ML18151A041

LER 87-019-00:on 870807,manual Reactor Trip Initiated Following Short Rampdown Due to Loss of Cooling & Oil Flow for Main Transformer B.Caused by Failed Undervoltage Relay. Relay & Local Annunciator Panel replaced.W/870904 Ltr

ML18151A041
Person / Time
Site:	Surry
Issue date:	09/04/1987
From:	Benson D VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
87-021, 87-21, LER-87-019, LER-87-19, NUDOCS 8709100301
Download: ML18151A041 (5)

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Unit. 1 TITLE (4) Manual Reactor Trip Due To Failed Relay In Main Transformer EVENT DATE (6) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8) MONTH DAY YEAR YEAR }ft MONTH DAY YEAR FACILITY NAMES DOCKET NUMBER(S) o I E ol 7 s 7 s 11 -o I 1 I 9 -o I o o I 9 o 14 a I 1 01s1010101 I I OPERATING MOOE (9) N THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Chock on* or moro of tho fol/ovyin11}

(11) 20.402(b) 20.405(0)

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LICENSEE CONTACT FOR THIS LER (12) NAME TELEPHONE NUMBER AREA CODE D. L. Benson Station Manaaer 8 I O 14 31 517 1 *-1 31 11 RI ll COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 113) CAUSE SYSTEM COMPONENT . TURER R~~o~~:gkE i!iil!i!i!i!i!i!i!ii!ii!i!i!iii!i!i!i!i!i!i!i!i!ill!l CAUSE SYSTEM COMPONENT MANUFAC-.

TURER y i= I I IY I CIA~ IR r. I n I~ I n V li!iiiiiiii!i!i!i!i!i!iiii!i!ilillilillli!ililiiliili I I I I I I I i!!lli!i!l!ill!lil!i!i!i!i!iii!l!iii!i!i!i!i!i!ii!ili SUPPLEMENTAL REPORT EXPECTED 114) n YES /If v*s. compl*t* EXPECTED SUBMISSION DATE/ ABSTRACT (Limit to 1400 spoc*s, i,o,, oppro1timote/y fift**n 1Jn11f*-spoc*

typewritten linos} 116) I I I I I I I I I I I I I I EXPECTED SUBMISSION DATE (15) 'lllli!liiiili!ilili!i!iliiiiiiiiiliii::ii:iiililiii MONTH DAY YEAR I I I On August 7, 1987 at 0120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br />, with the unit at approximately 98% power, a manual reactor trip was initiated, following a short rampdown, due to loss of cooling and oil flow for the 'B' Main Transformer

{EIIS-XFMR}.

The transformer local annunciator panel {EIIS-ANN}

had failed to initiate a TROUBLE alarm on the control room annunciator panel. Following ihe trip, all control and protection systems functioned properly except: -One channel of source range nuclear instrumentation (SR NI) {EIIS-IG}

did not automatically reinstate.

-The 'A' main feedwater pump (MFP) {EIIS-P} did not automatically trip and the pump's minimum flow recirc. valve did not open on a low feedwater flow condition.

Operators manually reinstated the SR NI and tripped the 'A' MFP. The unit was quickly stabilized at hot shutdown.

Power was lost to the 'B' Main Transformer cooling fans and oil circulating pumps when an undervoltage relay {EIIS-RLY}

in *the cooling control circuit failed. The relay and annunciator panel failures are attributed to aging. One channel of SR NI failed to reinstate due to compensation of one channel of IR NI. The 'A' MFP did not trip and its minimum flow recirc. valve did not open due to a failed air regulator diaphragm to the pneumatic pressure switch which senses main feedwater flow. The failed relay and the local annunciator panel were replaced.

The transformer was checked for winding or other internal damage and was determined to be undamaged.

Since the relay and annunciator failures are attributed to aging, additional transformer circuit components susceptible to failures due to their age will be identified~O-,, and replaced.

1 e ,i,"L I J 8709100301 8~28 :DR ADOCK O PDRO NRC Form 361:l NRC Form 31141A (9-831 FACILITY NAME 111 POW 28-06-01 e e LICENSEE EVENT.REPORT (LER) TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION APPROVED 0MB NO. 3150--0104 EXPIRES: B/31 /111 DOCKET NUMBER (21 VEAR L!,R NUMBER UII ::::::::::

SEQUENTIAL

.. REVISION ::::;:::;:

NUMBER .. : ... NUMBER PAGE (31 Surry Power Station, Unit 1 o 15 Io Io IO I 2 IR In RI .7 -n I , I a -n In *nl ., OF n I ,, TEXT ,,, --a ,eqund, u* .<<lltioMI NRC Fann ...... , 1171 NRC FORM 3S6A 19-831 1.0 Description of the Event on August 7, 1987 at 0120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br />, with tbe unit at approximately 98% power, a manual reactor trip was initiated, following a short rampdown, due to loss of cooling and oil flow for the 'B' Main Transformer

{EIIS-XFMR}.

During his rounds, the outside plant operator noticed the cooling fans for the 'B' Main Transformer were stopped and that oil was flowing from a relief valve on the transformer.

He informed the Shift Supervisor and the decision was made to initiate a rampdown and, subsequently, a manual reactor trip to prevent trans.former damage due to overheating.

The transformer local annunciator panel {EIIS-ANN}

had failed to initiate a TROUBLE alarm on the control room annunciator panel. Immediately following the trip, all control and protection systems functioned properly except: One channel of source range nuclear instrumentation (SR NI) {EIIS-IG}

did not automatically reinstate due to under-compensation of one channel of intermediate range (IR NI) {EIIS-IG}, and the 'A' main feedwater pump (MFP) {EIIS-P} did not automatically trip and* the pump's minimum flow recirc. valve did not open on a low feedwater flow cond~tion.

2.0 Safety Consequences and Implications A manual reactor trip from full power is well within the bounds of the UFSAR safety and accident analyses and all safety related and other systems required to shut the plant down safely functioned as designed.

Therefore, this event did not constitute an unreviewed safety question and the health and safety of the public were not affected.

• U.S.GPO: 1988-0-624*538/466 NRC Form 3118A 19-831 FACILITY NAME (11 ~-... _,,,, __ ._,_ .... *-.... _ ...... **-**-'**---*,:

.. *-*-e LICENSEE EVENT REPORT ILER) TEXT CONTINUATION DOCKET NUMBER (2) VEAR POW 28-06-01 U.S. NUCLEAR REGULATORY

~OMMISSION APPROVED 0MB NO. 3150~104 EXPIRES: 8/31/111 LER NUMBER (Ill PAGE (31 Surrv Power Station Unit 1 o 1s Io Io Io I 218 IO 81 7 -Ol 119 -O I C OI 3 OF O 14 TEXT (If""""~ o ,eqund, u* IMldllioMI NRC Form :m.1'1/ 1171 NRC FORM 366A 19-83) 3. 0 , Cause Power was lost to the 'B' Main Transformer cooling fans and oil circulating pumps when an undervoltage relay {EIIS-RLY}

in the cooling control circuit failed. The relay and annunciator panel failures are attributed to aging. Without cooling, the transformer began to overheat and oil pressure increased causing the relief valve to lift. One channel of SR NI failed to reinstate due to under compensation of one channel of IR NI. The 'A' MFP did not trip and its minimum flow recirc. valve did not open because they failed to receive the low feedwater flow signal. The air regulator to the pneumatic pressure switch which senses main feedwater flow was found to have a ruptured diaphragm.

This resulted in an erroneous high feedwater flow signal in the MFP/recirc.

valve logic circuit. 4.0 Immediate Corrective Action Control room operators manually reinstated the SR NI and tripped the 'A' MFP. Appropriate plant procedures were followed .and the unit was quickly stabilized at hot shutdown conditions.

The Shift Technical Advisor performed critical safety function status tree reviews to ensure plant parameters were observed and maintained within safe limits. 5.0 Additional Corrective Actions The Main Transformer cooling circuit under voltage relay and the local annunciator panel were replaced.

The transformer was checked for winding or other internal damage and was determined to be undamaged based on an oil analysis and a high potential winding continuity test.

• Compensating voltage was adjusted on the IR NI and the air regulator diaphragm for the feedwater flow pressure switch was replaced.

The 'A' MFP trip and recirculation valve logic circuit was tested to ensure proper operation.

• U.S.GPO: 1988*0-1124*538/465

... NRC Form 3811A 19-831 FACILITY NAME 111 . '.*,,,., .. ,.--.,-*,.~-*

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• e POW 28-06-01 LICENSEE EVENT REPORT (LERI TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION APPROVED 0MB NO. 3150--0104 EXPIRES: 8/31 /BB DOCKET NUMBER 121 YEAR LER NUMIIER 1111 **********

SEQUENTIAL

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REVISION ..........

NUMBER * ..... NUMIIER PAGE (31 Surry Power Station. Unit 1 01s101010121slo1Rl7 -nl, b -1nh-nJllOFn ILI TEXT 1/f --II ,equltw/, ua .,,,,,,.,,_

NRC .Fann .-.,.*,1 1171 NRC FORM 366A 19-831 6.0 *Actions Taken To Prevent Recurrence Preventive maintenance was performed on the three main transformers.

Since the relay and annunciator failures were attributed to aging, additional transformer control and protection circuit components susceptible to failures due to their age will be identified and* replaced.

7.0 Similar Events None. 8.0 Manufacturer/Model Number Transformer:

General Electric Single ~hase Step-up Power Transformer Failed Relay: General Electric CR120E UV re-lay.

• U.S.GP0:19B6-0-624*536/4_55

'* \ e September 4, 1987 U.S. Nuclear Regulatory Commission Document Control Desk .016 Phillips Building Washington, D.C. 20555 Gentlemen:

-VIRGINIA ELECTRIC AND POWER COMPANY Surry Power Station P. 0. Box 315 Surry, Virginie 23883 Serial No.: 87-021 Docket No. : .50-280 Licensee No.: DPR-32 Pursuant to Surry Power Station Technical Specifications, Virginia Electric and Power Company hereby submits the following Licensee Event Report for Surry Unit 1. REPORT NUMBER 87-019-00 This report ha.s been reviewed by the Station Nuclear Safety and Operating COIIIJ!littee and will be reviewed by Safety Evaluation and Control.

• Very truly yours, David L. Benson Station Manager Enclosure cc: Dr. J. Nelson Grace Regional Administrator Suite 2900 101 Marietta Street, NW Atlanta, Georgia 30323