ML19270F684

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LER 79-003/03L-0 on 790119:reactor Core Isoloation Cooling Sys Turbine Steam Exhaust Check Valve Cv 1-1301-41 Was Leaking.Caused by Dirty Valve Internals.Valve Internals Cleaned & Valve Reassembled
ML19270F684
Person / Time
Site: Quad Cities Constellation icon.png
Issue date: 02/16/1979
From: Kooi M
COMMONWEALTH EDISON CO.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML17296A304 List:
References
LER-79-003-03L-09, LER-79-3-3L-9, NUDOCS 7903070386
Download: ML19270F684 (2)


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L. While performing local Icak rate testing, the Reactor Core Isolation Cooling System i e ;3  ; (RCIC) turbine steam exhaust check valve CV 1-1301-41 was found to have a leak rate i 7 of 396.3 SCFH. In the event of a high suppression chamber pressure, stop check  :

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h 1

Ol The valve internals were found to be di rty. thus preventina a good disc-to-seat seal, I l: lil l The valve internals were cleaned and the valve reassembled. A local leak rate test I jil7j l was then performed and the leak rate was found to be 0.0 SCFH. I 1 3 l 11 141 l l 7 8 9 30 A JS  % POWER OTHER STATUS IS Y DISCOVERY DESCntPTION 1-1 L 8 9 W@ l o10 l o l 0 l@l 12 11 NA 44 l lBl@l 45 46 Local Leak Rate Testing EO i

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l. LER NUMBER: LER/R0 79-03/03L-0 ll. LICENSEE NAME: Commonwealth Edison Company Quad-Cities Nuclear Power Station Ill. FACILITY NAME: Unit One IV. DOCKET NUMBER: 050-254 V. EVENT DESCRIPTION:

On January 19, 1979, while performing Local Leak Rate Testing, the Reactor Core Isolation Cooling System (RCIC) turbine steam exhaust check valve CV 1-1301-41 was found to have a leak rate of 396.3 SCFH. The test was performed according to procedure QTS 100-21 by closing the 1-1301-64 stop check valve and pressurizing the volume between the two valves. The Technical Specification leak rate limit for any one primary containment isolation valve is 18.36 SCFH. Work request 357-79 was written to repair the valve.

VI. PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The purpose of check valve CV 1-1301-41 is to prevent the back flow of steam from the pressure suppression chamber into the RCIC system.

In the event of a high suppression chamber pressure, stop check valve 1-1301-41 was operable. It also could have been manually shut to minimize leakage back to the RCIC turbine. The leakage through CV 1-1301-41 did not render the RCIC system inoperable, nor incap-able of performing its intended function when needed.

Vll. CAUSE:

Upon disassembly, the valve internals were inspected and the valve disc and seating surfaces were found to be dirty, thus preventing a good disc-to-seat seal. Further inspection revealed no other abnormalities which could have caused the failure. Check valve CV 1-1301-41 is an 8 inch, 150 pound swing check valve manufactured by Crane Company.

Vill, CORRECTIVE ACTION:

The valve internals were c1 caned and the valve was reassembled. A local leak rate test was then performed and the leak rate was found to be 0.0 SCFH.