ML19343A795

Forwards LER 80-040/03L-0

ML19343A795
Person / Time
Site:	Cooper
Issue date:	11/07/1980
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19343A796	List: ML19343A795 ML19343A798
References
CNSS800685, NUDOCS 8011210488
Download: ML19343A795 (2)

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COOPER NUCLEAR STATION s

i a Nebraska Public Power District "" " * "A"E 7"~WM;"!,".i.^n" "

%i CNSS800685 November 7, 1980 h d.,

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Mr. K. V. Seyfrit, Director 5Q 7 y U.S. Nuclear Regulatory Commission ^Q gg Office of Inspection and Enforcement g N g Region IV g a 3

611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Dear Sir:

This report is submitted in accordance with Section 6.7.2.B.2 of the Technical Specifications for Cooper Nuclear Statio'n and discusses a reportable occurrence that was discovered on October 17, 1980. A li-censee event report form is also enclosed.

Report No.: 50-298-80-40 Report Date: November 7,1980 Occurrence Date: October 17, 1980 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition which could have prevented the performance of an in-tended safety function of a portion of an engineered s3fety feature system. Tha 4160 V breaker 1FS would not close automatically as required by Technical Specification 3.9.A.1.

Conditions Prior to Occurrence:

Steady state power operation at 99% thermal power. The normal transformer, the startup transforect, and the emergency transformer were energized. Both diesel generators were operable.

Description of Occurrence:

At approximately 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on October 17, 1980, a control room operator noticed that the white light above control switch 1FS on BD-C was not lit. This white light,-when on, indicates that 4160 V breaker 1FS is ready to close automatically if either breaker IFA or 1AF trip or an undervoltage condition occurs on 4160 V bus IF.

8011219N 3

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L Mr. K. V. Seyfrit-November 7,1980 Page 2.

Designation of Apparent Cause of Occurrence:

The apparent cause of this occurrence has been attributed'to im-i proper makeup of the auxiliary contact 1-lT in breaker EGl.

Analysis of Occurrence:

Breaker 1FS ties 4160 V bus IF to the emergency transformer if 4160 V bus IF becomes de-energized. Since the normal and the startup transformers were energized and breakers 1FA and LAF closed, 4160 V bus.lF remained energized. Redundant bus 1G and its associated breakers remained operable. This occurrence did not disable manual control of breaker 1FS and presented no adverse potential conse-quences from the standpoint-of public health and safety.

Corrective Action:

The auxiliary switch operating linkage was lubricated and manually operated several times to insure free operation of the mechanism.

This auxiliary switch and associated operrting linkage on all 4160 V breakers will be replaced with SB-1 switches at the first sched-uled refueling outage after parts are available.

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

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