05000280/LER-1975-001, Submittal of Abnormal Occurrence Report No. AO-S2-75-01, the Flooding of the Valve Pit Containing Service Water Valves MOV-SW-203A, B, C, D

Submittal of Abnormal Occurrence Report No. AO-S2-75-01, the Flooding of the Valve Pit Containing Service Water Valves MOV-SW-203A, B, C, D

ML19095A781
Person / Time
Site:	Surry
Issue date:	01/24/1975
From:	Stallings C Virginia Electric & Power Co (VEPCO)
To:	Moseley N NRC/RGN-II
References
399 AO-S2-75-01, LER 75-001-00
Download: ML19095A781 (5)

LER-1975-001, Submittal of Abnormal Occurrence Report No. AO-S2-75-01, the Flooding of the Valve Pit Containing Service Water Valves MOV-SW-203A, B, C, D

Event date:
Report date:
2801975001R00 - NRC Website

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. Serial No.* 399 PO&M/JTB:clw

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. Licens-~/No... :DPR..:37

-* _ Pursuatj.~ to. Surry/Power Station Technical Specification 6.~6.B.1~

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ABNORMAL OCCURRENCE REPORJ_'_

REPORT NO. AO-S2-7.5-0l THE FLOODING Ori THE VALVE.PIT CONTAINING SERVICE WATER VALVES MOV-SW-203A,B,C,D JANUARY.9,* 1975 DOCKET NO. 50-281 LICENSE NO. DPR-37 SURRY POWER STATION VIRGINIA ELECTRIC AND POWER COMPANY

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INTRODUCTION

In accordance with Technical Specification 6.6.B.l for Surry Power Station; Operating License Number DPR-37, this report describes an abnormal occurrence which occurred *on January 9, 1975.

The Directorate of Regulatory Operations, Region II, was notified on January 9, 1975.

The occurrence reported herein is classified as an abnormal occurrence pursuant to Technical Specification LO. I. 6 which states, "An abnormal occurrence is defined as:

Enginee.red safeguard system malfunction or other component or system malfunction whi.ch rendered or could render the

• engineered safeguard system incapable of performing its intended function."

The occurrence described herein involved the inoperability of the flow paths of the service water to the recirculation spray system heat exchangers, during power operation of Unit No. 2.

II.

SUMMARY OF OCCURRENCE On January 9, 1975 at approximately 1215 hours0.0141 days <br />0.338 hours <br />0.00201 weeks <br />4.623075e-4 months <br />, with Unit No. 2 at 80 per cent power, it was discovered that a high water level existed in the sump area of the high pressure heater drain pumps.

Using a portable sump pu:inp, station personnel began to pump this water to a floor drain.

When the Shift Supervisor learned of the high level in the high pressure heater drain pump sump, he checked the recirculation spray service water valve pit (RS valve pit).* Finding it full of water, he manually started the Unit No. _2 turbine building sump pumps, and dispatched electricians to check the motor control centers for the service water valves in the recirculation spray system to determine if a ground fault existed.

Upon' receipt of the information that a ground did exist, an orderly shutdown was ~egun at 150 MWe/hr.

'V The water level in the RS valve pit was reduced using a portable pump and the valves were manually opened.

The reactor power decrease was then halted and power was escalated.

The valve pit was completely emptied and new motor operators installed.

III. ANALYSIS OF OCCURRENCE The RS valve pit containing the recirculation spray valves MOV-SW-203A, B,C,D has an overflow connection to the turbine building sump, as does the high pressure drain pump sump.

The turbine building sump pumps had been shut off in connection with a test in which the flow rate to the sump is calculated by means of monitoring the change in sump level over one (1) hour.

The personnel conducting this test were dispatched to handle a station emergency and were not available to monitor the sump level.

The sump filled and overflowed to the RS valve pit and high pressure drain pump sump through the respective connecting overflow pipes.

The action of the Shift Supervisor in starting the sump pumps stopped the flow to the RS valve pit and drained the RS valve pit to the level of the overflow pipe.

It was then necessary to use the portable pump to uncover the motor operators on the valves.

IV.

CORRECTIVE ACTION TO PREVENT RECURRENCE The occurrence would not have happened if the level in the turbine building sump had been visually monitored during the flow test.

The instructions for this test have been revised to require such surveillance.

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V.

ANALYSIS AND EVALUATION OF SAFETY IMPLICATIONS OF THE OCCURRENCE The MOV-SW-203A,B,C,D are normally closed, and are automatically opened on a containment high-high pressure signal.

These valves allow service water to flow through the recirculation spray heat exchangers, and open as part of the unit response to a loss of coolant accident.

Once these valves had been opened and flow to the recirculation spray heat exchangers had been established, the reactor power could be safely escalated.

During the time interval in which the motor operators were submerged and the valves were closed, it is possible that the valves would have failed to open during a LOCA of sufficient magnitude to cause a containment high-high pressure.

Operator action would have been required to manually open the valves.

This could have.been accomplished even with the pit filled with water.

VI.

CONCLUSIONS The licensee concludes that:

1.

The occurrence described herein was caused by the failure of station personnel to monitor the level of the sump during a flow calculation test.

2.

The occurrence reported herein did not affect the safe operation of the station.

3.

The occurrence described herein did not adversely affect the health or safety of the general public.