ML20084H408

AOs BFAO-50-260/747W & BFAO-50-260/7410W:on 740814 & 21, FCV 1-52 & Fvc 1-27 Outboard Containment Isolation Valves in Steamlines B & D,Respectively,Failed to Open When Manually Actuated.Caused by Foreign Particles

ML20084H408
Person / Time
Site:	Browns Ferry
Issue date:	09/06/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084H411	List: ML20084H408 ML20084H413
References
NUDOCS 8305040119
Download: ML20084H408 (3)

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o_ o 1n TENNESSEE VALLEYTENNESSEE CHAa a ANOOGA, AUTHORITY il EMU/ /" .

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Acting Director of Licensing 4 " p.. Q j D Office of Regulation Q Wi' A N( Qg [ir.('.'f U.S. Atomic Energy Cc= mission j Washington, DC 20545 '

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Dear Mr. Case:

TENNESSEE VALLEY AUIHORITY - BRGIUS FERRY UUCLEAR PIANT UNIT 2 -

DOCKET NO. 50-260 - FACILITY OPERATING LICEUSE DPR ABNORl/AL OCCURRENCE REPORTS EFAO-50-260/747if AND BFAO-50-260/741G1 Please refer to rv letter to Mr. John F. O' Leary dated August 23, 1974, on this sub, ject.

The enclosed report is to provide' details concerning valves FCV l-52 and FCV 1-27 which failed to open when ranually actuated and is submitted in accordance with Appen.11x A to Regulatory Guide 1.16, Revision 1, October 1973 These events occurred on Browns Ferry Nuclear Plant unit 2 on August 14 and August 21 1974, respectively.

3 Very truly yours, TENNESSEE VALLEY AUTHORITY

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E. F. Thomas

/gfDirect;or of Power Production Enclosure CC(Enclosure):

Mr. Norran C. Moseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtree Street, IM., Suite 818 Atlanta, Georgia 30303 i

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• Report flo.: Final Report for BFAO-50-260/7474 and IFAO-50-260/7410R September 6, 1974 Report Date:

Occurrence Date: August 14 and August 21, 1974, respectively Facility: Browns Ferry IIuclear plant unit 2

. . Identification of Occurrence On August 14 and 21,1974, unit 2 valves FCV l-52 and FCV l-27 failed to open when manually actuated. Thece valves are the cutbcard ecntainment isolaticn valves in steamlines "D" and "B," respectively.

Conditionc Prior to Occurrence i

i The reactor was in a chutdcun condition with reactor pressure at approximately 100 psig when FCV l-52 failed and still in shutdown ecndition, but at atmospheric pressure, when FCV l-27 failed.

Designatien of Arparent Cause of Occurrence Invest $gation revealcd that the poppets of both valves had beccme wedged in the valve bodies. This wed;ing vac apparently initiated by fcreign particles beccming trapped between the bearing surfaces of the poppets, and valve bodies causing metal deformation. A small amount of abrasive caterial was fcund in steamline "B."

Analysis of Occurrence The reactor vac in a shutdown condition at the time and all other MSIV's were operational. There was no unsafe ccnditien since these valves failed in the shut position, and there were no adverse effects on the health and safety of the public as a recult of thece failures.

Corrective Action

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The valves' operator and cover were remaved leaving the valve stem and poppet assembly in the valve body. Jacks were used to remeve the poppets frcm the valve body. The bearing surfaces of the poppets and valves bcdies were Balled on the top side and bottom side,180 apart.

The cutside diameter of the poppets bearing surfaces and incide dinneter of i the valve bodies were teacured and the clearances appeared to be slightly less than current manufacturer tolerances of 0.025" to O.CLO" on the diameter.

l' The poppets were put in a lathe and metal removed to repair bearing surfaces i and bring clearances to within specified tolerances. The valve bores were i also hand-honed where they had been scored. The valvec were reassembled and l all MSIV's were fluched fcr 1 hcur by blewing steam to the condencer thrcugh one line at a time at approximately 5-percent reacter power.

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_ Corrective Action (continued)

The valves were satisfactorily leak tested and closing time adjusted after reassembly. Until ';C-percent pcwcr is re. ached., increased surveillance testing for all unit 2 MSIV's '.:ill be implemented. The valves will be operated weekly and strche time cheched to monitor any changes.

Fai3ure Data .

No previous failuren of this nature have been experienced with these valves.

Valve Data 26-inch Main Steam Isolation Valve Pitnufacturer: Atwood and Morrill Ccmpany, Salen, Fassachusetta Valve Drawin6 Ho.: 20851-H, Sheets 1 and 2

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