ML20057A634
| ML20057A634 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 09/09/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20057A632 | List: |
| References | |
| NUDOCS 9309150080 | |
| Download: ML20057A634 (3) | |
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e W ASHIN GT ON, D.C. 205 %-4001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N05.18 AND 4 TO FACILITY OPERATING LICENSE NOS. NPF-87 AND NPF-89 TEXAS UTILITIES ELECTRIC COMPANY. ET AL.
COMANCHE PEAK STEAM ELECTRIC STATION. UNITS 1 AND 2 DOCKET NOS. 50-445 AND 50-446
1.0 INTRODUCTION
By application dated September 3,1992, Texas Utilities Electric Company (the licensee) requested a change to the Technical Specifications (Appendix A to Facility Operating License No. NPF-87) for the Comanche Peak Steam Electric Station (CPSES) Unit 1.
By letter dated March 17, 1993, the licensee expanded the application to include CPSES Unit 2.
The licensee proposed to change the referenced evaluation model (EM) for the small break loss of coolant accident (SBLOCA) from the older EM based on the WFLASH code to a newer EM based on the NOTRUMP code. The Administrative Controls section of the Technical Specifications will be revised to delete the reference to WCAP-8200, "WFLASH, A FORTRAN-IV PROGRAM FOR SIMULATION OF TRANSIENTS IN A MULTI-LOOP PWR,"
i Revision 2, June 1974.
The deleted reference is replaced by WCAP-10079-P-A, "NOTRUMP, A NODAL TRANSIENT SMALL BREAK AND GENERAL NETWORK CODE," August 1985, WCAP-10054-P-A, " WESTINGHOUSE SMALL BREAK ECCS EVALUATION MODEL USING THE NOTRUMP CODE," August 1985, and WCAP-11145-P-A, " WESTINGHOUSE SMALL BREAK LOCA ECCS EVALUATION MODEL GENERIC STUDY WITH THE NOTRUMP CODE," October 1986.
The request came as a result of the licensee discovering that the WFLASH code calculated peak clad temperature (PCT) as stated in 10 CFR 50.46 would exceed the PCT limit of 2200*F because of the conservative nature of the code and because of penalties due to plant modifications and analysis changes. The NOTRUMP-based EM calculates a more realistic and much lower PCT than the WFLASH-based EM predicts for CPSES.
2.0 EVALUATIDN CPSES Unit 2 currently uses NOTRUMP for SBLOCA calculations. The FSAR for Unit 2 was amended before licensing to reference the use of NOTRUMP for the SBLOCA analysis.
The Administrative Controls Section of the Technical Specifications for Unit 2 require the use of NOTRUMP for SBLOCA. The NOTRUMP code was reviewed and approved for evaluating SBLOCA for Westinghouse NSSS designs by the NRC in 1985.
The plant design parameters of CPSES Unit I are similar if not identical to those of Unit 2 such that using the NOTRUMP code is reasonable and appropriate.
Therefore, in light of the fact that NOTRUMP has been approved for Unit 2, the staff concludes that it can be used to 93091500 % N ob 45 PDR ADO ppg P
. demonstrate compliance with requirements for CPSES Unit I for SBLOCA and be put in the Administrative Controls Section of Technical Specifications.
An analysis was performed on Unit 1 of CPSES with NOTRUMP to recalculate the PCT for the SBLOCA.
A three-inch break in the cold leg was chosen as the SBLOCA scenario to analyze because it is the most limiting SBLOCA for CPSES Unit 2.
The limiting break for Unit 2 was determined by calculating a spectrum of different breaks. Given the similarity in designs, the limiting break size is not expected to be different for Unit 2.
There are two differences that are significant. Unit I uses a model D4 steam generator and Unit 2 uses a model D5 steam generator. The two plants also use different fuel designs. Unit 2 utilizes a 17 X 17 optimized fuel assembly which has a slightly smaller clad outer diameter, 0.360 inch, and lower gap gas pressure, 275 psig.
Urit I utilizes a 17 X 17 standard fuel assembly with a clad outer diameter of 0.374 inches and 450 psig gap gas pressure. These differences were incorporated into the NOTRUMP model and the PCT was calculated for Unit 1.
The three-inch break in the cold leg yielded a PCT of 1418'F and a local zirconium-water oxidation react'on of 0.55 percent.
Both results are well below the 10 CFR 50.46 requirenents. The result of the same calculation for Unit 2 yielded a PCT of 1434*F.
The core-wide oxidation would not exceed requirements set by 10 CFR 50.46 and the long term coolability of the fuel would also be maintained.
The results indicate CPSES Unit I continues to meet all applicable requirements.
The evaluation model based on the NOTRUMP code for SBLOCA analysis is appropriate for CPSES Unit 1.
The analysis conclusions based on the NOTRUMP evaluation model are also appropriate. The analysis shows that CPSES Unit I continues to fulfill the requirements set by 10 CFR 50.46.
The staff finds i
these results reasonable and appropriate.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Texas State official was notified of the proposed issuance of the amendmen'.s.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change 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 NRC staff has determined that the 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 occupation &l radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (58 FR 19488). Accordingly, the 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 the amendment.
5.0 CONCLUSION
The Comission has concluded, based on the consideration discussed above, that:
(1) there is 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 Comission's regulations, and (3) the issuance of the amendments will not be inimical to the comon defense and security or to the health and safety of the public.
Principal Contributor:
C. Jackson Date:
September 9, 1993