barrier performance equivalent to that established by the GL 86-10 acceptance criteria.
In addition, the NRC staff recognized that the 1-hour and 3-hour raceway fire barrier systems are unique and that additional guidance on the proper implementation of the GL 86-10 acceptance criteria would be useful.
AREAS OF CONCERN The experiences with Thermo-Lag fire barrier systems at TU Electric recounted above raised the following general concerns:
The fire endurance test acceptance criteria used by other fire barrier (1) vendors, applicants, and licensees may not meet the acceptance criteria of GL 86-10, and may not fully demonstrate the fire barrier performance intended.
(2)
Certain past cable functionality testing (i.e., circuit integrity monitoring may not fully demonstrate the intended capability of protected circuits to function during and after a postulated fire.
FIRE ENDURANCE CAPA8ILITY 1
NRC Oualification Reouirements and Guidance for Fire Barriers Section 50.48 of 10 CFR requires that each operating nuclear power plant have a fire protection plan that satisfies GDC 3.
GDC 3 requires that structures, i
systems, and components important to safety be designed and located to minimize, in a manner consistent with other safety requirements, the probability and effects of fires.
Fire protection features required to
i Generic Letter 86-10, Supp. 1 September XX, 1993 satisfy GDC 3 include features to ensure that one train of those systems necessary to achieve and maintain shutdown conditions be maintained free of fire damage. One means of complying with this requirement is to separate one safe shutdown train from its redundant train with fire-rated barriers.
The level of fire resistance required of the barriers,1-hour or 3-hours, depends on the other fire protection features in the fire area.
The NRC issued guidance on acceptable methods of satisfying thagegulatory requirements of GDC 3 in Branch Technical Position (BTP) Auxili'ary and Power Conversion Systems Branch (APCSB) 9.5-1, " Guidelines for Fire Protection for Nuclear Power Plants;" Appendix A to BTP APCSB 9.5-1; BTP Chemical Engineering Branch (CMEB) 9.5-1, " Fire Protection for Nuclear Power Plants;" and GL 86-10.
In the BTPs and in GL 86-10, the staff stated that the fire resistance ratings of fire barriers should be established in accordance with NFPA Standard 251,
" Standard Methods of Fire Tests of Building Construction and Materials," by subjecting a test specimen that represents the materials, workmanship, method of assembly, dimensions, and configuration for which a fire rating is desired to a " standard fire exposure.'"
Some licensees have used the acceptance criteria of ANI Information Bulletin The No. 5 (79), to evaluate the performance of their fire barrier systems.
ANI test methodology requires the cables within the fire barrier test specimen be monitored for circuit integrity while the test specimen is subjected to a test fire that follows the standard time-temperature curve of the American Society of Testing and Materials (ASTM) Standard E119, " Standard Methods of Fire Tests of Building Construction and Materials," and to a hose stream test.
Under this criterion, the fire barrier system is evaluated by monitoring the capability of the cables inside the fire barrier to pass a low voltage circuit integrity test. During the fire and hose stream tests, if cable circuit integrity is maintained, the tests are considered successful.
The ANI test methodology does not specify the following GL 86-10 acceptance criteria:
(1)
The fire barrier design has withstood the fire endurance test without the passage of flame or the ignition of cotton waste on the unexposed side for a period of time equivalent to the fire-resistance rating required of the barrier.
(2)
Analysis of temperature levels recorded on the unexposed side of the fire barrier demonstrates that the maximum temperature rise does not exceed 139 *C [250 *F] above ambient temperature.
(3)
The fire barrier remains intact and does not allow water to be projected beyond the unexposed surface during the hose stream test., " Interpretations of Appendix R," to GL 86-10, provided additional guidance with respect to the term " free of fire damage" as used in Appendix R.
Interpretation 3, " Fire Damage," stated:
"In promulgating Appendix R, the American Society for Testing and Materials (ASTM) Standard E119 was adopted by NFPA as NFPA Standard 251.
i
(
Generic Letter 86-10, Supp. 1 September XX, 1993 Commission has provided methods acceptable for assuring that necessary structures, systems, and components are free from fire damage (see Section III.G.2a, b, and c), that is, the structure, system or component under consideration is capable of performing its intended function during and after the postulated fire, as needed."
The review guidance provided in Enclosure A (1) clarifies the applicability of the test acceptance criteria stated in GL 86-10 to raceway fire,Aarrier systems, (2) specifies a set of fire endurance test acceptance criteria which are acceptable for demonstrating that fire barrier systems can serve the required fire-resistive function and maintain the protected safe shutdown train free of fire damage, (3) specifies acceptable options for hose stream testing, and (4) specifies acceptable criteria for functionality testing of cables when a deviation would be necessary, such as if the fire barrier temperature rise criteria are exceeded and the cable sustains visible damage.
The test methods and acceptance criteria specified are acceptable for determining the adequacy of fire barrier systems proposed by licensees or applicants in the future to satisfy NRC fire protection rules and regulation.
Applicants or licensees may propose alternative test methods and acceptance criteria to demonstrate an equivalent level of protection; the staff will review such proposals on a case-by-case basis.
Enclosure B is a comparison of this review guidance against the GL 86-10 neptance criteria.
Fire ty:orance and Functionality Tests - Evaluation and Acolication of Test Results The fire endurance qualification test is successful if the following conditions are satisfied (see Enclosure C, " Fire Barrier Testing Acceptance Criteria / Logic Diagram"):
(1)
The internal temperature of the fire barrier system, as measured on the exteriorsurfaceoftheracewayorcomponent,Qidnotrisemorethan 139 *C [250 *F] above its initial temperature:' or j
3 (2)
The thermal limits specified under (1), above, were exceeded and a j
visual inspection of the protected component or cables revealed no signs i
The 163 *C [325 "F1 temperature condition specified in GL 86-10 was 2
established by allowing the internal temperature to rise 139 *C [250 *F] above i
1 ambient laboratory air temperature which was assumed to be 24 *C [75 *F] during the fire test.
When the temperature criterion is exceeded, component operability at the 3
temperature conditions experienced by the component during the fire test must be assessed.
That is, the fire endurance test results that are judged acceptable on the basis of a visual inspection of certain components may not be applied to other components without a specific evaluation.
j i
j Generic Letter 86-10, Supp. 1 September XX, 1993 I
of degraded conditions' from the thermal effects of the fire exposure; and (3)
The fire barrier system remained intact during the fire exposure and hose stream tests without developing any openings through which the protected component, raceway, or cables are visible.
For raceway fire barrier systems, the staff adopted the hose Arpam testing methodology specified in NUREG-0800, " Standard Review Plan (SRP) for the Review of afety Analysis Reports for Nuclear Power Plants," Section 9.5.1, "Guidelint > for Fire Protection for Nuclear Power Plants," Revision 2, July 1981, Position 5.a.
This SRP position established the acceptability of using the fog nozzle method for hose stream testing of fire barrier penetration seals.
The fog nozzle hose stream method is an acceptable option for tests of the entire raceway fire barrier system under the new staff position.
The review guidance provided in Enclosure A clarifies that, if cables show signs of thermal degradation during the fire test, the licensee can submit to the staff for review a deviation based on a demonstration of the functionality of the thermally degraded cables and provides specific guidance for demonstrating cable functionality, including subjecting the cables to megger and high-potential tests.
The results of these tests can be used to determine the insulation-resistance characteristics of the thermally damaged cable and to determine if the cable insulation would have been sufficient to maintain circuit functionality during and after the fire exposure.
IMPLEMENTATION This section describes how the NRC plans to use the review guidance contained in Enclosure A.
After this supplement to GL 86-10 is issued, except in those cases in which an applicant or licensee has proposed an acceptable alternative fire endurance test method and acceptance criteria that demonstrate an-equivalent level of fire protection, the NRC will use the methods and the criteria specified in the enclosed review guidance to (1) evaluate fire endu.mqce testing programs proposed by licensees or applicants in the future for demonstrating compliance with pertinent NRC fire protection rules and regulations and (2) review the adequacy of the fire barrier systems proposed in the future by applicants or licensees.
ACTIONS RE0VESTQ None.
" Examples of thermal degradation of cable jacket and insulation materials swollen, split, cracked, blistered, melted, or discolored jacket; exposed are:
shield; exposed, degraded, or discolored conductor insulation; and exposed copper conductor.
e s
Generic Letter 86-10, Supp. 1 September XX, 1993 REPORTING RE0VIREMENTS None.
BACKFIT DISCUSSION The guidance transmitted by this generic letter supplement wilMe used by the staff for review and evaluation of the adequacy of fire barrier systems and fire endurance tests that may be proposed in the future to satisfy NRC fire protection rules and regulations. This guidance refines and clarifies the guidance specified in Generic Letter 86-10 for application in that future review context; specifically it (1) clarifies the applicability of the test acceptance criteria stated in GL 86-10 to raceway fire barrier systems, (2) specifies a set of fire endurance test acceptance criteria which are acceptable for demonstrating that fire barrier systems can serve the required fire-resistive function and maintain the protected safe shutdown train free of fire damage, (3) contains acceptable options for hose stream testing, and (4) specifies acceptable criteria for functionality testing of cables when a deviation would be necessary, such as if the fire barrier temperature rise criteria are exceeded and the cable sustains visible damage.
No generic or plant-specific backfitting is intended or approved at this time in connection with issuance of this review guidance.
The staff may consider the need for further generic action in that regard, if the industry guidance currently under development for addressing the pertinent fire protection issues, is substantively inconsistent with this staff review guidance; but such action would be separately justified in accordance with the criteria of 10 CFR 50.109 and existing NRC backfit procedures.
Similarly, if plant-specific backfits are proposed by the NRC staff consistent with this review guidance, the proposed backfits would be justified on a case basis in accordance with the criteria of 10 CFR 50.109 and existing NRC backfit procedures.
L If you have any questions about this matter, please contact the contact listed below or the appropriate Office of Nuclear Reactor Regulation project manager.
Sincerely, James G. Partlow Associate Director for Projects Office of Nuclear Reactor Regulation
6 7-September XX, 1993 Generic Letter 86-10, Supp. 1
Enclosures:
A.
NRC Staff Position on-Fire Endurance Test Acceptance Criteria for Fire j
i Barrier Systems Used To Separate Redundant Safe Shutdown Trains Within the Same Fire Area.
B.
Comparison of Staff Position on Fire grec Endurance Test Acceptance Criteria for Fire Barrier Systems used To Separate Redundant Safe Shutdown Trains Within the Same Fire Area to the Acceptance Criteria of GL 86-10.
C.
NRC Fire Testing Acceptance Criteria Logic Diagram.
D.
List of Recently issued Generic Letters Technical
Contact:
Patrick M. Madden, NRR (301) 504-2854 Lead Project Manager:
William M. Dean, NRR (301) 504-1321
[G:\\GL8610\\GL86105.09A]
,.w-
Enclosure A DRAFT FIRE ENDURANCE TEST ACCEPTANCE CRITERIA FOR FIRE BARRIER SYSTEMS USED TO SEPARATE REDUNDANT SAFE SHUTDOWN TRAINS WITHIN THE SAME FIRE AREA I.
BACKGROUND In 1975, the Browns Ferry Nuclear power plant experienced a seffnus electrical cable tray fire.
This fire had a significant impact on operator response to the event from a safety perspective.
The fire caused spurious instrumentation indications and affected the control of several safety systems.
As a result of this fire, the NRC issued the following fire protection guidelines and regulations concerning fire protection programs at nuclear power plants:
May 1, 1976 Branch Technical Position (APCSB) 9.5-1, " Fire Protection Program."
February 24, 1977 Appendix A to Branch Technical Position APCSB 9.5-1, " Guidelines for Fire Protection for Nuclear Power Plants Docketed Prior to July 1, 1976."
February 19, 1981 10 CFR 50.48, " Fire Protection."
February 19, 1981 Appendix R to 10 CFR 50, " Fire Protection Program for Nuclear Power Facilities Operating Prior to January 1979."
July 1981 NUREG-0800, Standard Review Plan (SRP), 9.5.1,
" Fire Protection for Nuclear Power Plants."
in addition to the above fire protection guidance and regulations, the NRC, in an effort to clarify its fire protection requirements to the industry, issued-Generic Letter (GL) 81-12, " Fire Protection Rule (45 FR 76602, November 19, 1980)," February 20, 1981; GL 83-33, "NRC Position on Certain Requirements of Appendix R to 10 CFR 50," October 19, 1983; and GL 86-10
" Implementation of Fire Protection Requirements," April 24, 1986. GL 86-10, which took precedence over previous staff guidance, provided staff interpretations to Appendix R and answers to industry questions relating to the implementation of Appendix R.
The NRC, in an effort to give the licensees more flexibility to make changes to their plant specific fire protection program, issued GL 88-12, " Removal of Fire Protection Requirements From Technical Specifications." Through the implementation and the adoption of a standard license condition, a licensee can make changes which do not adversely affect plant ability to achieve and maintain post-fire safe shutdown to their j
fire protection program in accordance with 10 CFR 50.59, i
The aforementioned NRC documents provided the industry with NRC staff guidance concerning fire barriers separating plant fire areas, including the fire resistance (endurance) ratings for these barriers and the qualification testing that establishes their fire resistance ratings.
In addition, these 1
l
. documents provided guidance on combustibility of structural materials and the testing required to demonstrate low flame spread properties.
The following sections of this document provide the objective for providing i
safe shutdown related fire barriers in nuclear power plants, definition of fire protection terms related to fire barriers, and the NRC fire endurance testing acceptance criteria for fire barriers used to separate safe shutdown functions within the same fire area.
II.
OBJECTIVE OF FIRE BARRIERS USED TO SEPARATE SAFE SHUTDOWLQFCTIONS WITHIN THE SAME FIRE AREA Fire rated barriers are used in nuclear power plants to provide fire area separation between redundant safety related components and safe shutdown functions. They provide fire resistance protection, as required by Appendix R', to one safe shutdown train in those fire areas which contain both trains.
The objective of the safe shutdown related Appendix R fire barrier is to ensure that a safe shutdown train is conservatively protected from fire-related thermal damage. The necessity for these fire barriers has been verified by multiple probabalistic risk assessments (PRAs).
These PRAs indicate, even with these fire barriers installed, fires provide a major contribution to core melt probabilities.
It is the position of the NRC that fire endurance ratings of building construction and materials are demonstrated by testing fire barrier assemblies in accordance with the provisions of the applicable sections of NFPA 251,
" Standard Methods of Fira Tests of Building Construction and Materials," and ASTM E-119, " Fire Test of Building Construction and Materials." Assemblies which pass specified acceptance criteria (e.g., standard time-temperature fire endurance exposure, unexposed side temperature rise, and hose stream impingement) are considered to have a specific fire resistance rating. to GL 86-10, Interpretations of Appendix R, provided additional guidance with respect to the term " free from fire damage."
Interpretation 3,
" Fire Damage," states, "In promulgating Appendix R, the Commission has provided methods acceptable for assuring that necessary structures, systems, and components are free from fire damage (see Section III.G.2a, b, and c),
that is, the structure, system or component under consideration is capable of performing its intended function during and after the postulated fire, as needed."
GL 86-10, Response 3.2.1, also stated that, "The resulting 325 "F cold side temperature criterion is used for cable tray wraps because they perform a fire barrier function to preserve the cables free from fire damage.
It is clear that cable that becins to dearade at 450 *F is free from fire damage at 325 "F."
(Emphasis added.)
In addition, the staff's response stated that, "for newly identified conduit and cable trays requiring such wrapping new materials which meet the 325 'F criterion should be used, or justification For advanced reactor designs, redundant safe shutdown functions are 1
required to be located in separate 3-hour fire areas. - -.
4 should be provided for the use of material which does not meet the 325 *F criterion.
This may be based on an analysis demonstrating that the maximum recorded temperature is sufficient 1v below the cable insulation ignition temperature."
(Emphasis added.)
The basic premise of the NRC fire resistane.e criteria is that fire barriers which do not exceed 163 *C [325 'F] cold ',ide temperature and pass the hose stream test provide adequate assurance that the shutdown capability is protected without further analyses.
If the temperature criteria is exceeded, sufficient additional information is needed to perform an engiJiygring evaluation to demonstrate that the shutdown capability is protected.
III. DEFINITIONS In order to support the understanding of the technical terms used throughout this document, the following definitions are provided.
Combustible Material - Material that does not meet the definition of non-comoustible.
Fire Barrier - Those components of construction (walls, floors and their supports), including beams, joists, columns, penetration seals or closures, fire doors, and fire dampers that are rated by approving laboratories in hours of resistance to fire and are used to prevent the spread of fire.
Raceway Fire Barrier - Non-load bearing partition type envelope system installed arour.o electrical components and cabling that are rated by approving laboratories in hours of resistance to fire and are used to maintain safe shutdown functions free from fire damage.
Fire Resistance Ratina - The time that materials of a test assembly have withstood a standard ASTM E-119 fire exposure and have sucessfully met the established test acceptance criteria (Fire Barrier Testing Acceptance Criteria refer to Sections IV, V and VI).
Noncomoustible Material - (a) Material which in the form in which it is used and under the conditions anticipated, will not ignite, burn, support combustion, or release flammable vapors when subjected to fire or heat; (b)
Material having a structural base of noncombustible material, with a surfacing not over 1/8-inch thick that has a flame spread rating of not higher than 50 when measured using ASTM E-84 Test " Surface Burning Characteristics of Building Materials."
(Note - There is an exception to this definition as defined by BTP Appendix A, Position D. 1. d.
This position allows the use of combustible interior finishes when listed by a nationally recognized testing laboratory, such as Factory Mutual or Underwriters Laboratories, Inc. for a flame spread, smoke and fuel contribution of 25 or less in its use t
configuration.)
'l IV.
FIRE ENDURANCE TESTING ACCEPTANCE CRITERIA FOR FIRE BARRIER WALLS, FLOORS,'AND CEILINGS USED TO SEPARATE SAFE SHUTDOWN FUNCTIONS WITHIN THE SAME FIRE AREA To demonstrate the. adequacy of fire barrier walls, floors, ceilings, and enclosures, barrier designs should be verified by fire endurance testing. NRC fire protection guidance refers to the guidance of NFPA 251 and ASTM E-119 as acceptable test methods for demonstrating fire endurance performance.
w The following are the fire endurance testing acceptance criteria for the subject fire barriers:
The fire barrier design has withstood the fire endurance test without the passage of flame or the ignition of cotton waste on the unexposed side for a period of time equivalent to the fire resistance rating required of the barrier; The temperature levels recorded on the unexposed side of the fire barrier are analyzed and demonstrable that the maximum temperature does not exceed 139 *C [250 'F] above ambient; and The fire barrier remains intact and does not allow projection of water beyond the unexposed surface during the hose stream test. (For acceptable hose stream test methods and time of application - See Section VII.)
If the above criteria are met for fire barrier walls, floors, and ceilings separating safe shutdown functions within the same fire area, the barrier is considered to be acceptable.
NRC fire protection guidance also ensures that door and ventilation openings 7
and penetrations are properly protected. The guidance requires that these openings be protected with fire doors and fire dampers which have been fire tested and listed by a nationally recognized testing laboratory (e.g.,
Underwriters Laboratories or Factory Mutual).
In addition, the construction and installation techniques for door and ventilation openings and other penetrations through these fire barriers should be appropriately qualified by fire resistive testing.
The guidance of NFPA 251 and ASTM E-Il9 should be consulted with regard to construction, materials, workmanship, and details such as dimensions of parts, and the size of the specimen (s) to be tested.
In addition, NFPA 251 and ASTM E-119 sFoulu be consulted with regard to the placement of thermocouples on the specimen.
V.
ELECTRICAL RACEWAY AND COMPONENT FIRE BARRIER SYSTEMS FOR SEPARATING SAFE SHUTDOWN FUNCTIONS WITHIN THE SAME FIRE AREA The NRC provided guidance in Appendix A to Branch Technical Position 9 5-1, Position 0.3.(d), for cable tray fire barriers.
This fire protection guidance i
states that the design of fire barriers for horizontal and vertical cable trays should, as a minimum, meet the requirements of ASTM E-119, " Fire Test of Building Construction and Materials," including hose stream test. On November 19, 1980, the NRC issued Appendix R to 10 CFR Part 50.
The technical basis for Section III.M " Fire Barrier Penetration Seal Qualification," states that " Fire barriers are ' rated' for fire resistance by being exposed to a
' standard test fire.'
This standard test fire is defined by the American Society of Testing and Materials in ASTM E-119."
In addition, this technical basis stated that "If specific plant conditions preclude the installation of a 3-hour fire barrier to separate the redundant trains, a 1-hourgy re barrier and automatic fire suppression and detection system for each redundant train will be considered the equivalent of a 3-hour barrier."
In 1984 Appendix R workshops held with industry, and later in GL 86-10, the staff provided guidance related to fire barrier designs for raceways.
In, Question and Answers, to this GL, Question 3.2.1., " Acceptance Criteria," the staff provided guidance on the cold side temperature for fire barrier cable tray wraps.
In response to this question the staff stated that the acceptance criteria contained in Chapter 7 of NFPA 251, " Standard Methods of Fire Tests of Building Construction and Materials," pertaining to non-bearing fire barriers was applicable to cable tray fire barrier wraps.
Chapter 5 of NFPA 251 explains the conduct of the fire test.
The following is the NFPA 251 acceptance criteria:
The wall or partition shall have withstood the fire endurance test without the passage of flame or gases hot enough to ignite cotton waste, for a period equal to that for which classification is desired; The wall or partition shall have withstood the fire and hose stream test ac specified in Chapter 5, without passage of flame, or gases hot enough to ignite cotton waste, or of the hose stream.
The assembly shall be considered to have failed the hose stream test if an opening develops and permits projection of water from the stream beyond the unexposed surface during the hose stream test; and Transmission of heat through the wall or partition during the fire endurance test sb ' not have been such as to raise the temperature on its unexposed face more than 139 *C [250 *F] above its initial temperature.
The staff considers the fire endurance qualification test to be successful if the following conditions are met:
i The internai temperature of the fire barrier system, as measured on the exterior surface of the raceway or compongnt, did not exceed i
139 *C {250 *F) above its initial temperature ; or (Staff Guidance: NFPA 251/ ASTM-E119 allows this temperature to be determined by averaging thermocouple temperature readings.
For the purposes of this criterion, thermocouple averaging can be used provided similar series of thermocouples (e.g., cable tray side rail) are averaged together to determine temperature performance of acceptancearealsoplacedonthetemperaturesmeasur'pitionsof the raceway fire barrier system.
In addition, the caed'by a single thermocouple. Under the conditions of acceptance, if any single thermocouple exceeds 30 percent of the maximum allowable temperature rise (i.e., 139 *C + 42 *C = 181 *K (250 *F + 75 'F - 325 *F] the test is considered to have exceeded the criteria temperature limit.)
Where the above thermal limits are exceeded, a visual inspection of the cables is required. Cables when inspected shall not show 3
signs of degraded conditions' resulting from the thermal affects of the fire exposure; and (Staff Guidance: For those cases where signs of thermal degradation to the cables is present, it is considered that the fire barrier did not perform its intended fire resistive function.
For those barriers which are not capable of performing their intended function, a deviation based on demonstrating that the functionality of thermally degraded cables was maintained and that these cables would have adequately performed their intended function during and after a postulated fire exposure may be granted. Attachment I to this proposed position provides a suggested methodology for demonstrating the functionality of safe shutdown cabling during and after a fire test exposure.)
The 163 C [325 F] temperature condition was established by allowing the internal temperature on the raceway to rise 139 *C (250 *F) above ambient laboratory air temperature, assumed to be 24 *C (75 F), during the fire test.
For components, when the temperature criteria is exceeded, an 3
assessment of component operability at the temperature conditions which would be experienced by the component during the fire test is required that is, raceway fire endurance tests which are judged acceptable on the basis of a visual inspection of certain components may not be applied to other components without a specific evaluation.
' Examples of thermal cable degradation are: Jacket swelling, splitting, cracking, blistered melted, or discoloration; shield exposed; conductor j
insulation exposed, degraded, or discolored; bare copper conductor exposed.
I The raceway fire barrier system shall have remained intact during the fire exposure and water hose stream test without developing any openings through which the electrical conductor or raceway _is visible.
Section VII identifies acceptable hose stream test methods and the time of application.
l The test specimen shall be representative of the construction for which the fire rating is desired, as to materials, workmanship, and details such as dimensions of parts, and shall be built under representative conditions.
Raceway fire barrier systems being subjected to qualification 4, ipa endurance testing should be representative of the end use.
For example, if it is intended to install a cable tray fire barrier system in the plant without protecting the cable tray supports, then the test program should duplicate these field conditions.
In addition, the fire testing program should encompass the raceway sizes and the various configurations for those fire barrier systems installed in the plant.
It should be noted that several test specimens will be required in order to qualify various sizes of horizontal and vertical runs of cable trays and conduits, junction boxes and pull boxes, etc.
The raceway design used for testing should be constructed with materials and configurations representative of in plant conditions (e.g., mass associated with typical steel conduit, steel cable trays).
Measuring cable temperatures is not considered a reliable means for determining excessive temperature conditions which may occur at any point along the length of the cable during the fire test.
In lieu of measuring the unexposed surface temperature of the fire barrier test specimen, methods which will adequately measure the surface temperature of the raceway (e.g., exterior of the conduit, side rails of cable trays, bottom and top of cable tray surfaces, junction box external surfaces) can be considered as equivalent if the raceway components used to construct the fire test specimen represent plant specific components and configurations. The metal surfaces of the raceway, under fire test conditions, exhibit good thermal conductivity properties. Temperatures measured on these surfaces provide a conservative indication of the actual temperature rise within the fire barrier system.
ANI criteria for testing fire barriers recommends the cable temperatures be monitored by thermocouples.
Industry considers this the proper location for determining the temperature rise within the raceway fire barrier system.
Since cable jackets have a low thermal conductivity, the actual local temperatures of the cable jackets, indications of barrier failure, and internal fire barrier temperature rise conditions during the fire exposure are masked.
Monitoring cable temperatures can give indications of low internal fire barrier temperature conditions during the fire endurance test. Using this temperature monitoring approach, cable damage can occur without indication of excessive temperatures on the cables.
This linked with no loss of circuit integrity would give indications of a successful test. The staff considers monitoring the cable temperature as the primary means of determining barrier performance to be nonconservative. As discussed above, temperatures monitored on the exterior surface of the raceway provide a more representative indication of fire barrier performance.
The following are acceptable placements of thermocouples on raceway fire l
barrier enclosures, j
measure the temperature of the conduit by placing the Conduits -
thermocouples every 6-inches on the conduit surface underneath the fire barrier material.
Cable Trays - measure temperature rise of cable tray by placing the thermocouples on the exterior surface of the tray side rails underneath the fire barrier material.
In addition to placing thermaf,ouples on the side rails, thermocouples shall be attached to two 14 gagd" bare copper conductors.
The first copper conductor will be installed on the bottom of the cable tray rungs along the entire length of the cable tray run.
The second conductor shall be installed along the outer top surface of the cables closest to the top and towards the center of the fire barrier. The bare copper wire is more responsive, than cable jackets, to temperature rise within the fire barrier enclosure.
The temperature changes measured along the bare copper conductors provide indication of joint failure or material burn through conditions.
Thermocouples shall De placed every 6-inches along the cable tray side rails and along the bare copper conductors.
In addition, thermocouples shall be placed every 12-inches on the surf ace of the outer cables nearest to the raceway and on the surface of the cables nearest to the underside of the top of the fire barrier.
Temperature conditions on the raceway during the fire test will be determined by averaging the temperatures measured by the thermocouples.
In determining the raceway temperature conditions, the thermocouples measuring similar fire barrier areas of performance shall be averaged together and the basis of acceptance will be bas, on these individual averages.
The following method of averaging shall be ollowed:
Conduits - The thermocouples applied to the outside metal surface of the conduit will be averaged together.
Cable Trays - The thermocouples on each cable tray side rail shall be averaged separately.
For example, thermocouples placed on one side rail will be averaged separately from the other side rail.
In addition, the temperature conditions measured by thermocouples on the bare copper conductors shall be averaged separately.
Cables - The thermocouples used to measure individual cable temperatures will be used for engineering purposes and shall not be used for evaluating the performance of the fire barrier system.
For each thermocouple group, the averages shall not exceed 139 "C [250 *F)In above the initial temperature at the onset of the fire endurance test.
addition, the temperature of each individual thermocouple will be evaluated.
Individual thermocouple conditions shall not exceed the 139 *C [250 "F]
temperature rise by more than 30 percent. i
VI.
HOSE STREAM TESTIflG tlFPA 251 and ASTM E-119 allow some flexibility in hose stream testing. The standards allow the hose stream test to be performed on a duplicate test specimen subjected to a fire endurance test for a period caual to one-half of that indicated as the fire resistance rating, but not for more than I hour (e.g., 30 minute fire exposure to qualify a 1-hour fire rated barrier).
For safe shutdown related fire barrier systems, the staff finds the hose stream application specified by the NFPA 251 acceptable, t1FPA.gls requires the stream of water to be delivered through a 6.4 cm [2\\-inch]' hose discharging through a standard 2.9 cm (1%-inch] playpipe nozzle onto the test specimen after the fire exposure test.
The stream is applied with the nozzle orifice positioned 6.1 meters [20 feet) away from the center of the test specimen at a pressure of 207 kPa [30 psi gauge].
The application of the stream is to all exposed parts of the specimen for a minimum duration of 1 minute for a 1-hour barrier and 2 minutes for a 3-hour barrier.
As an alternate, the application of the hose stream test on the test specimen can be performed immediately after the completion of the full fire endurance test period.
If this method is used to satisfy the hose stream testing criteria, the following hose stream applications are considered acceptable:
The stream applied at random to all exposed surfaces of the test specimen through a 6.4 cm [2%-inch] national standard playpipe with a 2.9 cm [1%-inch] orifice at a pressure of 207 kPa [30 psi] at a distance of 6.1 meters [20 feet] from the specimen (duration of the hose stream application - 1 minute for a 1-hour barrn.r and 2 minutes for a 3-hour barrier); or The stream applied at random to all exposed surfaces of the test specimen through a 8.3 cm [1 -inch] fog nozzle set at a discharge angle of 30 degrees with a nozzle pressure of 517 kPa [75 ps., and a minimum discharge of 284 1pm (75 gpm] with the tip of the nozzle at a maximum of 1.5 meters (5 feet] from the test specimen (duration of the hose stream application - 5 minutes for both 1-hour and 3-hour barriers); or The stream applied at random to all exposed surfaces of the test specimen through 8.3 cm (1 -inch] fog nozzle set at a discharge angle of 15 degrees with a nozzle pressure of 517 kPa [75 psi] and a minimum discharge of 284 1pm (75 gpm] with the tip of the nozzle at a maximum of 3 meters (10 feet] from the test specimen (duration of the hose stream application - 5 minutes for both 1-hour and t
3-hour barriers).
VII.
FIRE BARRIER C0t480STIBILITY f4RC fire protection guidelines and requirements establish the need for each nuclear power plant to perform a plant-specific fire hazard analysis.
The fire hazard analysis shall consider the potential for in-situ and transient i
fire hazards and combustibles.
With respect to building materials (e.g.,.
4 cable insulation and jackets, plastics, thermal insulation, fire barrier materials), the combustibility, ease of ignition, and flame spread over the surface of a material shall be considered by the fire hazards analysis.
One method of determining combustibility is by subjecting a sample of the fire barrier material to a small scale vertical tube furnace as described by ASTM E-136.
The flashover ignition temperature, as determined by ASTM-D1929, and the flame spread characteristics, as determined by ASTM E-84, of the fire barrier material shall be evaluated. The potential heat release of the material shall also be determined and factored into the fire hazards analysis.
Theheatreleaseofthematerialcanbedeterminedbytesting(p}he
Fire barrier materials used as radiant energy heat shields inside containment and used to achieve a combustible free zone are required to be noncombustible as defined in Section III.
VIII. REFERENCES Nuclear Reaulatory Commission 1.
May 1, 1976 Branch Technical Position (APCSB) 9.5-1, " Fire Protection Program."
2.
February 24, 1977 Appendix A to the Branch Technical Position APCSB 9.5-1, " Guidelines for Fire Protection for Nuclear Power Plants Docketed Prior to July 1, 1976."
3.
February 19, 1981 10 CFR 50.48, " Fire protection."
4.
February 19, 1981 Appendix R to 10 CFR 50, " Fire Protection for Nuclear Power Plants."
5.
February 20, 1981
" Staff Position - Safe Shutdown Capability,"
6.
July 1981 NUREG - 0800, Standard Review Plan (SRP), 9.5.1,
" Fire Protection for Nuclear Power Plants."
7.
October 19, 1983 "NRC Positions on Certain Requirements of Appendix R to 10 CFR 50," (Generic Letter 83-33).
8.
April 24, 1986
" Implementation of Fire Protection Requirements," (Generic Letter 86-10).
American Society for Testina and Materials (ASTM) 1.
ASTM E-84 Test " Surface Burning Characteristics of Building Materials."
2.
ASTM E-119, " Fire Test of Building Construction and Materials."
3.
ASTM E-136, " Behavior of Materials in a Vertical Tube furnace at 750*C.".
1 4.
ASTM D-1929, " Test Method for Ignition Properties of Plastics."
5.
ASTM D-3286, " Test Method for Gross Calorific Value of Solid Fuel by the Isothermal-Jacket Bomb Calorimeter."
American Nuclear Insurers ( ANil 1.
July 1979, ANI Information Bulletin No. 5 (79) test criteria for " Fire Endurance Protective Envelope Systems for Class lE Electrical Circuits."
National Fire Protection Association (NFPA) 1.
NFPA 251, " Standard Methods of Fire Tests of Building Construction and Materi al s. "
2.
NFPA 259, " Standard Test Method for Potential Heat of Building Mate ri al s. "
5 i
i ATTACHMENT 1 ACCEPTABLE METHODS FOR DEMONSTRATING FUNCTIONALITY OF CABLES PROTECTED BY RACEWAY FIRE BARRIER SYSTEMS DURING AND AFTER FIRE ENDURANCE TEST EXPOSURE a.
INTRODUCTION
-mm The NRC considers fire barrier systems that meet the acceptance criteria adequate under NRC fire protection regulations.
The licensee, where the criteria are not met, can submit an engineering analysis to the staff that clearly demonstrates the functionality of the protected cables.
This engineering analysis should consider the cable insulation type, actual voltage and current conditions, cable function, and thermal i
affects on the cable and its ability to function.
This evaluation shall l
also consider cable operating temperatures within the fire barrier at the onset of the fire exposure.
b.
CABLE CIRCUIT INTEGRITY TESTING ANI Criteria in 1981, American Nuclear Insurers (ANI) developed a fire endurance test criteria for raceway fire barrier systems.
This criteria, " Fire Endurance Protective Envelope Systems for Class IE~ Electrical Circuits,"
specifies a circuit integrity test. The intent of this test was to identify the onset of fire damage to the cables within the raceway fire barrier test specimen during the fire endurance test period.
The circuit integrity test voltage is 8 to 10 volts DC; therefore the loss of circuit integrity under these voltage conditions may only occur as a result of a dead short or open circuit.
During actual fire testing conditions of raceway fire barrier systems i
thermal damage to the cables has resulted. This thermal damage has led to cable jacket and insulation degradation without the loss of circuit j
integrity as monitored using Afl! criteria.
Since cable voltages used for ANI circuit integrity testing do not replicate cable operating i
voltages, loss of cable insulation conditions can exist during the fire test without a dead short occurring.
It is expected that if the cables were at rated power and current a fault would propagate.
Therefore, the i
use of ANI circuit integrity monitoring during the fire endurance test 1s not considered a valid method for demonstrating that the protected shutdown circuits are capable of performing their required function during and after the test fire exposure.
c.
CABLE INSULATION TESTING The two principal materials used as cable insulation and cable jackets by the nuclear industry are thermoplastics and thermosetting polymeric materials.
A thermoplastic material can be softened and resoftened by heating and reheating.
Conversely, thermosetting cable insulation i
materials cure by chemical reaction and do not soften when heated.
Under excessive heating thermosetting insulation becomes stiff and brittle. Electrical faults may be caused by softening and flowing of thermoplastic insulating materials at temperatures as low as 149 *C
[300 *F).
Thermosetting electrical conductor insulation materials usually retain their electrical properties under short-term exposures to temperatures as high as 260 *C [500 *F].
Insulation resistance (Megger) testing provides an indication of the condition of the cable insulation resistance, whereas the high potential '(Hi-Pot) test provides assurance that the cable has sufficient dielectric strength to withstand the applied rated voltage.
A cable insulation failure usualbresults from two breakdown modes:
one failure mode is excessive dielectric loss which is due to low insulation resistance, and the other failure mode is overpotential stress which is due to loss of dielectric strength of the insulation material.
If megger tests are not performed at frequent intervals during the fire exposure, indications of insulation damage may go undetected.
Insulation, when removed from elevated temperatures will reset. Megger testing of insulated cables after the fire endurance test and after the cable has sufficiently cooled may not detect degradation in the insulation resistance.
Therefore, wet or dry megger of cables after a fire exposure does not provide reasonable assurance that the cables would have functioned as intended during the fire exposure.
To provide reasonable assurance that the cables would have functioned during and after the fire exposure, megger tests need to be performed before the fire test, at multiple time intervals during the fire exposure (i.e., every 20 minutes during the 1-hour fire test and every hour during the 3-hour fire test) for instrumentation cables only, and after the fire endurance test to assess the cable insulation resistance levels. This testing will assure that the cables will maintain sufficient insulation resistance levels necessary for proper operation of instruments.
The megger tests (pre-fire. during the fire [if performed], and immediately after the fire test conditions) should be done conductor-to-conductor for multi-conductor and conductor-to-ground for all cables.
The minimum acceptable insulation resistance (IR) value, using the test voltage values as shown in the table below, is determined by using the following expression:
IR (Mega-chms) 1 LL(1 Meaa-ohm per KV) + 1 1
- 1000 (ft) 1 Length (ft)
Additionally, in determining the insulation resistance levels required for nuclear instrumentation cables, an assessment of the minimum insulation resistance value (e.g., one mega-ohm) and its potential impact on the functionality of these cables shall be evaluated.
In addition, an AC or DC high potential (Hi-Pot) test for power cables greater than 1000 volts shall be performed after the post-fire megger tests to assess the dielectric strength.
This test provides assurance that the cable will withstand the applied voltage during and after a fire. The high potential test shall be performed for a 5 minute duration at 60 percent of either 80 volts / mil ac or 240 volts / mil dc (e.g., 125 mil conductor insulation thickness x 240 volts dc x 0.6
-18,000 volts dc ).
The table below summarizes the megger and Hi-Pot test voltages which, when applied to power, control and instrumentation cables, would constitute an acceptable cable functionality test.
.w OPERATING MEGGER TEST HIGH P0TENTIAL TYPE VOLTAGE 1_
VOLTAGE TEST VOLTAGE POWER 2 1000 vac 2500 ydc 60% x 80 V/ mil (ac) 60% x 240 V/ mil (dc)
POWER
< 1000 vac 1500 vdc #
NONE INSTRUMENT s 250 vdc 500 vdc NONE AND
$ 120 vac CONTROL
- A megger test voltage of 1000 vdc will be acceptable provided a Hi-Pot test is performed after the megger test for power cables rated at less than 1000 vac.
d.
CABLE THERMAL EXPOSURE THRESHOLD The following is an acceptable analysis method for evaluating the cable functionality.
This analysis is based on determining whether a specific insulation material will maintain the electrical integrity and operability of protected cables within a raceway fire barrier system during and after an external fire exposure. In order to determine cable functionality, it is necessary to consider the operating cable temperatures within the fire barrier system at the onset of the fire exposure and the thermal exposure threshold (TET) temperature of the cable.
For example, if the TET of a specific thermoplastic cable insulation (Brand X) is 149 *C
[300 *F) and the normal operating temperature within the fire barrier system is 66 *C [150 *F], then the maximum temperature rise within the fire barrier system shall not exceed 83 *C [150 *F] during exposure to an external fire of a duration equal to the required fire resistance t
rating of the barrier.
For this example the TET limit for Brand X cable is 83 *C [150 *F) above the cable operating temperatures within the fire barrier system at the onset of the external fire exposure. The cable TET limits in conjunction with a post test visual cable inspection and the Hi-Pot test described above should readily :iemonstrate the functionality of the cable circuit during and after a fire.
The cable normal operating temperature can be determined by loading cable specimens installed within a thermal barrier system in the test configuration with rated voltage and current. The TET temperature limits for most cable insulation may be obtained from the manufacturer's published data which is given as the short-circuit rating limit. With the known TET and normal operating temperature for each thermal barrier system configuration, the maximum temperature rise limit within a fire barrier system may then be determined.
- ys:t
Enclosure B COMPARISON OF PROPOSED FIRE ENDURANCE TESTING CRITERIA FOR FIRE BARRIER SYSTEMS USED TO SEPARATE SAFE SHUTDOWN FUNCTIONS WITHIN THE SAME FIRE AREA PROPOSED CRITERIA GL 86-10 CRITERIA RATIONALE FOR CHAN3E Temperature, as Temperature, as Temperature - Difficult measured on the measured on the to measur M uniform external surface of the unexposed side of the temperature on the fire Raceway, should not fire barrier material, barrier material exceed 163 "C [325 "F]
should not exceed surface. Raceway temps (Note 1).
163 *C [325 *F].
provide good indication of internal temp-rise
! This temperature is and potential barrier
! determined by averaging failure locations temoerature readings of during the test.
similar series of thermocouple (e.g.,
cable tray side rail).
(Note 2)
Barrier Condition -
Barrier Condition - The Barrier Condition -
Raceway fire barrier barrier shall have Cotton waste has not shall remain intact. No withstood the fire and been used in raceway visible signs of hose stream test fire barrier testing as 1
conductor or raceway without the passage of an indicator of barrier after fire and hose flame or hot gasses hot failure. Visual stream test.
enough to ignite cotton inspection process waste.
provides a better indication of barrier condition after the fire and hose stream j
test.
Hose Stream testing is Hose Stream testing is Hose Stream - To required. (solid stream required. (solid stream reflect alternative J
test as required by test as required by methods found NFPA 251 on second test NFPA 251) acceptable (Note 3).
specimen after being The use of a fog nozzle subjected to a fire for the hose stream at the end of a full exposure of 1/2 duration (Note 4) or a duration of the fire fog stream after the test provides a good full fire exposure.)
method for testing erosion and cooling effects.
L_
-i PROPOSED CRITERIA GL 86-10 CRITERIA RATIONALE FOR CHANGE Cable condition - If Cable condition - No Cable condition - The the above temperature consideration given to objective of these fire limit is exceeded, the determining the barriers is.to assure cable condition must be material condition of that thermal damage to visually inspected.
the cable, protected safe shutdown Cables when inspected cables or components should show no signs of does not occur.
i
W degraded conditions resulting from the thernial affects of the fire exposure.
GUIDANCE FOR ENGINEERING EVALUATIONS JUSTIFYING DEVIATIONS FROM THE FIRE BARRIER ACCEPTANCE CRITERIA Functionality is needed Functionality - No Functionality is to be demonstrated if guidance provided. Up considered to be a any of the preceding to licensees to deviation from the criteria are exceeded demonstrate by acceptance criteria and (Note 5).
engineering analysis, must be justified on a Analysis kept on file case-by-case basis i
Methods includes megger for NRC review.
which includes an j
testing of cables Engineering analysis assessment of cable i
before, during generally based on jacket material.
(instrumentation cables internal temperature only) and immediately below the ignition after the fire exposure temperature. No and subjecting power consideration given cables which have cable operating voltage ratings 21000 temperatures within the vac to a Hi-Pot test barrier at the onset of (60%) immediately after the fire exposure.
the fire exposure.
Demonstration of functionality shall also consider operating temperature of the cables inside the fire barrier at the onset of the fire exoosure.
Combustibility of a fire barrier system should be demonstrated by testing to ASTM-E136.
Certain applications of fire barriers materials (e.g., radiant energy heat shield inside containment) are required by Appendix R to non-combustible.
Note 1 - The 163 *C [325 'F] temperature condition was established by allowing the internal temperature on the raceway surface to rise a maximum of 139 *C
[250 *F] above ambient laboratory air temperature, assumed to be 24 *C
[75 *F], during the fire test.
I
=
Note 2 - NFPA 251/ ASTM-E119 allows the temperature condition to be determined by averaging the thermocouple readings. The conditions of acceptance are also placed on the temperature conditions measured by a single thermocouple.
Under 1
these conditions of acceptance, if any single thermocouple exceeds 30 percent above the maximum allowable temperature rise (i.e., max. allowable 139 *C +
42 *C = 181 *C [250 *F + 75 *F - 325 *F)) the test is considered to have exceeded the criteria temperature limit.
Note 3 - SRP 9.5.1 recognizes the use of a fog stream as an alternative hose stream testing method for qualifying fire barrier penetration 4 gals.
i Note 4 - The application of this hose stream test method provides assurance that the fire barrier system has sufficient structural integrity to resist minor fire related barrier breaches caused by falling objects.
Note 5 - A fire barrier system which does not meet the performance conditions of the fire endurance acceptance criteria is considered not to be a rated fire barrier.
For those performance conditions (i.e., high raceway temperature, barrier openings, water projection, cable damage) which deviate from this acceptance criteria, an engineering analysis which clearly demonstrates the functionality of the protected component (s) or cable (s) can be submitted to the staff for review. These deviations will be evaluated by the staff on a case-by-case basis.
l 4
NRC FIRE TESTING ACCEPTANCE CRITERIA LOGIC DIAGRAM FIRE TEST HOSE BARRIER l
Asm-EM 9 S REAM CONDITION ;
l NOT OK l
l OK > 250 F RISE OK VISUAL INSP CABLES NOT OK 4
FIRE BARRIER DEVIATIQN CONDlTlQN NATEQ FIRE BARRIER EJ i
g; R
ENGINEE alNG EVALUAT ON DEIViONSTildYE FUNCTf0NA'LlTY y3C REVlEW y
l
DiC[OSURE 2 L
CRGR REVIEW PACKAGE To issue to all holders of operating licenses PROPOSED ACTION:
or construction permits for nuclear power reactors additional NRC guidance that clarifies previous staff positions on fire endurance test acceptance criteria for fire barrier systems used to separate redundant safe shutdown trains within theasame fire area.
CATEGORY:
2 FOR CONTENT OF PACKAGE SUBMITTED TO CRGR RESPONSE TO REOUIREMENTS FOR REVIEW or staff position as (i)
The proposed generic requirement it is proposed to be sent out to licensees.
Response
to Generic Letter.(GL) 92-08 The proposed supplement forwards the NRC staff position on fire (Enclosure 1) acceptance criteria for fire barrier endurance test safe shutdown trains systems used to separate redundant within the same fire area (Enclosure 2) to the licensees.
This proposed staff position clarifies the positions in GL 86-10, " Implementation of Fire Protection Requirements," April 24, 1986, on fire barrier systems used to gain compliance with Section
" Fire Protection of Safe Shutdown Capability,"
III.G, of Appendix R, " Fire Protection Program for Nuclear Power Facilities Operating Prior to January 1,
1979,"
to Title 10 of the Code of Federal Reaulations (10 CFR Part 50).
(ii)
Draft staff papers or other underlying staff documents supporting the requirements or staff positions.
Response
Section III.G of Appendix R to 10 CFR Part 50 established the requirement for the use of fire barrier systems to separate redundant safe shttdown trains within the same fire area. In addition,Section III.G of Appendix R established the 1-or 3-hour fire-resistive performance requirement for these barriers.
In GL 86-10, the NRC provided additional guidance to the industry on fire endurance testing and acceptance criteria for raceway fire barrier systems used to separate safe shutdown functions within the same fire
GL 86-10, Question 3.2.1, focused on the fire area.
endurance testing acceptance criteria established by National Fire Protection Association (NFPA) Standard 251, " Standard Methods of Fire Tests of Building Construction and Materials," Chapter 7,
" Tests of Nonbearing Wall and Partitions."
In addition, Enclosure i " Interpretations of Appendix R," to GL S6-to the 10, provided additional guidance with respect term " free of fire damage."
In this enclosure, the staff stated that the fire protection methods established by Appendix R provide an acceptable means for ensuring that necessary structures, systems, and components are free of fire damage; that is, the structure, system, or component under consideration is capable of performing its intended function during and after the postulated fire.
The staff position is a-supplements the guidance in GL 86-10.
comparison of the fire endurance test acceptance criteria in the staff position with those established by GL 86-10.
In response to Texas Utilities Electric Company's (TU Electric) Thermo-Lag fire barrier testing program for Comanche Peak Unit 2 and the failures (e.g.,
barrier burnthrough, cable thermal degradation) associated with fire barrier systems installed on conduits and cable trays, the NRC issued Bulletin 92-01, " Failure of Thermo-Lag 330 Fire Barrier System To Maintain Cabling i
in Wide Cable Trays and Small Conduits Free From Fire Damage," June 24, 1992; and Bulletin 92-01, Supplement 1, " Failure of Thermo-Lag 330 Fire Barrier System To Perform Its Specified Fire Endurance Function,"
August 28, 1992.
As a result of ongoing concerns associated with the TU Electric testing program (i.e.,
its use of American Nuclear Insurers Information Bulletin No. #5 (79), " Fire Endurance Protective Envelope Systems for Class 1E Electrical Circuits," to establish the fire resistive rating of the barriers, and the use of low voltage circuit integrity monitoring to demonstrate cable functionality) the NRC developed draft guidance on fire endurance test acceptance criteria for fire barrier systems used to separate redundant safe shutdown trains within the same fire This guidance was used to assess the area.
acceptability of TU Electric fire endurance testing acceptance criteria.
On October 29, 1992, in a letter to TU Electric, the NRC confirmed that the fire endurance and cable functionality testing acceptance criteria proposed to qualify the Comanche Peak Unit 2 Thermo-Lag fire barrier systems were acceptable. -
T m
+
. ~
4
- 1992, At a public meeting with NUMARC on November 18, the proposed. fire endurance testing acceptance criteria were discussed with industry and were appended to the
+
meeting minutes and placed in NRC's public document Attendees asked if they could provide written room.
They were told that they could submit them,
. comments.
and that the comments would be discussed with CRGR, be revised before that the proposed criteria would notat.a later date.
it was published for public comment Excerpts from the comment letters received are included in Enclosure 5.
t The staff plans to use the staff position to evaluate ongoing testing programs being conducted by the Tennessee Valley Authority (TVA) and NUMARC, and by others in the future.
The following references are provided with this review package:
(1)
Appendix R, " Fire Protection Program for Nuclear Power Facilities Operating Prior to January 1,
1979," to 10 CFR Part 50 (2)
Generic Letter 86-10, " Implementation of Fire Protection Requirements," April 24, 1986 (3)
American Society of Testing and Materials (ASTM) l Standard E119, " Standard Metnods of Fire Tests of Building Construction and Materials" (4)
National Fire Protection Association-(NFPA)
Standard 251, " Standard Methods of Fire Tests of Building Construction and Materials" (5)
American Nuclear Insurers (ANI) Information Bulletin No. 5 (79) "ANI/MAERP Standard Fire Endurance Test Method To Qualify a Protective Envelope or Class IE Electrical Circuits,"
July 1979, (6)
Letter of October 29, 1992, from NRC to TU-Electric, "Thermo-Lag Fire Barrier Testing Acceptance Criteria" The staff will provide the following additional references on request:
NRC Bulletin 92-01, " Failure of Thermo-Lag 330~
(1)
Fire Barrier System To Maintain Cabling in Wide Cable Trays and Small Conduits Free From Fire i
Damage," June 24, 1992.
(2)
NRC Bulletin 92-01, Supplement 1,
" Failure of Thermo-Lag 330 Fire Barrier System To Perform Its Specified Fire Endurance Function,"
August 28, 1992 (3) 10 CFR 50.48, " Fire Frotection" (4)
NRC Thermo-Lag Fire Barrier Designs and Installations Action Plan, July 1, 1992 (5)
Information Notice 91-47, " Failure df' Thermo-Lag Fire Barrier Material To Pass Fire Endurance Test," August 6, 1991 L
Information Notice 91-79, " Deficiencies in the (6)
Procedures for Installing Thermo-Lag Fire Barrier Materials," December 6, 1991 (7)
Information Notice 92-46, "Thermo-Lag _ Fire Barrier Material Special Review Team Findings, Current Fire Endurance Tests, and Ampacity Calculation Errors," June 23, 1992 (8)
Information Notice 92-55, " Current Fire Endurance i
Test Results for Thermo-Lag Fire Barrier Material," July 27, 1992 (9)
Generic Letter 92-08, "Thermo-Lag 330-1 Fire j
Barrier Systems," December 17, 1992 (10) Office of the Inspector General Inspection Report,
" Adequacy of NRC Staff's Acceptance and Review of Thermo-Lag 330-1 Fire Barrier Material," Case 91-04N, August 12, 1992 l
(iii)
Each proposed requirement or staff position shall contain the sponsoring office's position as to whether the proposal would increase requirements or staff
{
positions, implement existing requirements or staff positions, or would relax or reduce existing requirements or staff positions.
i
Response
The proposed NRC staff position on fire endurance test acceptance criteria clarifies existing acceptance criteria established by GL 86-10 and does not reject fire endurance test of raceway fire barrier past systems that may have been perf ormed.taa this previous criteria.
The proposed position provides an interpretation of UFPA Standard 251, Chapter 7,
" Tests of Bearing Wall and Partitions," on how this standard.-.
4 The should be applied to raceway fire barrier systems.
proposed position also incorporates the fire hose stream testing criteria for fire barrier penetration Standard Review Plan seals specified in NUREG-0800,which the staff found acceptable, (SRP) Section 9.5.1, and applies these criteria to raceway fire barrier The hose stream testing approach is not a new systems.
its imposition on the testing of criterion; however, raceway fire barrier systems can be considered a new position.
In addition, it provides licensees with guidance, which was not previously provided in of thermocoples on the test GL 86-10, on the placement specimen and the type of tests needed to verify cable functionality when the fire barrier test specimen does
- However, the specified acceptance criteria.
not meet it enhances guidance provided in GL 86-10 and is considered necessary in order to assur compliance with GDC 3, 10 CFR Section 50.48, and Appendix R to 10 CFR Part 50.
(iv)
The proposed method of implementation with the concurrence of OGC (Office of the General Counsel) on the method proposed.
Resnonse implementation will be by providing the The method of staff's position and the information on fire endurance testing acceptance criteria through the proposed OGC has reviewed the generic letter supplement.
proposed supplement and the staff position on fire endurance testing and has no legal objections to their issuance.
the Regulatory analyses generally conforming tc
'v) and NUREG/CR-directives and guidance of NUREG/BR-0058 3568.
Response
is not applicable as the issue is a compliance This backfit.
Identification of the category of reactor plants to (vi) which the generic requirement or staff position is to apply.
Response
The proposed staff position on fire endurance testing acceptance criteria is to apply to all holders of operating licenses or construction permits for commercial nuclear power reactors.
(vii)
For backfits other than compiiance or adequate protection backfits, a backfit analysis as defined in 10 CFR 50.109.
The backfit analysis shall include, for each category of reactor plants, an evaluation which demonstrates how action should be prioritized and scheduled in light of other ongoing regulatory activities.
The backfit analysis shall document for j
consideration information available concerning any of the following factors as may be appropriate and any other information relevant and material to the proposed action:
(a)
Statement of the specific objectives that the propoced action is designated to achieve; (b)
General description of the activity that would be in order to required by the licensee or applicant complete the action; i
(c)
Potential change in the risk to the public from the accidental offsite release of radioactive material;
'd)
Potential impact on radiological exposure of facility employees and other onsite workers; (e)
Installation and continuing costs associated with the action, including the cost of facility downtime or the cost of construction delay; (f)
The potential safety impact of changes in plant or operational complexity, including the relationship to proposed and existing regulatory requirements and staff positions; (9)
The estimated resource burden on the NRC associated with the proposed action and the availability of such resources; (h)
The potential impact of differences in facility type, design, or age on the relevancy and practicality of the proposed action; (i)
Whether the proposed action is interin or final, and if interim, the justification for imposing the proposed action on an interin basis; (j)
How the action should be prioritized and scheduled in light of other ongoing regulatory activities. -.
t
~
The'following information may be appropriate in' j
this regard:
The proposed priority or schedule, 1.
A summary of the current backlog of existing 2.
requirements awaiting implementation, An assessment of whether implementation of 3.
existing requirements should be deferred as a
.e result, and Any other information that may be considered f
4.
appropriate with regard to priority, schedule, or cumulative impact.
Fcr excmple,-
could implementation _be delayed pending s
public comment?
Response
This is not applicable as the issue is a compliance backfit.
(viii)
For each backfit analyzed pursuant to 10 CFR 50.109 ( a) ( 2 )
(i.e., not adequate protection backfits and not compliance backfits) the proposed office director's determination, together with the rationale i
for the determination based on the considerations'of paragraphs (i) through (vii) above, that t
is a substantial increase in the overall (a) there i
protection of public health and safety or the common defense and security to be derived from the proposal; and (b) the direct and indirect costs of implementation,'
for the facilities affected, are justified in view of this increased protection.
Resoonse This is not applicable as the issue is a compliance backfit.
(ix)
For adequate protection or compliance backfits evaluated pursuant to 10 CFR 50.109 (a) (4 )
l (a) a document evaluation consisting of:
(1) the objectives of the modification (2) the reasons for the modification
],
i
the basis for invoking the compliance or (3) adequate protection exemption.
(b)
In addition, for actions that were.immediately effective (and therefore issued without prior CRGR review as discussed in III.C) the evaluation shall' document the safety significance and appropriateness of the action taken and (if consideration of how costs' contributed applicable) to selecting the solution among various acceptable alternatives.
Response
During its review'of Thermo-Lag fire barriers,_the (a) staff found that some licensees did not follow the staff's GL 86-10 guidance on fire endurance testing acceptance criteria.
On the basis of this review, the staff concluded that the fire-resistance ratings for the Thermo-Lag fire barriers installec by the licensees were indeterminate and in some cases these fire barrier perform their specified systems as designed cannotcertain Thermo-Lag fire functions.
Therefore, barrier configurations do not meet the NRC's requirements.
The staff's identification of Thermo-Lag fire barrier s'fstems that did not adequately perform their specified fire-resistive functions is' documented ir. NRC Bulletin 92-01,
" Failure of Thermo-Lag 330 Fire Barrier System To Maintain Cabling in Wide Cable Trays and Small Conduits Free From Fire Damage," June 24, 1992, in its supplement, " Failure of Thermo-Lag 330 and Fire Barrier System To Perform Its Specified Fire Endurance Function," August 28, 1992.
In GL 92-08, the NRC identified three principal the fire endurance capability areas of concern:
)
of Thermo-Lag 330-1 barriers, the ampacity derating of cables enclosed in Thermo-Lag 330-1 barriers, and the evaluation and application of the results of tests conducted to determine the fire endurance ratings and ampacity derating factors for these barriers.
The staff position provides an acceptable fire endurance test acceptance criteria that ensures that fire barrier systems used to separate redundant safe shutdown trains within the same fire area provide the level of fire endurance intended by licensees.
fire barrier systems tested _to the Therefore, acceptance criteria established by the staff the requirements of 10 CFR position will meet" Fire Protection," and of General Design 50.48, 3, " Fire Protection," of (GDC)
Criterion
" General Design Criteria for Nuclear Appendix A, 50.
One-means of l
Power Plants," to 10 CFR Part j
complying with these requirements is to separate one safe shutdown train from its redundant train The level of fire with fire-rated barriers.
resistance. required of the barriersna hour i
or 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />, depends on the.other fire protection
'i features in the fire area.
The types of fire barriers addressed by the position are installed at most operating power either a reactor sites and are required to meet condition of a plant's operating license or the requirements of Section III.G of Appendix R to 10 The position clarifies the fire CFR Part 50.
acceptance criteria for fire endurance test barrier systems used to separate redundant safe shutdown trains within the same fire area established by GL 86-10 and provides definitive methods for determining the functionality of the cables associated with those fire barrier test specimens that, when tested, did not successfully meet the acceptance criteria established by the position.
The staff position is needed to ensure that the staff has adequare review guidance to evaluate on i
going and future industry fire barrier testing Therefore, the position establishes activities.
I fire endurance testing acceptance criteria that fire barriers when tested to these ensure that criteria will perform their fire-resistive function as specified in Appendix R and will.
provide a level of fire protection that will one train of safe shutdown functions ensure that This clarifies NRC is free of fire damage.
acceptance existing GL 86-10 fire endurance test identifies acceptable hose stream
- criteria, testing options and provides criteria for cable functionality testing when the internal fire barrier temperature rise criterion is exceeded and This position identifies cable damage is visible.
fire endurance testing acceptance criteria which will demonstrate compliance with the fire protection requirements of Section III.G of Appendix R to 10 CFR 50.
_g-I
i To provide the information' requested in GL.92-08, licensees may.have to conduct fire endurance tests
+
and cable functionality analyses.
In addition, as a result of these tests, fire barriers may have to be modified to achieve compliance.
NUMARC has agreed to coordinate an industry Thermo-Lag fire
~
barrier testing program.
This-program if conducted following the guidance of the proposed' staff position, will reduce the impact on individual licensees.
The new staff position will also be used generically by the staff'to evaluate future industry and plant-specific fire barrier testing programs.
Providing clear, definitive guidance reduces uncertainties in fire barrier testing programs.
This minimizes the potential for tests to be conducted under criteria that are not technically acceptable to the staff, thereby-reducing costs to the industry.
The additional purpose for issuing this-staff position is to ensure that future industry and licensee site-specific testing is performed under established criteria.
These criteria and fire endurance testing of barrier subsequent enhancements are necessary to eliminate the current need for fire watches.
Northeast Utilities in its response to NRC Bulletin 92-01 estimates that it will cost $1 million per year for the firewatches at its Millstone facility.
(b)
This is not applicable.
For each evaluation conducted for proposed relaxations _
(x) or decreases in current requirements or staff' positions, the proposed office director's determination, together with the rationale for the determination based on the considerations of paragraphs (i) through (vii) above, that the public health and safety and the common (a) defense and security would be adequately protected
- if the proposed reduction in requirements or positions were implemented, and saving attributed to the action would be the cost (b) substantial enough to justify taking the action.
Response
relax This is not applicable as this position does not or decrease current regulatory requirements.
9 for information under 10 CFR 50.54(f)
(xi)
For eacn request (which is not subject to exception as discussed in III.A) an evaluation that includes at least tne l
following elements
\\
i (a)
A problem statement that describes the need for the information in terms of potential safety benefit.
(b)
The licensee actions required and the cost to develop a response to the information request.
(c)
An anticipated schedule for NRC use of the information.
(d)
A statement affirming that the request does n21 1
other i
impose new requirements on the licensee, than for the requested information.
Response
This is not applicaole as no response is required.
(xii)
An assessment of how the proposed action related to the Commission's Safety Goal Policy Statement.
Resoonse The guidance from the Regulatory Analysis Steering Group (Memorandum of August 20, 1991, from C.J.
- Heltemes, Jr., to J.M. Taylor, " Commission Paper on Safety Goal Implementation") indicates that the staff need not address safety goals because the staff's.
positions and guidance in the communication are based on compliance with existing regulations and licensee commitments..
l
i i
)
CRGR PACKAGE GENERIC BACKFIT PEPORTING REOUIREMENTS FORM Please respond to all items.
to be submitted for staff approval before plant I.
Is a report restart or (for construction permit holders) before issuance of the operating license?
Response
no.
If "yes," is there need for review guidance?
Provide reason i
if review auidance is not needed.
I 1
Response
Not applicable.
If review guidance is needed, does it accompany the CRGR package?
Provide reason if guidance does not accompany i
package.
l
Response
The supplement to GL 92-08 forwards a staff position and is considered review guidance for evaluating ongoing and future licensee and industry raceway fire barrier tests.
The proposed acceptance criteria provide reasonable assurance that a fire barrier system, when tested under and successfully meeting these criteria, will be capable of performing its fire-resistive function 50.
as specified in Appendix R to 10 CFR Part This will ensure that the protected safe shutdown function will be maintained free of fire damage.
II.
Is a report to be submitted - but no affect on operation?
Response
The staff will use the proposed position as guidance to review the adequacy of future industry or licensee fire endurance testing programs.
(a)
Does the staff intend to review all submittals?
Resconse The staff intends to review in detail licensee or industry raceway fire barrier testing programs conducted in response to GL 92-08.
Future will industry and plant-specific fire barrier test be reviewed against the guidance provided in the staff position.
If "yes,"
is there need for review guidance?
Provide reason if review guidance is not needed.
_=_
q Eesconse The staff position is the review guidance the
- staff will follow when it reviews future fire endurance testing programs.
l (b)
If the staff does not intend to review all submittals, are reports needed for other reasons?
Response
Not applicable.
III. No report need be submitted, but quality records need to be i
maintained for audit or inspection by the staff; Reporting requirement is only to provide notification of completion of requested actions.
Resconse Not applicable.
If "yes," is there a need for inspection guidance?
Provide reason if inspection guidance is not needed.
Response
Not applicable.
If inspection guidance is needed, does it accompany the CRGR package?
Provide reason if guidance does not accompany package.
Response
Not applicable.
IV.
No quality records for staff audit required.
Reporting requirement is only to provide notification of completion of requested actions.
Response
Not applicable.
No response of any type is required.
Response
Not applicable.
i.
r v
T w
v T--
wv
ENC [DSURE 3 PUBLIC COMMENTS RECEIVED ON THE STAFF'S POSITION ON FIRE ENDURANCE TEST ACCEPTANCE CRITERIA FOR FIRE BARRIER SYSTEMS USED TO SEPARATE REDUNDANT SAFE SHUTDOWN TRAINS WITHIN THE SAME FIRE AREA the NRC staff met with the Nuclear On November
,1992, and Resources Council (NUMARC) to discuss fire barrier Management testing acceptance criteria for fire barrier systemg,that are safe shutdown trains within the same used to separate redundant At this public meeting, the NRC staff presented a fire area.its proposed position on fire endurance test acceptance copy of criteria for these fire barrier systems to NUMARC and asked for its comments.
In a letter of December 8, 1992, NUMARC submitted its comments on the proposed staff position on behalf of the NRC staff industry.
In addition to the NUMARC comments, received public comments from the Tennessee Valley Authority and from fire barrier manufacturers.
Excerpts from the comment letters are given below.
Comments are not summarized but quoted directly.
The staff will develop its responses to these comments after other public comments are received.
The staff plans to P ace a summary of these comments in the Federal Recister notice l
detailing the new staff position.
I.
Anonymous letLer dated November 30, 1992, addressed to the Honorable Ct. airman Ivan Selin.
COMMENT 1 "The acceptance of the fog nozzle appeared to be based that the standards allow youoto' around two facts; the fact burn for one hour and hose stream and if you fail you can run for 30 minutes and hose stream again therefore the full hour can be the fog nozzle, the other is that the Utilities-will fight their fires with fog nozzles."
COMMENT 2
','The standard was written f or another purpose entirely when-it addressed the hose stream, we now require no water to pass the barrier."
COMMENT 3
[American Society for Testing and Materials}
"The new ASTM standard for envelopes still allows the second burn but requires both hose streams be solid."
_i_
COKMENT 4 "U.L.'s (Underwriters Laboratories) new envelope standard uses solid hose streams."
COMMENT 5 industry specifically has the "The penetration seal authority under NUREG-0800 to use the fog nozzle however has always used the solid stream because the fog nozzle produced weak systems in the market place."
COMMENT 6 "The staff recognized that the NRC had no standard for envelope systems and recognized the ANI [American Nuclear Insurers) #5 standard along with NFPA [ National Fire Protection Association) 251, both solid stream but more than allow the ANI wnich has been used until now wouldn't that the second burn and wouldn't certainly allow the fog nozzle."
COMMENT '
"Until now there hasn't been any systems either in seals or envelopes accepted with the f og nozzle as the industry standard."
COMMENT 8 "Any fire fighting school teaches you to fog nozzle to cool if closer to the fire for personnel protection but and get out to quench the burning embers and actually put you want the fire turn the nozzle to solid stream.
Would you garden fire with your garden hose on fan hose your burning house spray?
I think not."
1992, to Tennessee valley Authority letter dated December 3,
!I.
Conrad E. McCracken, Chief, Plant Systems 3 ranch.
(This letter is included as Attachment 1.)
COMMENT 1 "Since minor differences exist between the standard in the draft laboratory nethods and the specific criteria NRC document, it is likely that confusion will occur at a later date regarding the acceptability of these "different" nethods unless the issue is clearly addressed now."
"TVA recommends that the draft NRC document be revised to recognize UL Subject 1724, and other relevant laboratory i
standards, as an applicable method for performing the fire j
Tests conducted in accordance with exposure tests.
all the laboratory standards should be required to meet as if acceptance criteria incorporated in those standards, the laboratory performed the tests.
To avoid the need to produce an exhaustive list of relevant standards, TVA recommends that the NRC document be revised to state, ' Fire exposure tests may also be performed in accordance with standard test methods of Nationally Recognized Testing Laboratories (such as UL Subject 1724).'"
..4 COMMENT ?
"The draft criteria have been developed as part of addressing the acceptability of Thermo-Lag fire barrier systems, which were not rated by a nationally recognized fire testing laboratory.
Other barrier systems exist which were so rated.
For example, Minnesota Mining &
Manufacturing Co.
(3M) electrical protective systems of various types have been rated / listed by Underwriters Laboratories, Inc.
These ratings qualify these systems as rated fire barriers as required by 10 CFR 50 Appendix R in for fire doors, exactly the same manner as similar ratings fire dampers, etc.
Again TVA considers it important that the draft criteria explicitly state that such approved ratings are not invalidated.
TVA recommends that the include a statement such as ' Raceway fire barrier document systems which have been rated by a Nationally Recognized Testing Laboratory (e.g., Underwriters Laboratory or Factory Mutual) are acceptable for use without further testing or analysis.'"
COMMENT 3 "NRC has explicitly reviewed and approved specific nppendix R deviations and exemptions for electrical fire barrier systems at many nuclear power plants.
Imposition of additional, or changed, requirements to circumstances which under have been reviewed and approved constitutes a backfit 10 CFR 50.109.
Such changes should be addressed on an individual basis, in accordance with backfit procedures.
criteria should explicit state that they do not The draft invalidate previous NRC-approved deviations or exemptions."
COMMENT 4 "The formula for determining minimum acceptable insulation 3 of the resistance for cables (which appears on page attachment to the draft criteria) is taken directly from
[ Institute of Electrical and Electronics Engineers)
IEEE 690-1984, section A.10.1.
The megger tests for which this include formula is to be used to determine acceptance values tests to be done during exposure to fire temperatures (for instrumentation cables) and immediately after such exposure.
This IEEE standard establishes the acceptance criterla for new cables at room temperature immediately following installation.
Applying this formula for determining the acceptance values for insulation resistance tests to be conducted at elevated temperatures has the affect of imposing more restrictive requirements than the cable had to due to the recognized inverse relationship meet when new, between insulation resistance and temperature.
This would be a backfit which TVA considers technically Tf' appropriate.
NRC should apply the IEEE 690-1984 criteria for assessing as minimum insulation resistance at room temperature, intended."
COMMENT 5 to the criteria requires an evaluation of "The attachment the impact minimum insulation resistance value on the functionality of instrumentation cables, in addition to the insulation testing.
This implies the need to perform accuracy calculations.
Sucn calculations are inherently application-specific, and would have to be performed for each specific instrument circuit in a power plant which is This protected by a Thermo-Lag fire barrier enclosure.
would be a major effort which would not materially add to the information obtained from the megger and hipot testing.
The NRC's insulation resistance acceptance criteria should be of a go/no go nature (e.g.,
IEEE 690-1984), and accuracy calculations should only be required for cables which do not pass these criteria.
The paragraph immediately following the formula on page 3 of the attachment should be deleted."
tOMMENT 6 "The concept of thermal exposure thresnold (TET) is being applied inappropriately in section d.
of the attachment to the dratt criteria.
TET limits are established to address concerns of potential degradation of cable insulation due to elevated temperatures associated with circuit faults.
Exceeding TET limits does not imply an instantaneous failure of cable insulation, but rather establishes a need to long-term acceptability of the cables after it has evaluate experienced sucn temperatures.
The visual inspections and megger and hipot testa called for by these draft criteria constitute an evaluation to determine whether the insulation has been damaged.
TVA recommends that the cencept of TET be deleted from these criteria."
s i
III. Nuclear Management and Resources Council (NUMARC) letter dated December 8,
1992, to Conrad E.
McCracken, Chief, Plant Systems Branch.
(This letter is included as Attachment 2.)
COMMENT 1 "In the case of TSI (Thermal Science, Inc.] fire barriers, the NRC has formally declared, through Bulletin 92-01 and its supplement, that existing installations are indeterminate and subject to reverification. the draf t acceptance criteria have been developed primarily for the purposes of application to future fire tests to address the TSI situation, and would apply as well to other fire barrier testing that may be performed in the future.
The NRC document discussing the criteria should therefore clearly state that the test and acceptance criteria are forward looking and do not result in the need for retesting or analysis of fire barriers previously evaluated and found acceptable by licensees in accordance with NRC Generic Letter 86-10, unless they have been formally identified by the NRC as indeterminate."
COMMENT 2 "The NRC draft document discusses the needed for an engineering evaluation to demonstrated functionality in the event that temperature limits are exceeded, or visual damage is observed to the barrier or the cable.
The draft document states that NRC review and approval of this engineering evaluation will be necessary.
While we are hopeful that the NUMARC industry testing program will provide enclosure upgrades that will not require the use of these engineering evaluations, there is nonetneless a potential that forthcoming utility efforts to address installed Thermo-Lag contigurations could result in submittal of large numcer of such evaluations, and corresponding delays in the NRC approval cycle.
We therefore, believe the process for NRC review and approval, as outlined in the draft document, should provide that existing utility compensatory measures -
can be removed following completion of the engineering analysis and any associated modifications to the barrier system.
MRC Generic Letter 86-10 provides that utilities could document these type of analysis for subsequent NRC review during inspections, and NRC has indicated in the Ncvember 13 Commission Briefing that inspections are planned for the 1994-1995 time frame.
We believe there would be a benefit to developing a generic framework for these analysis, and providing guidelines that would allow for the removal of compensatory measures prior to completion of NRC Industry would be willing to work with NRC through review.
NUMARC to develop such guidelines to the extent they are
_5_
i necessary beyond the explicit evaluation criteria that will be provided in the final form of the NRC document."
COMMENT 3 should more "The criteria. and accompanying flow charts, clearly address the process for testing with empty enclosures and the use of air oven cable tests or other cable performance data, on the basis of measured temperature profiles from the fire tests."
.n<
COMMENT 4 "Page 3 of the NPC draft document discusses thermocouple placement consideration.
The discussion notes that
' industry considers [ placement of thermocouples on cables) the proper location for determining the temperature rise While industry considers that protection of the cables, rather than the enclosure, is the fundamental safety function, we agree that placement of thermocouples on the cables is not the best approacn.
We would note that the industry position paper on test criteria, provided to NRC on October 26, recommends that thermocouples be placed on copper conductors, and that testing be performed with empty enclosures.
Furthermore, we believe that the copper conductors should provide for measurement of temperatures on surfaces of the enclosure that the cable may realistically come in contact with.
With respect to cable trays, we do have a concern that the NRC draft document specifies use of We a copper conductor underneath the cable tray rungs.
believe the appropriate placement for the copper conductor is on top of the cable tray rungs, as this will provide for of temperatures that would be experienced by measurement installed caoles."
COMMENT 5 "The attachment to the NRC draft document discuss acceptable methods for determining cable functionality.
Section b.
discusses cable circuit integrity testing, and concludes that this is not a valid method for demonstrating that the protected shutdown circuits are capable of performing their required function.
We agree with this statement, and believe the criteria should explicitly state that circuit integrity monitoring need not be performed. This will simplify the test procedure and provide for more timely performance of post exposure megger testing."
COMMENT 6 "The second paragraph of page 4 of the attachment discusses cable normal operating temperature and its effect on the I l
i 1
We agree that cable normal total temperature rise.
operating temperature is a consideration in the engineering evaluation; however, we would note the following; Initial operating temperature is only a consideration a.
for power cables, of control and instrument cables that may be in the same enclosure with power cables.
be considered Elevated operating temperature need not for instrument and control cables in separate enclosures.
b.
Power cables will not be subject to rated voltage and current prior to the fire exposure, and may only be intermittently energized, or not energized at all, The analysis should assume prior to the exposure.
realistic conditions rather than rated voltage and current as stated.
At the November 19 meeting, NRC stated that the analysis should assume operating voltage and normal current conditions.
The effect of initial temperature on endpoint is not a c.
simple function of adding the difference between the initial temperature and the ambient air temperature to the measured temperature rise. Appendix V of NUMARC's criteria submittal of October 26 provides a heat draft transfer calculation relative to the effect of initial 1
temperature on the endpoint temperature of 90 C versus 23 C.
This calculation shows the effect to be minimal (12 C) at one hour, and negligible at three hours.
The attachment to the NRC draft document should allow transfer calculations to determine the the use of heat endpoint temperature rise."
COMMENT 7 "The attachment to the NRC draft document should state that comparison of fire test temperature profiles to existing EQ
[ equipment qualification) and LOCA [ loss-of-coolant-accident) test results, or air oven test results, is an acceptable approach to demonstrate cable functionality."
COMMENT 8 "TVA submitted comments on the NRC draft document by letter 1992.
Item 6 of that letter questions to you of December 3,
the appropriateness of the cable thermal exposure threshold (TET) as a measure of short term cable operability.
We concur with this comment."
_7
COMMENT o
" Item 4 of the TVA letter referenced above questions the use of the formula for determining minimum acceptable insulation resistance on page 3 of the attachment to the NRC draft document.
We concur with this comment.
The given formula is taken from IEEE 690-1984, section A.10.1, and is intended for use with new cables at room temperature.
Testing of cables at elevated temperatures (i.e.,
immediately following the fire test) to this criteria represents a more when new.
restrictive requirement that the cable has to + meet The formula should only be used for cables tested at room temperature."
IV.
Nuclear Information and Resource Service (NIRS) letter dated December 15, 1992, to James Taylor, Executive Director for Operations.
(This letter is included as Attachment 3.)
COMMENT 1 "C) Combustibility.
The NRC has not responded to NIRS' allegation the Thermo-Lag is combustible, contrary to 10 CFR 50 Appendix A and R. The NRC's own testing (and dramatic color photographs) indicate that Thermo-Lag is indeed combustible.
We understand, however, that the NRC is preparing an Information Notice acknowledging Thermo-Lag's we understand the NRC may require combustibility.
- Further, utilities to consider Thermo-Lag in their analysis of fire loads.
It would indeed be ironic to have the fire protection material listed as part of the fire protection problem.
Moreover, Thermo-Lag is often used in areas required to be free of combustible material.
This is itself is evidence of an uncorrectable regulator violation and by itself should require removal of all Thermo-Lag material from use as fire barrier."
COMMENT 2 "E) Hose Stream.
The NRC staff, in its proposed fire barrier criteria, incorrectly would allow the use of fog ASTM nozzle, rather than full-force hose stream test.
E-119, the standard fire test used by the NRC and passed by We other products, requires a full-force hose stream test.
also note that the new, as-yet-unnumbered, ASTM test for electrical raceways also would require a full hose stream This again shows the appearance of unwarranted test.
favoritism towards Thermal Science, Inc."
-B-
1 V.
Minnesota Mining and Manufacturing Company (3M) letter dated December 18, 1992, to Ralph Architzel, Chief, Special l
Projects Section, Plant Systems Branch.
(This letter is i
included as Attachment 4.)
COMMENT 1 "Do the letters of acceptance and license to operate issued i
l by the NRC covering these installations remain valid?
If i
not, why not?"
l COMMENT 2 l
"3M fire barrier product has over the years been continuously tested to American Nuclear Insurers (ANI) l standards, as adopted by the NRC, and by test facilities, CSTB in France, and Certified Testing Laboratories (CTL).
Unlike the in-house testing practice and procedure of some Manufacturers, 3M's product testing was conducted in its facilities under procedures correlated with UL and Factory Mutual Insurance standards, resulting in a 3M product classified and approved by these organizations.
"Ouestion:
Does the NRC accept tests conducted under the above procedures and witnessed, approved and certified by Twin Cities Testing, a nationally recognized testing service, to be valid confirmation of the basis tests and criteria originally established for 3M products at UL and SWRI (Southwest Research Institute)?"
COMMENT 3 "3M has over the years accumulated a substantial body of data based upon use of a specified 12 inch spacing of thermocouples during fire tests, as directed by ANI.
Current testing procedures now indicate a 6 inch spacing requirement.
It is 3M's intent to conduct all future testing in accordance with this revised procedure.
"Ouestion:
Does the NRC accept the validity of previously developed data generated at the manufacturers expense in accordance with the established 12 inch standard?"
COMMENT 4 "Previously established test protocol and performance place emphasis on product capability with respect to specified areas of vital concern to public health and safety, including combustibility, toxicity, seismic performance,
_9_
weight, and ampacity derating.
Current efforts to re-evaluate test criteria are focused on product fire i
performance.
"Ouestion:
Does the NRC intend to establish as part of the current test reevaluation program an equal emphasis on all aspects of the above areas of product j
performance relating to health and safety issues?
How and when will these areas of concern be addressed in order to enable manufacturers to respond to customer demands for qualified product?"
COMMENT 5 "The original NRC test standard for non-combustibility was ASTM E84.
In the current test reevaluation process the NRC has ind'.cated that ASTM E136 will now be applied.
At the NRC public meeting on November 19, 1992, it was stated by NRC representatives that standard E136 would be interpreted to mean a product equivalent in non combustibility to fire rated gypsum board.
"Ouestion:
Will the E136 standard as defined in the Novemoer 19 meeting be applied against all existing installations regardless of manufacturer?"
COMMENT 6 "The hose stream requirements of NFPA 251, ASTM E119, and ASTM E814 have long been recognized as providing the mechanical means of determining fire carrier product performance with respect to thermal shock, effects of erosion and the ability to resist mechanical abuse.
The new test protocol allows for fog nozzle testing in lieu of the solid stream test.
"Ouestion:
What is the basis upon which the substitute fog nozzle test has been determined to provide equivalent test results regarding these critical product performance characteristics."
COMMENT 7 "At the present time there are fire barrier systems of either one or three hour performance duration at the various utility plant locations.
These systems have been provided by one or the other of several manufacturers.
"Ouestion:
Does the NRC intend that both systems are subject to the entire revised testing protocol and specified performance criteria?"
VI.
Minnesota Mining and Manufacturing company (3M) letter dated January 22, 1993, to Ashok C.
Thadani, Director, Division of Systems Safety and Analysis.
(This letter is included as.)
COMMENT 1 "3M, working with Underwriters Laboratories, has tried various methods for evaluating cable functionality, including oven testing to establish failure p'6Ints, meggering before and after fire testing in both air and water, circuit integrity testing under low and high amperage loads during fire testing, and other means.
3M is willing to make this information available to the industry to help develop a functionality test method.
The question still exists on proper selection of the cable to be tested should it be artificially aged before testing, as aged cables will function differently than new cables.
Cables of the same design, labeled XLPE/PVC, can fail in an oven evaluation test at temperatures as low as 163*C [325*F) and as high as 399'C [750*F), even though the cables are thought to be identical.
The choice of cable will be crucial to testing cable functionality."
VII. Darchem Engineering Ltd letter dated February 2, 1993, to Ralph Architzel, Chief, Special Projects Section, Plant Systems Branch.
(This letter is included as Attachment 6.)
CoKMENT 1 "The fire test proposals at present do not indicate the number, size and types of cable to be used in the fire tests apart from the single cable loading."
COMMENT 2 "The concern is that the new proposals allow for a relaxation in the hose stream criterion by including a Water fog as an option.
We believe that the penetrating power that the impact of a solid hose stream imparts to the fire protection system around a raceway will not be reproduced by the water fog.
This will mean that fire fighting teams will be restricted in their choice of equipment and methodology for tackling the blaze to penetrating through electrical circuit protection systems that have been qualified against the water fog criteria.
It will also mean fire protection systems may not have the ability to withstand even small amounts of falling debris.
We therefore recommend the existing solid hose stream test is used without alternative."
COMMENT 3 "The ASTM E136 test method is traditionally used for indicating if a building material will either aid combustion or add appreciable heat to an ambient fire. It is also used for checking insulation materials, in particular calcium silicate which can have a high paper content.
l the implementation of ASTM E 136 test method as We support we believe this test provides essential data in assessing the suitability of materials for use in a fire protection system.
However the present ASTM E136 standard as it stands excludes coating materials.
We would urge that a complete
)
representative section of material including any coating is l
to be tested."
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