05000265/LER-1980-036-03, /03L-0:on 801203,electromatic Relief Valve 2-203- 3D Failed to Open During Reactor Pressure Rise Subsequent to Scram.Caused by Excessive Steam Leakage Between Retainer Plug Into Vol Below Main Disc.Valve Replaced

/03L-0:on 801203,electromatic Relief Valve 2-203- 3D Failed to Open During Reactor Pressure Rise Subsequent to Scram.Caused by Excessive Steam Leakage Between Retainer Plug Into Vol Below Main Disc.Valve Replaced

ML19340E140
Person / Time
Site:	Quad Cities
Issue date:	12/29/1980
From:	Kopacz J COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19340E137	List: 05000265/LER-1980-036, Forwards LER 80-036/03L-0 05000265/LER-1980-036-03, /03L-0:on 801203,electromatic Relief Valve 2-203- 3D Failed to Open During Reactor Pressure Rise Subsequent to Scram.Caused by Excessive Steam Leakage Between Retainer Plug Into Vol Below Main Disc.Valve Replaced
References
LER-80-036-03L-04, LER-80-36-3L-4, NUDOCS 8101060492
Download: ML19340E140 (2)

LER-1980-036, /03L-0:on 801203,electromatic Relief Valve 2-203- 3D Failed to Open During Reactor Pressure Rise Subsequent to Scram.Caused by Excessive Steam Leakage Between Retainer Plug Into Vol Below Main Disc.Valve Replaced

Event date:
Report date:
2651980036R03 - NRC Website

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LICENSEE EVENT REPORT

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REPORT 0 ATE 80 EVENT DESCRIPTION AND PRC8 ABLE CONSEQUENCES h Ic1t' To control reactor pressure rise subsecuent to a reactor scram and isolation.

l f7; T) l Electromatic Relief Valve 2-W -30 failed to open, one Electromatic Relief Valve l

I o l.il L was of adecuate capacity to control reactor pressure.

Relief valves 203-3C 3E 38 l

IO lsl I and 3A were successfully operated during the transient. All other safety and l

relief valves were operable and water inventory was maintained by the feedwater l

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7K N JJ J4 Jb 26 31 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h li l0 l l The cause of failure was excessive steam leakage between the retainer Olua into the l

WI volume below the main disc. The 2-203-3D Electromatic Relief valve was reolaced l

with a spare that has the retainer plug seal welded instead of spot welded. The l

gl gl newly installed valve was tested satisfactorily.

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LER NUMBER: LER/R0 80-36/03L-0 j

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LICENSEE NAME:

Commonwealth Edison Company i

quad-Cities Nuclear Power Station a

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FACILITY NAME:

Unit Two I

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DOCKET NUMBER: 050-265 j

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EVENT DESCRIPTION

On December 3,1980, the Unit Two reactor scrammed and isolated from the main condenser af ter receiving a main steam line high flow signal.

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To control the pressure rise subsequent to the scram and isolation, I

Electromatic Relief valves were manually actuated. At this time, l

valve 2-203-30 failed to open. The valve was successfully operated during cool down at 400 psig reactor pressure.

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PROBABLE CONSEQUENCES OF THE OCCURRENCE:

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The effect of one electromatic relief valve failing to open was minimal.

One electromatic relief valve was of adequate capacity to control reactor pressure. Relief valves 2-203-3C, 3E, 3B, and 3A were success-fully operated during the transient to dissipate torus heat load. All other safety and relief valves were operable and reactor water inventory was being maintained using the feedwater system. Therefore,

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this occurrence had minimal consequences.

Vll. CAUSE:

i The failure of the 2-203-3D Electromatic Relief valve was caused by excessive leakage between the retainer plug into the volume below the main disc. This area was designed to leak a small amount to allow the area behind the disc to be pressurized, thus holding the disc firmly against its seat. The pilot valve was designed to vent the volume behind the main disc allowing it to open. The excessive leakage was more than the pilot valve could handle, causing the volume to remain pressurized. The electromatic relief valve, type 1525-VX, is manufactured by the Consolidated Valve Division of Dresser industries.

Vill. CORRECTIVE ACTION:

Previous corrective actions for this type of failure have been to spot weld the retainer plug. Current repair procedures have been changed to seal weld the retainer plug instead of using the spot weld technique.

The relief valve was replaced with an identical type spare with the retainer plug seal welded. All relief valves are now seal welded to prevent the failure as described above.

The newly installed relief valve was then successfully tested.

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