05000298/LER-1980-003, Forwards LER 80-003/03L-0

Forwards LER 80-003/03L-0

ML19294B437
Person / Time
Site:	Cooper
Issue date:	02/06/1980
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19294B438	List: 05000298/LER-1980-003, Forwards LER 80-003/03L-0 05000298/LER-1980-003-03, /03L-0:on 800111,during Valve Realignment Per Special Procedure 80-1,PC-230MV Was Not Closing Completely. Caused by Improper Assembly of Gear Limit Switch in Limitorque Model SMB00 Operator
References
CNSS00084, CNSS84, NUDOCS 8002280374
Download: ML19294B437 (2)

LER-1980-003, Forwards LER 80-003/03L-0

Event date:
Report date:
2981980003R00 - NRC Website

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CNSS800084 February 6, 1980 Mr.

K.

V 3eyfrit U.S. Nuclear Regulatory Conmission Office of Inspection and Erforcement Region IV 611 Ryan Plaza Suite 1000 Arlington, Texas 76011

Dear Sir:

This report is submitted in accordance with Section 6.7.2.3.2 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on January 11, 1980.

A li-censee event report form is also enclosed.

Report No.:

50-298-80-03 Report Date:

February 6, 1980 Occurrence Date: January 11, 1980 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition which lead to operation in a degraded mode permitted by a limiting condition for operation established in Section 3.7.D.2 of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was at a steadv state power level of approximately 98%

of rated chermal power.

Description of Occurrence:

While resetting the open limit switch to limit the valve opening to 45 as required by the NRC (reference letter Thomas A. Ippolito to J. M. Pilant dated October 23, 1979, " Interim Position For Con-tainment Purge and Vent Valve Operation"), PC-230MV was observed to stop closing before the valve was fully closed.

Designation of Apparent Cause of Occurrence:

The cause of this occurrence was attributed to maintenance work done November 29, 1979.

(Reference LER 79-39.)

During this work, the Limitorque geared limit switch was taken apart and apparently reassembled incorrectly.

1/

7 l

4 I

800228037'[

Mr. K. V. Seyfrit February 6, 1980 Page 2.

Analysis of Occurrence:

PC-230MV is a 24 inch butterfly valve manufactured by Allis-Chalmers with a Limitorque SM300 operator.

It is the inboard of two valves in the suppression chamber ventilation line. These valves receive a closure signal by a Group 2 isolation signal.

During operation these valves are both normally closed.

Inspection of the valve revealed that the closed limit switch was stopping the valve approximately 50 before it was completely shut.

The geared limit switch was removed and it was found to have in-proper gear alignment. Durit.g the previous repair the gears had dropped off of the shaf t during assembly and had not been replaced with correct alignment.

The downstream valve PC-245AV was closed the entire time that the valve was not shut completely and would have providea the contain-ment isolation had one been required. This occurrence presented no adverse consequences from the standpoint of public health and safety-

Corrective Action

The Limitorque geared limit switch was repaired so that all gears were properly aligned and the valve closed completely. The valve was operated several times to verify proper operation. The elec-tricians were given additional training in the maintenance and repair of geared limit switches.

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