ML20085L876

Ro:On 710710,during Initial Startup Testing,Hpci Turbine Stop Valve Would Not Reset Rendering Sys Incapable of Providing Coolant Injection as Required by Tech Specs.Caused by Misaligned Limit Switch on HPCI Control Valve

ML20085L876
Person / Time
Site:	Dresden
Issue date:	07/18/1971
From:	Hoyt H COMMONWEALTH EDISON CO.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085L879	List: ML20085L876 ML20085L885 ML20085L891
References
NUDOCS 8311030331
Download: ML20085L876 (2)

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Commonwealth Edison Company O N at PlRST N A T IO N A L PLAZA

• C H l C A G O. ILLINOIS Ad&een Reply ser POST OFFICI 80I 767

• C H I C A G O, BLLlHoss 60690 Dresden !!uclear Power Station R. R. #1 I! orris, Illinois 60430 July 18, 1971

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Y Dr. Peter A. :forris Director Division of Reactor Licensing U. 3. Atomic Energy Commission h' N4 Washington, D. C. 20545 f,-

SUBJECT:

LICENSE DPR 25, DRESDEN la: CLEAR POWER STATION UNIT 13 SECTIONS 6.6. A.1 AND 6.6.B.2 0F TECHNICAL SPECIFICATIONS

Dear Dr. Morris:

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This is to report a condition relating to the operation of the station wherein, during initial 350 psig plant startup testing, the High Pressure Coolant Injection (HPCI) turbine stop valve would not reset.

Failuro of the stop valve to reset rendered the system incapable of providing coolant injection as required by Section 3.5,.C.1 of the Dresden Unit 3 Technical Specifications Froblem and Ir.vestigahlons Planned HPCI startup testing was initiated at a reactor pressure of 350 psig on July 10, 1971. At 2130 hours0.0247 days <br />0.592 hours <br />0.00352 weeks <br />8.10465e-4 months <br /> it was found that the HPCI turbine stop valve would not open. The required surveillance program was j

then initiated. Subsequent investigation revealed the trouble was caused by a misaligned li:ait switch on the HPCI control valve which was in the colentid circuit for the stop valve. The relay logic associated with the system had actusted nor tally. Repositioning of the limit switch was completed by 2400 hours0.0278 days <br />0.667 hours <br />0.00397 weeks <br />9.132e-4 months <br /> on the same day and the HPCI tests were begun at 0030 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> on July 11, 1971. The runs, successfully completed, included both manual and automatic starts.

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LUFY SENT REGION "

n Dr. Peter A. I' orris 2 0

July 13, 1971 Conclusion Previous tests of the HPCI system were conducted on July 6, l')71.

The operation lasted almost two hours and it is believed that the limit switch became misaligned at that time. Subsequently, tests of the HPCI systen have been conducted at 650 pair reactor pressure on July 15, manual and automatic starts, and today at 1000 psig, manual start.

Since the subsequent tests have been satisfactcry, no further action is planned.

Sincerely, H. K. Hoyt Superintendent HKH:13 0

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