05000353/LER-1992-001, :on 920104,high Pressure Coolant Injection Sys, D24 Emergency Diesel Generator D RHR Sys & D Core Inoperable Due to Blown Fuse.Switches in Card File E21A-Z3D Inspected. Failed Switch Replaced

:on 920104,high Pressure Coolant Injection Sys, D24 Emergency Diesel Generator D RHR Sys & D Core Inoperable Due to Blown Fuse.Switches in Card File E21A-Z3D Inspected. Failed Switch Replaced

ML20091P692
Person / Time
Site:	Limerick
Issue date:	01/28/1992
From:	Doering J, Madsen G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-001, LER-92-1, NUDOCS 9202030251
Download: ML20091P692 (4)

LER-1992-001, on 920104,high Pressure Coolant Injection Sys, D24 Emergency Diesel Generator D RHR Sys & D Core Inoperable Due to Blown Fuse.Switches in Card File E21A-Z3D Inspected. Failed Switch Replaced

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function
3531992001R00 - NRC Website

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10 CFR 50.73 4

PHILADELPHIA El.ECTRIC COMPANY LIMERICK GENER ATING ST ATION P. O, DOX A S AN ATOG A PENNSY LV ANI A 19454

{215) 337 1200 s at, teoo January 28, 1992

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Docket No. 50-353 License No. NPF-85 mo...................

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

Licensee Event Report Limerick Generating Station - Unit 2 This LER reports an event where a Unit 2 pressure indicaling switch shorted to ground causing a blown fuse that made the High Pressure Coolant Injection (HPCI) system, the 024 Emergency Diesel Generator, the 'O' Residual Heat Removal system, and the 'O' Core Spray system inoperable,

Reference:

Docket No. 50-353 Report Number:

2 92-001 Revision Number:

00 Event Date:

January 4. 1992 Report Date:

January 28, 1992 Facility:

Limerick Generating Station P.O. Box 2300 Sanatoga, PA 19464-2300 This LER is being submitted pursuant to the requirements of 10 CFR 50,73(a)(2)(v).

Very truly.yours, 7q N

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T. T. Martin, Administrator, Region 1 USNRC T. J. Kenny, USNRC Senior Resident Inspector, LGS 030002 92020'10251 720128

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On January 4, 1992, a Unit 2 pressure indicating switch shorted to ground causing a blown power supply fuse that made the High Pressure Coolant injection (HPCI) system, the D24 Emergency Diesel Generator, the 'O' Residual Heat Removal system, and the 'O' Core Spray system inoperable. After removing the failed pressure indicating switch, the fuse was replaced, When the HPCI system instrumentation was reenergized an anticipated HPl system isolation occurred.

Tne HPCI systr7 isolation was reset and the HPCI system was declared operable.

The actual consequences of this event were minimal. The failed pressure indicating switch was replaced on January 4, 1991. Similar pressure indicating switches in the same card file we e inspected and confirmed to not have the same condition. The failed pressure indicating switch has been sent to the manufacturer for performance of a failure analysis. The results of the failure analysis conducted by the manuf acturer will be reviewed to determine if additional corrective action needs to be taken.

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Unit Conditions Prior to the [ vent:

Unit 2 was in Operational Cendition 1 (Power Operation) operating at 100% power level. There were no structures, systems, or components out of service that contributed to this event.

Description of the Event:

On January 4, 1992, at 0600 hoars, a failure of a pressure indicating switch (Ells:PIS) caused a power supply fuse to blow.

The blown fuse deenergized card filt E21 A-Z33 and its associated instrumentation used to automatically initiate multiple safety systems. At 0650 hours0.00752 days <br />0.181 hours <br />0.00107 weeks <br />2.47325e-4 months <br />, operators determined that the deenergized instrumentation made the High Pressure Coolant Injection (HPCl) 3 system (Ells:BJ), the 024 Emergency Diese s Gener ator (EDG) (Ells:EK), the 'D' 7

Residual Heat Removal (RHR) system (Ells:80), and the 'O' Core Spray (CS) system (Ells:BM) inoperable. At 0658 hours0.00762 days <br />0.183 hours <br />0.00109 weeks <br />2.50369e-4 months <br />, operators reduced power in accordance with the action specified by Technical Specifications (TS) Section 3.0.3.

Instrumentation and Control (l&C) technicians removed and tested CS system and RHR system pressure indicating switches until they identified switch PIS 2N690H was shorted to grocnd. After removing PIS-42-2N690H, the fuse was replaced. When card file E21A-230 and its associated instrumentation, including the HPCI system instrumentation, was reenergized, an anticipated HPCI system isolation occurred. The HPCI system isolation resulted from the trip unit switch electronics reenergizing at 6 faster rate than their associated transmitter e!9ctronics. lhe trip unit switch electronics sensed an input signal below their low trip setpoint and initiated the HPCI system isolation.

Operators reset the HPCI system isolation in accordance with General Plant (GP)

Procedure GP-8, " Primary and Secondary Containment Isolation Verification and Reset." Operators then declared the HPCI system operable at 0738 hours0.00854 days <br />0.205 hours <br />0.00122 weeks <br />2.80809e-4 months <br /> and exited TS Se_ tion 3.0.3.

PIS-42-2N690H was replaced on January 4, 1992. The 024 EDG, the 'O' RHR system, and the 'O' CS system were declared operable after ILC technicians reinstalled all pressure indicating switches and completed functional testing of the switches. A one hour notification w3s made to the NRC at 0748 hours0.00866 days <br />0.208 hours <br />0.00124 weeks <br />2.84614e-4 months <br /> on January 4, 1992, with a followup notification at 0845 hours0.00978 days <br />0.235 hours <br />0.0014 weeks <br />3.215225e-4 months <br /> in accordance with the requirements of 10 CFR 50.72(b)(1)(i)(A) because a TS required plant shutdown was initiated.

This notification was also made in accordance with the requirements of 10 CFR 50.72(b)(2)(iii)(A) because the HPCI system was unable to perform its safety ionctions of maintaining the reactor in a safe shutdown condition and mitigating the consequencas of an accident. The notification made in accordance with the requirements sf 10 CFR 50.72(b)(2)(ii) for the HPCI system isolation, an Engineered Safety feature (ESF) actuotion, was a conservative measure because the ESF actuation resulted from a preplanned sequence aring reactor operation and did not need to be reported. This LER is being submitttd in accordance with the requirements of 10 CFR 50.73(a)(2)(v).

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Analysis of the Event

The actual consequences of this event were minimal in that an accident condition did not occur during the time in which the HPCI system, the 024 EDG, tht 'D' RHR system, and 'D' CS system were inopereble. The period of time in which the HPCI system was inoperable was limited to 48 minutes. The period of timt in which i

the 024 EDG, the 'O' kHR system, and the 'O' CS system were inoperable was limited to 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> 58 minutes.

Although the systems were inoperable because they would not automatically initiate under all accident conditions; operators could have manually initiated these systems to perform their safety function.

If an accident had occurred while all affected systems were inoperable, sufficient Erergency Core Cooling Systems and AC power sources were available to maintain safe shutdown of the reactor and mitigate the consequences of an accident.

Ccuse of the E.ent:

The cause of this event was the failure of PIS-42-2N690H wt1:h resulted in a blown power fusa. PIS-42-2N690H has been sent to the manutacturer for performance of a failure anaiysis. The results of the failure analysis will be relied upon to identify the cause of failure to PIS-42-2N690H.

Corrective Actions

PIS-42-2N690H was replaced on January 4, 1992. Similar pressure indicating switchas in card file E21A-230 were inspected and confirmed to not have the same condition. The results of the failure analysis conducted by the manufacturer will be reviewed to determine if additional corrective action needs to be taken.

Previous Similar Occurrences:

None Tracking Codes: B - Design, manufact, const/ install deficiency

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