ML19319E267

Discusses Fuel Rod Bowing in B&W Fuel & Reduction in DNBR Due to Fuel Rod Bowing.Acceptable Method to Accommodate DNBR Reduction Requested W/Fuel Cycle 2 Reload Submittal.Forwards Interim Safety Evaluation.W/O Encl

ML19319E267
Person / Time
Site:	Rancho Seco
Issue date:	01/07/1977
From:	Reid R Office of Nuclear Reactor Regulation
To:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
References
NUDOCS 8004010540
Download: ML19319E267 (1)

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January 7, 1977 DISTPilBUTION

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0 Local PDR

' Docket !!o. 50-312 ORB #4 Rdg.

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T. J. Carter n1 R.' Reid R. Ingram y

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• E Facramento l'unicinal Utili*.y District V. Rooney-(2)

ATTH: Mr. J. J. Ma ttinne M. Fletcher F

Assistant General !!anager _

Attorney, OELD an f Chief Er.9 neer OI&E (3) 1 6201 S Street D. Eisenhut P. O. i'ox 15530 T. B. Abernathy Sacra.anto, Chif fornia 95813 J= R. Buchanan ACRS (16)

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Pl!!CHC SEC0 NUCLEAP. GENERATIl!G STATI0H

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39 f.uqust 9,1976, Westinghouse Electric Corporation presented data to the ie'C staff which showed that previously develo,ned methods for accountinq

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-for the.effect of fuel rod ocuing on departure from nucloate boiling nay not contain adequate thervol margin when unheated rods (such as thinble M

tubes).are present. He have evaluated the inpact of the Westinghouse cata on all operating pressurized water reactors (PWs),

liedels for treating the effects of fuel rod bowinq on thermal-byoraulic perfomance have been derived for all PUR's. The nodels are based on the propensity of the r..

'indivice.1 fuel designs to how and on the thercal analysis nothods used to predict the cociant conditiocs for both normal operation and anticipated transients.

_l The staff has revicued the extent of rod boutng which occurs with Babceck t<

.Uilcox (P,LU) ft:el. Based on this review, an eeuation was derived for

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the cicarance reduction between fuel rods th:e in fuel rcri bouing as a function of burnue:-

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% is th? nundle 2veracc t'urnuo, am! e,b tr enMrical constants fi tt<:d to P'J' rod bx data.

Thn' reduction in derarture fro, niicleate boilin? ratio (DH!M) dur. to funi E-9

. red bntdnq is assumed to ' vary linearly with the recoction 19 cle rance rM1 but can never ne !cer (t 9 i.'

Enetween the tw.1 roris (or fuel rad anq thimla F2

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'than th5t cue to the pi tch reduction factor ut.en-in the t ercul a-alysis.

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District: Sobcock:8.llilecx claicec and the stat f approved cre11t for the follouing thernal 'raargins: '

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T10w Area (Pitch) reduction

=:H Densification-Power Spike reooval Er. cess Flow over.that used in safety ant. lyses

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l Based on this review and the themel nargins presented by- 0?A! to offset the nerr Wstinghouso data, a reduction in DNBR is reoutred for Rancho Seco. The L.

folleuing tablo gives the values for the reduction of Ot;BR required.

fiundle Averace-Burnub

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Cycle 1 J(0 - 15000 8F4 0-

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tqe Cycle 2 (15000 - 24000 PW )

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Cycle'3 (24000 - 33000 I w )

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Additional -infornation on the derivation of tiie above rm! action, as v.?11 as rore extensive back';round inforestion concernino red bev, are coattined in the en::losure to this letter.

You are requesteo to prcvide an acceptable nethod of acc(randating the abcVe

Dt'M reduction in connection witn your reloed spirittal for fuel cycle 2.

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k Sacranento Nuicipal littlity District '

=s Also, because :futrire changes in the thernel varcin croof ts which CSU-

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hr.s-clair =d to effset the D'riOR reduction for your facility c y renuire

- coxr.ensurate changes,in the D:@l penalty, you are requested to subnit, inithin 30 days

~a list of the aoolicabic cre.11ts for future reference

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on the Rancho: Seco cioctet.

Sincerely, cri M G:"Il W Robert V. Reid, Chief

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Onoratinn Deactors Eracch #4 5- :.1 D'ivision'of Operatinn Reactors

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Enclosure:

'Interin SEP. on Ef fects of T

Fuel Rod Bowina on Thor.a1

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ilarqin Calciilations for Lipst Water Peactors J

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':bb Sacramento Municipal Utility District cc: - David S. Kaplan, Secretary and General Counsel

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6201'S Street f=E

- Post Office Box 15830 Sacramento California 95813

=r Business and Municipal Department k bl Sacramento City-County Library 1

828 I Street

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Sacramento,. California. 95814 Chief. Energy Systems

, Analyses Brench (AW-459).

.0ffice of Rat.?ation Programs U. S. Environmental Protection Agency 1

Room 645, East Tower jg.!

401 M Street, S.W.

.a jjj Washington, D.C.

20460 U. S. Environmental Protection Agency

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Region IX-Office i

ATTN:

EIS COORDINATOR 100 California Street

- San' Francisco, California 94111 4

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