ML20125B305

Discusses Suppl 1 to Change Request 3,requesting Addl Change to TS of Operating License DPR-22

ML20125B305
Person / Time
Site:	Monticello
Issue date:	12/21/1972
From:	Ziemann D US ATOMIC ENERGY COMMISSION (AEC)
To:	Mayer L NORTHERN STATES POWER CO.
References
NUDOCS 9212090300
Download: ML20125B305 (4)

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UNITE,0 STATES d"

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k ATOMIC ENERGY COMMISSION l'

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's WASHING TON, D.C. 20S43 s

necembe r 21, 1972 l

Docket No. 50-263 i

Northem States Power Conpany

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L. O. Fhyer, P.E.

Dimetor of Nuclear Support Services Minneapolis, Minnesota 55401 Gentlenen:

Your letter dated September 22, 1972, filed as Supplenent No. _1 to ChanEp Pequest No. 3, mqmsted additional changes to the 'Ibchnical Specifications of Provisional Operating License No. DPR-22 for the htnticello Nuclear Generating Plant.

Part of the mquested chargs

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mlatesto the matrictions cn tre sequence of centrol md withdrawal and insertion such that the maximum mactivity worth of any with-drawn control md would not, in the event of a md drop, have tnac-ceptable conseqtences. 'Ihe need for this change msults fmm a massessmnt of the control md drop accident as discussed in General Electric Topical Beport NED0-10527 " Bod Dmp Accident Analysis for Large Boiling Water Ibactors", dated March 1972.

In evaluating the consequences of a md dmp accichnt, two ccaditicra rust be satisfied:

1.

'Ibe maximum enthalpy of the fuel nust be less than that vhich would produce procpt dispersal of finely fragnented fuel into the coolant with consequent largp pressums and pmssum rim rates. AnmMn enthalpy of less than 280 calories /gmm satisfies this ccndition.

2.

'Ibe radiaticn doses dte to fuel failums maulting fmm a ocntrol md dmp acc1&nt must be within the guidelines of 10 CFR Part 100. Your Final Safety Analysis Ibport (FSAR) uses 170 calories / gram as the thmshhold for fuel failum for analysis of the accicbnt ocnsequerces.

In your FSAR, the consequences of a contml md drop accident assuned j

a mactivity insertion of 0.025 &lta k during hot standby which msulted in a calculated peak fuel enthalpy of 250 calories / gram and 330 fuel mds exceeding 170 calories / gram. 'Ibe basis for the the 0.025 &lta k mactivity insertion is not stated in your FSAR but appmximates j

the maximum mactivity worth of a contml rod msulting from a ningle operator ermr, based on a rod withdrawal seqtence for thich the maximtm worth of an in-sequence rod is about 0.01 chlta k.

i 9212090300 721221 PDR ADOCK 05000263 P

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Northem States Power Cocpany i i

Your proposed changes to the Technical Specifications for the M:nticello Nuclear Generating Plant specify that the maximtun reactivity worth of an in-sequence ecntrol md shall be 0.015 delta k.

'Ib evaluate l

whether this specification provides the same safety margin in the l

event of a red drop accident as was assessed in your FSAR, the fol-l lowing additional infomation is required:

1.

Is the General Electric Topical Nport,- NEDO-10527-

" Rod Drop Accident Analysis for. Large Boiling Water Nactors", dated March 1972 ccnsidend fully appli-cable to the hbnticello Nuclear Generating Plant?

l If not, provide a detailed analysis of any diffbrences.-

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Figum 3.9 of NEDO-10527 indicates that the nnximum i

mactivity wrth of an in-sequence rod is -less than 0.01 delta k.

Are there any circunstances when the j

maximum reactivity worth of an in-eequence Ind would exceed 0.01 delta k at the Fbnticello Nuclear e

Generating Plant? If so, describe the' specific events i

or ccnditions sich would cause the increase and ichn-j tify-the magnitude of the inemase.

3 Ibes an increase in the maximtrn reactivity worth of j

an in-sequence-Iod affect th? =J mun reactivity worth i

j of an out-of-sequence rod, asstming a single operator error?

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Fbr a control rod mactivity worth of 0.015 delta k, 1

pInvide the msults of your calculaticns of the max-imum enthalpy and the number of fuel elements exceeding 170 calories / gram resulting from a rod drop accident.

I If either of these results are gmater than those presented in your FSAR, provich a justification for the increase.

Your respcnse to the above is requested within thirty days frun the-date-of this letter with three s1 ned orig!nals and nineteen additional 1

E copies.

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' Sincerely,

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' Dennis L. Zie

, Chief 1

Operating & actors Branch #2 j

l Directorate of Licensing cc: See-next pas j.

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Northem States Fbwr Company r-cc: Gerald Chamoff Shaw, Pittman, Potts, Tmwbridge & Paddan 910 - 17th Stmet, N. W.

Washingtcn, D. C.

20006 Envimnnental Library of Minnesota g

m 1222 S.E. 4th Stmet r.

Minneapolis, Minnesota 55414 4

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Meetheast States Pouer Osmpany 2-1.[

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901 62B14 Otagsbeff Snow, Pittamus, Putts, Thundatdge & Ma&hn ple - 17th steset, u. v.

mMage=, p. c. 20006 Brvivesumental Library of Minnesota f

1222 8.E. 4tta Street Mhstoapolis, MLnnesota 55414 Distribution et File RP Reading File Branch &ading File J. R. Buchanan, ORE T. W. Laughlin, DTIE D. J. Skovholt, L:0R ACRS (16)

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Gallo, 000 Seiffert, OGC D. L. Zie:wn, L:0R-2 T. J. Carter, L:0R R. W. N id, L:OR-2 R. M. Diggs, L:OR-2

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• Form AEC.318 (Rev. 9-53) AECM 0240

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