ML25196A358
| ML25196A358 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/11/1976 |
| From: | Moeller D Advisory Committee on Reactor Safeguards |
| To: | Anders W NRC/Chairman |
| References | |
| Download: ML25196A358 (1) | |
Text
ADVISORY COMMITTEE ON REACTOR SAFEGUARD~
NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 Honorable William A. Anders Olairman U. s. Nuclear Regulatory Conmission Washington, OC 20555 March 11, :1.976 SUbject:
REPORI' 00 PROPOOED RES'IORATIOO AND OPERATIOOAL TtSl'!M; OF Bl01NS FERRY NlCLFAR PI.ANT, UNITS l AND 2
Dear Mr. Anders:
At its 191st meeting, March 4-6, 1976, the Advisory Conmittee on Reactor Safeguards met with the Tennessee valley Authority (TVA) to review repairs and nooifications to be made to the Browns Ferry Nuclear Plant, Units l and 2 prior to restart of these t.mits following the fire on flarch 22, 1975. 'Ihese matters were previously considered at a Subcorrmi.ttee meeting on February 27, 1976, in Washington, OC.
During its review, the Conmittee had the benefit of discussions with representatives and consultants of the Tennessee Valley Authority and the Nuclear Regulatory Conmission (NRC)
Staff. '!he Conmittee also had the benefit of the documents listed.
'!he Browns Ferry Nuclear Plant consists of three boiling water reactors.
At the time of the fire U'lits 1 and 2 were operating and U'lit 3 was still t.mder construction. Following the fire the fuel was removed from tbits 1 and 2 and since has remained stored in the fuel storage pools. 'lbe Tech-nical Specifications were changed to provide for protective measures for the fuel while in the storage pools.
'IVA has conducted an extensive program to determine damage from the fire.
It was concluded that the major damage occurred in the reactor building, outside the cable spreading roan where the fire started. '!here has been no evidence of significant structural damage and only minor damage to piping systems. 'Jhere was extensiv~ damage to electrical cables, trays and conduits. '!here was extensive deposition of soot on all equipnent located in the reactor building below the refueling floor. 'Ibis soot contained an estimated 1400 pot.mds of chloride. All damage occurred in the reactor building outside the containrnent.
Based on its assessment of the damage from the fire, TVA has developed and carried out a program for restoration of U'lits 1 and 2. 'Ibis has consisted of replacing, from terminal to terminal, all damaged cables in the reactor protection system, primary containment isolation system and engineered safeguards systems.
Some other cables that were damaged have been repaired by splicing.
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lk>norable William March 11, 1976 Because of the extensive nature of these repairs it is extremely important that preoperational tests ascertain that repairs have been adequate to restore required ft.mctions. Test procedures are being prepared by 'IVA and are being reviewed by the NRC Staff. '!he ACRS wishes to be informed of the results of these tests prior to startup of units 1 and 2. A cleaning program has been carried out to remove the*soot, and tests have been conducted to detennine damage fran the soot. 'Mlil.e the cleaning program seems adequate, effects of the chlorides, such as stress corrosion cracking, may not be evident for sane time.
'IVA has proposed a surveillance program to detect future deterioration that might be caused by these chlorides.
'!he NRC Staff is reviewing the program to detennine its adequacy. '!he ACRS emphasizes the importance of such a program and wishes to be kept informed of the results.
Of the 9500 electrical conductors involved, 45% have been replaced entirely and criteria for splicing the remainder have been developed and followed.
Additional heat and smoke detectors have been installed. A fire retardant coating, Flamemastic 71A, has been used to reduce flanunability. Fire watches have been established. Autanatic fire protection systems and hand-held fire suppression systems will be installed to pranptly suppress fires that may occur. water spray will be used at critical locations. Olanges in camrunications are planned. '!he Corrmittee believes that these represent significant improvements in fire protection.
Some of the fire control provisions and in particular the gross application of Flamemastic 71A might involve long-term effects that warrant surveillance.
'!he cocooning of the electrical and control cables with Flamemastic 71A changes the working environment, and an arrangement for opening sane portion of the cable bundles to inspect their condition periodically would seem to be appropriate.
'!he fire retardant action of the Flamemastic 71A has not been clearly described and, while tests indicate that it is effective, more information about its chemical behavior in the presence of a fire would be desirable.
If the supplier of the material cannot provide the chemical information, the NRC Staff should request an independent laboratory to investigatf-its behavior as a precautionary measure to determine the toxicity and CO.L.cosive properties of the chemicals evolved during a fire.
'!he criteria for access for fire fighting purposes, while difficult to define, should be set forth by the NRC Staff for Applicants, so that there is a basis for judging the adequacy of the provisions. '!he situation at Browns Ferry is governed largely by the already constructed installation, but there may be opporbmities for improving or modifying what is prolX)sed.
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lbnorable William March 11, 1976 Since the 'IVA is self-insured in accordance with federal policy, its installations do not have the normal fire insurance surveillance used by private installations. '!he 'IVA has established an independent fire protection staff within its organization. However, a newly established unit may not have either adequate status or experience to be wholly effective and should be supplemented by an outside review agency to assure a broad and unconstrained evaluation of fire protection require-ments.
verification of the adequacy of the fire protection training programs proposed by 'IVA should be part of the N.RC regulatory plan. '!he training program should include both initial training and periodic retraining of personnel.
Following the Browns Ferry fire the NRC Executive Director for Q?eratiOllS set up a special review group to detennine what should be learned from this incident. 'Ibis group has made reconmendations that apply to future reactors, to reactors that are already operating, and to the NRC regulatory process. '!he review group points out that its recormnendations are not specific to any single plant and that its recanmendations*are based on knowledge at the time of this investigation. '!he ACRS wishes to be kept infonned of the specific application af the review group's recorrmendations as they apply to Browns Ferry, to the develo:pnent of additional informa-tion on fire prevention, fire fighting and quality assurance and the improvement of NRC policies, procedures and criteria.
'!he Conmittee expects to review generically several safety questions related to boiling water reactors, including Mark 1 torus response, during the next several months.
'Ihese questions as they may relate to Browns Ferry will be addressed in the Committee's generic reports on these subjects,.
'!he Advisory Conmittee on Reactor safeguards believes that, if due regard is given to the items mentioned above, and subject to satisfactory comple-tion of the planned restoration and subsequent operational testing, there is reasonable assurance that the Browns Ferry Nuclear Plant, Units I and 2, can be operated at power levels up to 3293 Mwt:, subject to the conditions of the Coomittee's reports of September 21, 1972, and JRcember 11, 1973, without undue risk to the health and safety of the public.
Sincerely yours, f)-tUL_V,~
Dade w. M:>eller Cllairman 168
Honorable William A..Anders March 11, 1976
'.a:!ferences
- 1. *plan for Evaluation, Repair, and Return to Service of Browns Ferry Nuclear Plant, lllits 1 and 2 as a Result of the March 22, 1975, Fire" by the Tennessee Valley Authority and Revisions 1 through 37 to that plan.
- 2.
0 Recalmendations Related to Browns Ferry Fire" (NORliG-0050)
Report by Special Review Group dated February 1976.
- 3. Safety Evaluation by the Division of Q;>erating Reactors Supporting the Q;>eration After the Restoration and ftt>dification of the Browns Ferry Nuclear Plant, lllits 1 and 2 following the March 22, 1975, Fire dated February 23, 1976.
- 4.
NRC letter to Tennessee Valley Authority dated May 9, 1975, issuing temporary Tech Specs fox-use during recovery fran fire damage.
- 5. Tennessee valley Authority letter dated Jlmell, 1975, regarding 0A provisions during cable splicing operations.
- 6. NRC letter to Tennessee Valley Authority dated June 13, 1975, modifying the Tech Specs for the period when Untts 1 and 2 were defueled and the fuel stored in the fuel pools.
- 1. Tennessee Valley Authority letter dated August 18, 1975, forwarding responses to NRC questions relating to the Browns Ferry fire.
- 8. Tennessee Valley Authority letter dated August 21, 1975, ccmnenting on the capability of obtaining total independence of redundant systems.
- 9. Tennessee valley Authority letter dated August 29, 1975, carmi.tting itself to certain actions.
- 10. Tennessee valley Authority letter dated September 15, 1975, formally camdtting TVA to actions i:egarding fire protection systems.
- 11. Tennessee valley Authority letter dated N:>vember 17, 1975, regarding procedures for full-scale flame tests of wall penetration seal designs.
- 12. Tennessee Valley Authority letter dated December 8, 1975, regarding heat shield barrier design.
- 13. NRC letter to Tennessee valley Authority dated December 19, 1975, modifying the Tech Specs to reflect reduced cooling requirements for the fuel stored in the fuel pools.
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Bmorable William A. Meiers
-s-March 11, 1976 References - Continued
- 14. Tennessee Valley Authority letter dated January 15, 1976, transmitting data fran fire tests performed on candidate electrical cable wall penetration seal/fire stop designs.
- 15. Tennessee Valley Authority letter (tmdated) to B. C. Rusche transmitting Enclosures 1, 2 and 3 re: ~ndations of fire consultants and TVA resl:X)nses; and additional infonnation on the "Plan lor Evaluation, Repair, and Return to service of Browns Ferry Nuclear Plant, tmit 1 and 2.
- 16. Tennessee Valley Authority consultant's (Associated Fire Protection Consultants, Inc.) letter rel:X)rts dated February 25 and March 4, 1976.
- 17. NRC letter to ACRS dated March 4, 1976, forwarding the SUmmary Report of the NRC's Fire Protection Consultant.
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