ML20084T996

Ro:On 700529,one of Five Electromatic Relief Valves (2C) Failed to Open During Surveillance Test.Linkage Adjustment Nut on Pilot Valve Stem Adjusted

ML20084T996
Person / Time
Site:	Dresden
Issue date:	06/08/1970
From:	Hoyt H COMMONWEALTH EDISON CO.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084U000	List: ML20084T996 ML20084U014 ML20084U018
References
01992, 1992, NUDOCS 8306240387
Download: ML20084T996 (2)

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o '* qc *2 ~a Morris, Illinois 60450 lyn y' June 8, 1970 Nkh Dr. Peter A. Morris Director Division of Reactor Licensing U. S. Atomic Energy Comission Washington, D. C. 20545

SUBJECT:

LICENSE DPR-19, DRESDEN NUCLEAR PO'42R STATION UNIT #2, SECTION 6.6.C OF THE TECHNICAL SPECIFICATION.

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Dear Dr. Morris:

This is to report a condition relating to the operation of the station, which during a surveillance test of the electromatic relief valves serving the automatic blowdown system, one of the five electromatic relief vaivc= (20) failed ro open.

_ Problem, Investigation and Corrective Action The problem was discovered at 1:30 a.m. on May 29, 1970 during surveillance testing as required by section 4.5.C.2 of the Technical Specification. As reported in our letter to you dated June 2,1970, the HPCI system was taken out of service at 12:50 a.m. on May 29, 1970 .

Locd reduction was initiated in preparation for orderly plant shutdown and an evaluation of the situation was made, which indicated that the relief valve solenoid-operated pil.ot was opening, but not sufficiently to actuate the relief valve. Plans were mcde for drywell entry at low power to check the pilot valve stroke and make adjustments. This was done. At 3:00 p.m.

the relief valve was operated satisfactorily. Daily surveillance testing following restoration of the system to operational status showed that the system has remained fully operational.

The problem was similar to the 2D valve failure to operate as reported in our letter of May 22, 1970, execpt for the adjustment that was-required. The 2D valve required repositioning of the actuating roller on the colenoid linkage, whereas the 20 valve required adjustment of the 3 linkage adjust =ent nut (one turn) on the pilot valve stem. Ihe problem with I 2D valve vacMiiered~dtiririfthedirst-hot opetution of the valve during the startup tests and because all others operated satisfactorily it was .

considered at that time that proper adjustments did exist on all valves.

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, ,, , .Dr. feterA. Morris Juna 8, 1970 o O As a result of the accond f ailure to operate, pilot valve stroke will be checked on all five valves as a check against manufacturW recomendationT'an'd a comparison made between each valve.

A review of the situation has been made by the Station Review Board which concurred that the Technical Specification requirements were met and that the corrective action is appropriate.

Sincerely, bd'/ 4)2f ,

H. K. Hoyt ;c HKH: GLR:sjb s

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