05000298/LER-1983-003, Forwards LER 83-003/03L-0.Detailed Event Analysis Submitted

Forwards LER 83-003/03L-0.Detailed Event Analysis Submitted

ML20073S354
Person / Time
Site:	Cooper
Issue date:	04/29/1983
From:	Thomason P NEBRASKA PUBLIC POWER DISTRICT
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20073S356	List: 05000298/LER-1983-003, Forwards LER 83-003/03L-0.Detailed Event Analysis Submitted 05000298/LER-1983-003-03, /03L-0:on 830403,indication & Control Power for Reactor Bldg Exhaust Valve HN-260MV Failed,Resulting in Valve Not Automatically Closing on Isolation Signal.Caused by Burned Out Lamp.Lamp & Fuse Replaced
References
CNSS830306, NUDOCS 8305060574
Download: ML20073S354 (2)

LER-1983-003, Forwards LER 83-003/03L-0.Detailed Event Analysis Submitted

Event date:
Report date:
2981983003R00 - NRC Website

text

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COOPER NUCLEAR STATION Nebraska Public Power District

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CNSS830306 April 29, 1983 3gg]}g]3 V'

MAY - 21983 Mr. John T. Collins, Regional Administrator 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.3 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occur-rence that was discovered on April 3, 1983. A licensee report form is also enclosed.

T li-11 Report No.:

50-298-83;03 Report Date:

April 29, 1983 Occurrence Date:

April 3, 1983 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

A condition which led to operation in a degraded mode as indicated by a limiting condition for operation established in Paragraph 3.2.D.2 of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was operating at approximately 100% of rated thermal power and reactor pressure was approximately 1000 psig.

Description of Occurrence.

While conducting normal operational tours and inspections, on-shift personnel noted the reactor building outboard ventilation exhaust valve HV-260MV position indicating lights were extinguished and the fuse for the valve's control power circuit was blown.

Designation of Apparent Cause of Occurrence:

The apparent cause of this occurrence was attributed to a shorting of the indicating light bulb which caused the control and indicating circuit fuse for HV-260MV to blow.

Analysis of Occurrence:

Reactor building ventilation exhaust isolation valve HV-260MV is one of four reactor building ventilation exhaust valves in two parallel paths 8305060574 830429 PDR ADOCK 05000298 S

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Mr. John T. Collins April 29, 1983 Page 2 required to shut in order to establish secondary containment isolation.

As a result of the blown fuse in the control and indicating circuit, this valve would not have responded to an automatic isolation signal.

However, two redundant air operated valves in the two parallel exhaust flow paths were available had they been required for automatic containment isolation. -Additionally HV-260MV could have been shut

. manually if required for isolation.

The first indication of a problem was failure of the local indicating light. When the lamp lens was removed, it was noted the lamp was broken.

Apparently the bulb was stuck too tightly in the socket for normal removal and was broken when bulb replacement had been previously attempted.

Other indications were normal and a work item tracking form was initiated. The subsequent day the remote indicator lamp was out and the control power fuse had blown. As soon as this was noticed, the fuse immediately replaced and shortly thereafter (same day) the broken was lamp base post was removed and a new lamp was installed.

These repairs were implemented with satisfactory results.

It was determined during the repair that the bulb filaments were ip contact with each other, causing a direct short.

This occurrence presented no adverse consequences from the standpoint of public health and safety.

Corrective Action

The broken lamp base post was removed and a new lamp was installed.

The control-power tuse was replaced. No further action is required.

Sincerely, p.x % w P. V. Thomason Acting Station Superintendent Cooper Nuclear Station PVT:KRW:cg Attach.