05000339/LER-1981-049-03, /03L-0:on 810612,during Periodic Test,Casing Cooling Pump 2-RS-P-3A Tripped.Caused by Power Supply Breaker Opening on Overcurrent Due to Excessive Load Created by Misalignment of Bearing Holders & Caps.Bearings Aligned

/03L-0:on 810612,during Periodic Test,Casing Cooling Pump 2-RS-P-3A Tripped.Caused by Power Supply Breaker Opening on Overcurrent Due to Excessive Load Created by Misalignment of Bearing Holders & Caps.Bearings Aligned

ML20009G192
Person / Time
Site:	North Anna
Issue date:	07/09/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009G179	List: 05000339/LER-1981-049, Forwards LER 81-049/03L-0 05000339/LER-1981-049-03, /03L-0:on 810612,during Periodic Test,Casing Cooling Pump 2-RS-P-3A Tripped.Caused by Power Supply Breaker Opening on Overcurrent Due to Excessive Load Created by Misalignment of Bearing Holders & Caps.Bearings Aligned
References
LER-81-049-03L, LER-81-49-3L, NUDOCS 8108030409
Download: ML20009G192 (2)

LER-1981-049, /03L-0:on 810612,during Periodic Test,Casing Cooling Pump 2-RS-P-3A Tripped.Caused by Power Supply Breaker Opening on Overcurrent Due to Excessive Load Created by Misalignment of Bearing Holders & Caps.Bearings Aligned

Event date:
Report date:
3391981049R03 - NRC Website

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4 U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT U CE [L/ (6)

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DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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On June 12, 1981 while in Mode 1 operation, the casing cooling pump (2-RS-P-3A)/

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was declared inoperable when it failed to meet the acceptance criteria of the /

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periodic test.

Since the casing cooling pump was repaired within 7 days as

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required by T.S. 3.6.2.2, the health and safety of the public was not affected./

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This event is reportable pursuant to T.S. 6.9.1.9.b.

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SYSTEM

CAUSE

CAUSE COMP.

VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

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SEQUENTIAL OCCURRENCE REPORT REVISION LER/R0 EVENT YEAR REPORT NO.

CODE TYPE NO.

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REPORT NUMBER

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP.

COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER [E/ (18)

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The failure of the pump was due to misalignment of the bearing holders and

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caps.

This caused the power supply breaker to open cn overcurrent due to the /

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excessive load created by this misalignment.

The bearings were aligned and the/

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pump operated for 30 minutes to verify that the corrective actions were

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adequate.

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FACILITY METHOD OF STATUS

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NA

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Surveillance Test

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ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36)

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PDR ADOCK 050 PDR NRC USE ONLY

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NAME OF PREPARER W. R. CARThRIGHT PHONE (703) 894-5151

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a Virginia Electric and Power Company North Anna Power Station, Unit #2

Attachment:

Page 1 of 1 Docket No. 50-339 Report No. LER 81-049/03L-0

Description of Event

On June 12, 1981 while performing periodic test (2PT-64.4A) on the casing cooling pump (2-RS-P-3A), the pump tripped and was declared inoperable as per T.S. 3.6.2.2.

Probable Consequences of Occurrence The casing cooling system provides an independent chilled water supply to the suction of the outside containment recirculation spray pump to ensure an adequate NPSH during a postulated LOCA. Since the casing cooling pump was restoied within the requirements of the action statement of T.S. 3.6.2.2, the health and safety of the public were not affected.

Cause of Event

The failure of the pump was due to the power supply breaker opening on overcurrent.

The overcurrent condition was created by excessive electrical loading on the motor due to misaligned bearings.

The misalignment occurred when a preventative maintenance check of the pump required repacking of the pump shaft thrust bearing.

This was performed on May 24, 1981.

This required removal of the bearing cap that maintains axial alignment of the pump shaf t.

When the cap was replaced, the technical manual procedure for realigning the shaft and establishing impeller position was used, but the retaining bolts were not properly tensioned.

This allowed the axial alignment to shift when the pump was operated thereby creating the excessive load on the metor.

The initial pump operation following the preventive maintenance (PM-M-20-F/A-11) was not long enough to create sufficient misalignment to allow this problem to surface.

The subsequent operability check of the pump, via the periodic test (2-PT-64.4A) performed on June 12, 1981, provided sufficient run time to reveal this problem.

Immediate Corrective Action

The bearings were cleaned and aligned.

When completed, the pump was operated for 30 minutes to verify the adequacy of the cor-m 'ive action.

Scheduled Corrective Action No further action required.

Actions laken to Prevent Recurrence This event was the result of personnel error.

The individual involved was reinstructed on the technical manual procedure.

Generic Implications There are no generic implications as a result of this event.