05000298/LER-1980-030, Forwards LER 80-030/03L-0

Forwards LER 80-030/03L-0

ML19338C787
Person / Time
Site:	Cooper
Issue date:	08/21/1980
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19338C788	List: 05000298/LER-1980-030, Forwards LER 80-030/03L-0 05000298/LER-1980-030-03, /03L-0:on 800813,during Normal Surveillance Testing of RHR Motor Operated Valves,Rhr Loop B Suppression Pool Cooling Inboard Throttle Valve Would Not Operate.Caused by Failure of Key Between Motor Pinion Gear & Motor Shaft
References
CNSS800515, NUDOCS 8009050284
Download: ML19338C787 (2)

LER-1980-030, Forwards LER 80-030/03L-0

Event date:
Report date:
2981980030R00 - NRC Website

text

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'm COOPER NUCLEAR STATION i%' s Nebraska Public Power District

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.w CNSS800515 August 21, 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:

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 13, 1980. Messrs.

Spangler and Westerman were notified by telephone on August 13, 1980 and an initial notification was telecopied to your office on August 14, 1980 in accordance with the requirements of IE Bulletin 80-17.

A licensee event report form is also enclosed.

Report No.:

50-298-80-30 Report Datt:

August 21, 1980 Occurrence Date: August 13, 1980 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

Conditions which may have led to operation in a degraded mode permitted by a limiting condition for operation as delineated in Section 3.5.B of the Technical Specifications.

Conditions Prior to Occurrence:

Reactor power was at approximately 96% of rated power.

Description of Occurrence:

During routine surveillance testing of RHR motor <perated valves, RHR-MO-34B, the "B" Loop suppression pool cooling throttle valve would not operate.

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8009050 A Y

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Mr. K. V. Seyfrit August 21, 1980 Page 2.

Designation of Apparent Cause of Occurrence:

The operator is a Limitorque SMB-4.

The motor was removed and the key between the motor pinion e.ar and the motor shaft was found sheared.

Analysis of Occurrence:

RHR-MO-34B is the RHR "B" Loop suppression pool cooling inboard throttle valve.

It is a primary containment valve which isolates the torus from the RRR system.

It is a normally closed valve.

If open during LPCI initiation, it receives a close signal. The subject valve failed in the closed position. Had the subject valve failed in the open position, RHR-MD-39B, the outboard isolation valve, would have closed allowing LPCI injection with the "B" Loop.

The torus cooling mode of the "B" Loop of RHR was inoperable, however torus cooling could have been supplied by the "A" RHR Loop.

During this event, both diesel generators and the redundant loop of RHR were operable. This occurrence presented no adverse conse-quences from the standpoint of public health and safety.

Corrective Action

The motor and motor shaft pinion gear key were replaced. The motor shaft was worn due to rotation inside the pinion gest. This is a repetitive occurrence, reference LER's 76-14 and 77-11.

The key has been sent to the manufacturer, Limitorque Corporation, for analysis. An updated report will be issued upon completion of the j

analysis by the Limitorque Corporation.

Sincerely, U.

. Lessor Station Superintendent Cooper Nuclear Station LCL:cg Attach.

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