ML20006A888

LER 90-001-00:on 900104,HPCI Pump Declared Inoperable Due to Rated Flow Not Maintained During Surveillance Testing. Caused by Component Failure.Defective Resistor Replaced & Procedure 34SV-E41-002-1S performed.W/900122 Ltr

ML20006A888
Person / Time
Site:	Hatch
Issue date:	01/22/1990
From:	Hairston W, Tipps S GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HL-932, LER-90-001, LER-90-1, NUDOCS 9001300439
Download: ML20006A888 (6)

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f U. W ilfO(WT ' < t1 HL-932 000150 January 22, 1990 U.S. Nuclear Regulatory Commission  !

ATTN: Document Control Desk Washington, D.C. 20555 PL ANT HATCH - UNIT 1  :

NRC DOCKET 50-321 -

OPERATING LICENSE OPR-57 l LICENSEE EVENT REPORT COMPONENT FAILURE RESULTS IN INOPERABILITY OF HIGH PRESSURE COOLANT INJECTION SYSTEM

, Gentlemen: ,

1 In accordance with the requirements of 10 CFR 50.73 (a)(2)(v), Georgia '

Power Company is submitting the enclosed Licensee Event Report (L:R) concerning a condition that could have prevented an Engineered Safety  :

Feature (ESF) from fully performing its safety function. This event  :

occurred at Plant Hatch - Unit 1.

Sincerely, i

W./. A M W. G. Hairston, III

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Enclosure:

LER 50-321/1990-001 i

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Mr. L. P. Crocker, Licensing Project Manager - Hatch U.S. Nuclear Reaulatory Commission. Reaion II Mr. S. D. Ebneter, Regional Administrator Mr. J. E. Menning, Senior Resident Inspector - Hatch i

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On 1/4/90 at approximately 0739 CST, Unit 1 was in the Run mode at an approximate power level of 2430 CMW (approximately 100% of rated thermal power). At that time, the High Pressure Coolant Injection (HPCI, EIIS Code BJ) system was declared inoperable because rated flow was not maintained during the performance of normal surveillance testing. An investigation later discovered that a failed resistor resulted in a loss of the power supply to the electronic governor controlling the HPCI turbine speed. The defective resistor was replaced, procedure 34SV-E41-002-lS, "HPCI Pump Operability", was performed successfully, and HPCI was declared operable on 1/4/90 at appNximately 1130 CST.

The cause of this event is component failure. A failed resistor de-energized the electronic governor power supply. This component failure appears to be an isolated event.

The corrective action was to replace the resistor assembly and verify HPCI pump operabili ty.

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SUMMARY

OF EVENT On 1/4/90 at approximately 0739 CST, Unit 1 was in'the Run mode at an approximate '

power level of 2430 CMWT (approximately 100% of rated thermal power). At that time, the High Pressure Coolant Injection (HPCI, EIIS Code BJ) system was declared inoperable because rated flow was not maintained during performance of normal surveillance testing. An investigation later discovered that a failed resistor resulted in a loss of the power supply to the electronic governor controlling the l HPCI turbine speed. The defective resistor was replaced, procedure 34SV-E41-002-1S, "HPCI Pump Operability", was performed successfully, and HPCI was declared operable on 1/4/90 at approximately 1130 CST. ,

The cause of this event is component failure. A failed resistor de-energized the electronic governor power supply. This component failure appears to be an isolated event. The corrective action was to replace the resistor assembly and verify HPCI l pump operability.

l DESCRIPTION OF EVENT On 1/4/90 at approximately 0739 CST, testing of the HPCI pump was in progress using procedure 34SV-E41-002-lS, "HPCI Pump Operability". Upon manual system initiation, pump flow increased to rated as required. However, after approximately 20 seconds, the pump speed and flow began decreasing and continued to decrease until the operator terminated the test by manually closing the steam supply isolation velve, 1E41 F001. Operations personnel then declared HPCI inoperable and a Limiting Condition for Operation (LCO) 1-90-006 was entered as required by the Technical Specifica tions.

l Instrument and Control (I&C) personnel investigating the. decreased flow discovered a failed resistor in the electronic governor power supply circuitry. This resistor is part of a bank of resistors which reduce a 120 Yde power supply input to an output voltage of 48 Vdc to the governor. The failed resistor resulted in an open circuit, thus deenergizing the electronic governor and causing a decrease in HPCI pump speed. The defective resistor was replaced. Procedure 34SV-E41-002-lS was performed successfully and HPCI was declared operable at approximately 1130 CST on 1/4/90.

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CAUSE OF THE EVENT The root cause of this event was component failure. A failed resistor caused a ,

loss of the power supply to the electronic governor. The failure history of the resister was assessed, by reviewing the Nuclear Plant Reliability Data System f records and via discussions with the vendor of the electronic governor power supply, and this component failure appears to be an isolated event.

REPORTABILITY ANALYSIS AND SAFETY ASSESSMENT This report is required per 10 CFR 50.73'(a)(2)(v) because a component failure occurred in the HPCI system which would have prevented the system from functioning as designed to mitigate the consequences of an accident. The failure would have prevented the HPCI system from reaching or maintaining design flow upon initiation of the system.

The HPCI system is provided to assure that the reactor is adequately cooled to limit fuel clad temperature in the event of a small break in the nuclear boiler system causing a loss of coolant which does not result in rapid depressurization of the reactor vessel. The Automatic Depressurization System (ADS, EIIS Code JE) is a backup for the HPCI system. Upon ADS initiation, the reactor is depressurized to a point where either the Low Pressure Coolant Injection (LPCI, EIIS Code B0) system or the Core Spray (CS, EIIS Code BM) system can operate to maintain adequate core cooling.

In the event addressed in this report, the HPCI system was inoperable. The LPCI  ; )

pumps and their associated equipment, ADS, and both loops of CS were operable. l Based upon the Unit 1 Final Safety Analysis Report, either loop of the CS system l or the LPCI system, consisting of two operable pumps in one Residual Heat Removal  !

(RHR, EIIS Code B0) loop and at least one operable pump in the other RHR loop, can supply sufficient cooling to the reactor for any rupture of the nuclear safety l boundary up to and including the Design Basis Accident (DBA).

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Based on the above information .it is concluded that this event had no adverse impact on nuclear plant safety. The above analysis is applicable to all reactor power levels in which the HPCI system is required to be operable. Therefore, it i

is concluded that this event would not have been more severe had it occurred under other reactor operating conditions.

CORRECTIVE ACTION The defective resistor was replaced and the HPCI system was proven operable by.

successful completion of procedure 34SV-E41-002-lS. ,LC0'l-90-006 was terminated on 1/4/90.

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- . w e, u nt, ADDITIONAL INFORi% TION No systems other than the HPCI system were affected by this event.

Previous events in which HPCI was inoperable were reported in LER's:

50-321/1988-012, dated 9/20/88 50-321/1988-017, dated 1/5/89 50-321/1989-006, dated 4/18/89 Corrective actions for these events would not have prevented this event because the previous events were caused by personnel error or failure of a different component within the HPCI system.

Failed Component Identification:

MPL (Plant Index loantifier): 1E41 -R764-3 Manufacturer: Woodward Company Vendor Part Number: 8270281 Type: Resistor I

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