ML20009B903
| ML20009B903 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 07/09/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20009B901 | List: |
| References | |
| NUDOCS 8107170339 | |
| Download: ML20009B903 (4) | |
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0 UNITED STATES 8 }
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NUCLEAR' REGULATORY COMMISSION E
WASHINGTON, D. C. 20555
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% [,,P SAFETY EVnLUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDFINT N0. 67 TO FACILITY OPERATING LICENSE 110. DPR-39 AND AMEhDMENT NO. 64 TO FACILITY OPERATING LICENSE NO. OPR-?3 COMMONWEALTH EDISON C019ANY ZION STATION, UNITS 1 AND 2 DOCKET NOS, 50-295 AND 50-304 Introduction In a letter of request (Ref.1), Commonwealth Edison (CECO) has proposed an amendment to Facility Operating Licenses DPR-39 and DPR-48 to incorporate changes in the Technical Specifications for the Zion Station, Units I and 2.
The proposed changes consist of the elimination of a rod bow Fa g penal ty.
Our evaluation of these changes is given below.
Evaluation The rod bow F AH calculated as a function of region-average burnup and are en ressed in the following manner:
5urnup Reduction in F g g
(mwd /MtU)
(%)
0-11,000 0
11,000-47,000 0-8.8 (linear ramp)
>47,000 8.8 Subsequent +- t,'RC approval of the aformentioned F penalty, Westinghouse AH I
ubmitted (Ref. 2) test results on the effects of a bowed rod on critical heat flux. These results showed a significant reduction in the presupposed l-l-
DNBR penalty on the basis of a new small gap (85% closura) test. Consequently, the NRL approved (Ret. 3), for Westinghouse applications, the use of a less conservative reduction-in-DNBR-versus-gap-closure model.
l 8107170339 810709 PDR ADOCK 05000295 L
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9 In References 1 and 4 CECO has' requested elimination of the F4H penal ty because of (a) the proposed use of the less conservative reduction-in-C';BR-versus-gap-closure model and (b)'the applic. tion of generic thermal margins that are available to of fset DNBR reducti9ns due to fuel rod bcning.
The NRC has generically approved the new DNBR-closure model, and we find CECO's request to apply the nooel to tne Zion analyses to De acceptable.
In regard to using tneraal r..argins to of fset tne resicaal Ftg penalty tnat remains af ter application of tne nes. DNbk-closure mocel, tne staff nas cade ~ an inceper. dent calculation to cetermine the magnitude of margin r^ quired. This calculation was performed by way of tne generic metnodology (Ref. 5) for interim rod bowing analyses. Specifically, the approved (Ref. 6) Uestinghouse rod bow nagnitude correlation (Ref. 2) was used in conjunction with the new ONBR-closure medel. The resulting margin.needed to offset the reduction in DNBR was found to be zero until a burnup of 8660 !Md/MtU, whereupon the required margin monotonically increases to the following values at a ournup of 33,000 liud/MtU:
1.12.5% for all loops in service.
2.14.9% for loss-of-flow accident analyses.
In Reference 4 CEC 0 has identified a total of 18.1% DNBR cargin that is available from the following sources:
1.
4.8% from using 1.30 DNBR limit in analysis rather than allowed 1.24 design limit.
2.
3.3% from pitch reduction.
3.
3.0% from using 0.019 thermal diffusion coefficient in analysis rather than allowed 0.038 value.
4.
7.0% from new densification model tnat eliminates poner spike effect on DNB.
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. These margins have been previously approved (Ref. 5) for the Zion type of fuel desig'1, and CECO has stated that these margins are to be used solely for this application.
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Summary Lonsequently, we conclude that the combination of tne new reduction-in-DNBR-versus-gap-closure model with the generic thermal margins are sufficient f
to completely eliminate the roa bow FaH penal ty.
Therefore, we agree with the CECO preposal to delete the F g cenalty factor from tne.echnical 3
Specifications. We also agree with CEC 0's proposed revision to the Basis to the Technical Specifications to reflect the basis for discot.tinuing rod bow penalty calculations which is that the availability of sufficient generic thermal margin is maintained. This allocation of margin (l.e.,14.9% DNBR) was recorded on page 68 of the Basis to the Technical Specifications.
Consequently, we find CECO's proposal for the removal of the rod bow F g 3
penalty acceptable.
REFERENCES 1.
Letter from T. R. Tram, CECO, to H. R. Denton, NRC, April 13, 1978.
2.
Letter from C. Eicheldinger, Westinghouse, to D. F. Ross, NRC, October 24, 1977.
3.
Letter from J. F. Stolz, NRC, to T. M. Anderson, Westinghouse, April 5,1979.
4.
Letter from T. R. Tram, CECO, to H. R. Denton, NRC, June 5,1981 5.
tiemorandum from D. F. Ross and D. G. Eisenhut, NRC, to D. B. Vassallo anc K. R. Goller, " Revised Inter'.m Safety Evaluation Report on the Effects of Fuel Roc Bowing on Thermal flargin Calculations for Lignt Water Reactors,"
February 16, 1977.
6.
Memorandum from R. O. Meyer, NRC, to D. F. Ross, " Revised Coefficients for Interim Rod Bowing Analysis," March 2,1978.
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e Environmental Consideration We have determined that the amendments do. not authorize a change in effluent types or total amounts nor an increase in' power level and
- will not result in any significant environnental impact. Having nade this determination, we have further concluded that the amerdments involve 'an action which is insignificant from the standpoint of environnental inpact and, oursuant tc 10 CFR 51.5(d)(4), nat an environmental impact statement or negative declaration and environ-mental impact appraisal need not be prepared in connection with the issuance of these amendnents.
Conclusion We have concluded, based on the considerations discussed above, that:
( because the amendments do not involve a significant increase in the probability or consequences of accidents previously considered and do not involve a significant decrease in a safety margin, the amendments do not involve a significant hazards consideration, (2) there is. reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed nanner, and (3) such activities will be conducted in compliance with the Connission's regulations and the issuance of these amendnents will not be ininical to the common defense and security or to the health and safety of the public.
Date:
July 9, 1981 i
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