05000298/LER-1979-022, Forwards LER 79-022/03L-0

Forwards LER 79-022/03L-0

ML19208D440
Person / Time
Site:	Cooper
Issue date:	09/07/1979
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19208D441	List: 05000298/LER-1979-022, Forwards LER 79-022/03L-0 05000298/LER-1979-022-03, /03L-0:on 790812,water from Carbon Absorber Housing of Standby Gas Treatment Sys a Sprayed Carbon Absorber Trays,Rendering Trays Inoperable.Caused by Inadequate Seating Area Between Valve Clapper & Latch
References
CNSS790421, NUDOCS 7909280431
Download: ML19208D440 (2)

LER-1979-022, Forwards LER 79-022/03L-0

Event date:
Report date:
2981979022R00 - NRC Website

text

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Coo ER NUCLEAR 5T ATioN P.o. box 98 BRoWr4VILLE. NEBR ASKA 68321 Nebraska Public Power Distn. t TEcEaso~E mn.m.n c

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CNSS790451 September 7, 1979 Mr. K. V. Seyfrit U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Suite 1000 Arlington, Texas 76011

Dear Sir:

This report is submitted in accordace.e with Section 6.7.2.B.2 of the Technical Specifications for Cooper NuclcRr Station and discusses a reportable occurrence that was discovered on Au c-r 12, 1979. A li-s censee event report form is also enclosed.

Report No.:

50-298-79-22 Report Date:

September 7, 1979 Occurrence Date: August 12, 1979 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition which resulted in operation in a degraded mode per-mitted by a limiting condition for operation established in Section 3.7.B.3 of the Technical Specifications.

Conditions Prior to Occurrence:

Reactor was operating at approximately 78% of rated thermal power.

Description of Occurrence:

A station operator observed water coming out of the carbon adsorber housing for Stando'y Gas Treatment System "A".

Upon further inspec-tion the carbon adsorber within the housing was found to have been sprayed by the fire protection deluge system with water.

Designation of Apparent Cause of Occurrence:

The apparent cause nf the occurrence has been attribut2d to in-adequate latching surface area between the deluge valve clapper and latch allowing the clapper to open and spray the carbon adsorber.

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Mr. K. V. Seyfrit September 7, 1979 Page 2.

Analysis of Occurrence:

The function of the Standby Gas Treatment System is to filter the atmoapheric effluent from the primary and secondary containments to limit the radioactive release to the environment.

The deluge system was designed to extinguish any fire in the carbon adsorber due to high loading of radioactive iodine resulting from a postulated accident involving significant release of radioactive iodine and thus prevent re-release of radioactive iodine due to oxidation of the carbon adsorber. The wetting of the carbon adsorber resulted in reduced capability of the carbor. adsorber to remove radioactive iodine from the air.

The surface area between the latch and the clapper was insuffi-cient, allowing some wear induced by the normal pressure variations in the water supply system. This allowed the clapper to open after a minimal amount of wear had occurred.

The redundant system.

Standby Gas Treatment System "B",

was operable during this occur-rence.

This occurrence presented no adverse consequences from the standpoint of public health and safety.

Corrective Action

The deluge valve clapper and latch assembly were replaced and adjusted to insure that adequate seating area was established between the latching surfaces. The carbon adsorber was dried out.

The deluge system for Standby Gas Treatment System "A" was placed in service and no leaks were evident. Upon conpletion of a func-tion test of the deluge valve and a Standby Gas Treatment Oper-ability Test, Surveillance Procedure 6.3.19.1, Standby Gas Treat-ment System "A" was declared operable.

The remaining plant deluge valves will be inspected for leakage during the next annual in-spection.

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

1033

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