ML25196A415
| ML25196A415 | |
| Person / Time | |
|---|---|
| Issue date: | 07/14/1976 |
| From: | Moeller D Advisory Committee on Reactor Safeguards |
| To: | Rowden M NRC/Chairman |
| References | |
| Download: ML25196A415 (1) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, D. C. 20555 Honorable Marcus A. Rowden Chairman US Nuclear Regulatory Commission Washington, OC 20555 July 14, 1976
Subject:
REPOID' ON WESTINGHOUSE ELECTRIC O)RPORATION REFERENCE SAFETY ANALYSIS REOORJ.', RESAR-3S
Dear Mr. Rowden:
At its 195th meeting, July 8-10, 1976, the Advisory Committee on Reactor Safeguards completed its review of the Westinghouse Electric Corporation's application foi: a Preliminary Design Approval (Pll1\\) for a standardized nuclear steam supply system consistin;J of a pressurized water reactor as described in its Reference Safety Analysis Report, RESAR-3S.
A subcom-mittee meeting was held with representatives of the Applicant and the Nuclear Regulatory Commission (NRC) Staff in Washington, DC, on June 16, 1976. The Committee had the benefit of discussions with representa-tives of the NRC Staff aoo the Westinghouse Electric Corporation. The Committee also had the benefit of the documents listed below.
RESAR-3S is a Westinghouse standardized four-loop, single-unit nuclear steam supply system with a core thermal power of 3411 MWt.
Systems within the scope of RESAR-3S include the reactor core, reactor coolant system and supports, chemical aoo volume control system, emergency core cooling system, boron recycle system, residual heat removal system, fuel handling system, and associated instrumentation aoo controls for these systems.
RESAR-3S is similar to the nuclear steam supply system of the SNUPPS projects, reviewed in ACRS reports of September 17, October 16, and December 11, 1975. The ACRS report of September 18, 1975 reviewed the Westinghouse nuclear steam supply system RESAR-41. Significant features, other than those associated with the higher power level, which were incorporated in RESAR-41 but are not in RESAR-3S, include longer fuel assemblies, a rapid refueling system, an emergency boration system, and the use of three independent injection trains in the emergency core cooling system (ECCS).
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Honorable Marcus A. Rowden 2 -
July 14, 1976 RESAR-3S has been designed for application to an envelope of plant sites which includes provision for a Safe Shutdown Earthquake with a max:imtmt horizontal ground acceleration of 0.4g.
RESAR-3S provides for those safety-related interface requirements that are essential to designing the balance of plant to be consistent with the assumptions used in the accident analyses. Since the utility-applicant is responsible for instituting the quality assurance programs necessary to assure that all safety-related design requirements have been met, these matters will be reviewed in more detail with the utility-applicants on a case-by-case basis. The Committee recomnends that during design, procurement, construction, and startup, timely and appropriate interdisciplinary system analyses be carried out to assure complete functional compatibility across each interface for the entire spectrum of anticipated operations and postulated design basis accident conditions.
For multiple reactor units at a single station, the Committee anticipates that safety-related items in RESAR-3S would be separately provided for each reactor unit.
An issue to be resolved prior to preliminary design approval for RESAR-3S involves the possibility of a single failure leading to the loss of the residual heat removal system. The Committee reconmends that this matter be resolved in a manner satisfactory to the NRC Staff and wishes to be kept informed.
The committee reconmends that Westinghouse emphasize analytical and experi-mental programs to substantiate the conservatisms in the current Westing-house ECCS evaluation model and to establish the accuracy and uncertainties in their best-estimate calculations. Timely progress reports should be provided.on the performance of the 17xl7 fuel, the control systems, im-provements in the best estimate analyses, test verification of analytical methods, and reliability studies undertaken to establish meaningful improvements in components, systems, and arrangements for ECC systems and the dependent auxiliaries necessary to sustain the heat transport systems. The Comnittee recamnends that if studies establish that ECCS improvements, such as obtainable from higher reflooding rates, can be achieved, consideration should be given to incorporating them into RESAR-35.
Further review should be made on the adequacy of the RESAR-3S provisions for the maintenance, inspection, and operational needs of the plant through-out its service life and for eventual deconmissioning. In particular, the Committee believes that the NRC Staff and the Westinghouse Electric corporation should review methods and procedures for minimizing, and, if necessary, for removing ~ccumulations of radioactive contamination so that maintenance and inspection programs can be 100re effectively and safely carried out.
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Honorable Marcus A. Rowden 3 -
July 14, 1976 The Committee believes that Westinghouse and the NRC Staff should con-tinue to review RESAR-3S for design changes that will further inprove protection against sabotage.
Generic problems relating to large water reactors are discussed in the Committee's report dated April 16, 1976. The Committee believes that procedures should be developed to incorporate approved resolution of these items into RESAR-3S.
The Committee believes that, subject to the above camnents, RESAR-3S can be successfully engineered to serve as a reference system.
REFERENCES Sincerely yours,
/),ULW,C)r/~
Dade W. Moeller Chairman
- 1. Westinghouse Electric Corporation, "Reference Safety Analysis-35 (RESAA-3S) ", Volumes 1-8, July, 1975.
- 2. Amendments 1-10 to RESAR-3S.
- 3.
USNRC, "Report to the Advisory Committee on Reactor Safeguards in the Matter of Westinghouse Electric Corporation Reference Safety Analysis Report, RESAR-3S," May 25, 1976.
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