ML20078E781

Forwards LERs 79-035/01X-1,81-008/03X-2,81-030/03X-2 & 81-055/03X-1

ML20078E781
Person / Time
Site:	Fort Saint Vrain
Issue date:	09/27/1983
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20078E784	List: ML20078E781
References
P-83325, NUDOCS 8310060388
Download: ML20078E781 (5)

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/ Pubik Service comp:my of Odersde g ?g1 16805 Road 191/2, Platteville, Colorado 80651-9298 September 27, 1983 _

U No P-83325  ! s$@$0SO@  !

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~\ b Mr. John T. Collins, Regional Administrator ~

Region IV Nuclear Regulatory Commission 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Reference:

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

Dear Mr. Collins:

Enclosed please find a copy of Reportable Occurrence Report No.

50-267/79-35, Reportable Occurrence Report No. 50-267/81-008, Reportable Occurrence Report No. 50-267/81-030, and Reportable Occurrence Report No. 50-257/81-055, Finals, 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. 50-267/79-35, Reportable Occurrence Report No. 50-267/81-008, Reportable Occurrence Report No.

50-267/81-030, and Reportable Occurrence Report No. 50-267/81-055.

Very truly yours, i

L,n L laa ,bmy )j & *h7a3h Don Warembourg Manager, Nuclear Production DW/djm Enclosures cc: Director, MIPC 100 831006 N e30926 NMS LIC30 07-01173- r.gg m l[

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REPORT DATE: September 27, 1983 ' REPORTABLE OCCURRENCE 79-35 ISSUE 1 OCCURRENCE DATE: August 31, 1979 Page 1 of 4 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD COUNTY ROAD 19 1/2 PLATTEVILLE, COLORADO 80651-9298 l REPORT NO. 50-267/79-35/01-X-1 l Final IDENTIFICATION OF OCCURRENCE:

An engineering field audit and preliminary analysis of a random l sample of safety related system piping and associated hangers found l inconsistencies that may have jeopardized the operability of systems in the event of a design basis earthquake. ,

l Due to these inconsistencies, Public Sertice Company elected to l suspend operation of the Fort St. Vrain, Unit N; 1, at 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on September 1, 1979.

I Ja investigation of the inconsistencies was initiated.

l This is reportable per Fort St. Vrain Technical Specification AC 7.5.2(a)9.

EVENT DESCRIPTION:

l Pursuant to IE Bulletin No 79-14, Public Service Company of Colorado l completed the field audit and a preliminary engineering analysis of a random sample of as-built safety related piping isometric and associated hanger drawings as committed to in Public Service Company letter P-79161.

The audit included a field verification of the as-built installation j of the piping shown on 26 Class I piping isometric drawings and the l

94 associated hanger drawings. The general validity of the seismic l

design inputs documentation on 18 of the isometric drawings and 64 of the hanger drawings was confirmed. ,

On the remaining eight isometric drawings and 30 hanger drawings, inconsistencies judged to be potentially significant were identified between the field installation and the reference documentation.

An analytical evaluation of the noted isometric drawing l l inconsistencies indicated that they would not result in invalidation l of the seismic qualification of the piping depicted on the subject isometric drawing.

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. t REPORTABLE OCCURRENCE 79-35 ISSUE 1 Page'2 of 4 i

4 An analytical analysis of the inconsistencies identified in the l hangers indicated that 18 of the hangers of concern fulfilled Class I design requirements.

l The remaining 12 hangers appeared to have inconsistencies that may l have jeopardized the operability of the associated systems in the event of a design basis earthquake. Because the sampling of i isometric drawings and associated hangers was made on a random basis, l no conclusions ~could be drawn as to the continued operability of  ;

those systems or portions of systems required. to remain operable during and after a design basis earthquake.

On the basis of the results of the audit, Public Service Company of l Colorado cencluded that the piping system seismic hanger / support l system for the Class I. piping may not have been installed per the design requirements defined in the Final Safety Analysis Report and may require corrective modifications to bring the "as-built" systems into agreement with the design intent.

Because of the inconsistencias noted, the Public Service Company of l Colorado temporarily suspended speration of the Fort St. Vrain unit j l at approximately 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on September 1, 1979.

After further analysis, using more sophisticated analytical methods, l it was determined that none of the systems examined as of September i 13, 1979 were impaired per the Final Safety Analysis Report since the '

l l individual hangers were acceptable or, the associated piping and its l remaining hangers would remain operable during the design basis earthquake.

CAUSE DESCRIPTION:

The inconsistencies between the design and installation of the various hangers required re-analysis of the piping / hanger systems. '

'The time involved did not allow a final resolution of the problem before a report was submitted. Therefore, the plant was shutdown l pending outcome of the investigation and remained in a shutdown l condition until September 15, 1979, when the reactor was taken l critical. Reactor power operation (greater than two percent) resumed l September 25, 1979, after inconsistencies noted in a random sample l audit conducted on safety related piping systems had been resolved.

I l After completion of the random sample audit, a comprehensive program l to comply with the requirements of IE Bulletin No. 79-14 was begun in l late 1979.

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REPORTABLE OCCURRENCE 79-35 ISSUE 1

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Page 3 of 4 l CORRECTIVE l ACTION:

l As a follow-up effort to IE Bulletin No. 79-14, the Fort St. Vrain l Seismic Piping System Redocumentation Program was initiated.

l Correction of all identified discrepancies and distribution of final l drawings and analytical packages has been completed in accordance l with IE Bulletin No. 79-14 and the Seismic Redocumentation Program l Procedures.

l No further corrective action is anticipated or required.

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' REPORTABLE OCCURRENCE 79-35 ISSUE 1

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Prepared By: EME . M Duane L. Frye #

Senior Technical Services Technician e

Reviewed By: w Fran t f. Novachek Technical Services Er.gineering Supervisor Reviewed By: d. fr7 1 M A - If, L. M. McBride '

Station Manager Approved By: YmWM Don Warembourg &

Manager, Nuclear Production

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