ML20151H800
| ML20151H800 | |
| Person / Time | |
|---|---|
| Issue date: | 05/25/1983 |
| From: | Vollmer R Office of Nuclear Reactor Regulation |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20151H089 | List:
|
| References | |
| FOIA-88-92 GL-82-21, NUDOCS 8306150039 | |
| Download: ML20151H800 (11) | |
Text
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UNITED STATES
- 9
'l p ( g NUCLEAR REGULATORY COMMISSION g j WASHINGTON, D, C. 20555
% .',Y. . ** MAY 2 51983
- l MEMORANDUM FOR: Darrell G. Eisenhut, Director l Division of Licensing
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FROM: Richard H. Vollmer, Director Division of Engineering
SUBJECT:
NRC POSITIONS ON CERTAIN REQUIREMENTS OF APPENDIX R T0 10 CFR 50 On March 1, 1983, we met with representatives of the Nuclear Utility Fire l Protection Group (NUFPG) to discuss clarification of certain requirements i of the Fire Protection Rule, Appendix R to 10 CFR 50. These requirements have been misinterpreted by some licensees represented by NUFPG when they !
evaluated their plants for conformance with Appendix R.
We informed
, these licensees of their misinterpretation of our requirements in our 1 SERs.
l During our meeting with NUFPG, it became clear that other licensees may have misinterpreted Appendix R. To assure that all licensees use a con-sistent interpretation, we believe that a letter to all licensees to Qf inform them of the staff position on these issues is appropriate.
are the staff positions that should be included in such a letter.
Enclosed We suggest that the letter take a form similar to your Generic Letter No.
82-21, and be sent to all licensees and applicants. In addition, because
, these positions should be c raidered during inspections, the Regions
- should also be informed.
g This information need not be reviewed by CRGR because it is a delineation I of the positions the staff has been implementing in the reviews of fire protection programs and Appendix R exemptions.
b h.dk Richard H. Vollmer, Director Division of Engineering l
Enclosures:
As stated cc: See next page i
Contact:
R. Ferguson .
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S( N ] h /)('#o
.. py 2 5 N Darrell G. Eisenhut -
2-cc: W. Johnston V. Benaroya R. Ferguson T. Wambach S. Trubatch !
R. Eberly S. Pawlicki <
T. Sullivan
. O. Parr V. Panciera J. Taylor J. Stang D. Kubicki f F. Nolan S. Ebneter, Region I T. Conlon, Region II s C. Norelius, Region III G. Madsen, Region IV P. Sternberg, Region V D. Notley W. Shields F. Miraglia l(I . D. Crutchfield b) F. Rosa M. Srinivasan R
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- = s T(1 ALL LICENSEES AND APPLICANTS OF NUCLEAR POWER REACTORS o
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Gentlemen: -
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SUBJECT:
TECHNICAL SPECIFICATIONS FOR FIRE PROTECTION AUDITS -
(Generic Letter No. 82- ) _ , _ ..
The Technical Specifications for fire protection require:
(a) an annual fire protection and loss prevention i inspection and audit uf.ilizing either qualified- )
offsite licensee personnel or an outside fire '
protection firm:
1 (b) a biennial audit of the Fire Protection Program -
e and implementing procedures; and ,
(c) a triennial fire protection and loss prevention "
inspection and audit utilizing an outside qualified fire consultant. '
l We have received inquiries about the differences between these three I audits, both as to the scope of the audits and the make-up and qualifi-cations of the inspectors and auditors. We have, therefore, prepared f - ' the enclosed guidance which is what we believe would be a comprehensive I and conscientious audit program. Such a program would be responsive to (k ' the overall programatic requirements contained in 10 CFR 50.48(a) and guideline positions in BTP 9.5-1.
Enclosure 1 discusses the general scope of the three audits and the j composition and qualifications of the audit teams. Section 10 of I Enc'.csure 2 provides additional information with regard to the 24 month !
, audi , Enclosure 2 is excerpted from a document entitled "Nuclear Plant Fire , Protection Functional Responsibilities, Administrative Controls and l
Quality Assurante" which was sent to all licensees and applicants in '
g 1977. Enclosure 3 describ'es elements that should be included in the l
annual and triennial audits.
1 This guidance is provided for your information. No written response is 1 required.
incerely, 3 ,
j 4.. <
Nrr . E1 u, ctor Division of Licensing -
Enclosures:
As stated O
g e
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-NRC Staff Positions on Certain Requirements of Appendix R to 10 CFR Introduction During our reviews of Appendix R exemption requests and our review of applications for operating licenses, it has become apparent that certain requirements of Appendix R to 10 CFR 50 and the corresponding guidelines in SRP 9.5-1 may not be interpreted correctly. On March 1,
- . 1983, members of the staff met with representatives of the Nuclear Utility Fire Protection Group (NUFPG) to discuss clarification of certain requirements. At that meeting, the staff agreed to send the staff positions on these issues to all licensees.
5 f 1.0 Section III.G Fire Protection of Safe Shutdown Capability
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j 1.1 Detection, Suppression, and Fire Areas
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Several subsections, i.e, III.G.2.b, III.G 2.c, III.G.2.e require that s fire detectors and an automatic fire suppression system be installed fin the fire area. To satisfy this requirement, (1) the fire detectors
- need to be installed throughout the fire area, (2) the automatic suppression system needs to be installed throughout the fire area, !
t- and (3) the fire area needs to be separated from other areas by boundary fire barriers (fire-rated walls, floors or roofs with any i i
, openings or penetrations protected with seals or closures having a 1 fire resistance rating equal to that of the barrier).
In some fire areas, the provision of a fire detection and a fire suppression system throughout the fire area may not significantly increase the level of fire safety afforded by partial coverage,or the installation of a fire suppression system throughout the area l
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may be detrimental to overall plant safety. The fire protection for such areas will be evaluated under~the exemption process where'it is -
clearly demonstrated, by a fire protection engineering analysis,~
that the installation of a fire detection and fire suppression in only select locations within the fire area will provide an equivalent level of protection.
Prior to Appendix R, some fire hazard analyses conducted to satisfy NRC Supplementary Guidance for Fire Protection Program Evaluation, September 1976, used "fire zones",(not bounded by fire barriers) rather than "fire areas" (bounded by fire barriers). In some cases, the licensee delineated fire zones by logical physical divisions or equipment groupings. In other cases, fire areas were delineated by existing fire barriers. However,Section III.G of Appendix R sets forth the requirement for fire protection for safe shutdown capability on the basis of fire areas. To the extent that the previous evalua-4' tions by the licensee and the staff were based on fire areas, they are in compliance with Appendix R. If the previous evaluations were based on fire zones, and the separatior, between the "fire zones"
, does not comply with the separation requirements in Section III.G
,of Appendix R, the technical requirements of Appendix R have not a been met. Previous acceptance by the staff of features not specifi-c' ally identified in Section III.G does not relieve the licensee of g its responsibility to comply with Section III.G or to request an exemption from these requirements based on justification provided ;
by the fire hazards analyses for the fire area under consideration.
Basis for Detection and Suppression The fire detection and fire suppression systems to be installed "in the area" should be provided in conformance with appropriate industry standards (such as National Fire Protection Association Standards Nos. 13 and 72E) on the basis of sound fire protection principles.
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i General industry practice, as exemplified by the following references from the National Fire Protection Association (NFPA) Fire Protection Handbook and NFPA Standards, is to install fire protection throughout an area:
. . . complete installation of sprinklers throughout a building is necessary for complete protection of life and property.
No areas should be left unprotected.
It is risky to omit sprinklers from any single area because it is judged that the hazard is not sufficient to warrant them."1 "The basic principles for providing proper protection are namely:
(1) Sprinklers installed throuahout the premises . . ."2 ir f "When complete coverage is required, (Fire) detection devices should be installed throughout all parts of the building." i
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Basis __for Fire Areas The fire protection requirements are intended to provide reasonable
' assurance that at least one safe shutdown division is free of fire T damage after a postulated fire in any fire area. Licensees are l required to identify all those redundant shutdown systems that may be affected by a single fire within the plant. Because it is not possible to predict occurrence, locality, or severity of fires, the area of potential fire and fire suppressant influence needs to be defined by boundaries that can reasonably be expected to contain the flame, heat, and hot gases that will result from a fire. This definition of "fire areas" is predicated on sound fire protection engineering principles as they apply to the limiting fire and fire suppressant damage to redundant shutdown equipment and cables with due consideration to the propagation of fire and smoke. Fire areas defined by non physical boundaries, such as "logical divisions or i
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equipment grouping", cannot be expected to restrict fire and smoke spread. An Appendix R compliance analysis that is not based on fire -
areas d'efined by a three-hour fire rated wall, ceiling and floor or by equivalent protection, such as a justified fire barrier of less fire resistance, does not provide reasonable assurance that the limits of fire or fire suppressant damages to shutdown systems have been defined.
In many plant areas, the erection of physical barriers between redundant shutdown systems is precluded by the location of cable trays, HVAC ducts and other plant features. In such situations, we have accepted, in concept, the use of an automatic fire suppression system l which discharges a "water curtain" across the boundary area separating l the redundant systems. The design of such "water curtains" have not v been codified; i.e. , the National Fire Protection Association Standards i do not address the use of fire suppression systems for such applications.
However, we are currently working with several applicants and licensees to define design > aquirements which will satisfy our mutual concerns.
Our present position is that such systems should feature close-spaced open-head sprinklers with water discharge initiated by tripping a s deluge valve activated by cross-zoned smoke detectors. Where smoke spropagation does not represent a hazard to redundant shutdown systems, T a close spaced closed head sprinkler system may be deemed acceptable.
$heresuch"watercurtains"areusedtheoperationofsuchsystems
- - should not endanger safety systems on either side of the "water curtains".
The term "fire barrier" is defined on page 2 of BTP APCSB 9.5-1, Guide-lines for Fire Protection in Nuclear Power Plants", dated May 1, 1976.
This definition also applied to Appendix A to BTP APCSB 9.5-1. A fire area is defined as "that portion of a buildino or olant that is senmtad from other areas by boundary fire barriers (walls, floors and , roofs) with any openings or penetrations protected with seals or closures having a fire resistance rating equal to that of the barrier." Because this definition appeared to be well understood and accepted by both applicants and licensees, the definition was not repeated in Appendix R.
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l 1.2 Structural Steel Related to Fire Barriers Subsection III.G.2.a requires that structural steel forming a part of or supporting fire barriers separating redundant trains to have a fire rating equivalent to the fire resistance of the barrier.
Basis The protection of structural steel is required because steel loses strength when subjected to temperatures that may be attained in a fire.
1100'F is normally considered to be the critical temperature. At this temperature the yield stress in steel has decreased to about 60 percent of the value at room temperature. This is approxir.:ately the level normally used as the design working stress. Because steel has a high thermal conductivity, and heat is transferred away from a localized 3 heat source rather quickly, a relatively long period of time is l 5 required to reach the critical temperature. However, an exposure fire that distributes heat over a greater area may reduce this time
, considerably, and unprotected structural steel may result in the 8
, structural failure or collapse of a fire barrier in a significantly-
'less time than the rating of the barrier. In cases where the 5
s,tructural steel is not protected and has a lower fire rating than the required rating of the fire barrier, an exemption must be 4 .
requested and justified by a fire hazards analysis which shows the temperature the steel will reach during a fire and the ability of the steel to carry the required loads at that temperature.
1.3 Fixed Suppression System Subsection III.G.3.b requires "a fixed fire suppression system" to be installed in a fire area for which an alternative or dedicated. shutdown capability has been provided to meet the requirements of subsection III.G.3.
To satisfy this requirement, the fixed fire suppression system shall have discharge heads and the distribution piping for such heads installed.
Hose stations do not satisfy this requirement.
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I Basis 1
Themajorityofareasforwhichanalternativeordedicatedshutdown capability is provided contain large concentrations of cables and, I therefore, have high fire loadings. In adriition, access for fire
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fighting may be hampered by congestion and smoke. A fixed fire suppression system should be capable of controlling a fire in such areas even under limited access conditions.
< l.4 Intervening Combustible Section III.G.2.b, requires the "separation of redundant trains by more than 20 feet with no intervening combustible . . ."
r f Plastic jackets and insulation of electrical cables should be considered
- - as an intervening combustible. The amount, configuration, and fire retardant treatment of the cables should be given careful consideration.
An exemption must be requested and justified if the 20' separation distance contains such materials.
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, Basis I
Aumerous comprehensive flammability tests conducted by the Electric r._ Power Research Institute (EPRI NP-1200, EPRI EL-1263), Factory Mutual (Contract RP-1165-1), and Sandia National Laboratories (NUREG/CR-2431 among others) have shown that burning plastic cable insulation repres-ents a significant fire hazard. These tests were conducted on both l IEEE-383 qualified and unqualified cable. While the qualified cable exhibited a tendency to ignite and propagate flame less rapidly, combustion of grouped cables continued at significant levels.
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l In particular, grouped vertical cables which are not protected by a l fire propagation retardant, such as, metal tray covers or fire retardant coating's, can result in rapidly developing fires with high heat release rates.
2.0 Section II.B Fire Hazards Analysis 2.1 Transient Fire Hazards This section requires that the fire hazard analysis for the plant consider potential transient fire hazards. To meet this requirement, the fire hazards analysis for each fire area should consider a conservative bounding value for a transient fire hazard that could
? reasonably be expected at some time over the life of the plant.
Basis t ) During the life of the plant, transient combustible materials may be located in or pass through safety related areas. These hazards arise from activitica associated with operation, maintenance, repairs, or
, modifications. They may arrive deliberately under approved work permits
,or inadvertently as a temporary expedient. Usually, a fire involving g such materials would not overpower the fire protection features provided In accordance with Section III.G and therefore, are only of concern h when exemptions or deviations are requested.
Over the past several years, several attempts have been made by the NRC and industry to establish criteria for establishing "design basis transient combustibles." For example:
- 1. The maximum amounts permitted by the plants administrative controls or some multiple of that amount.
- 2. Selected amounts of (e.g. 1 pt, Iqt, 1-20 gal.) a combustible liquid e.g., acetone, heptane, lube oil, solvents.
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lf However, none of these criteria have stood up to critical evaluation as to why they are bounding conditions., For this reason, we have specified the protection to be afforded for an area rather than the "design basis exposure fire" for such an area.
In considering "transient combustibles" when evaluating exemption requests we consider: (1) the physical attributes of the area that will tend to limit the amounts of transient combustible e.g. , restricted access due to environment within the area, location of area or physical access limitations, (2) whether the fire area is required to be manned con-tinuously by the plant Technical Specifications, (3) the physical attributes of the fire area and configuration of the systems of concern
[, which comply to their capability to limit fire and fire suppressant r damage, and (4) the safety significance of the systems of concern.
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References l
- 1. "Fire Protection Handbook," Fourteenth Edition, National Fire
{
, Protection Association, Quincy, Massachusetts, 1976, p. 14-10. l 1 l
'2 . "Standard for the Installation of Sprinkler Systems," NFPA 13-E 1978, page 13-67, paragraph 4-1.1.1.
- 3. "Fire Protection Handbook," Fourteenth Edition, National Fire Protection Association, Quincy, Massachusetts, 1976, p. 12-20.
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