ML19337B557

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Forwards LER 80-033/03L-0
ML19337B557
Person / Time
Site: Cooper Entergy icon.png
Issue date: 09/08/1980
From: Lessor L
NEBRASKA PUBLIC POWER DISTRICT
To: Seyfrit K
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19337B559 List:
References
CNSS800548, NUDOCS 8010070296
Download: ML19337B557 (2)


Text

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[,[' COOPER NUCLEAR STATION

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$, . ii,'{ Nebraska Public Power District

  • 9'A*l *oOAhn*ffi CNSS800548 September 8, 1980

' Mr. K. V. Seyfrit, Director U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011 Dear Sir

  • 1 1

This report is submitted in accordance with Section 6.7.2.B.2 of the '

Technical Specifications for Cooper Nuclear Station and discusses a  ;

reportable occurrence that was discovered on August 28, 1980. A li- l censee event report fort is also enclosed.

Report No.: 50-295-80-33 Report Date: September 8,1980 Occurrence Date: August 28, 1980 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition which resulted in operation in a degraded mode per-mitted by the limiting condition for operation established in Section 3.7.D.2 of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was at a steady state power level of approximately 99%

of rated thermal power.

Description of Occurrance:

Dering routine . cveillance, PC-232MV, drywell ventilation supply line inboard isolation valva, failed in mid-position and would not open or close.

Designation of Apparent Cause of C:currence:

The motor operator is a Limitcrque SMB-00. Examination of the geared limit switches revealed that the melamine coated contact cam -

was broken where it was pinned to the drive shaf t. 4 80 f>J 10 0 7 o;2% S S//

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Mr. K. V. Seyfrit '

September 8, 1980 Page 2.

Analysis of Occurrence: {

PC-232MV is the drywell ventilation supply line inboard isolation I valve. PC-238AV is the outboard backup valve. These valves are used to shut off the air ventilation supply line tc isolate primary containment. If either valve fails the other can be closed to isolate the line. This was done when PC-232MV failed to operate.

PC-232MV can also be closed manually, if necessary. ThiI line could have been isolated if required. Consequently, this occur-i rence presented no adverse consequences from the standpoint of public health and safety.

The limit switch assembly of the operator was carefully inspected.

No particular reason for the failure was determined. A similar event occurred in November 1978 (LER 79-39).

Corrective Action:

The operator cam was replaced with an identical melamine coated spare cam. The broken cam has been sent to the manufacturer, Limitorque Corporation, for analysis. An updated report will be issued upon completion of the analysis.

Sincerely,

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

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