ML16224A783

Requirements for Full-Height, Full-Pressure Integral System Testing of the Westinghouse AP600 Passive Plant Design

ML16224A783
Person / Time
Issue date:	03/10/1992
From:	Ward D Advisory Committee on Reactor Safeguards
To:	Selin I NRC/Chairman
References
D920310
Download: ML16224A783 (2)

Text

D920310 The Honorable Ivan Selin Chairman U.S. Nuclear Regulatory Commission Washington, D.C. 20555

SUBJECT:

REQUIREMENTS FOR FULL-HEIGHT, FULL-PRESSURE INTEGRAL SYSTEM TESTING OF THE WESTINGHOUSE AP600 PASSIVE PLANT DESIGN During the 383rd meeting of the Advisory Committee on Reactor Safeguards, March 5-7, 1992, we discussed the issue of the requirements for full-height, full-pressure (FHFP) integral system testing of the Westinghouse Electric Corporation's AP600 passive plant design. We also considered this matter during our 382nd meeting, February 6-8, 1992, and our 381st meeting, January 9-11, 1992. Our Subcommittee on Thermal Hydraulic Phenomena met on March 3, 1992, and December 17, 1991, to discuss this matter.

During these meetings, we had the benefit of discussions with representatives of the NRC staff and the Westinghouse Electric Corporation and of the referenced documents.

We have been asked to comment on two separate but related actions.

The first is a user-need letter from the Office of Nuclear Reactor Regulation (NRR) to the Office of Nuclear Regulatory Research (RES) requesting that FHFP integral system testing for the AP600 passive plant design be carried out by the NRC. The RES response to the user-need letter is the recommendation to the Commission in SECY-92-037. The second is the recommendation made in SECY-92-030 that Westinghouse also be required to do FHFP integral system testing.

Westinghouse has planned a robust separate effects test program combined with low-pressure integral system testing. Westinghouse believes that the behavior of AP600 under high-pressure conditions is well enough understood and that the Westinghouse low-pressure test program combined with high-pressure separate effects tests will fully address all areas of need. On the one hand, Westinghouse believes it is premature to be asked to do FHFP integral system testing. On the other hand, the staff believes that potential complex interactions taking place at high pressure are sufficiently important and insufficiently understood to require FHFP integral system testing. The staff made a good case in support of its views, however, neither Westinghouse nor the staff has done enough work to defend their positions convincingly. A technically sound approach would be to wait until the Westinghouse test program is complete, and then consider the need for FHFP integral system testing. The present certification schedule precludes this approach.

Inasmuch as FHFP integral system testing will require at least three to four years to complete, there is a risk that the present certification schedule will be affected unless the test program is begun now. We believe that the likelihood of such an impact is

great. If the present certification schedule is to be adhered to, we recommend that a FHFP integral system testing program be initiated now.

The need for both Westinghouse and NRC to embark on separate testing programs was not demonstrated in the numerous presentations we have received. We recommend that a joint program be implemented in order to bring the best technical expertise to bear, to limit costs to both Westinghouse and the NRC, and to ensure the acceptability of the results.

Further, we recommend that the joint test program be modeled after the cooperative approach used to study small-break LOCAs in Babcock and Wilcox plants (the MIST program). In that case, a program of tests and associated analyses was established that was jointly planned, managed, and funded by the NRC, the vendor, the associated Owners Group, and the Electric Power Research Institute (EPRI). In this case, consideration should be given to joint financing of the proposed program by such entities as DOE, EPRI, Westinghouse, and the NRC.

If a decision is made to go forward with FHFP integral system testing, we would like the opportunity to perform a more definitive review. We have concerns about the adequacy of the foreign test facilities under consideration.

Sincerely, David A. Ward Chairman

References:

1. U.S. Nuclear Regulatory Commission, SECY-92-030, Memorandum to the Commissioners from James M. Taylor, NRC Executive Director for Operations, dated January 27, 1992,

Subject:

Integral System Testing Requirements for Westinghouse's AP600 Plant

2. U.S. Nuclear Regulatory Commission, SECY-92-037, Memorandum to the Commissioners from James M. Taylor, NRC Executive Director for Operations, dated January 31, 1992,

Subject:

Need for NRC-Sponsored Confirmatory Integral System Testing of the Westinghouse AP600 Design

3. Letter dated January 30, 1992, to B. A. McIntyre, Westinghouse Electric Corporation, from D. M. Crutchfield, NRC Office of Nuclear Reactor Regulation,

Subject:

AP600 Design - Issues to be Resolved by High-Pressure, Full-Height Integral Testing

4. Letter dated February 25, 1992, to I. Selin, NRC Chairman, from C. Caso, Westinghouse Electric Corporation,

Subject:

Westinghouse Comments on SECY-92-030

5. Memorandum dated November 15, 1991, to E. Beckjord, NRC Office of Nuclear Regulatory Research, from T. Murley, NRC Office of Nuclear Reactor Regulation,

Subject:

Research User Need for Confirmatory Thermal-Hydraulic Testing of Westinghouse AP600 Design