05000267/LER-1983-014, Forwards LER 83-014/03L-0.Detailed Event Analysis Encl

Forwards LER 83-014/03L-0.Detailed Event Analysis Encl

ML20073J540
Person / Time
Site:	Fort Saint Vrain
Issue date:	04/08/1983
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20073J542	List: 05000267/LER-1983-014, Forwards LER 83-014/03L-0.Detailed Event Analysis Encl 05000267/LER-1983-014-03, /03L-0:on 830309,emergency Set 1B Emergency Diesel 1D Tripped Due to Dc Electrical Sys Intermittent Ground. Caused by Loose Conduit Termination Lock Nut.Nut Tightened & Secured
References
P-83140, NUDOCS 8304190323
Download: ML20073J540 (4)

LER-1983-014, Forwards LER 83-014/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2671983014R00 - NRC Website

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public Service Company Cf Onnarth

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16805 Road 19 1/2, Platteville, Colorado 80651-9298 April 8, 1983 Fort St. Vrain Unit No. 1 P-83140 Mr h

T. Collins, Regional Administrator gl g Nuclear Regulatory Commission

lif j!j 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Reference:

Facility Operating License No. DPR-34 Docket No. 50-267

Dear Mr. Collins:

Enclosed please find a copy of Reportable Occurrence Report No. 50-267/83-014, Final, submitted per the requirements of Technical Specification AC 7.5.2(b)2.

Also, please find enclosed one copy of the Licensee Event Report for Reportable Occurrence Report No. 50-267/83-014.

Very truly yours, 42[

s Don Warembourg Manager, Nuclear Production DW/cls Enclosure cc: Director, MIPC garn8aa a88%

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REPORT DATE:

Aoril 8.1983 REPORTABLE OCCURRENCE 83-014 ISSUE O OCCURRENCE DATE:

March 9, 1983 Page 1 of 3 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PLATTEVILLE, COLORADO 80651-9298 REPORT NO. 50-267/83-014/03-L-0 Final IDENTIFICATION OF OCCURRENCE:

On March 9, 1983, while operating at 29% reactor power, the 10 emergency diesel of IB emergency set tripped during the performance of the weekly load test surveillance.

This is reportable as a degraded mode of LCO 4.6.I(d) per Fort St.

Vrain Technical Specification AC 7.5.2(b)2.

EVENT

DESCRIPTION

On March 9, 1983, while operating at 29% reactor power, the weekly standby diesel generator test (SR 5.6.la-w) was conducted.

The portion of the test for 1A emergency generator set was satisfactorfly

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completed, and the test of IB emergency generator was started at e-1242 hours on March 9, 1983.

At approximately 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, the Control Room operators observed a DC bus ground alarm and the KW load on the 18 generator set fluctuating between 300 KW and 0 KW.

Following approximately three of these fluctuations, the breaker tripped on the 1B emergency generator, shutting down the generator set.

Plant Electricians investigating the nature of the trip discovered that an electrical conduit lock nut had worked loose from a conduit termination point and caused an intermittent ground of the DC electrical system affecting the engine speed governor.

Electrical personnel reconnected the loose conduit lock nut.

The Surveillance Test (SR 5.6.la-w) for IB emergency diesel generator was restarted at 1523 hours0.0176 days <br />0.423 hours <br />0.00252 weeks <br />5.795015e-4 months <br /> and satisfactorily completed at 1825 hours0.0211 days <br />0.507 hours <br />0.00302 weeks <br />6.944125e-4 months <br /> on March 9, 1983.

CAUSE

DESCRIPTION:

A loose conduit termination lock nut caused an intermittent ground of the direct' current (DC) electrical system affecting the engine speed governor.

The resultant load cycling caused the 18 diesel generator trip.

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4 REPORTABLE OCCURRENCE 83-014 ISSUE O Page 2 of 3 CORRECTIVE ACTION:

The conduit termination lock nut was retightened and secured.

Emergency generator set IB was retested and returned to service.

No further corrective action is anticipated or required.

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1 REPORTABLE OCCURRENCE 83-014 ISSUE O Page 3 of 3 Prepared By:

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Tooert A. Dicks? son Senior Technical Services Technician 1

$n Reviewed By:

Frank' J /Novachek Technical Services Engineering Supervisor Reviewed By:

F// 1 7/7eaC A d

L. M. McBride Station Manager Approved By:

Md icee/I1In Don Warembour@

Manager, Nuclear Production 6