ML20237E326

Safety Evalution Supporting Amend 113 to License DPR-46

ML20237E326
Person / Time
Site:	Cooper
Issue date:	12/21/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20237E296	List: ML20237E294 ML20237E309 ML20237E326
References
NUDOCS 8712280272
Download: ML20237E326 (3)

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1. o UNITED STATES

!" N. NUCLEAR REGULATORY COMMISSION h  : WASHINGTON, o. C. 20555

\...../ SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.113r0 FACILITY OPERATING LICENSE NO. DPR-46 NEBRASKA PUBLIC POWER DISTRICT COOPER NUCLEAR STATION DOCKET NO. 50-298 .

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1.0 INTRODUCTION

By letter dated October 20, 1987 (Change No. 46) the Nebraska Public i Power District (the licensee) requested an amendment to Facility Operating License No. DPR-46 for the Cooper Nuclear Station (CNS). The amendment would modify the Technical Specifications (Section 5 " Design Requirements") i related to fuel storage. The amendment request resulted from circumstances ,

described in Licensee Event Report 86-034, wherein it was determined that  !

the Technical Specifications had previously, unknowingly, been violated. J

, A later safety analysis determined that the required safety margins had not been violated.

2. 0 DISCUSSION AND EVALUATION I

change of nomenclature: The proposed amendment would change the name of the new fuel storage facility to the new fuel storage vault. This change is for editorial consistency only and is of no safety significance. The i change is therefore acceptable. I New fuel storage vault: The proposed amendment would add a statement that the new fuel storage vault K-effective limits are maintained when the maximum, exposure-dependent K-infinity of the individual fuel bundles are equal to or less than 1.29. This change would create a new limitation to ensure that no new fuel can be stored in the new fuel storage vault that could not also be permitted to be stored in the spent fuel storage pool.

The proposed K-infinity limit of 1.29 was selected to be consistent with t the proposed below-described, new limitation for storage of spent fuel in '

the spent fuel storage pool. The proposed K-infinity limit is less than (more conservative than) the value of 1.31 presently acceptable on the basis of conformance to Standard Review Plan Section 9.1.1 acceptance criteria for new fuel storage facility criticality as shown by analyses using the General Electric MERIT code. Since the margin to criticality would not be reduced and remains consistent with Standard Review Plan acceptance criteria, the proposed change is acceptable. [ Note: The MERIT code has been previously accepted by the staff for use in fuel storage criticality calculations (Ref: Dockets 50-321 & S0-366 Safety Evaluation dated April 21,1980).]

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• Spent fuel storage pool: The proposed amendment would add a statement that the spent fuel storage pool K-effective limits are satisfied when the maximum, exposure-dependent K-infinity of the individual bundles is equal to or less than 1.29. Existing limitations that U-235 axial loading of fuel in the spent fuel storage pool not exceed 14.5 grams per axial centimeter and calculated spent fuel pool K-effective not exceed 0.9271 would be deleted. The Standard Review Plan (SRP) acceptance criteria specify that the K-effective of a spent fuel storage pool be less than or equal to 0.95 and that this limit be reflected in the facility Technical Specifications. However, the actual K-effective of spent fuel in a storage pool is not directly measurable by installed instrumentation.

Because the K-eff of a fuel pool is not directly measured, it is necessary to use other means to assure that the desired safety margin is available.

The method currently specified in the Technical Specifications is to limit the U-235 loading of the stored spent fuel assemblies to 14.5 grams per centimeter. This value corresponds to a worst case configuration of 2.83 w/o fuel enrichment and a calculated K-effective of 0.9271. An equally effective and more readily implemented method of ensuring spent fuel pool criticality safety is to limit the K-infinity of the individual fuel assemblies in the pool. The latter method allows new fuel designs to be stored in the spent fuel storage pool and allows for manufacturing toler-ances, while maintaining the same safety limit K-effective. Analyses using the previously accepted and experimentally verified MERIT program have shown that if the fuel assembly K-infinity is limitea to 1.29, the i spent fuel pool K-effective value will not exceed the existing 0.95 SRP l limit. The proposed change would allow greater flexibility in selection I of fuel designs to be stored in the spent fuel pool and would provide greater assurance that the margin to criticality is not inadvertar.tly violated. . Based on conformance to Standard Review Plan criteria, the proposed change is acceptable.

3.0 ENVIRONMENTAL CONSIDERATION

S This amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in ,

10 CFR Part 20. The staff has determined that the amendment involves no '

significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that l the amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, the amendment steets l the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(M. no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

4.0 CONCLUSION

We have concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public  ;

I will not be endangered by operation in the proposed manner, and (2) such  !

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activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

Date: December 21, 1987 Principal Contributor: W. Long i

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