05000280/LER-1982-050-03, /03L-0:on 820817,charging Pump Svc Water Low Pressure Alarm Sounded.Svc Water Pump 10B Auto Started But Did Not Restore Sys Pressure.Caused by Insufficient Npsh. Svc Water to Chiller Reduced & Pump Vented

/03L-0:on 820817,charging Pump Svc Water Low Pressure Alarm Sounded.Svc Water Pump 10B Auto Started But Did Not Restore Sys Pressure.Caused by Insufficient Npsh. Svc Water to Chiller Reduced & Pump Vented

ML20027B295
Person / Time
Site:	Surry
Issue date:	09/10/1982
From:	Joshua Wilson VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20027B291	List: 05000280/LER-1982-048-03, /03L-0:on 820813,discovered That Uncollected Leakage of 2-CH-P-1C Was in Excess of Tech Spec Limit.Two Pumps Simultaneously Inoperable,Contrary to Tech Specs.Leak Caused by Loose Flange Bolt.Bolt Lubricated 05000280/LER-1982-050-03, /03L-0:on 820817,charging Pump Svc Water Low Pressure Alarm Sounded.Svc Water Pump 10B Auto Started But Did Not Restore Sys Pressure.Caused by Insufficient Npsh. Svc Water to Chiller Reduced & Pump Vented 05000280/LER-1982-081-03, /03L-0:on 820823,steam Flow Transmitter FT-1-495 Failed Low.Caused by Faulty Power Supply.Power Supply Replaced.Affected Instrument Channel Checked Satisfactorily & Returned to Svc ML20027B290
References
LER-82-050-03L-01, LER-82-50-3L-1, NUDOCS 8209200246
Download: ML20027B295 (3)

LER-1982-050, /03L-0:on 820817,charging Pump Svc Water Low Pressure Alarm Sounded.Svc Water Pump 10B Auto Started But Did Not Restore Sys Pressure.Caused by Insufficient Npsh. Svc Water to Chiller Reduced & Pump Vented

Event date:
Report date:
2801982050R03 - NRC Website

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't ATTACHMENT 1 SURRY POWER STATION, UNIT NO. 2 DOCKET NO:

50-281 REPORT NO:

82-050/03L-0 EVENT DATE:

08-17-62 TITLE OF THE EVENT:

2-SW-P-10A & B Inoperable

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1.

DESCRIPTION OF THE EVENT:

With the unit at full power, and the 10A service water pump running, the charging pump service water pump discharge low pressure alarm sounded.

l The 2-SW-P-10B pump auto started, but did not restore system pressure.

This is contrary to T.S.3.3. A.8(b) and is reportable per T.S.6.6.2.b(2).

2.

PROBABl.E CONSEQUENCES and STATUS of REDUNDANT EQUIPMENT:

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

The low pressure alarm was in for only 20 minutes and the charging pump bearing temperatures remained within specifications, therefore the health and safety of the public were not affected.

3.

CAUSE

The low pressure alarm causing the 10B pump to auto start was due to reduced flow through a partially clogged 10A pump strainer. This strainer has 1/16 inch holes in it.

Engineering Study 82-39, recommended that the charging pump service water pump strainers have 1/8 inch holes.

The 10B service water pump was air bound and could not restore pressure above the alarm point. The presence of air in the pump is due to insuf ficient 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 water 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

One chiller unit was shutdown and the 10B pump vented and started. The pump ran for a few minutes and became air bound again. After a second venting the pump ran with no further problems.

5.

SUBSEQUENT CORRECTIVE ACTIONS:

The 10A pump strainer was cleaned, the 10A pump was returned to service, and the 10B pump was placed in standby.

P g3 2 Rsp:rt No. 82-050/03L-0 l

1 6.

ACTION TAKEN TO PREVENT RECURRENCE:

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. The 10A pump strainer will be changed with one that has 1/8 inch holes.

7.

GENERIC IMPLICATIONS:_

The NPSH problem is generic at both Surry units.

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