ML19343D107

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Fulfills 801006 Commitment to Provide Analysis of Asymmetric Blowdown Loads in LOCA for Mixed (Westinghouse & C-E Fueled) Core.Concludes That Asymmetric Loading Effects Concerns Resolved.Loading Effects on ECCS Analysis Under Review
ML19343D107
Person / Time
Site: Millstone Dominion icon.png
Issue date: 04/01/1981
From: Counsil W
NORTHEAST NUCLEAR ENERGY CO.
To: Clark R
Office of Nuclear Reactor Regulation
References
A01183, A1183, TAC-47355, TAC-47389, TAC-47473, NUDOCS 8104090449
Download: ML19343D107 (2)


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HARTFORo, CONNECTICUT 061Gi pan e m esii k L J = % l,l'J O C .~.

& ~1 19/N April 1,1981 #

Docket No. 50-336 D c3

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Director of. Nuclear Reactor Regulation Attn: Mr. Robert A. Clark, Chief h _

p' Operating Reactors Branch #3 U. S. Nuclear Regulatory Commission Washington, D.C. 20555

References:

(1) R. A. Clark letter to W. G. Counsil, dated October 6,1980.

(2) W. G. Counsil letter to R. A. Clark, dated September 10, 1980.

(3) Gesinski, L.T. , and Chiang, D. , " Safety Analysis of the 17 x 17 Fuel. Assembly for Combined Seismic and Loss of Coolant Accident,"

WCAP-8236, December, 1973 (h) W. G. Counsil letter to R. A. Clart , dated June 11, 1980.

Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 Resolution of Cycle 4 Startup Commitments In . Reference (1), the NRC Staff issued License Amendment No. 61 and the supporting Safety Evaluation to Facility Operating License No. DPR 65, for Millstone Unit No. 2. Documented in Reference (1) was a commitment for Northeast Nuclear Energy Company (NNECO) to provide, by April 1,1981, an analysis of the asymmetric blowdown loads in a LOCA for a mixed (Westinghouse and Combustion Engineering fueled)

Core.

In response to that commitment , NNECO hereby provides the following information.

An evaluation hus been performed for Millstone Unit No. 2 to determine the effects of asymmetric LOCA loads for a full core of We.atinghouse fuel assemblies and a transition core of Westinghouse and Combustion Engineering fuel.

Tha analytes utilized the Millstone Unit No. ? core plate motion time history developed as part of the reactor coolant system asymmetric LOCA loads evaluation program. This information has been previously docketed by Reference (2). The analytical model used for both the all Westinghouse core and the mixed core evaluation was that previously submitted by Westinghouse in Reference (3), and was approved by the NRC Staff.

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2 Due to the proprietary nature of the vendor fuel parameters , the transition core was evaluated by perfor=ing sensitivity analyses. In each case Westinghouse fuel asee=blies were located on the periphery of the core.

In all cases analyzed (all Westinghouse core and transiticn cores), the maximu calculated grid impact forces occur at the peripheral fuel assembly 1ccation, adjacent to the core shroud. The grid i= pact forces rapidly attenuate for the fuel asse=bly positions inward from the periphery. H e analyses de=onstrate that the li=iting case is for a core of all Westinghouse fuel, in which four (h) grids in tLe peripheral asse=bly exceed their elastic li=it.

The applicable transition core am'ysis does not predict grid i= pact leads en the interier fuel asse=bly locaticns which exceed grid elastic limits. As such, no grid deformatien is predicted at fuel assembly locations interior to the core periphery. Therefore, NNECO concludes that there re=ain no further concerns with respect to asy==etric loading effects en the Cc=bustien Engineering fuel at Millstone Unit No. 2.

NNECO, in conjunction with the fuel vendor , is currently evaluating the effects of the postulated asyn=etric leadings en the 2CCS cnslysis previously docketed by Reference (4). 2e results of these evaluations are scheduled to be provided to the Staff cn cr about June 1, 1961.

We trust ycu find this information satisfactory.

Very truly yours, NORTFEAST NUCLEAR E'iER3Y COFPANY

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/ l /) }7M1A W. G. Coussil Senicr Vice President