ML19331E244

Final Interim Deficiency Rept Re 6-inch Borg-Warner Gate Valves.Valves May Fail Due to Error in Design.Gate Could Disengage from Guide,When Valve in Backseat Position.Valve Failure May Lead to RHR Sys Degradation

ML19331E244
Person / Time
Site:	Hartsville
Issue date:	08/29/1980
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:
References
10CFR-050.55E, 10CFR-50.55E, NCR-HNP-A-084, NCR-HNP-A-085, NCR-HNP-A-086, NCR-HNP-A-85, NCR-HNP-A-86, NUDOCS 8009090434
Download: ML19331E244 (2)

Text

TENNESSEE VALLEY AUTHORITY

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400 Nstn$$ StireetNo Sh iI '

August 29, 1980 Mr. James P. O'Reilly, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region II - Suite 3100 101 Marietta Street

. Atlanta, Georgia 30303

Dear Mr. O'Reilly:

HARTSVILLE NUCLEAR PLANT - REPORTABLE DEFICIENCY - DEFICIENT SIX IUCH BORG-WARNER GATE VALVES (NCR 23)

Initial recort of the subject deficiency was made to NRC-0IE, Region II Inspector R. W. Wright on August 1, 1980. In compliance with parar aph 50.55(e) of 10 CFR Part 50, we are enclosing the final report of the subject deficiency. If you have any questions, please call Jim Domer at FTS B57-2014.

Very truly your, TENNESSEE VALLEY AUTHORITY

.% .%24

. M. Mills, Ma nager Nuclear Regulation and Safety Enclosure -

cc: "r. Victor Stello, Director (Enclosure)

Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission ~

'fashington, DC 20555 fot4' 8000090 W An Equal Opportunity Employer

ENCLOSURE

, HARTSVILLE NUCLEAR PLANT A UNIT 1 DEFICIENT 6" GATE VALVES (BORG-WARNER) 10CFR50.55(e)

NCR 23 REPORT NO. 1 (FINAL)

On August 1, 1980, TVA informed NRC-OIE Region II Inspector, R. W.

Wright, of a potentially reportable condition under 10CFR50.55(c) regardir.g deficient 6" gate valves. The valves were manufactured by-Borg-Warner, Nuclear Valve Division, Van Nuys, California, who reported this to NRC-0IE Region V pursuant to 10CFR21. ,This is the final report on this condition.

Description of Deficiency TVA has received two 6" gate valves which may fail due to an error in design. If all worst case tolerances which are specified actually exist, the gate could disengage from the guide when the valve is in the backseat (full open) position. This could render the valve inoperable in the full open position. One valve is located in the Residual Heat Removal (RHR) system and the second valve is in the Drywell Chilled Water system.

Safety Imolications The valve in the RER system is used to align Side II of the RHR system with *he Reactor Core Isolation Cooling (RCIC) system in order to su <1y-condensate to RCIC if needed. For all other modes of RHR system operation this valve is closed. Therefore, failure of this _

valve could lead to the degradation of RER system due to misalignment with RCIC and =3ke it susceptible to a single failure in Side I of RHR which could adversely affect plant safety. ,

The valve in the Drywell Chilled Water system is used as a containment isolation valve. Failure of this' valve in the full open position leaves isolation of that line susceptible to a single failure which could adversely affect plant safety.

Corrective Action The valves will be modified to eliminate the possibility of dis. engagement of the gate from the guide. A stem extension bushing

' will be installed to interface between the stem and the backseat.

TVA anticipates that the valves will be modified by March 1,1981.

This condition only applies to the two valves identified. All valves shipped after January 1, 1979 incorporated a different gate guide location such that this deficiency does not exist.

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