05000302/LER-1979-107-03, /03L-0:on 791120,following Routine Pressurizer Sampling,Chemical Addition Isolation Valve Would Not Close. Caused by Inadequate Design.Installed Mod 79-11-81 Providing Pneumatic Assist During Valve Closing

/03L-0:on 791120,following Routine Pressurizer Sampling,Chemical Addition Isolation Valve Would Not Close. Caused by Inadequate Design.Installed Mod 79-11-81 Providing Pneumatic Assist During Valve Closing

ML19260C363
Person / Time
Site:	Crystal River
Issue date:	12/12/1979
From:	Lancaster K FLORIDA POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19260C359	List: 05000302/LER-1979-107, Forwards LER 79-107/03L-0 05000302/LER-1979-107-03, /03L-0:on 791120,following Routine Pressurizer Sampling,Chemical Addition Isolation Valve Would Not Close. Caused by Inadequate Design.Installed Mod 79-11-81 Providing Pneumatic Assist During Valve Closing
References
LER-79-107-03L, LER-79-107-3L, NUDOCS 7912260243
Download: ML19260C363 (2)

LER-1979-107, /03L-0:on 791120,following Routine Pressurizer Sampling,Chemical Addition Isolation Valve Would Not Close. Caused by Inadequate Design.Installed Mod 79-11-81 Providing Pneumatic Assist During Valve Closing

Event date:
Report date:
3021979107R03 - NRC Website

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avsurgescasm,:n Ano aceaskaccasscutNess@f the pressurizer, it was discovered that 0050 following routine sampling o I

g,At Chemical Addition Isolation Valve CAV-2 would not close. This created an event gana-,'

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[ contrary to Technical Specification 3.6.3.1.

No effect unon tha n1,nr w o

ipublic. CAV-2 was closed manually and the valve operator was disabled. This is !

,the fifth occurrence reported for CAV-2.

Reference LER 77-36, 78-14, 79-37. and i

79-105.

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, tion 79-7-5 resulted in the installation of Modification 79-11-81 which providest

,,a pneumatic assist during valve closing operation.

The modification was com-t pleted and CAV-2 was returned to service at 1715 on 4 December 1979.

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' Name of preparer:

K. F. Lancaster

. (904 795-6486 (SEZ Al"'m SUP?TmrIA3I DECIL.AIICN SM) 7912260~ p/ 3

SUPPLEMENTARY INFORMATION Report No.:

50-302/79-107/03L-0 Facility:

Crystal River Unit #3 Report Date:

12 December 1979 Occurrenca Date:

20 November 1979 Identification of Occurrence:

Reactor Building Isolation Valve CAV-2 inoperable contrary to Technical Specification 3.6.3.1.

Conditions Prior to Occurrence:

Mode 1 power operation (100%).

Description of Occurrence:

At 0050 following routine sampling, it was discovered that Chemical Addition Isolation Valve CAV-2 would not close.

CAV-2 was closed manually and the valve operator disabled at 0052. An engineering evaluation activated from a previous event resulted in modification 79-11-81.

The modification was completed on 3 December 1979. CAV-2 was returned to service at 1715 on 4 December 1979 after satisfactorily completing Surveillance Procedure SP-370.

Designation of Apparent Cause:

The cause of this event is attributed to improper design.

Engineering evaluation revealed that the closing spring force was inadequate during valve closing operation.

The inadequacy of the spring is produced by an imbalance of forces acting on opposite parts of the valve seat when the valve is pressurized. The resultant upward force prevented the valve from closing.

Analysis of Occurrence:

No effect upon the plant or general public.

Corrective Action

Modification 79-11-81 provided a pneumatic device for an interim period to assist CAV-2 during valve closing operations.

Engineering work is progressing on the recommended permanent modification.

Failure Data:

This is the fifth occurrence of this reported for CAV-2.

Reference LER's 77-36, 78-14, 79-37, and 79-105.

1617 135

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