ML20009F025

Forwards LER 81-014/03L-0.Detailed Event Analysis Encl

ML20009F025
Person / Time
Site:	Cooper
Issue date:	06/24/1981
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20009F026	List: ML20009F025 ML20009F033
References
CNSS817077, NUDOCS 8107280614
Download: ML20009F025 (2)

Text

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COOPER NUCLE AR STATION Nebraska Public Power District "" " "*d" ZUM; UU.^>?^ "

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CNSS817077 June 24, 1981

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v Mr. K. V. Seyfrit, Director T- j L' -

T U.S. Nuclear Regulatory Commission JUL 2 71981

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Office of Inspection and Enforcement -

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Region IV cowsm* '

611 Ryan Plaza Drive },^

Suite 1000 -s f

Arlington, Texas 76011 4 m

Dear Sir:

This report is submitted in accordance with Section 6.7.B.2 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on June 8, 1981. A licensee event report form is also enclosed.

Report No.: 50-298-81-14 Report Date: June 24, 1981 Occurrence Date: June 8, 1981 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition occurred which resulted in operation in a degraded mode permitted by the limiting condition for operation established in Section 3.5.C.2 of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was operating at 23% of rated thermal power during a startup from refueling.

Description of Occurrence:

The HPCI pump turbine tripped prior to reaching rated speed and flow.

Designation of Apparent Cause of Occurrence:

The apparent cause of the occurrence was procedural inadequacy.

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8107280614 810624 PDit ADOCK 05000290 S PDR c

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4 Mr. K. V. Seyfrit June 24, 1981 Page 2 Analysis of Occurrence:

The HPCI system is designed to provide a source of high pressure water make-up to the reactor in the event of a small-line break in the nuclear process system boundary.

During routine surveillance testing the HPCI pump turbine tripped prior to reaching rated system flow. Investigation indicated the overspeed trip mechanism was causing the turbine trip. The oil supply to the trip unit was found to be at higher pressure than recommended by the vendor (Terry Steam Turbine). This occurred because the system valve line-up (Operating Procedure 2.2.33) in-dicated that the oil supply valve should be "0 PEN" when in fact the supply valve should be throttled to maintain approximately 20 psig to the trip unit. The excess oil pressure was tripping the turbine before it could attain rated speeds.

The HPCI system was inoperative for 53.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. During this time the redundant system, ADS, was operable as were RCIC and LPCI systems. This occurrence had no adverse effect on the public health and safety. This event is not repetitive.

Corrective Action:

The trip unit oil supply valve was throttled to maintain 20 psig to the unit. The HPCI system was tested and performed satisfactorily.

The Operating Procedure was revised to indicate that the supply valve should be throttled. No further action is planned.

Sincerely, m

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

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