ML19323B488

Final Deficiency Rept Re Potential Design Error in Reset Circuitry of Main Steam Trip Valves TV-MS201A,B & C.Valve in Affected Line Will Not Open Due to Pressure Differential Across Valve.Valve Control Circuits Will Be Redesigned

ML19323B488
Person / Time
Site:	North Anna
Issue date:	05/08/1980
From:	Sylvia B VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
References
412, NUDOCS 8005120439
Download: ML19323B488 (2)

Text

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i 8005120L/39 VractNzA ELECTRIC AND Powna CoxPANY kicnwown.Vamonw1A 23261 ,

! May 8, 1980 "r. Janes P. O'Pc111y, Director Serial !!o. 412 Office of Inspection & Enforcerent  ?:0/Pf!T:bau

'J . S . Nuclear oe gulatory Connission Docke t !!o . 50-330 Eegion II 101 ?'arie tta Street, Euite 3100 Atlanta, Georgia 30303 Nar ?!r. O'Pelliy:

Cn April 11, 1930, under the provisions of 10CFR50.55(e), the ??RC Pegion II was notified of a potential design error in the reset circuitry of !!ain Stean Trin valves TV-MS201A,B and C. Epecifically, the valves set a signal to return to a non-safety rode (open) upon reset of the nain steanline iso-lation siF nal uithout subsecuent operation of the control switch for each device. This equipnent operation is inconsistent with FSAR Connent 7.4 and contrary to FSAR Sect ion 7. 3.1. 5, page 7.3-36.

He trip valves close to prevent blowdown of the steam generators with a

nain stean nine break downstrean of the valves. Although the valves i receive a signal to open upon resetting the rain steanline isolation signal, the valve in the af fected line will not recpon because of tbc pressure differential across the valve.

Se control circuits for TV-?tF201A, B and C uill be redesigned and nodified for conpliance during the first l' nit 2 refueling outage. Plant safety is not conprenised by this delay because the following conditions vould have to be i

satisfied for these valves to return to their non-safety node.

1. The main stean nca-return valves (!3V's ) would have to be closed.

I 2.  ?!ain stean line isolation train A reset pushbutton vould have to l be re se t.

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3. 'ain stean line isolation train B reset pushbutton would have to be reset.

1 4 He nain stean bypass trip valves vould have to be opened.

~hese actions are necessary because the main secan trip valves cannot open uith genater than a 4 osi differential pressure.

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