ML17252A245

Letter Submitting Reportable Occurrence Number 050-249/1976-25 in Accordance with Technical Specifications, Section 6.6.B

ML17252A245
Person / Time
Site:	Dresden
Issue date:	11/04/1976
From:	Stephenson B Commonwealth Edison Co
To:	Keepler J NRC/RGN-III
References
BBS Ltr. #76-776
Download: ML17252A245 (3)

Text

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-4, 1976 Mr. James G. Keppler, Regional Director .

Directorate of Regulatory Operations - Region III U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 I

i Enclosed please find Reportable Occurrence report number 50-249/1976-25.

This report is being submitted to your office in accordance with the Dresden Nuclear Power Station Technical Specifications, Section 6.6.B. *

. . . ~'fYl~*

• h . B. Stephenson .

tation Superintendent Dresden N~clear Power Station

', BBS :jo Enclosure cc: Director of Inspection & Enforcement Director.of Management Information & Program Control File/NRC

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• LICENSEE EVENT REP OR.

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. *---* CATEGORY TYPE. SOURCE DOCKET NUMBER EVENT DATE REPORT DATE

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kQCAb *LEAK-RAT£ TSTIAlG-j FEE.DWAT£R CHEckl

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EVENT DESCRIPTION (Continued) the Tech Spec limit. A few days later, these check valves were pressurized with water to 500 PSIG in an attempt to more closely approximate accident con-ditions. Subseq~ent retesting of valves 3~220-58B and -62B yielded leakage rates of 15.9 and 29.7 SCFH respectively. Since the leakage through valve 3-220-58B was reduced to a value below Tech Spec limits, no further action was necessary. Valve 220-62B .was disassembled and inspected.

Redundant valves were available and operable during unit operation. This is a repetitive occurrence*. (50..:..249/1976-25)

CAUSE DESCRIPTION (Continued) these clear.ances and resulted in much lower leakage rates.

Disassembly of valve -62B revealed no defective components; the only abnormality was dirt in the valve* seat. The valve was cleaned, and the d.isc assembly and seai ring.were replaced as a precautionary measure *. Following reassem"ly, valve 220-62B was retested, and a leak rate of. 1.03 SCFH was obtained.

Because of the high incidence of initial LLRT failures on the* feedwater check vaJ_ves, the station has reevaluated the present method. of testing these.**

vaives ~ **A new method has* been developed which more closely represents the *

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'* a let.te~ will be submitted delineating .the station's 'prop_os~l.

Bo1h valves are *18-inch tilting disc check valves manufa'ctured by the Cra.ne Company ..