ML20238D177
| ML20238D177 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/04/1987 |
| From: | Jaffe D Office of Nuclear Reactor Regulation |
| To: | Mroczka E NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| GL-83-28, TAC-53920, NUDOCS 8709110021 | |
| Download: ML20238D177 (3) | |
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Docket No. 50-336
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September 4,1987 1
1 Mr. Edward J. Mroczka Senior Vice President Nuclear Engineering and Operations Northeast Nuclear Energy Company P. O. Box 270 Hartford, Connecticut.06141-0270 4
Dear Mr. Mroczka:
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SUBJECT:
MILLSTONE NUCLEAR POWFR STATION, UNIT NO. 2 (TAC'#53920)
We are in the process of reviewing your response to Generic Letter (GL) 83-28, Items 4.2.3 and 4.2.4, for Millstone Unit 2.
Please respond to the enclosed request for additional information within 60 days following receipt of this letter.
This request for additional information affects fewer than 10 respondents; therefore, OMB clearance is not required under P.L.96-511.
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Sincerely,
/S/
David H. Jaffe, Project Manager Project. Directorate I-4 Division of Reactor Projects 1/II 1
Enclosure-Request for Additional Information cc w/ enclosure:
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Mr. Edward J. Mroczka Millstone Nuclear Power Station Northeast Nuclear Energy Company Unit No. 2 cc:
Gerald Garfield, Esq.
Mr. Wayne D. Romberg Day, Berry & Howard Superintendent Counselors at Law Millstone' Nuclear Power Station City Place P. O. Box 128 Hartford, Connecticut 06103-3499 Waterford, Connecticut 06385 Regional Administrator, Region I U.S. Nuclear Regulatory Commission Office of Executive Director for Operations 631-Park Avenue King of Prussia, Pennsylvania 19406 Mr. Charles Brinkman, Manager Washington Nuclear Operations C-E Power Systems Combustion Engineering, Inc.
7910 Woodmont Avenue Bethesda, Maryland 20814 Mr. Lawrence Bettencourt, First Selectman Town of Waterford Hall of Records - 200 Boston Post Road Waterford, Connecticut 06385 Northeast Utilities Service Company ATTN: Mr. Richard R. Laudenat, Manager Generation Facilities Licensing Post Office Box 270 Hartford, Connecticut 06141-0270 Kevin McCarthy, Director Radiation Control Unit Department of Environmental Protection State Office Building Hartford, Connecticut 06106 Mr. Theodore Rebelowski U.S. NRC P. O. Box 615 Waterford, Connecticut 06385-0615 j
Office of Policy & Management ATTN: Under Secretary Energy Division 80 Washington Street Hartford, Connecticut 06106 Q___-____-_-________________
REQUEST FOR ADDITIONAL INFORMATION ITEM 4.2 (PARIS 354) 0F GENERIC Lt.ilER 83-28 j
MILLSTONE NUCLEAR STATION, UNIT 2 Item 4.2 of Generic l.etter 83-28 requires licensees or applicants to describe their preventive maintenance and surveillance program for ensuring reliable reactor trip breaker operation. Parts 3 and 4 of Item 4.2 pertains to life testing of an acceptable sample size of the breakers, and periodic replacement of the breakers or components consistent with demonstrated life cycles. The licensee submitted a response to Item 4.2 (Parts 3&4) by letter dated March 16, 1984.
In that response the licensee refers to the joint Combustion Engineering and B&W Owners Group (R&WOG) reliability data program for the GE AK-2 RTB.
B&WOG has concluded that the design of the GE AK RTBs is such that the breaker i
and its tripping devices are not susceptible to a wear related failure as are the Westinghouse RTBs. No analysis has been presented to support the B&WOG conclusion, or to show why the GE RTBs are less susceptible to wear than the Westinghouse RTBs.
In addition, B&WOG has not conducted cyclic testing of the GE AK RTDs, nor has aging been addressed.
If it can be demonstrated that the qualified life of the RTB exceeds the life of the plant, then the specific qualified life need not be identified.
In a practical sense, the intent of the life testing requirement of the generic letter would be satisfied by) demonstrating that the qualified life of the breaker (for the tripping function exceeds the expected use projected to the next refueling.
Cycle testing by the various owners groups, although it does not consider the effects of aging, may provide evidence to support continued use of the RTBs for one additional refueling cycle, provided that the individual breaker has not shown a sign of degradation based on the licensee's Parametric Trend Monitoring Program.
In this approach, the actual qualified life is not specifically identi-
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fied, but is only demonstrated to be adequate.
Ongoing life testing is an acceptable alternative to formal life testing for the purpose of establishing a specific qualified life for RTBs. Ongoing life testing i
will demonstrate that the qualified life, though not specifically known, is longer (in terms of cycles and time) than the integrated service that will be accumulated through the next refueling interval. The description of an ongoing qualification program should include the following:
(1) An estimate of the number of demands between refueling outages to which i
the RTB must respond, and the basis for the estimate.
(2) A definition of relevant, end-of-life related failures (Note that random failures occurring during the constant hazard rate portion of the " bathtub curve" (plot of failure rate vs. time) are not relevant to a life test).
The licensee should (a) identify the possible failure modes, (b) categorize each failure mode as an end-of-life type or not, and (c) present a general methodology for categorizing future failure modes that may not be included in(a).
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