ML20210P286
| ML20210P286 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 01/30/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20210P240 | List: |
| References | |
| TAC-62158, NUDOCS 8702130350 | |
| Download: ML20210P286 (3) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION L
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.12 TO FACILITY OPERATING LICENSE N0. DPR-80 AND AMENDMENT NO. 10 TO FACILITY OPERATING LICENSE NO. DPR-8?
PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-275 AND 50-323 INTRODUCTION By letter dated July 18, 1986, the Pacific Gas and Electric Company (PG&E),
licensee for the Diablo Canyon Nuclear Power Plant, Units 1 and 2, requested a License Amendment to change the combined Technical Specifications for Diablo Canyon Units 1 and 2, Section 3/4.2.1, " Axial Flux Difference" for Diablo Canyon Unit 2 (Ref. 11 The changes would implement a Westinghouse developed power distribution control methodology called Relaxed Axial Offset Control (RAOC) for Unit 2 after reaching a burnup of 8000 MWD /MTU in the first cycle.
The same change had previously been requested for Diahlo Canyon Unit I and was issued by the NRC as License Amendment No. 3 to Facility Operating License No.
DPR-80 (Ref. 2).
EVALUATION Westinghouse reactors have for a number of years operated under a power distribution control system called Constant Axial Offset Control (CAOC), which ensures peaking factors will remain below values assumed as input for accident analyses during normal operation of the power plant. Basically, CAOC achieves its result by requiring plant operation within a 5% flux difference (AI) around a measured target value.
By controlling the axial power distribution, the possible skewing of the axial xenon distribution is limited, thus minimizing xenon oscillations and their effects on the power distribution.
Plants have varying degrees of margin to the peaking factor limits which can be supported by CA0C. Westinghouse developed the RA0C methodology to directly detennine the allowed band of A I operation required to support any plant specific peaking factor limit. The NRC staff approved RAOC for referencing in licensing actions in a letter tn F. P. Rahe (Westinghouse) from C. Thomas (NRC), dated February 28, 1983 (Ref. 3).
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' The staff has reviewed the Technical Specification changes proposed by the licensee for Diablo Canyon Unit 2 and finds they correctly implement RA0C.
The staff has previously approved identical implementation of RAOC for Diablo Canyon Unit 1 in Amendment 3 to Facility Operating License DPR-80 (Ref. 2).
The staff, therefore, finds the proposed Technical Specification changes acceptable for Unit 2.
The anaylsis described by the licensee applying RA0C to Diablo Canyon Unit 2 is applicable only after the unit reaches 8000 MWD /MTU burnup in Cycle 1 and thereafter until the end of Cycle 1.
Cycle specific evaluations will be made by Westinghouse to determine if the allowable AI bar.d curve will remain valid or require revision by further Technical Specification change.
In addition to implementation of RA0C for Unit 2, the proposed amendment also changes some of the existing Technical Specifications pages for Unit 1.
These are needed to implement the Unit 2 changes and are, therefore, administrative and acceptable.
The licensee's submittal states that the implementation of RAOC is conditional upon NRC approval of a Unit 2 ECCS reanalysis using the revised Westinghouse 1981 ECCS Evaluation Model with BART, as well as reaching 8000 MWD /MTU burnup.
The above approval is for RA0C only and does not address the ECCS evaluation.
The staff has completed its evaluation of the ECCS analysis with the BART Evaluation Model and found it acceptable as stated in a letter from S. Varga (NPC1 to J. D. Shiffer (PG&E) (Pef. 4).
ENVIRONMENTAL CONSIDERATION These amendments involve a change in the installation or use of the facilities components located within the restricted areas as defined in 10 CFR 20. The staff has determined that these amendments involve 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 Comission has previously issued a proposed finding that these amendments involve no significant hazards consideration and there has been no public comment on such finding. Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of these amendments.
CONCLUSION We have concluded, based on the considerations discussed above, that:
(1) there is reasnnable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) 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.
PRINCIPAL CONTRIBUTOR:
M. Dunenfeld January 30, 1987
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References:
1.
Letter from J. R. Herrera (PG&E) to H. R. Denton (NRC), dated July 18, 1986 (DCL-86-203), " License Amendment Request 86-08, Technical Specification 3/4.2.1, Unit 2 Relaxed Axial Offset Control."-
2.
Letter from S. A. Varga.(NRC) to J. D. Shiffer (PG8E), "Diablo Canyon Nuclear Power Plant - Issuance of Amendment No. 3 to Facility Operating 4
License No. DPR-80 (Unit 1) and Amendment No. I to Facility Operating Licens No. DPR-82 (Unit 2)," dated November 29, 1985.
3.
Letter from C. Thomas (NRC) to E. P. Rahe (Westinghouse), " Acceptance for Referencing of Licensing Tcpical Report WCAP-1020f(P) (NS-EPR-2649)," dated February 28, 1983.
4.
Letter from S. A. Varga (NRC) to J. D. Shiffer (PG&E), " Lifting of Exemption from Requirement of 10 CFR 50, Section 50.46," dated January 22, 1987.
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