05000267/LER-1983-006, Forwards LER 83-006/03L-0.Detailed Event Analysis Encl

Forwards LER 83-006/03L-0.Detailed Event Analysis Encl

ML20069H118
Person / Time
Site:	Fort Saint Vrain
Issue date:	03/17/1983
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20069H121	List: 05000267/LER-1983-006, Forwards LER 83-006/03L-0.Detailed Event Analysis Encl 05000267/LER-1983-006-03, /03L-0:on 830215,loop 2 Pcrv Cooling Water Temp Exceeded 120 F.Caused by Blown Instrument Bus 2 Power Inverter Fuse.Instrument Bus re-energized & Power Inverter Repaired
References
P-83109, NUDOCS 8303280254
Download: ML20069H118 (5)

LER-1983-006, Forwards LER 83-006/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
2671983006R00 - NRC Website

text

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- u Public Service Company. f Od@md@

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16805 Road 19 1/2, Platteville, Colorado 80651-9298 March 17, 1983 Fort St. Vrain Unit No. 1 P-83109 "5p--

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1 Mr. John T. Collins, Regional Administrator 1

Region IV Nuclear Regulatory Commission 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. 50-267/83-006, 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 Occur once Report No. 50-267/83-006.

Very truly yours, h Ww>~Wy Don Warembourg F

Manager, Nuclear Production DW/cis Enclosure cc: Director, MIPC D

go 8303280254 830317 PDR ADOCK 05000267 S

PDR

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a REPORTABLE OCCURRENCE DISTRIBLTTON Number of Copies De p a r tme n t o f E ne r gy - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 (P Letter)

San Francisco Operationa Office ATTN California Patent Group 1333 Broadway Oakland. California 94612 Depa r t men t o f E ne rgy - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 (P Letter)

Mr. Glen A. Newby. Chief HTR Branch Division of Nuclear Power Development Mail Station B-107 Washington. D.C.

20545 De pa r t men t o f Ene r gy - - - - - - - - - - - *- - - - - - - - - - - - - - - - - - - 1 (P Letter)

Project Manager ATTN Dr. Beighley P. O. Box 81608 San Diego, CA 92138 Mr. John T. Collins Regional Administrator 1 (Original of P Letter)

Region IV

aciaar Regulatory Commission ell Ryan Plaza Drive Suite 1000 Arlington, Texas 76011 Mr. Philip C. Wagner. Project Manager 1 (P Letter)

Region IV Nuclear Regulatory Commission 611 Ryan Plaza Drive Suite 1000 Arlington Texas 76011 D i re c t o r - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1 (P Letter)

Of fice of Management Information and Program Control Nuclear Regulatory Commission Washington, D.C.

20555 INPO Records Center -------------------------------

1 (P Letter)

Suite 1500 1100 circle 75 Parkway Atlanta, Georgia 30339 l

Mr. Richard Phelps, FSV, GA Technologies. Inc., Site Representative ------- 1 (P Letter)

General Atomic Technologies. Inc.

16864 Weld County Road 19 1/2 Platteville. Colorado 80651 NRC Resident Site Inspector 1 (P Letter) l f

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I REPORT DATE:

March 17, 1983 REPORTABLE OCCURRENCE 83-006 ISSUE O OCCURRENCE DATE: February 15, 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. 50-267/83-006/03-L-0 Final IDENTIFICATION OF OCCURRENCE:

On February 15, 1983, the outlet temperature in Loop 2 of the prestressed concrete reactor vessel (PCRV) cooling water system (System 46) exceeded 120 degrees fahrenheit. This event constitutes operation in a degraded mode of LCO 4.2.15(b) and is reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2.

EVENT

DESCRIPTION

At 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br /> on February 15, 1983, with the plant operating at 38%

thermal power and approximately 85 MWE, a fuse in the non-interruptible instrument bus #2 power inverter (N-9235) failed. The instrument buses are provided to supply the power requirements (120 volt AC, single phase, 60 Hz) for plant instrumentation.

Among the instrumentation supplied by instrument bus #2 is the temperature controller for Loop 2 of System 46.

The loss of electrical power to this controller caused the temperature control valve to fail closed and interrupted service water cooling to Loop 2 of System 46.

This in turn, caused the PCRV cooling water outlet temperature to increase above the 120 degrees fahrenheit limit specified in LCO 4.2.15(b).

At approximately 1042 hours0.0121 days <br />0.289 hours <br />0.00172 weeks <br />3.96481e-4 months <br />, power was restored to instrument bus #2 by manually closing the tie breaker to instrument bus #3.

The temperature control valve for Loop 2 of System 46 immediately returned to normal operation, and service water cooling was restored.

The Loop 2 PCRV cooling water outlet temperature was greater than 120 degrees fahrenheit for approximately 25 minutes and reached a maximum of 124 degrees fahrenheit.

Refer to Reportable Occurrence 50-276/83-007 for further information regarding the instrument bus power loss.

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4 RE,3RTABLE OCCURRENCE 83-006 ISSUE O Page 2 of 3

CAUSE

DESCRIPTION:

Component failure.

A blown fuse, internal to the instrument bus #2 power inverter, caused the loss of electrical power to Loop 2 PCRV cooling water system temperature control components.

CORRECTIVE ACTION:

The Laop 2 PCRV cooling water temperature was returned to acceptable values by re-establishing power to instrument bus #2 from its backup power supply.

The blown fuse in the instrument power inverter was replaced, and the inverter was tested and returned to service.

No further corrective action is anticipated or required.

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d REPORTABLE OCCURRENCE 83-006 ISSUE O Page 3 of 3 Prepared By:

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. Y-. <g Duans L. Frye Senior Technical Services Technician i

Reviewed By:

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CEiirles Fuller Technical Services Engi e ing Supervisor

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Reviewed By:

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Edwin D. Hil P '

Station Manager Approved By:

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Don Warembourg g

Manager, Nuclear Production