ML20206E473

Nonproprietary Addl Info on Beaver Valley Power Station Unit 2 SER Confirmatory Issue 032

ML20206E473
Person / Time
Site:	Beaver Valley
Issue date:	03/31/1987
From:	Butler J WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML19292H087	List: ML20206E397 ML20206E452 ML20206E473
References
NUDOCS 8704130621
Download: ML20206E473 (6)

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ADDITIONAL INPGDETIN '-

W BVPS-2 SIR CCNFIIO9GtLW ISSUE 032 MARCH 1987 AU1 HOR: J. C. R7IIER 4

WESTINGHOUSE IIECIRIC CEPORATIN NUCIEAR ENSGY SYSIENS P.O. BOX 355 s PITISBURGH, PENNSYLVANIA 15230 i

8704130621 870407 PDR ADOCK 05000412 E PDR ,

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4 e AIIETIGEL INFGGGEIGi W BVPS-2 SER GMFIIt9GutY ISEE 032 Iritrc&x:ticm In Reference 1, Transient Analysis zuspcmded tc lac ocnoorns raised &aring evaluatism of a fhilure acdes evaluatica performed for Beaver Thlley thit

2. Referunas 1 addressed the immun of idisther the case idiere a single failure causing all three Feedwater control vialves (PCV) to open fully is bounded by the came currently presented in FSAR Section 15.1.2. Phr the amme total increase in fasentar fim, reference 1 states that as a result of the ocmaervative mixing and reactivity f==re=+ ammapticms used in the FSAR analysis, the case of me FCV cyaning bounds, in tarna of reactivity insertien, the case idiers two e acre PCYs open. As a result, it was otmcluded that the analysis presented in FSAR Section 15.1.2 (Full Power, cne PCV cpan) is scre limiting than a mee idiere two at acts FCYs fail cyan. Additional analyses were perfrweed for the FSAR sero power event to cxmfirm that the results and cemclusions of the PSAR sero power event bound a case idiere 3 FCVs open.

Reference 2 has requested that additional infonmation be provided to

• sgpcet the conclusions of Referenom 1. 1his information is prwided belw.

Pbr ocepletanass, the reopense prwided in Reference 1 is repeated belw, followed by the requestad additional informaticm.

Response Prwided n Reference 1 The analysis of the Feedwater Italfunction Event for Beaver Valley thit 2 presented in section 15.1.2 of the BVPS-2 FSAR -- that one FCV is inadwt.it.ly opened. This analysis was performed using assumpticms Wiicts bound an event idiers two ar more PCYs are opened. These asamptions include:

1. ( )**C mixirx[of the RCE fluid in the care inlet plenma is cxmeervatively =====d.

2. Reactivity f==dhar4r is ccmservatively weicfited in the quimL-.t of the acre affected by the FCV failure.

3. Main famowater flw to the affected steem generator is increased to the maxima aucunt thicit can be sustained by the fee $ater systam.

1ha fai11 rig open of one FCV results in an asyurrstric cooldown event. The first two assumpticms pavimina the iM of this asymetry by =mvimiming -

the resulting reactivity insertion. A more urtiform cooldown would result if two car more FCVs were cpened and as sucts the resulting reactivity inserticm would be more uniformly dispersed over the core. Pbr the some total increase in fee &mter fim, the case of one FCV cpening bounds, in taram of reactivity inserticm, the cases Wiers two cir more PCYs open.

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. 1he FSAR analysis ammauss an increase in fes&mtar f1w to 160% of ncminal to the affected loop far the full poWar casa. This increase in festatar .

flew is based gcm the meri== total as-tatilt delivery capability of the min Peasatar system with all three PCMs wide cyan. As a remalt, lf two ,

or acts FCYls fail cyan, the total increase in flow (i.e., em of all 1 cop 21cus) would be equal to or less than that ammmed in the PSAR ftr ena loop to thil open. The - - ./ in-i of cme FCV ikiling gen results in a concentretien of f1w to one loop id11 cts in cxz$metion witti the i conservative mixing and reactivity w assumpticms diar ===d above results in a commervative reactivity additism. As a result, the FSAR analysis =-= hug that ena FCV cpens bounds the case there a single fhilure casuses one er more FCVs to cyan.

She FSAR sero pcuer analysis ammans an increase in fes&mter flow of 170%

of ncaminal to the affected loop. This is the unwi== flowrata 1dticts can be delivered to cme stamm generator at sero pcWar. She envi== total -

t as-built delivery capability of the min Fes&mter system with all three PCVs open at sero power is 75% of ncminal (plant total). An analysis was t parfam=9 of this sero pcuer syssastric three loop event, using FSAR

. method but with reactivity f==e=r* [1 i

]**F,1his came was shown to be less limiting than the case currently presented in the FSAR.

A&iitionally, a most cxmservative acabination of inititiating events was l analyzed at sero power. For this case, the above mixing and reactivity fahic assunptions were unde, idtile feedwater flow was a====d to increase to cmly cme locp at the magnitude of the plant total increase in feedwater flw (75% of ncaninal plant total, 225% of ncaninal loop flm).

She results.of this very caneervative analysis, thou@l zore limiting than i

that of the current FSAR analysis, remain within the %ir.is criteria.

She analysis of the feedwater malfuncticm event presented in Section 15.1.2 of the Beaver Valley IR11t 2 PSAR === man that ena Fee &mtar ocmtrol valve fails open. In the analysis, conservative aamupticms are used with F an-.t, to RCS mixing, reactivity fandharic and feedwater ficw tilicts result in an event idlicts is acre limiting than a case there two or acts FCVs fail cpan.

s w itional Infarantirwi .

As additimial supporting informaticm, the results of three feedwater unlfuncticm cases are provided. She three cases are:

Case 1 FSAR analysis - Hot Zero Power, Single FCV fails open.to deliver 170% of ncuninal flow to affected steam generator.

Case 2 Hot Zero Ibwer, Shree FCVs fail open, eact1 deliver 75% of ncaninal flw.

Case 3 Hot Zero Power, Single FCV fails open to deliver 75% of l i

, ncsainal flow (plant total) or 225% of ncuninal locp flow. '

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. Wm of the fbilowing perumsters are pewided fcr Chess 1,2, ard 3

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Figure 1 -

Raclear Feuer vs. Time .

Figure 2 -

Cars Heat flux vs. Time Figure 3 -

Care Average Teperature vs. Time i l

Figure 4 -

DER vs. Time -

0:sparison of transient traces of Case 1 (FSAR analysis) ard Chas 2 (failure of 3 FCYs) shows that the FSAR case is indeed limiting &as to the conservative -- ./ ic- with respect to mixing and reactivity f==*=+-

case 3 presents a case disre the increase in f1w &as to the Qdlure of three FCVs is cxmeervatively modeled throu@t a single FCV. While Chre 3 is an overly ocnservative representaticm of the capability of the Det Main Pleadwater System, cxmparison of Case 2 and Case 3 demaistrates the iM of an asysstric foo&mtar malfunctica event (case 3) in mdman to a

^

ri -alc event (Case 2). W111e case 3 results in a -1drur1 W11 cts is sufficient to generate a SIS 41spial cm Iow Steam Pressure and results in Flee &mter Telaticm at WMy 35 seconds (results for Case 3 after .

35 seconds reflect the innlaticm of Flee & ster) the trerd price to FWI shows that Case 3 is more limiting then Onse 2. As the total increase in

• feedwf. ster f1w is the same for both cases, the results of cases 2 and 3 pewide sLgporting evidonom for the ocnclusions reactand for the FSAR full power event.

References:

1. 2NRC-6-054, 5-28-86

2. Telecon between USNRC, DLCo, and W, 3-5-87 k

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TIME ISEC Figure 1 - pel- Paar vs. Tim ,

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- TIME ~ ISECs Figure 2 - Core Best Flux vs. Tima l

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l TIME ISECs Figure 3 - Care Average Tamparature vs. Tim

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1 TIME ISECl Figure 4 - DGR vs. Tina

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