ML20196B848

Part 21 Deficiency Rept Re HPCI Suction Pipe Overpressure Transient.Initially Reported on 880129.Caused by Installation of Lift/Plug Check Valve.Potential Water Hammer Condition Corrected by Replacing Valve

ML20196B848
Person / Time
Site:	Fermi
Issue date:	01/29/1988
From:	Stramback G GENERAL ELECTRIC CO.
To:	Berlinger C Office of Nuclear Reactor Regulation
References
REF-PT21-88-008-000 MFN-088-88, PT21-88-008-000, NUDOCS 8802120164
Download: ML20196B848 (2)

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GENERAL $ ELECTRIC NUCLEAR ENERGY BUSINESS OPERATIONS GENERAL ELECTRIC COMPANY e 175 CURTNER AVENUE e SAN JOSE, CAUFORNIA 95125 MC 682, (408) 925-1913 January 29, 1988 MFN# 088 DLF8804 CBSLTR004-88 U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D.C.- 20555 Attention: Mr. C.H.Berlinger Gentlemen:

SUBJECT:

TELECON GERMANE-TO-SAFETY - HPCI SUCTION PIPE OVERPRESSURE TRANSIENT Please find the attached memo of telecon to you of January 29, 1988.

the telecon provided information on an overpressure transient in the HPCI suction pipe of a BWR.

Very truly yours,

< 4s>

G. . St mb ck Safety Evaluation Programs Manager Attachment cc: L.S. Gifford, GE-Bethesda l

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• l/C MEMO OF TELECON-Date: January 29, 1988 Time: 10:45AM Person calling:

p G.B. Strambac'c, D.L. Foreman Person called: C.H. Berlinger (NRC NRR, 301-492-8414)

Subject:

HPCI Suction Pipe Overpressure Transient Carl Berlinger was called in order to inform the NRC of a condition determined to be not reportable but considered to be Germane-to-Safety.

This conclusion is based upon GE completing its evaluation as to reportability under 10CFR Part 21.

During startup testing at a BVR-4, the plant experienced an overpressure transient downstream from the hPCI pump suction side check valve. The resulting impact on the suction side piping caused damage to installed gauges and the last transient (approx. 800 psig) caused damage to a pipe hanger approximately 60-75 feet upstream from the suction check valve.

These overprsssure transione.e (500 800 psig) occurred when the HPCI turbine tripped on overspeed while injecting to the reactor pressure vossol via the feedwater line with the reactor below 50% power.

A lift / plug check valve installed as the HPCI pump discharge check valve is deemed to have caused the overprassure transient. This valve must close before reverst: flow through HPCI, emanating from the RPV, can starc and before the suctien swing check valve closes, or a water hammer cot.dition is set up causing the overpressurization on the low pressure succion side of the pump. ,

This potential water hammer condition has been corrected by replacing the discharge lift / plug check valve with a faster acting swing check valve.

Since no reports of similar difficulties have been received previously from other BWR plants relative to startup transients, and since operating and requisition plant configurations of which we are aware now emp oy the faster action swing type check valve in the pump discharge line, this situation does not represent a substantial safety hazard at any other BWR.

GE is in the process of informing its customers of this conclusion of non reportability and has sent out information concerning the potential for overpressurization transients in systems employing check valves upstream and downstream of a pump. For systems employing such a configuration it was recommended that the check valve downstream of the pump be of the faster acting swing check variety to avoid these potential transients.

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