ML20085M328
| ML20085M328 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 01/04/1974 |
| From: | Eric Thomas TENNESSEE VALLEY AUTHORITY |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085M333 | List: |
| References | |
| AO-BFAO-7349W, NUDOCS 8311080254 | |
| Download: ML20085M328 (3) | |
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TENNESSEE VALCEY AUTHO AFTY t"""ET(
CHATTANOOGA, TENNESSEE
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(S f ith January 4,1J74 Q
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- (," M:, Spf..\\ [n Mr. John F. O' Leary, Director 9,
Directorate of Licensing
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Office of Regulation N
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U.S. Atomic Energy Cor: mission Washington, DC 20545
Dear Mr. O' Leary:
TEMTESSEE VALLEY AUTHORITY - BROUITS FERRY EUCLEAR PLANT UIIIT 1 -
DOCKET UO. 50-259 - FACILITY OPERATING LICENSE DPR ABUORI'.AL OCCURREICE REPORT BFAO-7349W The enclosed report is to provide details concerning reactor main steam relief valve PCV-1-18 bellows seal lenhage alam indicating light indicated bellows leakage which occurred on Browns Ferry Nuclear Plent unit 1 on December 25, 1973, and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973.
Very truly yours, TEMTESSEE VALLEY AUTHORITY
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E. F. Thomas Director of Power Production Enclosure CC (Enclosure):
Mr. Norecn C. Moseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtree Street, NW.
Atlanta, Georgia 30303
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1-f REGULATORY 0?ERATIONS FILE COPY 8311080254 740104 m
PDR ADOCK 05000259 204' 6
PDR COPY SENT REGION V_
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ABNORMAL OCCURRENCE REPORT Report No.--BFAO-7349W Report Date--January 4, 1974 Occurrence Dr.te--December 25, 1973 Facility--Browns Ferry Nuclear Plant unit 1 Identification of Occurrence Reactor main steen relief valve PCV-1-18 benows seal leakage alarm indicating light indicated bellows leakage.
Conditions Prior to Occurrence Reactor was at 50-percent ther=al power following a scheduled outage.
PCV-1-18 was one of three replace =ent valves instaned during the outage.
Description of Occurrence The bellows seal leakage alarm indicating light for PCV-1-18 was observed to indicate bellows leakage.
Designation of A parent Cause of Occurrence The exact cause of the occurrence cannot be determined until the pressure switch and bellows asse=bly are removed from the steen header. Suspected causes are a failed pressure switch, leeking pilot valve bellows, or bellows thread leakege.
The relief valve will be removed fro = the header, disassembled, and the component parts tested tst the earliest opportunity.
Analysis of Occurrence The pilot valve section of the Target Rock safety / relief valve is a small, low-flow pressure sensing and control element which actuates the ma.in valve. The key element of the pilot valve is a machined benous which acts as a combination piston, spring, and her= etic seal. Leakage past the bellows is monitored by a pressure switch and indicating light.
If the bellows chamber is leakirg, the popping pressure of the valve is shifted to a higher value depending on degree of leakage; and the valve will no longer operate as a pressure-activated safety valve at the original setpoint. However, the valve retains its capability to function for automatic blowdown and manual operation. The capacity of the other safety cnd relief valves is such that the unit may be safely operated with one relief valve inoperable.
Corrective Action The relief valve PCV-1-18 will be removed and replaced with another valve at the earliest opportunity, should it be determined that the bellows is defective. If the pressure switch is found to be defective, it will be changed out and the valve
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Failure Data Manufacturer--Target Rock Corporation Hempstead, Long Island, New York TypeValve--Safety /reliefvalve Model 67F Pilot operated Size--Inlet Flange = 6" Outlet Flange = 10" Serial No.--35 Setpoint--1,090 psi Capacity--800,000 lb/hrsaturatedsteam S
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