ML19254E204

Fowards LER 79-041/03L-0

ML19254E204
Person / Time
Site:	Fort Saint Vrain
Issue date:	10/25/1979
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19254E205	List: ML19254E204 ML19254E222
References
P-79248, NUDOCS 7910310318
Download: ML19254E204 (1)

Text

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d public service company ae cenendo 16805 Weld County Road 191/2, Pla.:teville, Colorado 80651 October 25, 1979 Fort S t. Vrain Unit No . 1 P-79248 Mr. Karl V. Seyfrit, Director Nuclear Regulatory C' nission Region IV Office of Inspection and Enforcement 611 Ryan Plaza Drive Suite 1000 Arlimton, Texas 76012 REF: Facility Operating License No. DPR-34 Docket No. 50-267

Dear Mr. Seyfrit:

Enclosed please find a copy of Reportable Occurrence Report No. 50-267/79-41/03-L-0, Preliminary, submittaa per the requirements of Tech-nical Specification AC 7.5.2(b)2.

Also, please find enclosed one copy of the Licensee Event Report for Reportabla Occurrence Report No. 50-267/ 79-41/ 03-L-0.

Very truly yours, Don Warembourg #

Manager, Nuclear Production DW/alk cc: Director, MIPC Y

\ h 7910810.3/5:

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. , , 3 REPOL. DATE: October 25, 1979 REPORTABLE OCCURRENCE 79-41 ISSUE O OCCURRENC' DATE: October 5,1979 Page 1 of 3 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 191/2 PLATTEVILLE, COLORADO 80651 REPORT No. 50-767/ 79-41/03-L-0 Preliminary IDENTIFICATION OF OCCURRENCE:

On four occasions between October 5,1979, and October 8,1979, malfunctions of helium circulator speed modifiers caused loss of Plant Protective System function of high speed trips. Each of the four malfunctions resulted in opera-tion under a degraded t.ade permitted by LCO 4.4.1 and are reportable per Fort St. Vrain Technical Specification AC 7.5.2(b)2.

EVENT DESCRIPTION:

Event 1 - Speed Modifier, SM-21165 On October 5,1979, at 1710 hours0.0198 days <br />0.475 hours <br />0.00283 weeks <br />6.50655e-4 months <br />, while operating at 30% thermal power and 76 W electrical power, operations personnel observed that one of three channels for the 1A circulato, speed protection tripped on low speed while the circulator u operating at approximately 4,500 rpm.

• Event 2 - Speed Modifier, SM-21165 On October 6,1979, at 1140 hours0.0132 days <br />0.317 hours <br />0.00188 weeks <br />4.3377e-4 months <br />, while operating at 29% thermal power and 82 W electrical power, operations personnel observed that one of three channels for the lA circulator speed protection tripped on low speed while the circulator was operating at approximately 4,500 rpm.

Event 3 - Speed Modiff er, SM-21165 On October 6,1979, at 2015 hours0.0233 days <br />0.56 hours <br />0.00333 weeks <br />7.667075e-4 months <br />, while operating at 38% thermal power and 114 W electrical power, operations personnel observed that one of three channels for the 1A circulator speed protection tripped on low speed while the circulator was operating at approximately 4,700 rpm.

Event 4 - Speed Modifier, SM-21161 On October 8,1979, at 2030 hours0.0235 days <br />0.564 hours <br />0.00336 weeks <br />7.72415e-4 months <br />, while operating at 50% thermal power and 150 W electrical power, operations personnel observed that one of three channels for the 1A circulator speed protection tripped on low speed while the circulator was operating at approximately 5,900 rpm.

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REPORIABLE OCCURRENCE 79-41 ISSUE O Page 2 of 3 EVENT DESCRIPTION (continued) :

Each of the four events resulted in loss of the speed signal and trip capa-bility in one of the three associated high speed trip channels for the 1A circulator. Two redundant channels were available and operable.

CAUS E DESCRIPTION:

Instrunent calibration drift due to bridge unbalance.

The balancing problem is caused by a change in resistance between the two leads of the speed element and ground at tha. circ.tlator conr.ection end. The difference in resistance occurs over a period of time in the cable connectors as a result of the temperature and humidity of the ambient air.

CORRECTIVE ACTION:

Adjusting the 1A circulator speed modifier restored overspeed protection '.o the affected channel.

As an interim measure, the adjustment of the speed modifiers is ueing checked on a weekly basis. ,

New connections have been ordered and will be environmentally qu lified for installation. The results will be reported in a future supplemental report.

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. , e REPORTABLE OCCURRENCE 79-41 ISSUE O Page 3 of 3 Prepared by: z s e44 Michael J. Ferri ( )

Technical ServiceY Engineer Reviewed by: . #

J. W. Wahm Q Technical Services Supervisor Reviewed by:

Frank M. Mathie Operations Manager Approved by: - YAx/ M Don Warembourg g Manager, Nuclear Production i