05000298/LER-1980-046, Forwards LER 80-046/03L-0

Forwards LER 80-046/03L-0

ML20002B974
Person / Time
Site:	Cooper
Issue date:	12/15/1980
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20002B975	List: 05000298/LER-1980-046, Forwards LER 80-046/03L-0 05000298/LER-1980-046-03, /03L-0:on 801117,isolation Valve on Discharge Line from Drywell Equipment Sump G, RW-A0-94,would Not Open. Caused by Hard & Worn U-cup Seal in Piston Air Operator. New Piston U-cups Installed & Valve Retested
References
CNSS800703, NUDOCS 8101070477
Download: ML20002B974 (3)

LER-1980-046, Forwards LER 80-046/03L-0

Event date:
Report date:
2981980046R00 - NRC Website

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COOPER NUCLEAR STATION 3y CNSS800703 December 15, 1980 7

Mr. K. V. Seyfrit, Director U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV C;

611 Ryan Plaza Drive U

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Suite 1000 Arlington, Texas 76011

Dear Sir:

This report is subeitted in accordance with Section 6.7.2.B.2 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on November 17, 1980. A licensee event report form is also enclosed.

Report No.:

50-298-80-46 Report Date:

December 15, 1980 1

Occurrence Date: November 17, 1980 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition resulting in operation in a degraded mode as permitted by the limiting condition for operation established in Section 3.7.D.2 of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was in cold shutdown.

Description of Occurrence:

During performance of Surveillance Procedure 6.3.1.4, an isolation.

valve on a discharge line from the drywell equipment sump "G" (RW-AO-94), would not open af ter being closed.

Designation of Apparent Cause of Occurrence:

The apparent cause of this occurrence was a hard and worn U-cup seal in the piston air operator.

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1 Mr. K. V. Seyfrit December 15, 1980 Page 2.

Analysis of Occurrence:

RW-AO-94 is the inboard isolation valve on the discharge line from drywell equipment drain sump "G".

This valve is a normally open valve and cicses on an initiation signal. The valve functioned properly during the surveillance procedure with respect to going closed. However, it would not reopen.

KR-AO-95 is the outboard isolation valve and was tagged closed following this occurrence.

RW-AO-94 is operated by a piston cylinder type air operator (Miller-64A) with a solenoid pilot valve which controls the air flow to the air operator.

RR-AO-94 :an also be manually operated with a hand-wheel.

At the time of this occurrence, the subject air operator would not open after it was closed with its control switch. The solenoid pilot valve was tested and found to be operational. The piston cylinder was disassembled and the piston U-cup seals were found to be hard and worn.

This is the second recent occurrence relating to this type of valve operator (reference LER 80-36).

In the previous occurrence it was determined that the valve op-I erator was sluggish due to staying in one position for a long period of time. The stated resolution of this problem was to increase cycle frequency and it is believed that this action has assisted in resolving the sluggish operation situation.

t This occurrence was initiated due to a hardened "U" cup seal on the piston. The subject valve operator had been in operation six years prior to this occurrence.

Based on this evaluation, it is apparent

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that the "U" cup seal material does not maintain its resilience for a long period of time. The recommended resolution of this occur-rence is to initiate a preventative maintenance program for air operators since there has been an increasing failure occurrence for these types of components.

This occurrence had no adverse affect on the public health and safety.

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Corrective Action

The solenoid pilot valve associated with the subject air operator l

was inspected and tested satisfactorily. The subject air operator l

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Mr. K. V.

Seyfrit December 15, 1980 Page 3.

was tested per Surveill:nce Procedure 6.3.1.4 after the new piston U-cup seals were installr' and RW-AO-94 was placed back into ser-vice. A preventative maintenance schedule for primary containment valves using the subject type of air operator has been established.

Sincerely.

L. C. Lessor Station Superintendent Cooper Nuclear Station LCL:cg Attach.