ML17249A717

Advises of Authorization to Use Previously Furnished Affidavits for Current Reload Review Re Cycle 10. Same Proprietary Matl Being Used

ML17249A717
Person / Time
Site:	Ginna
Issue date:	02/05/1980
From:	WIESEMANN R A WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:	ZIEMANN D L Office of Nuclear Reactor Regulation
Shared Package
ML17249A716	List: ML17249A715 ML17249A717
References
NS-RAW-005, NS-RAW-5, NUDOCS 8002250527
Download: ML17249A717 (12)

Text

Ntestinghouse Electric Corporation YYater Reactor Divisions iix&r Technology Oivision Box 355 PitlsburghPennsylvania 15230 February 5, 1980 NS-RAW-005 Mr.Dennis Ziemann, Chief Operating Reactor Branch S2 Division of Operating Reactors Office of Nuclear Reactor Regulation U.S.Nuclear Regulatory Commission Washington, 0.C.20555

SUBJECT:

Docket No.50-244, R.E.Ginna Nuclear Power Plant REF: Rochester Gas and Electric Company Application for Withholding, White to Ziemann, February 1980

Dear Hr.Ziemann:

The proprietary material for which withholding is being requested by Rochester Gas and Electric Company (RGE)is of the same technical type as that proprietary material previously submitted in connection with an NRC.Staff reload review.The previous application for withholding, AH-76-31, was accompanied by a non-proprietary affidavit signed by the owner of the proprietary information, Westinghouse

'Electric Corporation.

The subject.proprietary material is being submitted in support of the reload review msociated with RGE's R.E.Ginna Nuclear Power Plant, Cycle 10.On March 2, 1977, Westinghouse submitted a proprietary affidavit to supple-ment the non-proprietary affidavit accompanying application for withholding AW-76-31.Because the reload review material associated with Cycle 10 is of the same technical type as that associated with WCAP-9272, the proprietary affidavit submitted to supplement the previous justification is equally applicable to this material.Accordingly, this letter authorizes the utilization of the previously fur-nished affidavits in support of the reload review associated with RGE'.s R.E.Ginna Nuclear Power Plant, Cycle 10.

~P;Mr.D.Ziemann 0 Pw February 5, 1980 NS-RAW-005 Correspondence with respect to the proprietary aspects of the app1ica-tion for withho1ding or the Westinghouse affidavits shou1d reference CAW-80-08, and should be addressed to the under signed.Very'tru1y yours,~>&6M.a.KJ Robert A.Hiesemann, Manager Regulatory E Legislative Affairs/bek.cc: J.A.Cooke, Esq.(NRC)L.D.White (RGE)

Attachment B Response to Question 6 on Mixed Oxide Fuel (Proprietary)

~.

~g4 1 WESTINGHOUSE PROPRIETARY CLASS 2 6.The staff SER on Mixed Oxide Fuel states that use of U02 densification models for HOX should be verified.(l)

Since it appears that this assumption was used for the VOX fuel for Ginna, please verify this assumption.

Does the predicted amount of densification satisfy Reg.Guide 1.126.The current Westinghouse U02 fuel densification model was used to predict the densification performance of the tIOx fuels fabricated for Ginna.This empirical model, which was derived using only U02 performance data, uses fuel sintering temperature and sintered density to predict the extent of densification.-

The application of the model to lIO fuel is justified on X two bases;the similarity in procedure used in fabrication of NO fuel to X UO>procedures and the ability to conservatively predict the performance of previously irradiated t~i0 fuels.X While, studying the densification of pure U02, the relative dimensional ,stability of fuel was found to be strongly dependent on the pelletizing.process employed and the values of key processing parameters.

The processes used in pellet fabrication for Ginna are essentially identical v(ith those used.in preparing MO fuel previously irradiated by Westinghouse whose X performance is conservatively predicted by the U02 model.Further, the pelletizing processes used for preparing the Ginna Il0 fuel is very similar X to that used by Westinghouse to produce U02 fuel.The limiting processing

parameters, sintering temperature and final pellet density, were controlled to a range which produces U02 fuel with predicted performance within design requirements.

The Westinghouse experience with IIO densification performance during irradiation has been reported and compared wi th model predictions in WCAP-8349-P.

Theoretically, MO densification would be expected to X proceed at a lower rate than in UO since pore removal is directly related to local fission events.Densification or pore removal is a bu1k process and in U02 fuel the fission events are fairly uniformly distributed in the material and the product densifies uniformly.

.However, in MOthe fission events are concentrated in or very near to Pu02 particles which are free to densify independently of the U02 matrix.The low enrichment U02 matrix experiences a lower frequency oT fission events than normal enriched U02 fuel at similar burnup and should show a lower amount of densification.

The Westinghouse urSTINGHOUSE PROPRIETARY CLASS 2'2 experience with densification of MO fuel operated in a corrmercial power X reactor is compared with predicted values in Figure 1 which is taken'from MCAP-8349-P.

The Figure also contains data for the performance of a VO2 fuel with similar fabrication characteristics for direct comparison.

Figure 1 contains data for both mechanically mixed and"mastermixed" fuel.Mastermixed fuel is prepared by co-precipitating V02 and'Pu02 then mixing the Co-precipitated material with U02.The U02 model is a best estimate model and hence there should be'as many points with densification under predicted as overpredicted.

This is obviously not the case for either the U02 or MO fuel with the densification' being generally overpredicted.

Significantly, the prediction of the model was noticeably more conservative for the MO fuel than for the U02 with X similar processing history.As shown in Figure 1, the prediction for master mixed MO was less conservative than for'm chanically mixed MO.This is as X X~expected and further illustrates the lower densification expected from fuel'with inhomogenously distributed fission events.The performance of an MO fuel of higher Pu02 content which was operated in X the Saxton test reactor was also reported in MCAP-8349-P

.'his fuel, which.operated at higher temperatures than commercial power reactors,'as also found to densify less than predicted by the model.The predictive capability of the U02 model was further tested by evaluating the performance of the MO fuel in the EPRI MO.densification program.'hese X X fuels were prepared by a wide variation in processing variables and hence represent a range of conditions greater than was present in data on which the model was based.The performance of the EPRI fuels as reported in EPRI HP-637 are compared with model predictions in Figure 2.The data in Figure 2 indicate the model is essentially conservative for all fuels shown, even those unstable fuels prepared by procedures dissimilar to those for fuel on whose performance the model is based.For the stable fuels, those which densified<2 volume percent, the model is highly conservative in that it greatly overpredicts the densification.

The Ginna MO fuel is projected to behave stably;all currently manufactured Westinghouse U02 fuels are also projected to show'stable behavior.

)YESTlNG'HOUSE PRPPRIU~QY gQSS P sReg.Guide 1.126 does not indicate a maximum amount of densification allowable but, rather defines the amount of densification that must be assumed based on a'thermal resintering test.Design must account for the amount of densification assumed from the resinter test.Thermal resinter data is not available for the Ginna t10 fuel so an alternate X method must be chosen to predict the densification performance; the'ethod used was the Westinghouse U02 model.The accuracy of this model can be compared to the predictions from the thermal resinter model in Reg.Guide 1.126.The basis for establishing the relative abilities of the two models to predict performance was established by use of the EPRI data.The.predicted performance using the thermal resintering model is compared with actual performance in Figure 3.Examination of data in Figure 3 indicates the resinter model significantly overpredicts the amount of densification, especially in the.region of stable fuels (<2-v6lume percent densification) where the overprediction is as much as 2.5 percent.Comparison of Figures 2'C and 3 indicates the relative predictive abilities'of the two models.The comparison shows the two models are very similar, both models being generally conservative.

The degree of conservatism is found to be greater in the region of stable fuels.Similar numbers of data points are slightly under-predicted by the two models, however, the Westinghouse model is both more consistent and more conservative in the less than 2 percent densification

'ange which is representative of the Ginna HO fuel.X The data presented demonstrate that the Westinghouse U02 fuel, densification model yields predictions similar to'nd more reliably conservative for NO X fuel than the resinter model in Reg.Guide 1.126.'

STIIIGHOUSE PROPRIETARY CLASS I I 8198-I9).b,c)~E'1.0 O I C3 LEG EHO'HIXEO U02-3j, PuO~HASTERAIXEO UO2<<3$Pu02 Q UO>.0.0 0.0 , 0.5'.0 MEASURED STACK LEHGTH DECREASE, nL/L OR 1/3 Ap/p (PRESENT)Figure 1.Comparison oF Densification Data for UO-3%PuO with UO Both Fabricated under Similar Conditions to a Density of Approximately 91%T.D.

)VESTIWGHOUSE PROPRIETARY CI.aSS 2 Figure 2.Westinghouse U02 Model Prediction of Densification of EPRI MO Fuels X Qzz 0>>Qi>Q lg Q.Q>>Qp, QQ<<o EU 1 0 Qiz@<a O~'g Q I I pg rsQ<<~i;Q3<<7 (Dll Qa Q<<Qv Q MO Mechanically Mixed S MOMaster Mixed Q U02 Data Numbers indicate EPRI'fuel types.0 2 3 Actual Change in Density, 5

WESTINGHOUSE PROPRIETARY CUSS 2 Figure 3.Reg.Guide Prediction of EPRI MO Data X l9)9 Q I Qf w GQ cJ 3 2.CL Ol~l3 O f8~gg gg 0>~OI~gy Ol 8'bs\l7 (7 (p tg IX lk Q 0 Ik O MO Mechanically Mixed X I MOx Master t1ixed e U02 Data Numbers indicate EPRI fuel types.~1"0 2'Actual Change in Density