05000298/LER-1982-011, Forwards LER 82-011/03-0.Detailed Event Analysis Submitted

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Forwards LER 82-011/03-0.Detailed Event Analysis Submitted
ML20054G236
Person / Time
Site: Cooper Entergy icon.png
Issue date: 06/11/1982
From: Lessor L
NEBRASKA PUBLIC POWER DISTRICT
To: Jay Collins
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20054G237 List:
References
CNSS820352, NUDOCS 8206210305
Download: ML20054G236 (2)


LER-2082-011, Forwards LER 82-011/03-0.Detailed Event Analysis Submitted
Event date:
Report date:
2982082011R00 - NRC Website

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CNSS820352 June 11, 1982 Mr. John T. Collins, Regional Administrator U.S. Nuclear Regulatory Commission i Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 760l1

Dear Sir:

This report is submitted 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 May 14, 1982. A licensee event report form is also enclosed.

Report No.: 50-298-82-11 Report Date: June 11, 1982 Occurrence Date: May 14, 1982 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition occurred which resulted in operation in a degraded mode permitted by a limiting condition for operation established in RTS 3.7.D, Table 3.7.1 of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was operating at 84% of rated thermal power.

Description of Occurrence:

While performing Surveillance Procedure 6.3.1.4 (Timing and Op-erability Test), recirculation system sample isolation valve RR-740AV failed to close.

Designation of Apparent Cause of Occurrence:

The apparent cause of the occurrence was the failure of the sol- \

enoid pilot valve on the control air supply to RR-740AV.

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Mr. John T. Collins June 11, 1982 Page 2.

Analysis of Occurrence:

RR-740AV is the outboard isolation valve on the recirculation system reactor water sample line. The solenoid pilot valve that controls the air to the air operator on RR-740AV is an ASCO Model 832094 three-way solenoid valve. The air operator of RR-740AV opens the valve when pressurized with air. Spring pressure closes the valve when it is not pressurized. During the performance of Surveillance Procedure 6.3.1.4, RR-740AV failed to close properly.

During the investigation of this problem, the solenoid pilot valve was discovered to have a dirty slug inside the solenoid mechanism.

It is believed that this condition caused the slug to jam, pre-venting the solenoid from working properly to exhaust the air pressure from the air operator on RR-740AV. This solenoid valve was placed in service in 1980 as part of the preventative main-tenance program. To date this failure is unique. The control air line is equipped with an air regulator and a moisture separator which ensure that the control air supply is clean and dry. We do not believe therefore, that the control air system was the source of the dirt present in the solenoid valve. How the dirt was in-troduced into the valve is unknown.

RR-740AV is a normally open isolation valve which closes on a containment isolation signal. The redundant valve, RR-741AV, was operable so primary containment isolation capability was main-tained. This occurrence presented no adverse consequences from the standpoint of public health and safety.

Corrective Action:

The solenoid pilot valve, ASCO Model 832094, was removed and a new ASCO Model 832094 was installed. The Surveillance Procedure 6.3.1.4 was amended to include RR-740AV in a monthly cycle test instead of quarterly so that possible future failures may be de-tected sooner.

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

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