ML20085G947

AO BFAO-50-259/7454W:on 741010,main Steamline D Inboard Isolation Valve FCV-1-51 Failed to Close within Tech Spec Limits.Cause Under Investigation.Drywell Entry Will Be Made When Possible to Determine & Correct Problem

ML20085G947
Person / Time
Site:	Browns Ferry
Issue date:	10/18/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085G949	List: ML20085G947 ML20085G952
References
NUDOCS 8308290533
Download: ML20085G947 (2)

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, TENNESSEE VALL ,

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October 18, 1974

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77 {% h[e]l g$hg' %M Mr. Edson G. Case <s k . .k # ^( '/ , ,

Acting Director of Licensing * \

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. , U.S. Atomic Energy Co=nission Washington, DC 20545

Dear Mr. Case:

TENNESSEE VALLEY AUTHORITY - BR0'dNS FERRY ITUCLEAR PLANT UNIT 1 -

i DOCKET NO. 50-259 - FACILITY OPERATING LICENSE DPR ABNORMAL OCCURRENCEREPORTBFAO-50-259/7454W i

, The enclosed report is to provide details concerning FCV-1-51 main steamline "D" inboard isolation valve which failed to close within 3 to 5 seconds as required by the technical specifications and is submitted in accordance with Appendix A to Regulatory Guide 1.16, i Revision 1, October 1973. This event occurred on Browns Ferry Nucicar Plant unit 1 on October 10, 1974 Very truly yours,.

TENNESSEE VALLEY AUTHORITY

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1 rector of Power Production.

, Enclosure CC (Enclosure): .

Mr. Norman C. Ibseley, Director Region II Regulatory Operations Office, USAEC

230 Peachtree Street, NW., Suite 818 4 Atlanta, Georgia 30303 '

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. ABNORMAL OCCURRENCE REPORT

• Report No.: BFAO-50-259/7454W Report Date: October 18, 1974 Occurrence Date: October 10, 1974 Facility: Browns Ferry Huclear Plant unit 1 Identification of Occurrence FCV-1-51 main steamline "D" inboard isolation valve failed to close within 3 to 5 seconds as required by the technical specifications.

Conditions Prior to Occurrence The reactor was at approxi=ately 70-percent power.

Descriution of Occurrence While conductire a surveillance test, FCV-1-51 closed in 2.7 seconds.

Designation of Arcarent Cause of Occurrence The reactor has been operated continuously since the occurrence; therefore, no drywell entry has been =ade to deternine the cause.

Analysis of Occurrence The inboard isolation valve FCV-1-51 was closed and rc=ained closed until a temporary technical specification change was obtained. There were no adverse effects on the health or safety of the public as a result of this occurrence.

Corrective Action A dryvell entry vill be made at the earliest opportunity to detemine and correct the cause of the problem. A tcroorar/' change of the technical specifications was c.btained to permit operation with closure time as low as 2 seconds providing the average of the fastest valve of each pair in all four re.in steamlines is greater than 3.0 seconds.

Failure Data See Abnomal Occurrence Reports: BFAO-50-260/7412W, unit 2 BFAO-7438W, unit 1 BFAO-7412W, unit 1 BFAO-742W, unit 1 Valve Data 26" main steam isolation valve Manufacturer: Atwood and Morrill Company, Salem, Massachusetts Valve drawing No.: 20851-H, Sheets 1 and 2

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