ML17262A289

LER 90-015-00:on 901212,automatic Start of EDG a Occurred Due to Initiation Signal from Bus 14 Undervoltage Monitoring Sys.Caused by Failure of Solid State Switch Printed Circuit Board.Circuit Board replaced.W/910111 Ltr

ML17262A289
Person / Time
Site:	Ginna
Issue date:	01/11/1991
From:	Backus W, Mecredy R ROCHESTER GAS & ELECTRIC CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-015, LER-90-15, NUDOCS 9101160165
Download: ML17262A289 (11)

Text

ACCELERATED DI< RIBUTION DEMONST TION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR: 9101160165 DOC. DATE: 91/01/11 NOTARIZED: NO DOCKET FACIL:50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G 05000244 AUTH. NAME AUTHOR AFFILIATION BACKUS,W.H. Rochester Gas 6 Electric Corp.

MECREDY,R.C. Rochester Gas & Electric Corp.

RECIP.NAME RECIPIENT AFFILIATION LER 90-015-00:on 901212,automatic start of EDG A occurred R'UBJECT:

due to initiation signal from Bus 14 undervoltage monitoring D sys.Caused by failure of solid state switch printed circuit board. Circuit board replaced.W/910111 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:License Exp date in accordance with, 10CFR2,2.109(9/19/72). 05000244 A D

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL D PD1-3 LA 1 1 PD1-3 PD 1 1 JOHNSON,A 1 1

.,S INTERNAL: ACNW 2 AEOD/DOA 1 1' AEOD/DS P/TPAB 1 1 AEOD/ROAB/DSP 2 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB11 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB .1 1 NRR/DREP/PRPBll 2 2 NRR/DST/SELB 8D '1 1 NRR/DST/SICB 7E 1 1 '

NRR/DST/SPLB8D1 1 1 NRR/DST/SRXB 8E 1 RE 1 1 RES/DSIR/EIB 1 1 RGN ZZE 0 1 1 EXTERNAL: EGE(G BRYCE,J.H 3 3 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MAYS,G 1 1 NSIC MURPHYiG A 1 1 NUDOCS FULL TXT 1 1

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D NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOF I Pl-37 (EXT. 20079) TO ELlii'IINATEYOUR NAME FRY'I DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 31 ENCL 31

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'WEACOOErle 646.2700 Clnna NuClear Production January 11, 1991 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Subject:

LER 90-015, Safeguards Bus Undervoltage Relay Actuation Due to a Failed Solid State Switch Causes an Automatic Start of the "A" Emergency Diesel Generator.

R.E. Ginna Nuclear Power Plant Docket No. 50-244 In accordance with 10 CFR 50.73, Licensee Event Report System, item (a)(2)(iv), which requires a report of, "any event, or condition that resulted in manual or automatic actuation of any Engineered Safety Feature (ESF) including the Reactor Protection System (RPS)", the attached Licensee Event Report LER 90-015 is hereby submitted.

This event. has in no way affected the public's health and safety.

Very truly yours, Robert C. Me edy xc: U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Ginna USNRC Senior Resident Inspector

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The "A" Emergency Diesel Generator, after starting, attained proper voltage and frequency.

Bus 14 because Bus 14 was at By its design, it proper voltage fed from its did not close into normal power supply.

Immediate operator action was to verify that Bus 14 was energized and that the "A" Emergency Diesel 'Generator was operating properly.

Subsequently, the Control Room operators transferred Bus 14 from its normal supply to the "A" Emergency Diesel Generator as part of the repair procedure for the Bus 14 Undervoltage Monitoring System.

The cause of the event was determined to be a failure of a solid state switch printed circuit. board.

Corrective action taken was to replace the solid state switch printed circuit board with a qualified spare, followed by a satisfactory test and return to service. Long term corrective actions are discussed in Section V. B.

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HAC FMw 99EA V 9 HVCLEA4 4EOVLATOAY COMMISEIOM I94SI Sissies 4 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION AFFAOVEO OME MO SISO&IOS E~>4ES FACILITY IIAME III OOCKET HUMEE4 LTI LE4 HVMEE4 I ~ I ~ AOE IEI SSOVEWZSAL 4(vis<0 I MVM (4 MVU R.E. Ginna Nuclear Power Plant o2 44 9 0 0 1 5 20" TEXT lllnee ance 4 ~. vFF seecvW HlIC few JSS4'll IITI o s o o 0 0 7 PRE-EVENT PLANT CONDITIONS The plant was in the process of starting up subsequent to the plant trip of 12/11/90 (discussed in LER 90-013). The reactor was at approximately 34 full power, awaiting clearance that secondary chemistry parameters were within specification.

II. DESCRIPTION OP KTKRT A. DATES AND APPROXIMATE TIMES OP MOOR OCCURRENCES:

o December 12, 1990, 2044 EST: Event Date and Time o . December 12, 1990, 2044 EST: Discovery Date and Time 0 December 12, 1990, 2322 EST: Safeguards Bus 14 power supply manually transferred to "A" Emergency Diesel Generator December 13, 1990, 0644 EST: Safeguards Bus 14 normal power restored 0 December 13, 1990, 0644 EST: Safeguards Bus 14 "A" Emergency Diesel Generator power supply terminated and "A" Emergency Diesel Generator stopped and lined up for auto standby.

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On December 12, 1990 at 2044 EST, with the reactor at approximately 3% full power, the Control Room received the following alarm: L-14 (Bus, 14 Undervoltage Safeguards). Control Room operators immediately verified proper voltage on Bus 14 and that the normal power supply breaker was closed. The Control Room operators also verified that the "A" Emergency Diesel Generator had started and displayed proper voltage and frequency. By design, the "A" Emergency Diesel Generator did not close into Bus 14, as the Bus Voltage was normal and was still being supplied by its normal power supply.

Subsequently, at 2322 EST, the power supply to Bus 14 was transferred from the normal supply to the "A" Emergency Diesel Generator per Maintenance Procedure M-48.14 (Isolation of Bus 14 Undervoltage System for Maintenance, Troubleshooting, Rework and Testing).

This transfer was done so the Maintenance Department could troubleshoot, repair, test, and return to service the Bus 14 Undervoltage Monitoring System.

At 0644 EST, December 13, 1990, subsequent to the repair and return to service of the Bus 14 Undervoltage Monitoring System, Bus 14 normal power supply was restored and the "A" Emergency Diesel Generator was stopped and realigned for automatic standby.

C. INOPERABLE STRUCHlRESF COMPONENTS, OR SYSTEMS THAT CONTRIBUTED TO THE EV19iT:

None.

D. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None.

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E. METHOD OF DISCOVERY:

The event was immediately apparent due to alarms and indications in the Control Room.

OPERATOR ACTION:

Following the Bus 14 undervoltage alarm and the "A" Emergency Diesel Generator automatic start, the Control Room operators immediately verified proper voltage on Bus 14 via the normal power supply and that the "A" Emergency Diesel Generator displayed proper voltage and frequency.

Subsequently, the Control Room operators transferred Bus 14 from its normal supply to the "A" Emergency Diesel Generator per M-48.14 to facilitate troubleshooting, repairing, and testing of the Bus 14 Undervoltage Monitoring System.

G. SAFETY SYSTEM RESPONSES:

The "A" Emergency Diesel Generator automatically started and displayed proper voltage and frequency.

III. CAUSE OF KRHBFP A. IMMEDIATE CAUSE:

The automatic actuation of the "A" Emergency Diesel Generator was due to an undervoltage signal from the Bus 14 Undervoltage Monitoring System.

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The undervoltage signal from the Bus 14 Undervoltage Monitoring System was due to the internal failure of the system's solid state switch printed circuit board number two (2). This solid state switch printed circuit board is the interface mechanism between the solid state undervoltage monitoring relays and the mechanical actuation relays.

C. ROOT CAUSE:

The root cau'se was determined to be a failure of an electronic component.

IV. ANALYSIS OF EVENT This event is reportable in accordance with 10 CFR 50.73, Licensee Event Report System,. item (a)(2)(iv), which requires reporting of "any event or condition that resulted in manual or automatic actuation of any Engineered Safety Feature (ESF), including the Reactor Protection System (RPS)". The starting of the "A" Emergency Diesel Generator was an automatic actuation of an ESF system.

An assessment was performed considering both the safety consequences and implications of this event with the following results and conclusions:

There were no operational or safety consequences or implications attributed to the starting and loading of the "A" Emergency Diesel Generator becauseT o The "A" Emergency Diesel Generator operated as designed.

o Both Bus 14 power supplies (i.e. normal and emergency) were either in use or available throughout the event.

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Based on the above, health and safety was assured at all times.

it can be concluded that the public's V. CORRECTIVE ACTION A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:

0 The Maintenance Department, after troubleshooting the Bus 14 Undervoltage Monitoring System, determined that the problem was a solid state switch pri;nted circuit board in the system.

0 The Maintenance Department replaced the solid state switch printed circuit board with a qualified spare, tested the system satisfactorily, and returned it to service.

0 Operations, after the Bus 14 Undervoltage Monitoring System was restored to service, returned Bus 14 to its normal power supply and stopped the "A" Emergency Diesel Generator and realigned it for automatic standby.

B. ACTION TAKEN OR PLANNED TO PR&TENT RECUREMNCE:

o Thermography of the failed solid state switch printed circuit board was performed.

o - Results of this thermography will be provided to Electro-Mechanics, the system designer.

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VI. ADDITXONAL INFORMATION

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A. FAILED COMPONENTS.

The failed solid state switch printed circuit board number 2 was supplied by Electro-Mechanics, part number 33013; assembly number 03021-288.

PREVXOUS LERs ON SIMILAR EVENTS:

A similar LER event historical search was conducted with the following results: LER 88-008 (Safeguards Bus Undervoltage Relay Actuation Due to a Failed Solid State Switch Caused Automatic Start of "B" Emergency Diesel Generator) was a similar event. The root cause of LER 88-008 was a random failure of an electronic component, and no corrective action was deemed necessary to prevent recurrence.

C. SPECXAL CO19GKZS:

See LER 90-016 for a discussion of the Reactor Trip that occurred during this repair activity, and LER 90-017 for a discussion, of other events caused by this repair activity..