ML19263B210
| ML19263B210 | |
| Person / Time | |
|---|---|
| Issue date: | 12/28/1978 |
| From: | Hendrie J NRC COMMISSION (OCM) |
| To: | Corman J HOUSE OF REP. |
| Shared Package | |
| ML19263B211 | List: |
| References | |
| NUDOCS 7901150005 | |
| Download: ML19263B210 (4) | |
Text
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NUCLEAR REGULATORY COMt.11SSION 3 g(2R
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_e December cc,, _:/c CHAIRMAN The Honorable James C. Corman United States House of Representatives Washington, D. C.
20515
Dear Congressman Corman:
I am pleased to respond to your letter of November 7,1978, which reauests the status of the fire protection programs in nuclear power plants and states the view that fire prevention measures, such as installing flame retardant coatings to electrical cables, are preferable and more cost effective inan fire suppression me:hocs.
I would like firs: to address the status of the fire protection programs.
Since the occurrence of :ne fire a: the Browns Ferry Facility in March 1975, tne NRC has undertaken a substantial upgrading of fire protection provisions at nuclear power plants.
This incluced a tnorough stucy of the Browns Ferry fire to determine the lessons to be learnec, and to provice recommendations needec to cevelop licensing guicance for both new and operating plants.
This initial effort resultec in the issuance of NUREG-0050, Recommendations Related to Browns Ferry Fire, a copy of which is attached for your information.
inis report, wnicn forms the basis for our present regulatory guidance concerning fire protection, sets forth a aefense-in-ceotn concept which emphasizes echelons cf cefense against fires.
These echelons of cefense consist of:
1.
Preventing fires from getting star:ec.
2.
Detecting and extinguishing quickly sucn fires as co get star:ec and limi:ing their camage.
2.
Designing the plants to minimi;e the effect cf fires on essential func icns.
The report emphasizes that no one of these echelons can be perfect or complete anc that it is neir multiplicity, anc the cepth thus afforcec, that provide a 'high degree of safety in spite of lack of perfection in any given system.
The concept of defense-in-cepth nas been appliec by the s:af' in the follow-uc measures taken on all plants following :ne Browns Ferry rire, and in ceveloping fire protection guicelines for p :n new anc opera:ing plants.
7901150005-
Follow-up measures taken by the staff included (1) issuance of Inspection and En forcement Eulletins directed toward control of ignition sources and improved housekeeping procedures; (2) special inspections of fire stoos in operating plants; (3) improved inspection procedures for cables and penetration seals for plants under construction; and (4) alerting licensee's upper management to this concern. These measures orovided a prompt increase in fire protection of all plants while the more complex aspects of fire protection were under consideration. This interim protection has been strengthened by fire protection Technical Specification requirements for operating plants which cover existing fire protection systems, improved administrative controls for fire brigade strength and training, and controls for the use of combustibles and ignition sources within the plant.
During 1975 and 1976 the staff developed an extensive set of guidelines fcr # ire protection consiaerations in new plants.
Tnese guidelines were issued in the Standard Review Flan as a Branch Tecnnical Position (STp)
A53 9. 5-1 They were also issued for public comment as.egulatory Guide 1 12C in June 1975.
These guidelines place emonasis on cli nree ecneicns of defense-in-depth
-he first of which is fi re prevention -
Tne implementation of these guidelines for new clants assures that fire Orctection is taken into consideration as a basic part of the desicn ratner than as an adC-on after the design is otherwise ccmcleted.
Ccmtined with the NRC and the nuclear industry's conservative approach to consideration of other potential accidents, we believe that this program will result in an acceptable level of fire protection for new nuclear power plants.
A second aspect of the staff's effort invcives the evaluation cf operating reactor facilities tc assure tnat a level of fire protection commensurate to tnat required for new facilities is providec.
We have concludec tnat there is nc. basis to restrict the Operation of these facilities for suci'c safet / reasons.
This conclusion is basec or cur ;udgment ina.
.ne likelinc'cc of disructive fires cf ine. ma;nitude of the Browns r -r;.
e event is snail This judgment does not cerive solely from statistical eascning but ratner # rom the fire Drctecticr cccci:icrs existing i-the piants in 1975 an the sucsequent positive anc effective actions ta(en to inprove fire protection programs at these facilities since that time.
These actions have decreased tne likelihood of severe fires througn effective fire. protection and improved fire fignting ability. Appendix A to STP 9.5-1 which was issued in September 1975 sets forth the guidelines for tnis evaluation. All licensees have Deen reques ted to compare their facii4 ty's fire orctection program to tne new guicelines anc to presc e an extensive "fi e nazard analysis. ' These analyses were submittec c
. the NRC betaeen late 1976 and early 1973.
Considerab'e celay in the submittais from licensees was caused by the complexity of the required analyses and the need to obtain qualified fire protection engineers.
The NRC staff review of licensee's fire protection analyses began in early 1977.
The staff reviewers have been assisted by fire protection consultants having expertise in unique aspects of fire protection engineering.
The reviews are extensive and address such things as control of cc=bustibles, detection systems, suppression systens, fire retardant coatings and administrative controls. The fire protection reviews for all operating reactor facilities are targeted to be completed by June 1979; the target date to complete the implementation of fire protection modifications at most operating nuclear power plants is October 1980. As of December 1, 1978, reviews have been completed for 31 of the 70 coerating reactor facilities.
a'ith respect c your view concerning # ire preven-icr measures, :ne fcregoing descriction of the staff's fire protec:icn orogram illustrates the heavy emphasis na has been placed on fire prevention thrcugh administrative controls.
For example, where Cossible comDustiDies have been eliminatec and in certain instances wnere it nas no: Deen ocssible to elininate the comoustible inven:Ory, coatings
- r. ave :een ap;ilec 0 (1) reduce ignitability of cable groups, anc (') -ecuce fire : opaga-icn
- nrough cable groups.
Ap;endix A permits the use of flame retardant
- catings and these coatings have been applied or are prcacsec to te 2 olied tc certain electrical cables of a large nunter of opera:ir.;
piants.
As ciscussed accve, # ire crevention is one aspec Of tne NRC's defense-in-cepth ap;rcach.
However, an effective fire orctection proccam must include measures to cetect and extinguish promptly fires that co cccur In some areas of :ne plants we recuire that av cmatic # ire suco ession systems te ins alled, but the ca; ability to manually fign; a # ire has
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jec;ardiZe the safe shutdOw"i of the plan. One staf# re c u i res :ne ; c'.isicr f0r ei*her an alternate plan
- shutcCwn capaDility inde;endent cf :ne fire area or fire protection systems :na can be shown to prctect recundar.: electric cable divisions from electrical and ex;csure fi-es.
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I'.' car be Of further a:sistance, please ie; me know.
tN Sincerely,
\\l\\>' M L 4 Ws)eph M. Hendrie
Enclosures:
Recommenda tions Rela ted to Browns Ferry Fire Regulatory Guide i.120