ML20052D777

Ro:On 820415,steam Generator 1 Increased Primary to Secondary Leakage Rate of 0.049 Gpm from Valve.Cause of Leak Rate Unknown.Increase Appears to Be Related to Plant Shutdowns/Trips Experience in Thermal Cycling

ML20052D777
Person / Time
Site:	Millstone
Issue date:	04/29/1982
From:	Counsil W NORTHEAST NUCLEAR ENERGY CO.
To:	Clark R Office of Nuclear Reactor Regulation
References
A02357, A2357, TAC-48062, NUDOCS 8205070206
Download: ML20052D777 (2)

Text

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General Offices e Selden Street, Berlin, Connecticut

} UZ2rN.US7 R FORD CONNECTICUT 06101

"";'OCOO.'CC" (20m men L L J =:r = TOlr April 29, 1982

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Docket No. 50-336 'r A02357 /8 N'e3 v

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n c3274hQ Director of Nuclear Reactor Regulation Attn: Mr. Robert A. Clark, Chief ',5 ggnf{,j W2' 3 ;, /w

/f, Operating Reactors Branch #3 U. S. Nuclear Regulatory Commission 'b e',,',

Washington, D.C. 20555

Reference:

(1) W. G. Counsil letter to R. A. Clark, dated April 7, 1982, transmitting baseline primary-to-secondary leakage rates.

Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 Increased Primary-to-Secondary Leakage Rate 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 No. 1 Steam Generator determined on April 15, 1982 had increased by 0.049 gpm from the value provided in Reference (1).

The cause of the leak rate is not known; however, the increase appears to be related to the above average number of plant shutdowns / trips ex-perienced this operating cycle to date resulting in steam generator thermal cycling. The indicated leakage increases after each trip with a subsequent decrease upon return to sceady state conditions; however, these steady state leak rates are slightly higher after the transient.

An increase in leakage has not been identified during steady state power operation.

Any further degradation of the leakage rate will be readily identified by existing detection methods. The leak rates are determined on a daily basis, and any incremental increase of greater than or equal to 0.05 gpm in the steady state value for either steam generato,r 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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Subsequent to the leakage rate determination and verbal report on April 15, 1982, the Unit tripped as a result of a leak in the instrument air system. Following startup, 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:

0.094 gpm Steam Generator No. 1

<0.005 gpm Steam Generator No. 2 These leakage rate measurements were completed on April 27, 1982.

We trust you find this information satisfactory.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY I '

W. G. Counsil Senior Vice President i

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