ML20085L641

AO 50-267/75/11:on 750424,preliminary Calculations Indicated That Helium Bottles Supplying Reserve Shutdown Sys Did Not Have Adequate Restraint for Dbe.Cause Not Stated.New Bottle Racks Designed & Installed

ML20085L641
Person / Time
Site:	Fort Saint Vrain
Issue date:	05/07/1975
From:	Brey H PUBLIC SERVICE CO. OF COLORADO
To:	Howard E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
AO-50-267-75-11, NUDOCS 8311020186
Download: ML20085L641 (4)

Text

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O P. O. Box 301, Platteville. Colorado 80651  ;

May 7, 1975 lb l

i)y Mr. E. Morris Howard, Director -

Nuclear Regulatory Cornission Region IV Office of Inspection and Enforcement 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76012 REF: Facility Operating License

. No. DPR-34 Docket No. 50-267

Dear Mr. Howard:

Enclosed please find a copy of Abnornal Occurrence Repm-t No. .

50-267/75/11, Final, subr.itted per the requirements of *.

Technical Specifications.

Very truly yours, H. Larry Brey Superintendent-Operations Fort St. Vrain Nuclear

! Generating Station HLE:11 l r -- ..

cc: Mr. Angelo Giambusso 8311020186 750507

-gDRADOCKC5000267

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O REPORT DATEi May 2,1975 gNORMALOCCURRENCE OCCURhENCEDATE: April 24,-1975 t

- FORT ST. VRAIN NUCLEAR CENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO P. O. BOX 361 .

PLATTEVILLE, COLORADO 806511 REPORT No. 50-267/75/11 Final-IDENTIFICATION OF OCCURRENCE:

A question was raised concerning the seismic adequacy of helium bottics and

• their restraints which supply pressure to the reactor reserve shutdown system. Preliminary indications were that the bottles did not have adequate support and restraint to insure their function during a scismic event.

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CONDITIONS PRIOR ,

TO OCCURRENCE: Steady State Power -

Routine Shutdown Hot Shutclown' Routine Load ~ Change X' Cold Shutdown Other-(specify)

Refueling Shutdown Routine Startup 4

• The major plant parameters at the time of the-event were as follows:

Power Rtr. 0.0 ~ Wth i

Elcet. 0.0- We Secondary Coolant Pressure 1.233 pnig

-Tenperature -190 _ *F -

Flow 2974 x 103 ' #/hr.

Primary' Coolant Pressure 3 88 _ ,_ _ ' pair.

' Tempers;nre 212: . *F Core inlet 22?1 *r Core Got let Flov 4!! x.107 .. . f/hr.

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• V Pcgm 2 DESCRIPTION OF OCCURRENCE:

Preliminary calculations indicated that the helium bottles supplying the Reserve Shutdown System did not have adequate restraint to insure continued functional ability during a Design Basis Earthquake. The support system had not been certified.

APPARENT CAUSE OF OCCURRENCE: X Design Unusual Service Cond.

Including Environ.

4 Manufacture Component Failure Installation /Constr. Other (specify)

Operator ,

i Procedure-ANAINSIS OF OCCURRENCE:

The support of the Reserve Shutdown System bottles was analyzed by Sargent and Lundy Engineers, Chicago, Illinois, Design Architect / Engineer for Fort .

St. Vrain. This analysis was based on appropriate seismic criteria established for the continued safe operation of Class I components. The analysis proved that corrective measures would be required.

An inspection ucs made to insure that all associated piping was supported in accordance uith established criteria for.the support of two inch and under, Class I lines. The piping and valves were found to be adequately supported.

o CORPICTIVE ACTION:

New hottle racks were designed and installed. Additional support members were added below the hott1cs which increa.ced the natural vertical frequency' of the support system to well within the "rinid" range. Lateral braces were added to the RSD instrument racks (to which the bettic racks ar'e attached) to increase the natural horicoatal frequency of the synten-to Vell within the

" rigid" range. An additional support was added to each of: the thirty seven lines which attach to the helium presunrizing obttles for greater protect ion of those lines.

FATLUP.E DATA /

SIMll.A1: 1:EPO..rt:D OCCURRI:.W1.S:

.There him been no failure of duy component a woc ia t ed wi t h t 1.e I:e.scrve ShAldown bot t les or innt ru:sent iachn. Se inmie iles i .n def ie tene lei. for severa 1, d i: nec lat ed Cl a :.. 1 compaaent:c wre eariJ er repm i ed ' v in AlaDrn::1.Da urscave I:rpo rf ::o .

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PROGRA)MATIC IMPACT:

None CODE IMPACT:

None i .

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I Stibmitted : > fff v m Reader' Site Engineer Fort St. Vrain Nuclear j' Cenerating Station i .

Approved: c f., (,e.: m t. 5' N (, q .1-ll Frederic E. Swart-

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-Superintendent Nuc1 car Production Public Service Company of' Colorado 5

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