ML20204G414

Discusses Recent Steam Generator Tube Leakage & Concurs W/ Evaluation That Structural Integrity of Steam Generator Tubes Appears Adequate

ML20204G414
Person / Time
Site:	Millstone
Issue date:	03/16/1987
From:	Thadani A Office of Nuclear Reactor Regulation
To:	Mroczka E NORTHEAST NUCLEAR ENERGY CO.
References
NUDOCS 8703260392
Download: ML20204G414 (4)

Text

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. MAR 161987 L0ocket No. 50-336 5

s Mr. Edward J. Mroczka, Senior Vice President -

Nuclear Engineering and Operations Northeast Nuclear Energy Company P. O. Box 270 Hartford, Connecticut 06141-0270

Dear Mr. Mroczka:

On March 5, 1987, the NRC staff met with representatives of Northeast Nuclear Energy Company (NNECo) for the purpose of discussing the recent steam generator tube leakage at Millstone Unit 2. Based upon our discussions with NNEco and after consultation with the NRC Region I staff, we concur.with your evaluation that the structural integrity of the steam generator tubes appears adequate at this time. Our conclusions are partly based upon your commitment to observe an administrative primary-to-secondary leakage limit, through any one steam generator, of 0.15 gpm. In this regard, NNECo indicated that a change i to Technical Specification 3.4.6.2c would be proposed in the near future to formally incorporate the 0.15 gpm limit.

Should Millstone Unit 2 experience additional steam generator leakage as a result of a similar tube failure, and if the plant is shut down for repairs, we understand that the following elements will be incorporated

-in your program:

(1) Improved ECT examination of all tubes characterized to be in the same class as the leaking tube. The ECT technique should incorporate a probe

-that will detect circumferential defects. In this regard, we note that the recent outage resulted in a high man rem commitment as a result of the use of manual inspection methods. Some advanced planning, at this time, might improve this situation in the event of aa unexpected outage.

(2) Characterization of the defect. You should plan to remove one or more steam generator tube samples to evaluate the nature of the failure l mechanism.

(3) Prior to startup, you should provide the NRC staff with a detailed justification for continued operation based upon the inspection results.

Regardless of the need for additional steam generator tube inspection and/or repair during thc remainder of tha current fuel cycle, we expect that during B703260392 870316 PDR ADOCK 05000336 p PDR

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. Mr. E. J.'Mroczka the next refueling outage improved ECT data will be obtained for those steam generator tubes that have been classified as similar to the tube that recently experienced leakage and, in addition, a steam generator tube sample should be obtained.

Please keep us informed regarding steam generator tube leakage trends.

Sincerely, Original signed byt Ashok Thadani Ashok C. Thadani, Director PWR Project Directorate #8 Division of PWR Licensing-B cc: See next page DISTRIBUTION ACRS-10 Docket File BGrimes NRC PDR JPartlow L PDR DJaffe PBD-8 Rdg PKreutzer FMiraglia Gray File OGC-Bethesda NThompson EJordan 90e g ytac h ed.

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Please keep us inform'ed regarding steam generator tube leakage trends.

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Ashok C. Thadant, Direct)r

. PWR Project Directorate i/8 Division of PWR Licensin'J-B cc: See next page ,

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Mr. Edward J. Mroczka Millstone Nuclear Power Station Northeast Nuclear Energy Company Unit No. 2 cc:

Gerald Garfield, Esq. Mr. Stephen E. Scace 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 Mr. Wayne D. Romberg U.S. Nuclear Regulatory Commission Vice President, Nuclear Operations Office of Executive Director for Northeast Nuclear Energy Company Operations P. O. Box 270 631 Park Avenue Hartford, Connecticut 06141-0270 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 M. Kacich, 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 l

Office of Policy & Management ATTN: Under Secretary Energy Division 80 Washington Street Hartford, Connecticut 06106 l

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