ML20085L779

RO 50-267/75-1-A:on 750117,insp Revealed Discrepancies in Maintaining Loop & Bus Segregation Requirements.Caused by Error in Installation.Wires,Switches & Relays Not Meeting Segregation Requirements Separated

ML20085L779
Person / Time
Site:	Fort Saint Vrain
Issue date:	03/04/1975
From:	Brey H PUBLIC SERVICE CO. OF COLORADO
To:	Howard E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20085L781	List: ML20085L779 ML20085L783
References
RO-50-267-75-1A, NUDOCS 8311020446
Download: ML20085L779 (4)

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. D O public servlee company orcdasse i P. O. Box 361, Platteville, Colorado 80651 March 4, 1975 t

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3, Mr. E. Morris Howard, Director l ~ / O Nuclear Regulatory Commission l~ l.1 "J arf 15797.

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Region IV 'i-

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611 Ryan Plaza Drive

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Suite 1000 '

Arlington, Texas 76012 REF: Facility Operating License No. DPR-34 Dechet U0. 50 257

Dear Mr. Howard:

Enclosed please find a copy of Unusual Event Report No. 50-267/75/1-A, Final, submitted per the requirements of the Technical Specifications.

Very truly yours,

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',,. H. Larry Brey Superintendent-Operations Fort St. Vrain Nuclear Generating Station HLB:il ec: Mr. Angelo Giambusso , ,

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REPORT DATE: February 26, 1975 UNUSUAL EVENT -

OCCUPJtENCE DATE: Jancary 17, lo75_ _

FORT ST. VRAIN NUCLEAR GENERATING STATION

, PUBLIC SERVICE COMPNW OF COLORADO P. O. BOX 361 PLATTEVILLE, COLORADO 80651 REPORT NO. 50-267/75/1-A

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FINAL IDENTIFICATION OF OCCURRENCE:

An e3cetrical inspection of the main control board and auxiliary electrical equipment room revealed discrepancies in maintaining loop and bus segregdtion requirenents according to Specification 1-N-2, Supplement. The segregation violations are the accumulated results of modifications and revisions to the essential circuits since the initial audit involving single failure criteria.

CONDITIONS PRIOR TO OCCliRFD'CE: Steady State Power Routine Siv2tdovn Hot Shutdown Routine Load Change X Cold Shutdown Other (Specify)

Refueling Shutdown Routine Startup The major plant parameters at the time of the event were as follows:

Power ,- RTR 0 MWth Elect. O MWe Secondary Coolant Pressure O psig Temperature 0 *F Flow 0 #/hr.

Primary Coolant Pressure O psig Temperature N100 *F Core Inlet .

4100 *F Core Outlet ,

Flow 0 #/hr.-  !

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-Page 2 y DES 5RIPTIO'NOF OCCUltitENCE:

i Some of the colored insulated ulres used in the electrical installation '

work. to denote .non-interruptible Bus 1 and Eus 2 circuits and also some of the hand switches and relays used in essential circuits were not separated by the minimun distance to maintain segregation requirements.

APPARENT CAUSE '

OF OCCURRENCE: Design Unusual Service Cond.

Including Environ.

Manufacture Component Failure X -Installation /Const._ Other (specify)

.. , Operator

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Procedure ANALYSIS OF OCCURRENCE:

Wiring and schematic diagrams and the work sheets used during an original

-electrical audit were revicued to ensure that any modifications or revisions to essential circuits did not violate segregation requirements. All dis-crepancies found were referred to the general contractor for review and correction.

CORRECTIVE i .

_ ACTION: j Allcoloredinsulatedwiresusedinessentialcirbuitsthatdonotmeet.

segregation insulated requirements have been zipper tubed or changed to high temperature uires. Hand suitches and relays used :ba essential circuits that do -

not meet segregation requirements have been separated by asbestos barrier boards-on February 11, 1975.

An inspection was performed by Public Service CompanyLto ensure criteria.

chat all electrical installation work. is correct land meets segregation FAILURE DATA / .

_SIMILIAR REPORTED OCCURRENCES: i None O

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PROCPXI?!ATIC I!! PACT:

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jo;aes Reader APPROVED:hederic . Sw:trt E Site Engineer Superintendent, Production Fort St. Vrain Nuclear Fort St. Vrain Nuclear Cencrating Station Cencrating Station

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