ML20086S992

AO-S1-74-07:on 740512,boric Acid Transfer Pump Discovered Not Running.Caused by Motor Failure.Pump Motor 1-CH-P-2A Replaced

ML20086S992
Person / Time
Site:	Surry
Issue date:	06/25/1974
From:	Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Moseley M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20086S982	List: ML20086S980 ML20086S992
References
AO-S1-74-07, AO-S1-74-7, NUDOCS 8403060072
Download: ML20086S992 (7)

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/ /s r*f Y Mr. Norman C. Moseley, Director Scrial No. 174 Directorate of Regulatory Operations POSMi '1 TS:clw United States Atonic Energy Commission Region II - Suite 818 Docket No. 50-280 230 Peachtree Street, Northwest License No. DPR-32

' Atlanta, Georgia 30303

Dear Mr. Moseley:

Pursuant to Surry Power Station Technical Specification 6.6.D.1, the Virginia Electric and Power Company hereby submits forty (40) copics of Abnormal Occurrence Report No. A0-SI-74-07.

f The substance of this report has been reviewed by the Str. tion Nuc1 car Safety cnd Operating Connittec and vill be placed on the agenda for the next meeting of the system siuclear Sdety and Opetulling Committee.

Vcry truly yourc, ,

26. 2??.sd&a:.< l C. M. Stallings Vice President-Power Supply and Production Operations Enclosures 40 copics of A0-SI-74-07 e .

cc: Mr. K. R. Goller, Assistant Director for Operating Reactors .

t Mr. Stanicy Ragone. .) .

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1 ABNOPJfAL OCCURRENCE REPORT l

REPORT NO. A0-SI-74-07 J

i i FAILURE OF BORIC ACID TRANSFER PUMP 1-Cil-P-2A MOTOR l

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MAY 23, 1974 ,

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DOCKET NO. 50-280 1

2 LICENSE No. UPR-32 4

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SURRY POWER STATION a

W RGINIA EI.ECTRIC AND POWER C0!!PANY 1

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O O I. INTRODUCTION In accordance with Technical Specification 6.6.B.1 for Surry Power Station, Operating License Number DPR-32, this report describes an abnormal occurrence which occurred on May 12, 1974. The Directorate of Regulatory Operations, Region II, was notified on May 12, 1974.

The occurrence described herein is classified as an abnormal occurrence pursuant to Technical Specification 1.0.I.2 which states that "An abnormal occurrence is defined as: Any unit condition that results in v'iolation of a limiting condition for operations as established in these Technical Specifications."

The occurrence described herein involved a failure of a boric acid transfer pump (1-CH-P-2A) motor, which resulted in the violation of Technical Specification 2.2. This specification states that

" Rec 1.sulation be tweu. o ...it'. baron inicction tank and the horic acid tank (s) assigned to the unit shall be maintained."

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SUMMARY

OF OCCURRENCE On Iby 12, 1974, Unit No. I was operating at 100 per cent power and 815 MWe, Unit No. 2 was in the cold shutdown condition for maintenance.

At approximately 0030 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> while conducting a unit walkdown, it was discovered that boric acid transfer pump 1-CH-P-2A was.not running.

This pump was assigned to Unit No. I at this time. Pump 1-CH-P-2C was then placed into service and flow to the buron injection tank was re-established. Subsequent review of the log sheets revealed that flow existed on pump 1-CH-P-2A when the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> readings were taken on May 11, 1974. This indicated that pump 1-CH-P-2A was runnit:g l

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at that time. The discharge pressure of the pump is logged every eight (8) hours. Immediate efforts were made to determine the cause of the failure.

The boric acid transfer pump motors are two (2) speed squirrel cage 480 volt motors, Model TUDP, Style No. 69D42527, manufactured by the Westinghouse Electric Corporation.

III. ANALYSIS OF OCCURRENCE Initial' investigation was commenced with 1-CH-P-2A pump motor being bridged and meggered. This revealed that the motor had failed.

Pump motor 1-CH-P-2A was then replaced. Pump 1-CH-P-2C was removed from service and 1-CH-P-2A was put back in service. A load check was conducted on pump motor 2A with a r'eading of nine (9) amps indicated v.. moc. pt.cac on slc speed. 'ine full lead amp rating en elev eread is 13 amps per phase. This showed the motor to be operating properly.

The operator in the control room had no indication that the pump was not running since, when the thermal overload on the motor trips, the control circuit, including indicating lights, remain illuminated.

There are no alarms to annunicate that the pump was not running.

The motor which was removed from pump 1-CH-P-2A was disassembled and inspected. The stator winding insulation had failed causing a short in the windings and subsequent motor failure. The short was determined to be due to a small amount of grease which was found on the stator windings. The grease created a " hot spot" that resulted in an insulation failure.

O O Later investigation showed that the motor bearings were " scaled" bearings which do not require lubrication. Although the bearings were of the " scaled" type, the motor casing contained grease fittings for bearing lubrication. These grease fittings were inadvertently Icft on the motor, thus allowing overgreasing and overflow into the motor windings.

IV. CORRECTIVE ACTION TO PREVENT RECURRENCE As mentioned above, the immediate corrective action was to replace the burned out 1-CH-P-2A notor. The long tern corrective action will be to dismantle all four (4) boric acid transfer pump motors and determine the type of bearings. Some are thought to be "non-scaled" bearings which do requirc periodic lubrication. The various types will l

be so noted and appropriate lubrication schedules followed. Grease fittinga located at poir.:~ where a " scaled" bearing is present will be removed to prevent the problem of_overgreasing'as mentioned above. This will be completed by July 1, 1974.

In order to indicate actual operational status of the boric acid transfer pump in the control room, modifications to the control circuitry will be made. This modification will consist of wiring the indicating lights in series with the thermal overload. Therefore, if a thermal overload occurs it will be indicated in the control room.

The occurrence reported herein is not related to other failures or malfunctions of similar equipment.

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ANALYSIS AND EVALUATION OF SAFETY IMPLICATIONS OF OCCURRENCE The purpose of the boric acid transfer pump is to provide make-up to the reactor coolant system via the charging pumps and recirculation in the boric acid system. The. recirculation path recirculates boric

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acid solution between the boric acid tanks and the boron injection tank in the safety injection system. Recircedation to the boron injection tank assures that the tank is full of concentrated boric acid solution.

Each operating unit has two (2) pumps available for service on low or high speed as required. The recirculation mode requires only one (1) pump at low speed to maintain flow to the boron injection tank.

When make-up to the reactor coolant system is required, the pump automatically shifts to high speed. At the time of the occurrence, 1-Cll-P-2A was operating in the recirenis.s!.... mo<lo. Although s h s. n . w..r.

motor failed, this would not have prevented the boron injection tauk from performing its intended function had it been required. The full capacity of the tank was still availabic.

Since the boron injection tank remained full and could have performed its Intended function, this occurrence did not have any safety implications associated with it.

VI. CONCLUSIONS The licensee concludes that:

1. The motor failure was caused by overgreasing and subsequent overflow onto stator windings causing failure.

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2. Even though recirculation was lost to the boron injection tank, the tank did remain full and could have performed its intended function had it been required.

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

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

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