ML19305E822

Forwards LER 80-009/03L-0

ML19305E822
Person / Time
Site:	Cooper
Issue date:	04/28/1980
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19305E823	List: ML19305E822 ML19305E825
References
NUDOCS 8005200476
Download: ML19305E822 (2)

Text

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COOPER NUCLEAR $TATtoN Nebraska Public Power District ""

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CNSS800274 April 28, 1980 Mr. K. V. Seyfrit U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Suite 1000 Arlington, Texas 7,6011

Dear Sir:

This report is submitted in accordance with Section 6.7.2.B.4 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on March 29, 1980. A licensee event report form is also enclosed.

Report No.: 50-298-80-09 Report Pate: April 28, 1980 Occurrence Date: Sbrch 29, 1980 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

Degradation of the Reactor Equipment Cooling (REC) system piping.

Conditions Prior to Occurrence:

Reactor shutdown for scheduled refueling.

Description of Occurrence:

During a routine plant tour, a pin hole leak was discovered in the REC System on the upstream side of the isolation valve for the Reactor Equipment Cooling non-critical header.

1 Designation of Apparent Cause of Occurrence. j The apparent cause of the weld failure was intergranular cracking, l characteristic of intergranular stress corrosion in an environment

- l of NO3 and/or OH . The presence of the backing ring crevice in combination with the specialized water chemistry of this system is considered the major contribution to the failure.

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Mr. K. V. Seyfrit April 28, 1980 Page 2.

Analysis of Occurrence:

The REC System supplies cooling water to various essential com-ponents. In the event that the weld had failed completely, it could have been isolated from the essential portion of the system.

Thus, it would not have prevented the reactor from being safely shutdown. Additionally, the essential portion of the REC System has redundant loops for supplying cooling water to critical eq-uipment.

This occurrence presented no adverse consequences from the stand-point of public health and safety.

Corrective Action:

The subject w' eld will be replaced prior to startup. The evaluation of the failure mechanism is being further analyzed by the General Electric Company so that a recommended solution to this problem can be obtained. When their final recommendations are received, they will be reviewed and corrective action taken based upon their recommendations.

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

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