ML20077K961

Safety Evaluation Supporting Amend 110 to License DPR-25

ML20077K961
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Site:	Dresden
Issue date:	08/05/1991
From:	Office of Nuclear Reactor Regulation
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ML20077K957	List: ML20077K961
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Download: ML20077K961 (3)

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WASHINGTON, D C. 20%5 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 110 TO FACILITY OPERATING LICENSE NO. DPR-25 COMMONWEALTH EDISON COMPANY DRESDEN NUCLEAR POWER STATION, UNIT 3 DOCKET NO. 50-249

1.0 INTRODUCTION

Advanced Nuclear fuels (ANF) is currently utilized by Commonwealth Edison Company (the licensee) for the performance of the reload licer. sing calcu-lation for Dresden Station.

Recently, ANF received NRC approval of their advanced methodology package for BWR reload design and safety analysis.

By letter dated March 6, 1991, the licensee requested that the Dresden, Unit 3, Technical Specifications (TS) be modified to reflect the use of these NRC-approved methodologies for reload licensing calculations to determine the core operating limits at Dresden Station starting with Cycle 13.

2.0 EVALUATION The NRC staff has approved the following ANF Topical Reports on reload licensing and safety analysis methodologies which Dresden, Unit 3 is proposing to use starting with Cycle 13.

ANF-1125(P)(A), " Critical Power Correlation - ANFB" - This ANFB correlation provides a generic tool for evaluating critical power and assessing thermal margin for all ANF BWR fuel designs.

ANFB replaces the XN-3 calculation and will be used for both licensing and on-site core monitoring calculations and is applicable to all resident fuel types at Dresden Station, including those to be used for Unit 3, Cycle 13.

ANF-013(P)(A),"COTRANSA2: A Computer Program for Boiling Water Reactor Transient Analysis" - The COTRAN5A2 Code is a system transient analysis code for BWRs which will be used by ANF to evaluate postulated limiting transients for future Dresden reloads starting with Cycle 13 for Unit 3.

The code is based in part, on the previously approved X-COBRA and RELAX Codes.

ANF-524(p)(A), Revison 2, "ANF Critical Power Methodolody for Boiling Water Reactors" - This is used to calculate a Maximum Critical Power Ratio (MCPR) Safety Limit that ensures 99.9% of the fuel rods avoid boiling tran-

sition, it includes the MCPR calculational procedure with the wrresponding system and calculational uncertainties. The methodology also accounts for the effects of channel bow for single bundle lifetime channels.

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Q 2-XN-NF-80-19(P)( A), Volume 1, Supplement 3, Advanced Nuclear fuels Methodology for Bolling Water Reactors; Benchmark Results for the EK5MD-3G/MICR0 BURN-B Calculational Methodology" - The CA5MO-3G/MICRODURN-B Code is used by ANF for reload design, steady-state licensing, and plant core simulator support applications, it is multigroup transport theory calculation of the spatial flux and power distribution, cell multiplication, and isotopic depletion for two-dimensional BWR fuel assembly lattices and three-dimensional core simulation.

Consistent with NRC Generic letter (GL) 88-16 the licensee is proposing thatthefirstthreeoftheseapprovedtopicalreports,whichareusedto determine core operating limits, be incorporated by reference into Section 6.6.A.4.b of the Dresden, Unit 3, TS.

The fourth topical report (XN-NF-80-19(P)( A)) is currently referenced in Section 6.6. A.4 b.4 of the TS.

The licensee has stated that the new ANF critical power methodology, which is based on the staff approved ANF critical power correlation, accounts for the effects of channel bow for single bundle lifetime channels and is appli-cable for the Dresden, Unit 3 Cycle 13 reload since no second bundle life-time channels are being used.

The use of these new methodologies for Cycle 13 increases the MCPR Safety Limit from 1.05 to 1.08.

This increase accounts for the effects of channel bow differences in core modeling (0.02 delta CPR increase) and for an additional conservatism (0.01 delta CPR) that has been included to accommodate minor changes in future reload designs to facilitate reload licensing under 10 CFR S0.59.

As a result of this new methodology, the licensee has proposed an increase in the MCPR Safety Limit to 1.08 in Section 1.1. A of the Unit 3 TS.

The' staff has reviewed the licensee's proposed TS changes and determined they are acceptable.

This conclusion ir based on the followin the referenced methodologies have been previously approved by the staff;g:the same spectrum of limiting events for each reload will be used and analysed under the new methodology; the increased MCPR Safety Limit adequately accounts for the potential effects of channel bow under the new methodology for Dresden, Unit 3. Cycle 13 with some additional conservatism; and the new methodologies and MCPR Safety Limit increase will maintain the current margin of safety and fuel cladding integrity.

3.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Illinois State official was notified of the proposed issuance of this amendment. The State official had no comments.

4.0 ENVIRONMENTAL CONSIDERATION

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

L 10 CFR Part 20.

The NRC stu f has determined that the amendment involves no l-significant increase in the amounts, and no significant change in the types.

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. 1 of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.

The Conmission has previously issued a proposed finding that this amendnent involves no significant hazards consideration, and there has been no public comment on such finding (56 FR 15638). Accordingly this amendment meets the eligibilitycriteriaforcategoricalexclusionsetforthin10CFR51.22(c)(9).

Pursuant to 10 CFR 51.22(*u), no environmental im)act statement or environmental assessment need be prepared in connection with t1e issuance of the amendments.

5.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that:

(1) there,s reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendnents will not be inimical to the common defense and security-or to the health and safety of the public.

Principal Contributor:

Byron Siegel 1

Date:

August 5. 1991

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