ML19270F679

LER 79-003/03L-0 on 790119:valve MO1-220-1 Found Leaking at Rate of 43.8 Std Cubic Feet Per Hour.Caused by Dirty & Worn disc-to-seat Surfaces.Valve Disc Was Relapped & Valve Seat Cleaned

ML19270F679
Person / Time
Site:	Quad Cities
Issue date:	02/16/1979
From:	Robert Murray COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML17296A304	List: ML17296A303 ML19270F656 ML19270F659 ML19270F662 ML19270F668 ML19270F673 ML19270F676 ML19270F679 ML19270F682 ML19270F683 ML19270F684
References
LER-79-003-03L-06, LER-79-3-3L-6, NUDOCS 7903070363
Download: ML19270F679 (2)

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'~] ] [ While performing the local leak rate test on the volume between the main steam line j

-g; drain valves, valve MO 1-220-1 was found to have a leak rate of 43.8 SCFH. The  !

--1 i safety implications of this occurrence are minimal due to the fact that the redundant l t_

-- _.s,L isolation valve, MO 1-220-2 had no leakage and would have provided primary containment l

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h ltjoll The leakage was found to be through the valve disc and seat. The di sc-to-seat surfaces l

,i were dirty and the dis, slightly worn. The valve disc was relapped and the valve seat l l

,,; was cleaned". A second leak rate test was performed and the corrected leak rate from l the volume was found to be 10.5 SCFH. l l

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1. LER HUMBER: 79-03/03L-0 ll. LICENSEF NAME: Commonwealth Edison Company quad-Cities Nuclear Power Station 111. FACI LITY NAME: Unit One IV. DOCKET NUMBER: 050-254 V. EVENT DESCRIPTION:

On January 19, 1979, with the Unit One reactor shut down for a refueling outage, routine local leak rate test procedure QTS 100-4 was performed on the volume between main steam line drain valves, MO 1-220-1 and MO 1-220-2. The combined leak rate was found to be 43.8 SCFH. This is in excess of the 18.36 SCFH allowed by Technical Speci fica tion 4.7. A.2.1.2.b.

for any one isolation valve. The main steam lines were then filled with water, which imposed a head of approximately 25 psig on the MO 1-220-1 valve. A leak rate test was performed at 25 psig on the volume between the MO 1-220-1 and MO 1-220-2 valves. The results showed zero leakage through the MO 1-220-2 valve, thus it was resolved that the MO 1-220-1 valve was responsible for the leakage.

VI. PROBABLE CONSEQUENCES OF THE OCCURRENCE:

Main Steam Line Drain Valves MO 1-220-1 and M0 1-220-2 are normally closed during reactor power operation and are open during startups and shutdowns to drain the main steam lines.

The safety implications of this occurrence are minimized by the fact that the MO 1-220-2 valve was found not to be leaking.

Thus, primary containment integrity was not canpromised. The leakage path through this line could have been further Isolated oy closing valves MO 1-220-4 and 1-220-92, preventing any leakage f rom reaching the condenser.

Vll. CAUSE:

The leakage was found to be through the valve disc and seat.

The disc-to-seat surfaces were dirty and the disc slightly worn.

Valve MO 1-220-1 is a 3 inch carbon steel gate valve, manu-factured by the Crane Company, model number 783-U.

Vlli. CORRECTIVE ACTION:

The immediate corrective action was to write work request number 365-79 to repair the valve. The valve disc was relapped and the valve seat was cleaned. The valve was reassembled and a second local leak rate test was performed on the volume.

The corrected Icak rate for the volume was found to be 10.5 SCFH.