ML20126K152
| ML20126K152 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 05/04/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20126K151 | List: |
| References | |
| TAC-12663, TAC-12664, NUDOCS 8105120199 | |
| Download: ML20126K152 (3) | |
Text
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NUCLEAR REGULATORY COMMISSION 70, UNITED STATES
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 49 TO FACILITY OPERATING LICENSE NO. DPR-24 AND AMENDMENT NO. 55 TO FACILITY OPERATING LICENSE NO. DPR-27 WISCONSIN ELECTRIC POWER COMPANY POINT BEACH NUCLEAR PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-266 AND 50-301
==
Introduction:==
In a letter dated December 19, 1979 and supplemented by letter dated February 3, 1981 Wisconsin Electric Power Company (WEPCO) requested changes to the Technical Specifications of the Point Beach Nuclear Plant Unit Nos.
1 and 2.
These. changes would remove the rod bow penalty and requirements related to rod cluster control assembly (RCCA) misalignment and position indication. They would also make various administrative changes to section 15.3.10 of the Technical Specifications.
Discussion and Evaluation:
The rod bow penalty currently in effect for Point Beach Units 1 and 2 was proposed under Technical Specification Change Request Number 38 dated January 6, 1977 and was aporoved by amendments dated May 4, 1977.
The i
penalty is to offset the effects of a bowed rod on critical heat flux and is calculated as a function of region-average fuel burnup and is expressed as the following value:
Eurnup Recucsion in FoH (mwd /Mtu)
(%)
0-15,000 0-2 ramp 15,000-24,000 4
>24,000 6
penalty, Westinghouse j
Subsequent to NRC approval of the aformentioned F submittedtestresultsontheeffectsofabowedP$doncriticalheatflux 3
for Westinghouse PWR's. These results showed a significant reduction in the presupposed DNBR penalty on the basis of a new small gap (85% closure) test. The NRC then approved, for Westinghouse applications, the use of a j
less conservative reduction-in-DNBR versus gap-closure model.
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WEPC0 has requested elimination of the Fuseofthelessconservativereduction-ikHpenaltyb
-DNBR versus gap-closure model and I
(b) the application of generic thermal margin credits that are available l
to offset DNBR reductions due to fuel rod bowing. The NRC has generically approved the new DNBR model, and we find WEPCO's request to apply the model to the Point Beach analyses to be acceptable.
In regard to usii.g thermal margin credits to offset the residual FaH penalty that remains after application of the new DNBR model, the staff has made an independent calculation to determine the magnitude of margin i
required. This calculatior. was performed by way of the generic method.
olcgy for interim rod bowing analyses. Specifically, the approved Westinghouse rod bow magnitude correlation was used in conjunction with j
the new DNBR model. The resulting margin needed to offset the reduction in
~
DNBR was found to be zero until a burnup of 8660 mwd /Mtu, whereupon the required margin monotonically increases to the following values at a b,urnup of 33,000 mwd /MtU:
(1) 12.5% for all loops in service and (2) 14.9% for loss-of-flow accident analyses.
WEPC0 has identified a total of 18.1% DNBR margin credits that are 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 that eliminates power spike effect on DNB.
These margin credits have been previously approved for the Point Beach type of fuel design, and WEPC0 has stated that these credits are to be used solely for this application. Additionally, the Basis to the Technical Specifications is being revised to reflect the basis for discontinuing rod bow penalty calculations, which is that sufficient generic thermal margin credits be maintained to offset the rod bow penalty.
Based on the above evaluation, we find that the combination of the new I
reduction-in-DNBR versus gap-closure model with the generic thermal margin credits is sufficiently large to completely eliminate the rod bow F H t
penalty. Therefore, we agree with the WEPC0 proposal to delete the FaH penalty from the Technical Specifications.
In regard to the second proposed change, the results of our evaluation of the proposed Technical Specification changes related to inoperable and misaligned control rods (Sections 15.3.10.C.l.c and d, 15.3.10.C.2.a and b, and 15.3.10.0.1 and 2) are in agreement with those of the generic resolution of control rod position indicating system recui ements for Westinghouse
PWRs, and are therefore acceptable.
The proposed administrative changes to Section 15.3.10 of the Technical Specifications were submitted to reorganize and clarify this section of the Technical Specifications including updating of terminology and removal of references to equipment no longer applicable to the Point Beach Nuclear Plant facility such as references to part length control rods which have been removed from the core as per previous approval. We have reviewed
'the administrative changes to this section and find that they do not change the meaning or intent of the Technical Specifications and are therefore acceptable.
Environmental Consideratioti t
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 environmental impact. Having made this determination, we have further concluded that the amendments involve an action which is insignificant from the standpoint of environmental impa:t and, pursuant to 10 CFR $51.5(d)(4), that an environmental impact statement or negative declaration and environ-mental impact appraisal need not be prepared in connection with the issuance of these amendments.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) 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 manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
l Date: May 4, 1981
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