ML19323F220

Forwards LER 80-011/03L-0

ML19323F220
Person / Time
Site:	Cooper
Issue date:	05/12/1980
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19323F221	List: ML19323F220 ML19323F224
References
NUDOCS 8005280667
Download: ML19323F220 (2)

Text

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\ COOPER NUCLEAR STATION

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• h 'e" O !'I M 0 !!." ^1i W)TL2a Nebraska Public Power District CNSS800260 May 12, 1980 _-

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vr pil MAY I 61980 Mr. K. V. Seyfrit i )i U.S. Nuclear Regulatory Comnission i' ~

Office of Inspection and Enforcement .

Region IV 611 Ryan Plaza Suite 1000 Arlington, Texas 76011

Dear Sir:

"his report is submitted in accordance with Section 6.7.2.B.2 of the i Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on April 18, 1980. A licensee event report form is also enclosed.

Report No.: 50-298-80-11 Report Date: May 12, 1980 Occurrence Date: April 18, 1980 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 ,

Identification of Occurrence:

A condition which could have resulted in operation in a degraded mode established by a limiting condition for operation, Technical Specification 3.5.E.1.

Conditions Prior to Occurrence:

The plant was shutdown for refueling and maintenance.

Description of Occurrence:

While performing surveillance procedure 6.2.2.2.6 to verify the ability of the ADS to perform as described in the FSAR (Vol. III, Section 3.3.1), three of the six check valves upstream of the accumulators failed to hold the minimum pressure required in the procedure.

Designation of Apparent Cause of Occurrence:

The failure of the check valves was due to embrittlement of the

BUNA-N seats with age.

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soosu8o647 __5

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l Mr. K. V. Seyfrit May 12, 1980 Page 2.

Analysis of Occurrence:

The ADS accumulator check valves are DRAGON Model C12057R lift check valves. The valves permit instrument air to flow to the MSRV actuators during normal valve operation and prevent back flow of air when instrument air is lost and the accumulator is supplying air for MSRV actuation. If the check valves fail to seat upon loss of instrument air, the ability to actuate the ADS will be lost.

Since instrument air has never been lost during the operation of the plant, the ADS has always been operable. Additionally, bottled nitrogen acts as a backup source to the ADS accumulators. Conse-quently, this event presented no major consequences which were adverse to the public health and safety.

Corrective Action:

The six ADS check valves were removed from the system and new seats made of ethylene propylene material were installed. The valves were then bench tested and returned to the system. Following reassembly, surveillance procedure 6.2.2.2.6 was satisfactorily completed.

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