ML20085L955
| ML20085L955 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/07/1974 |
| From: | Eric Thomas TENNESSEE VALLEY AUTHORITY |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085L959 | List: |
| References | |
| AO-BFAO-7412W, NUDOCS 8311070046 | |
| Download: ML20085L955 (3) | |
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TENNESSEE VALLEY AUTHO AlW C'T 77.
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Mr. John F. O' Leary, Director Directorate of Licensing Office of Regulation U.S. Atomic Energy Co==ission Washington, DC 20545
Dear Mr. O' Leary:
TEliNESSEE VALLEY AUDIORITY - BROWNS FERRY NUCLEAR PLANT UNIT 1 -
DOCKET NO. 50-259 - FACILITY OPERATING LICENSE DPR ABNORMAL OCCURRENCE REPORT BFAO-7412W The enclosed report is to provide details concerning FCV-1-27 =ain steeHne B outboard isolation valve that closed more rapidly than the 3-to 5-second range recuired by technical specifications which occurred on Browns Ferry Nuclear Plant unit 1 on February 26, 1974,
'and'.is,,subm;Ltted,in,' accordance.with Appendix 4,to.', Regulatory Guide. 1.,.,,
t 1.16, Revision 1, October 1973 Very truly yours, r
TEt1NESSEE VALLEY AUTHORITY h:
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Enclosure kV CC (Enclosure):
Mr. Norman C. Moseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtree Street, NW., Suite 818 Atlanta, Georgia 30303 p
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ABNORMAL OCCURRENCE REPORT Report No.: BFAO-7412W Report Date: March 8, 1974 Occurrence Date: February 26,1cf74 Facility: Browns Ferry Nuclear Plant unit 1 Identification of Occu rence FCV-1-27 min stennline B outboard isolation valve closed more rapid 3y than the 3-to 5-second range required by technical specifications.
Conditions Prior to Occurrence The reactor was operating at approbrately 69-to 70-percent power. Startup test 25 was in progress for the first time at this power level. This test required the MSIV's to be closed one at a t4-a to observe transient response, to functionally test the valves, and to verify that the valve closing time was within the 3-to 5-second range specified in the technical specifications.
Description of Occurrence Main stennline isolation valve FCV-1-27 was actuated twice with closure times of 2.4 and 2.5 seconds during testing.
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,. Designation of Arcarent Canse.of.0ccurrence.
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.s Ioss of oil frem le*4 3 oil piping on the valve dashpot is believed to be the cause of the occurrence.
Analysis of Occurrence Unit 1 reactor is still in the startup phase and startup test 25 tested the IsIV's for the first time at this power level. The power increase experienced from closure of the other valves which were within the 3-to 5-second closure time period during this test was cpproximately 10 percent. The power increase experienced with the slightly faster closure of FCV-1-27 was in the range of 11 to 12 percent. This 3-to 2-percent difference is. inconsequential relative to safe operating limits. If en isolation signal had required the valve to close and had the valve failed to close conpletely, the redundant inboard valve would have provided the required isolation.
Corrective Action A steam tunnel entU vas made during unit operation on February 26, 1974, and the Auto-Ponent flow control valve was adjusted to restore the valve closure time to acceptable li=its.
On March 4, during the subsequent unit shutdown for relief valve modification.
the.13IV's were operated and the B outboard isolation valve indicating lights showed that the valve failed to close fully. Subsequent investigation revealed
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. -E Corrective Action (continued) that this was due to a combination of low oil level and the speed control valve being in the near full closed position. The leaking dashpot oil lines were repaired. The dashpot oil reservoir level was checked and found to be low of oil. Approximately one gallon of oil was added. The isolatio.n valve was
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then vented and' stroked several times. The isolation valve operated satisfactorily and was time set to 4.5 seconds. The remining seven isolation valve dashpots and piping were inspected for leaks. No indication of leakage was found.
Failure Data See previous report EF1.0-742W. Two w in steam isolation valves (FCV-1-26 and FC7-1-51) failed to =eet the 3-to 5-second closing time on January 8, 1974, on unit 1.
Valve Data:
1.
3/4" Auto-PonentFlowControlValve, Knob-Type; Auto-PonentDrawing No. FK-750, 2.
26" P.ain Stea= Isolation Valve:
Manufacturer:
Atwood & Morrill Company Sales, Passachusetts
-Yal've Drawing. Ro'.. 20851-H, Sheetai and -2 '
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