05000280/LER-2077-021-01, T Flooding of Valve Pit Containing Emergency Service Water Valves

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T Flooding of Valve Pit Containing Emergency Service Water Valves
ML19105A106
Person / Time
Site: Surry  Dominion icon.png
Issue date: 11/15/1977
From: Stallings C
Virginia Electric & Power Co (VEPCO)
To: O'Reilly J
NRC/IE, NRC/RGN-II
References
LER 1977-021-01T
Download: ML19105A106 (4)
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LER-2077-021, T Flooding of Valve Pit Containing Emergency Service Water Valves
Event date:
Report date:
2802077021R01 - NRC Website
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Virginia. *,uectric. and Powe):'.. Compatiy: her.eby: submits *8. copy of Reportable Occurrence No. -LER 77-021/0l~T-O.* *. ',

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LICENSEE CODE 14 15 LICENSE NUMBER 1-lo 10 1014 11 11 111 °101 I 10 25 26 LICENSE TYPE JO 57 CAT 58 CON'T

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.. "DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES@

-[Q]}] I During zero-power physics testing, the valve pit containing emergency service water

(Q]}] I valves MOV/203A/B/C/D was found floodeq.

The flooding disabled the motor operators [Q]I) J affecting their ability to respond.to ECCS signals.

The valve pit was pumped down

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the motor operators were repaired and returned to service in about 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

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CAUSE

CAUSE

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10 11 12 13 0/ LEA/RO CVeNTYSAR SEQUENTIAL REPORT NO.

REPORT J 7 I 7 J l=.I l I I NUMBER 21 22 23 24 26 ACTION FUTURE EFFECT SHUTDOWN T,!\\KEN ACTION ON PLl',NT MCTHOD HOURS in V:'\\1 nlr, I z*I'""".

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VALVE COMPONENT CODE SUBCODE SUBCODE AIL IV IE Jx 18 ~ i!_j@

18 19 20 OCCURRENCE REPORT CODE; TYPE I O I 1 I

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SUSMITTl:O NPR0-4 FORMSIIR.

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43 REVISION NO.

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32 COMPONENT TITTI [_During refueling outage, the emergency service water lines were opened for inspection and valve adjustment.

Subsequent to "tag-out" of the system, drain valves were opened to remove residual water.

The drain valves were overlooked when the system was returned to -service.. After the pit *was pumped down the valves were shut.

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FACILITY STATUS

% POWER OTHER STATUS Em W@ I al ol olI NA 8

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ACTIVITY CONTENT Q\\

.RELEASED OF RELEASE AMOUNT OF ACTIVITY ~

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9 10 11 44 PERSONNEL EXPOSURES

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METHOD OF DISCOVEfW W@l Operator 45 46 NA 45 DISCOVERY DESCRIPTION @

_LOCATION OF RELEASE @

80 80 80 80 NUMBER A

TYPE DESCRIPTION~

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9 11 12 13 60 PERSONNEL INJURIES Q

NUMBER DESCRIPTION~

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B 9 11 12 LOSS OF on DAMAGE TO FACILITY '43' TYPE

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10 NAME Of PREPAHEn T. L. Baucom 66 69 BO 0:

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021/01-T-0 Virginia Electric and Power Company Surry Power Station Docket No. 050-0281 Event Date 10-11-77 e

During zero power testing following refueling, the valve pit containing emergency service water valves MOV-203A/B/C/D was observed to be flooding.

The water reached the motor operators affecting their ability to respond to ECCS signals.

The valve pit was immediately dewatered and the source of the flooding was determined to be two open drain valves in the emergency service water lines.

The valves were shut and the flooding ceased.

Concurrently, compen-satory administrative controls were enacted, i.e. operations personnel were stationed at the valves to operate them manually if conditions demanded. Also, the motor operators were removed for repairs.

The repairs were completed and the valves made fully operable in 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

During the refueling outage, the emerge~cy service water lines were enter-ed for inspection and adjustment of the emergency service water valves.

Subse-quent to the "tag-out" of the system, the two-inch drain valves were opened to drain residual water from the lines.

Through personnel error, the valves were overlooked when the system was returned to service.

The actual flooding occur-red at a later time when the emergency service water valve was operotcd.

Per-sonnel were standing-by the condenser manways awaiting clearance to enter when the valve pit flooding occurred and was immediately observed.

The opening of the emergency service water valve admitted water to the piping and thereby to the open drain valves from which the flooding occurred.

It was later determin-ed that had the emergency service water valves actuated by an ECC_S signal, the valves would have reached their full open position before the flooding could have disabled the motor operators.

The station has an approved design change to implement modifications to limit the effects of flooding to safety related systems.

Seven of the eight sections of that design change have been completed.

Completion of the eighth section, involving sump level alarms, has been delayed by material procurement problems and manpower allocations, but is now being pursued as a priority action.

In addition, other corrective measures are being considered, among which are:

a.

blank flanging of drain valves

  • b.

reconfiguration of the valve pit The choice and status of the corrective actions will be the subject of a supple-ment report.

The health and safety of the general public were not affected by this event at the time of the flooding, immediate compensatory actions were taken; and had operation of the emergency service water valve not occurred and precipitated the flooding, response to a true ECCS signal would have been proper.

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RECf:JVE[) DOCUMENT f',:JC::~SlHG Ul'/iT 1971 NOV 17 MIi 10 I,+

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