05000280/LER-1982-073

LER 82-073/03L-0:on 820622,charging Pump Svc Water Pump 1-SW-P-10B Failed to Develop Adequate Discharge Pressure. Caused by Insufficient Npsh.Svc Water to Chillers Throttled to Provide Sufficient NPSH

ML20055B737
Person / Time
Site:	Surry
Issue date:	07/16/1982
From:	Joshua Wilson VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20055B734	List: 05000280/LER-1982-071 05000280/LER-1982-073 ML20055B733
References
LER-82-073-03L, LER-82-73-3L, NUDOCS 8207230223
Download: ML20055B737 (2)

LER-2082-073,

Event date:
Report date:
2802082073R00 - NRC Website

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ATTACHMENT 1 SURRY POWER STATION, UNIT NO. 1 DOCKET NO: 50-280 REPORT NO: 82-073/03L-0 EVENT DATE: 06-22-82 TITLE OF THE EVENT: 1-SW-P-10B Low Discharge Pressure

1. DESCRIPTION OF EVENT:

On June 22, 1982, with the unit at full power, charging pump service water pump, 1-SW-P-10B failed to develop sufficient discharge pressure. This event is contrary to Technical Specification 3. 3. A.8.b and is reportable per Technical Specification 6.6.2.b(2) .

2. PROBABLE CONSEQUENCES and STATUS of REDUNDANT EQUIPMENT:

The charging pump service water pumps supply water to the charging pump intermediate seal coolers and the charging pump lubricating oil coolers.

Since the redundant charging pump service water pump remained operable, public health and safety were not affected.

3. CAUSE:

The low discharge pressure was due to insufficient NPSH. Four charging pump service water pumps, along with three Air Conditioner Chiller units are located in No. 3 equipment room. The aforementioned components are supplied with service water, via rotating strainers, from two 6" supply lines. Each supply line is gravity fed from the intake canal. .

Two-inch branch lines supply service water to the charging pump service water pumps, while the service water lines to the chiller units are four-inch lines. In addition, the Unit No. 1 and Unit No. 2 'B' charging pump service pumps are located at a higher elevation.

Experience has shown that the performance of the charging pump service water pumps, especially the 'B' pumps, are sensitive to the available NPSH.

4. IMMEDIATE CORRECTIVE ACTION:

The innediate corrective action was to throttle the service water flow through the chillers and vent 1-SW-P-10B , thereby flooding the '10B' pump suction.

5. SUBSEQUENT CORRECTIVE ACTION:

No further actions were repaired.

6. ACTION TAKEN TO PREVENT RECURRENCE:

An engineering evaluation of the service water system is in progress. A design change has been initiated that will relocate two of the charging pump service water pumps, i.e. lower the pumps and increase the size of the suction piping to the pumps.

7. GENERIC IMPLICATIONS:

This is a generic problem to both units at Surry.

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