ML20011D439

LER 89-020-00:on 891117,determined That as-built Configuration of Housing for Both Trains of Containment Cooling Fan HXs Not Seismically Qualified to Withstand Sse. Addl Seismic Restraints installed.W/891218 Ltr

ML20011D439
Person / Time
Site:	Wolf Creek
Issue date:	12/18/1989
From:	Bailey J, Mike Williams WOLF CREEK NUCLEAR OPERATING CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-020, LER-89-20, NO-89-0217, NO-89-217, NUDOCS 8912270220
Download: ML20011D439 (5)

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W$LFCREEK NUCLEAR OPERATING CORPORATION

.' John A. Bausy ;

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, NO 89-0217.

U." S. Nuclear Regulatory Co:nmission

~ ATTN : '. Document' Control Desk-

.Q  ; Mail' Station P1-137 0 -Washington, D. c. 20555 Subjects l Docket No. 50-482: Licensee Event' Report 89-020-00 n

Gentlemen:

tThe attached Licensee Event- Report (LER) is -submitted pursuant to-lotCFR=50;73 (a)n(2) (ii) concerning a condition outside the design basis of the plant.L

'Very truly yours,-

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L John A.' Bailey Vice President.

..r 1 Nuclear., Operations JAB / a em'-

Attachment

-cci: B. L. Bartlett (NRC), w/a E.-J. Holler (NRC) w/a R=. .

D. Martin-(NRC), w/a

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D. V. Pickett (NRC), w/a cif. . -  ; P.O. Box 411/ Burungton, KS 66839 / Phone: (316) 364 8831

'%' ' 8912270220 891218 An Equel opportunity Employer hW/He/ VET M' ' '

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Wolf Creek Generatino Station 0l5tol0l0l4lg;7 1 lOFl O[4 Seismic Analysis Discrepancies Afiecting Containment Cooling Fan System Housj ng EVENT DATE (Si LER NUMBER ($1 REPORT DATE 17: OTHER f ACILITIES INVOL VED (St sat MONTH I DAY F AC4L'T v e. Awas DOCKET NUMBER,81 MONT H DAT YEAR YEAR SQu p a$ YEAR 0 16101010 1 l I c 1l1 1l 7 .

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- OPE R ATING .TMis REPORT IS SUSMITTEO PURSUANT TO THE REQUIREMENTS OF 10 CFR $: (Checa e or asore of the retroempf Ull MODE W } 20 402M 20 405(el 60.73teH2Hel 73.71161 POWER 30.4064sH1H4) . 60.36(sH O $0.73(aH2Hvl 73.714s!

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NAME TELEPHONE NUMBER ARE A CODE Merlin G. Williams - Managcr P1 ant Support 3l1;6 3i6i 4 l-i 8 i 8 l 3l1 COMPLETE ONE LINE FOR E ACh COMPONENT F AILURE DESCRISED lN TMl5 REPORT H3)

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,On Nov m ber 17, 1989, it es determined by a calculation ttat the as-ballt ,

configuration of the housing for both trains of containment cooling fan heat ~

exchangers a s not seismically qualified to withstand a Safe Shutdown Earthquake.- It e s further determined that this situation placed the Wolf Creek Generating Station in a condition outside the design basis of the

plant.

L This calculation was performed in response to a notification by the Architect / Engineer (Bechtel Power Corporation) of generic errors / discrepancies in the original seismic qualification report. Upon empletion of the calculation, both trains of containment cooling fans were declared inoperable. A plant modification package e s developed to install additional seismic restraints.- The installation of the restraints was conpleted on November 19, 1989 on the 'B' train and on Nuvwam: 20, 1989, on the 'A' train, thereby restoring both trains of containment cooling fans to operable status.

. A' detailed review and evaluation of the original seismic analysis methodology in cmparison to the conservative methodology utilized in Novmber, 2989, is being perfarned. The conclusions reached will be provided in a supplenent to this report.

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NRC Form 300 42w- . _ _ _ - - _ _ - _ - _ _ _ - _ _ _ _ - . _ _ _ _ - - - - _ - . _ . _ - - - _ - _ _ _ _ _ _ _ _ _ - _ _ _ . _ - _ . . - _ . _ - _ _ _ _ _ _ _ - _ _ _ - _ _ . _ - _ _ ;

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CILITY HAM tia DOCKE T NUMBER (2I LtR NUMSER (6) PAGE (3)

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.r On Novenber 17,1989, it was detemined that the as-built configuration of' the housing foi both trains of containment cooling fan heat exchangers [BK-

.HX) was not seismically qualified to withstand a Safo Shutdown Earthquake.  ;

It was further detemined that this situation placed the Wolf Creek '

Generating Station (NOGS) in a condition outside the design basis of the plant. 'Iherefore this report is being subnitted pursuant to 10CFR50.73(a)(2)(ii).

OtEKRIPTIGi T BVENT Wolf Creek Nuclear Operating Corporation (NCNOC) was notified by the plant's Architect / Engineer, Bechtel Power Corporation, that generic

- errors / discrepancies had been identified in seismic analysis reports prepared by American Air Filter (AAF). 'Ihese errors were discovered during-qualification of equiprent by analysis. 'Ihe only safety-related AAF Lequipnent installed at NOGS are the four containment cooling fan heat exchangers.

-After conducting a thorough review of the identified discropancies, NCNOC engineering personnel perfomed a calculation on.Novenber 17, 1989, which-detamined that the cooling fan heat exchanger housing would be over stressed when subjected to the peak ground acceleration for a Safe Shutd v p Earthquake. ' At that time the unit was operating in Mode 1, Power Operat.1,-

at approximately 100 peromt rated themal power.

Based on the calculation results, both trains of containment cooling fans were declared inoperable at 1151 CST on November 17, 1989. An entry was m3de into Technical Specification 3.6.2.3, Action 'b', which requires that L with two groups of containment cooling fans inoperable and both Containment l Spray Systens [BE] operable, restore at least one group of cooling fans to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least Hot Standby within the

-next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> and restore both groups of cooling fans to operable status within 7 days of initial loss

- or be in.at least Hot Standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Cold Shutdown within the following.30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

A plant modification package was developed to install additional seismic restraints to restore the containment cooling fans to npm-ahle status.

Installation of the restraints on the 'B' train containment cooling fan heat ll exchanger housings was conpleted at 1731 CST on Novenber 19, 1989, thereby restoring one train to operable status. Tnis modification subsequently was completed on the 'A' train containment cooling fan heat exchanger housings at 1305 CST on November 20, 1989, and Technical Specification 3.6.2.3, Action 'b was exited at that time. 'Ihroughout this event, the unit remained in Mode 1,. Power Operation.

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Offic form 306A - U.S. NUCLEAR 86004ATORY COMMISSION 7

• LICENSEE EVENT REPORT (LER) TEXT CONTINUATION sanovfo ove No mo-om EXPlRES: 8/31/08 9 ACittTY NAME (1) DOCKET NUMBER G5 LER NUM85R 16) PAGE (3) vE*a 5103^' b # 0e?0 i

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Further review and evaluation of the methodology utilized to detemine seismic qualification of the containment cooling fen heat exchanger housings is being omducted. 21s etfort includes a~ review of the j conservatisms utilized in the November,1989, calculation to detemine -

seismic qualificaticn. Also within the scope of this effort is a review to identify the root cause and any further required corrective measures.

Following conpletion of this effort, a supplement to this report will .be i subnitted describing the details of the review. % e expected subnission l

'date of the supplement is April 30, 1990.

p The present configuratica of the ocntainment cooling fan heat exchanger housings is adequate to ensure adherece to seismic design requiranants  ;

itdependent of the results of this evaluation effort. ,

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ADDITIG9L DilGMATIGi' The Containment Cooling System consists of two trains of Containment Spray i

- and two trains of containment cooling fans. Se current NOGS containment

[NH] analysis assumes the single failure of one protection train (i.e., loss

! .of one train of Containment Spray and one train of containment cooling fans) and therefore takes credit for one train of Containment Sp rf and one train

' of ccntainment cooling fans. Consequently, the situation described in this report, namely, the postulated failure of both trains of containment cooling fans upon occurrence of a Safe Shutdown Earthquake, represents a condition outside the design basis of the plant.

i In order to assess the consequences of failure of the Containment Cooling System a containment re-analysis was performed assuming the loss of all containment cooling fans. The main stu m1 Me break is the bounding event for peak pressure and peak tenperature'in containment, with peak pressure being the parameter of nost concern. The analysis concluded that with both l> trains of containment spray operating and an initial Refucling Water Storage

', Tank (RWST) (BP-3] tanperature of 100 degrees Fahrenheit or less, which is the base case temmture in the Updated Safety Analysis Report (USAR), the '

maxinum' containment pressure would remain within the containment design pressure. Assuming a failure of one train of containment spray and an

. initial RHST temperature of 75 degrees Fahrenheit or less (tauperature expected under current conditions), the design pressure of the containment

.would not be exceeded.

An evaluation of the probability of a seismic event which would exceed the original as-built capabilities of the containment cooling fan heat

. exchangers housings was performed. The evaluation concluded that the probability of' occurrence of a seismic event of the magnitude to cause l

extensive containment cooling fan heat exchanger housing damage is very low.

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l m LICENSEE EVENT REPORT (LER) TEXT CONTINUATION enaovto oue No. stso-oio4 Expiats; Staires F ACILITY NAMS t)) DOCKET NUMBER (21 LtR NUMBER (81 . PAGE (3) vsaa " O!,';l'.

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0l0 0l4 OF 0 l4 iExT ta more spece a revumed use emnonalNAC Form asE4'st(17) 1 Additionally, as statai in the NOGS USAR, in designing and analyzing for a f Design Basis Accident (i.e. , loss of coolant accident, nain staaml % break, ,

fuel handling accident, or steam generator tube rupture), these events are  !

not assumed to be the result of a tornado, hurricane, flood, fire, loss of j offsite power, or' seismic event. 'Ihe assumed operation of the Containment Cooling Systen, following a Design Basis Accident without a concurrent seismic event, is not affected by the seismic design concerns discussed in this report.

Based on the low probability of a seismic event occurring, the Design Basis Accident discussion in the USAR, and the results of the containment' analysis  ;

performed to specifically evaluate this condition, it is conclirtM that this l situation did not significantly jaq=rriize containment integrity.  ;

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'1here have been no previots similar occurrences. I i

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