B10672, Ro:On 830131,increased Primary to Secondary Leakage Rate Noted in Steam Generator 1.Caused by Expected Erosion in Leakage Area & Thermal Cycling Due to Power Transients & Plant Trips.Leakage Rate Measurements on 830202 Listed

Ro:On 830131,increased Primary to Secondary Leakage Rate Noted in Steam Generator 1.Caused by Expected Erosion in Leakage Area & Thermal Cycling Due to Power Transients & Plant Trips.Leakage Rate Measurements on 830202 Listed

ML20065A986
Person / Time
Site:	Millstone
Issue date:	02/10/1983
From:	Counsil W, Sears C NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	Clark R Office of Nuclear Reactor Regulation
References
B10672, TAC-48062, TAC-49793, NUDOCS 8302220349
Download: ML20065A986 (2)

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NOpfo<As1 umJCLE.R ENERGT Cow-February 10,1983 Docket No. 50-336 B10672 Director of Nuclear Reactor Regulation Attn: Mr. Robert A. Clark, Chief Operating Reactors Branch #3 U. S. Nuclear Regulatory Commission Washington, D. C. 20555

Reference:

(1) W. G. Counsil letter to R. A. Clark, dated July 9,1982, transmitting baseline primary to secondary leakage rates.

Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 Increased Primary to Secondary Leakage Rates This letter provides notification of an increased primary to secondary leakage rate, pursuant to the requirements of Technical Specification 3/4.7.1.4, Table 4.7-2. The steady state leakage rate for Steam Generator No. I determined on January 31,1983 has increased by greater than 0.05 gpm from the value provided in Reference (1).

The increase in the primary to secondary leakage rate in Steam Generator No. I has been a gradual process which can be attributed to erosion expected to occur across the leakage area. In addition, since the Reference (1) transmittal of baseline primary to secondary leakage rates, the plant has experienced a number of power transients and plant trips resulting in the thermal cycling of the steam generators. Thermal cycling has previously been identified as a potential cause of the primary to secondary leakage at Millstone Unit 2.

At present, Millstone Unit No. 2 is scheduled for a late May 1983 refueling outage. As such continued operation of the plant is planned for approximately j the next 3Y2 months. During the refueling outage, Northeast Nuclear Energy l Company plans to take the necessary actions to repair present defects in the l Steam Generators as part of its Steam Generator Maintenance project. Until that time any further degradation of the leakage rate will be readily identified by existing detection methods. The leak rates are determined on a daily basis, l and any incremental increase of greater than or equal to 0.05 gpm in the steady state value for either steam generator will be reported in accordance with Technical Specification Table 4.7-2. Prompt corrective action will be initiated for leakage in excess of 0.5 gpm per steam generator as required by Technical Specification 3/4.4.6.2 and 4.4.5.1.3.C. Thus, continued operation is justified and acceptable.

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'd Baseline leakage rate measurements were conducted in mode 1 at steady state operating conditions as required by Table 4.7-2 of the Technical Specifications.

The new baseline primary-to-secondary leakage rate in each steam generator has been determined to be:

0.286 gpm Steam Generator No.1 0,03! gpm Steam Generator No. 2 These leakage rate measurements were completed on February 2,1983.

We trust you will find this information satisfactory.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY W . b. Dunn W. G. Counsil Senior Vice President

b. b/L By: C. F. Sears Vice President Nuclear rnd Environmental Enginecing