ML20084H900
| ML20084H900 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/25/1974 |
| From: | Eric Thomas TENNESSEE VALLEY AUTHORITY |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084H899 | List: |
| References | |
| AO-BFAO-7417W, NUDOCS 8305060125 | |
| Download: ML20084H900 (2) | |
Text
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M Mr. John F. O' Lee.ry, Director
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U.S. Atomic Energy Co=nission
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Dear Mr. O' Leary:
TENITESSEE VALLEY AUTHORITY - BRCWNS FERIE UUCLEAR PLANT UNIT 1 -
DOCKET NO. 50-259 - FACILITY OPERATING LICENSE DPR ABNORl'AL OCCURRENCE REPORT BFAO-7417W The enclosed report is to provide details concerning failure of suppression chamber to drywell vacuum breaker valve FCV 64-28M to fully close as indicated by a check light which occurred on Browns Ferry nuclear Plant unit 1 on March 15, 1974, and is submitted in accordence with Appendix A to Regulatory Guide 1.16, Revision 1. October 1973.
Very truly yours, TENNESSEE VALLEY AUTHORITY
[
E. F. Thomas Director of Power Production Enclosure CC (Enclosure):
Mr. Norman C. Moseley, Director Region II Regulatory Operations Office, USAEC.
230 Peachtree Street, UW., Suite 818 Atlanta, Georgia 30303 1
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COPY SENT REGION 7
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O ABNORIRL OCCURRENCE REPORT Report No.:
BFAO-7417W Report Date: March 25, 1974-Occurrence Date':
>* arch 15, 1974 Facility: Browns Ferry Nuclear Plant unit 1 Ideatification of Occurrence
- Failure of suppression chamber to,drywell vacuum breaker valve FCV 64-28M to full,y close as indicated by a check light.
Conditions Prior to Occurrence The reactor was shut down and in hot standby at 880 psig.
Description of Occurrence At 8:30 p.m., following the completion of special test 29, it was discovered that the green check light for suppression chamber to drywell vacuum breaker valve FCV 64-28M failed to come back on when the valve operated. The other indicating lights for FCV 64-28M operated properly.
Designation of Armorent Cause of Occurrence The exact cause of the failure cannot be determined until the vacuum breaker valve inside the suppression chamber can be investigated.
Analysis of Occurrence The vacuum breaker is equipped with switches indicating disc opening.to approximately 80 degrees open and 3 degrees open and a check switch which indicates full,y closed. The vacuum breaker ve.lve is considered inoperable for full closure only because the valve position indicating li hts confirmed 5
opening and closure to within 3 decrees of fully closed. This is an allowable condition for reactor operation in accordance with technical specification 3.7.A.4.b.
Corrective Action Our investigation indicates that the check light circuit is open. Therefore, either the valve is not fully closed or the limit switch is out of adjustment
. or defective. A previous failure of an identical limit switch in this same location occurred February 21, 1974, and was reported in BFAO-7411W. During an outaco following that occurrence, the switch actuating plunger _was, found to be sticking. The switch was replaced with a new switch and the vacuum breaker valvi~6porated several tir.as satisfactorily. The valve and circuitry will be inspected end repairs made at the earliestopportunity-when suppression chamber entry can be made.
' Failure Data, Failure data will be reported when'the c'ause of the failure has been determined.
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