ML17250B053

LER 89-012-00:on 891007,turbine Runback to Approx 80% Reactor Power Occurred Due to Nuclear Instrument Sys Rod Drop Circuitry on Power Range Channel N-44.Cause Unknown. Restoration Procedure ER-NIS.3 performed.W/891106 Ltr

ML17250B053
Person / Time
Site:	Ginna
Issue date:	11/06/1989
From:	Backus W, Mecredy R ROCHESTER GAS & ELECTRIC CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-012, LER-89-12, NUDOCS 8911200124
Download: ML17250B053 (19)

Text

'cpMRATZD IFMBUTION DEMONS ATlON SYSTEM REGU ORY INFORMATION DISTRIBU SYSTEM (RIDS)

Ce ACCESSION NBR:8911200124 DOC.DATE: 89/11/06 NOTARIZED: NO DOCKET FACIL:50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G 05000244 AUTH. NAME AUTHOR AFFILIATION BACKUSgW.H. Rochester Gas & Electric Corp.

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

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 89-012-00:on 891007,turbine runback caused by nuclear instrument sys rod drop circuitry.W/891106 ltr.

W/8 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR TITLE: 50.73/50.9 Licensee Event Report g ENCL f SIZE:

(LER), Incident Rpt, etc.

NOTES:License Exp date in accordance with 10CFR2,2.109(9/19/72). 05000244 RECIPIENT COPIES RECIPIENT .COPIES h ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PDl-3 LA 1 1 PD1-3 PD 1 1 JOHNSONiA 1 1 INTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2 ACRS WYLIE 1 1 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 DEDRO 1 1 NRR/DEST/ESB 8D 1 1 NRR/DEST/ICSB 7 1 1 NRR/DEST/MEB 9H 1 1 NRR/DEST/MTB 9H 1 1 NRR/DEST/PSB 8D 1 1 NRR/DEST/RSB 8E 1 1 NRR/DEST/SGB 8D 1 1 NRR/DLPQ/HFB 10 NRR/DLPQ/PEB 10 1 1 NRR/DOEA/EAB NUDOCS-ABSTRACT ll 1 1

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ROCHESTER GAS AND ELECTRIC CORPORATION o 89 EAST AVENUE, ROCHESTER, N. K 14649.0001 TELEPHONE AREA CODE 7II5 546-2700 November 6, 1989 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Subject:

LER 89-012, NIS Dropped Rod Signal Causes Turbine Runback 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 Pro-tection System (RPS)", the attached Licensee Event Report LER 89-012 is hereby submitted.

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

Very truly yours, Robert C. Mecr dy General Manager Nuclear Production xco U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Ginna USNRC Senior Resident Inspector

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SACILITY NAME lll A R.E. Ginna Nuclear Power Plant TITLC 14 060004410F06 DOCKCT NVMI CA Ql NIS Dro Rod Si al Causes Turbine Runback EVEN'T O*TC III Ltl HUMICA (4 AESOAT OATE(n OTHCA SACII.ITIKIINVOLVCD III saOHTH OAY YEAN YEAH IKOVIHTIAL AIV4IO>> MONTH OAY YEAA SACILSTY NAMLI DOCKET NVMICA(SI Hvseolll HVMIISI 0 5 0 0 0 1 00789 89 THIS 0 1 001 AfSOAT II IUIMITTC0 WAIUAHTTO TH! AlOUIAEMCNTS OS 1 0 6 8 9 es>>e el Vse IHlorVot/ )11) 0 6 0 0 0 OSCAATIHO 10 CS A $ : /Ce>>a ooe ee MOOC I ~ I IIADKIII 10.eeM(e) X ~ II.TIle) Q IDsl TS.T)4)

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NAME TCLESSIOHE HUMIKA Wesley H. Backus AAtA COOC Technical Assistant to the ations Mana er 315 524-44 6 COMtLCTE ONC LINC SOA CACN COMSONKNT SAILVAE DESCAI ~ CD IH THIS AESOAT (11)

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On October 7, 1987 at 1734 EDST with the Reactor at approximately 994 full power, a turbine runback to approximately 804 reactor power occurred. This turbine runback was caused by Nuclear Instrument System Rod Drop circuitry on power range channel N-44, which occurred during the calorimetric adjustment and subsequent changing of position of the rod mode selector switch.

The Control Room operators performed the applicable steps of abnormal procedure AP-TURB.2 (Automatic Turbine Runback) and stabilized the plant.

Subsequently the Control Room operators defeated power range channel N-44 per equipment restoration procedure ER-NIS.3.

The underlying cause of power range channel N-44 causing the turbine runback is undetermined at this time.

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R.E. Ginna Nuclear Power Plant Uw PNC Ana ~'llllTl o s o o o 244 8 9 0 1,'2 00 PRE-EVENT PLANT CONDITIONS The unit was at approximately 994 steady state full power with no major activities in progress. The Control Room operators were performing operating procedure 0-6.3.2, (Maximum Unit Power Calculation Using the LEFM For Flow Measurement). (Note: "LEFM" is the Leading Edge Flow Meter)

II'ESCRIPTION OF EVENT A. DATES AND APPROXIMATE TIMES FOR MAJOR OCCURRENCES:

o October 7, 1989, 1734 EDST: Event date and time.

o October 7, 1989, 1734 EDST: Discovery date and time.

o October 7, 1989, 1734 EDST: Control Room operators performed the actions'f abnormal procedure AP-TURB.2 (Automatic Turbine Runback) and stabilized the plant at approximately 804 power.

o October 7, 1989, 1922 EDST: Started increasing load to approximately 100% full power.

B. EVENT:

On October 7, 1989 at 1734, with the reactor at approximately 994 full power, a turbine runback occurred. Prior to the turbine runback, the Control Room operators were adjusting gains on the power range channels per 0-6.3.2 to reflect calculated unit power. As part of this sequence of adjusting gains, the dropped rod mode selector switch was placed from "normal" to bypass thus defeating the turbine runback from this power range channel while the adjustment was being made. After power range channel N-44 bistables verified normal, the dropped rod mode selector switch was placed from "bypass" to "normal".

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I r vrar U r R.E. Ginna Nuclear Power Plant o 5 o o o 2 4489 0 1 2 0 30F 0 6 TTXT gr rvtt ~ r rrrttsL vtt eatWeret ASTC tSrr ~'SI I ITI At this time the turbine runback occurred and the Control Room operators entered and performed the actions of AP-TURB.2 (Automatic Turbine Runback).

The plant was stabilized at approximately 80% power and all systems and equipment performed normally.

During the runback the dropped rod stop bistable on the N-44 channel was observed to be Control Board annunciator E-28 (Power litRange and the Main Rod Drop, Rod Stop -54/5 sec) was lit.

Subsequently, after the plant was stabilized, power range channel N-44 was defeated per equipment restora-tion procedure ER-NIS.3 and higher supervision, the NRC and the Instrument and Control (I&C) Department were notified of the event. The Core Quadrant Power Tilt Ratio (QPTR) was checked tocontrol be within operating limits thus verifying that a rod had not dropped into the core.

After verifying that all control rods were in their required position the plant was returned to approxi-mately 1004 full power.

C. INOPERABLE STRUCTURES t COMPONENTS t OR SYSTEMS THAT CONTRIBUTED TO THE EVENT:

None.,

'. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None.

E~ METHOD OF DISCOVERY:

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

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MAC terse SSSA U.S NUCLSAO ASOULATOOY ~t%IOM 104S I llCENSEE EVENT REPORT (LER) TEXT CONTINUATION AttAOYSO OMO 1$0. SISO&104 SII ~ IASS SrsIrls tACILITYHAMS III OOCXSY NUMOlh ISI Llll MU$$ OS1 ISI ~ AOl ISI seoUerrTrAL ~ vrelOrr rrUM S rr rs R.E. Ginna Nuclear Power Plant 0 5 0 0 0 2 4 4 9 012 000 0~ 06 sss(Y (It rrrrse MMee ~ retest rree oAWRIV1$ $ 1C terr ~ $1 I ISI F. OPERATOR ACTION:

Immediate operator action was to stabilize the plant at approximately 80% reactor power by performing the applicable steps of AP-TURBe2 Subsequent operator action was to defeat power range channel N-44 per ER-NIS.3, notify Higher Supervision, the NRC and the I&C Department and verify the QPTR was within normal operating limits.

G. SAFETY SYSTEM RESPONSES:

The turbine generator decreased load automatically to approximately 804 reactor power due to the dropped rod runback circuitry.

III. CAUSE OF EVENT A. IMMEDIATE CAUSE:

The automatic turbine runback was 'caused by Nuclear Instrument System Rod Drop circuitry on power range channel N-44.

B. INTERMEDIATE CAUSE:

The Nuclear Instrument System Rod Drop Circuitry event on power range channel N-44 occurred during the calorimetric adjustment of power range channel N-44, and subsequent switching of the rod mode selector switch from "bypass" to "normal".

C~ ROOT CAUSE:

The underlying cause of the turbine runback from power range channel N-44 is undetermined at. this time. The I&C Department could not duplicate the event during subsequent troubleshooting efforts.

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~ )WC Are ~'llII9l 0 5 0 0 0 2 4 4 8 90 1 2 5 0~ 06 IV. ANALYSES OF EVENT The 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 automatic turbine runback was an automatic actuation of the RPS.

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 turbine runback event because:

o The event was immediately apparent.

o The turbine runback was in the conservative direction.

o All reactor control and protection systems performed as designed thus limiting the overall effects of the transient.

o The Control Room operators stabilized the plant very quickly.

Based on the above, it can be concluded that the public's health and safety was assured at all times.

VAC TOAM OSSA I9 55l

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/WC Ana ~'llIITI CORRECTIVE ACTION o 5 o o o 2 4 8 9 012 00 06 OF 0 6 A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:

o During subsequent, troubleshooting efforts, the I&C Department could not duplicate or identify any malfunctions that would have caused the turbine runback from power range channel N-44.

o After all troubleshooting efforts were completed, power range channel N-44 was returned to service.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

As the underlying cause of the event is still undeter-mined, I&C Department is planning to do a further analysis of power range channel N-44 circuitry to identify possible malfunctions that could have caused the event. For possible malfunctions that are identified, these circuits will be monitored during a future calorimetric adjustment, and I&C will perform appropriate troubleshooting.

Any further corrective action will depend upon reached from the above planned trouble- 'onclusions shooting.

VI. ADDITIONAL INFORMATION A. FAILED COMPONENTS:

None identified.

B. PREVIOUS LERs ON SIMILAR EVENTS:

A similar LER event historical search was conducted with the following results: No documentation of similar LER events with the same root cause at Ginna Station could be identified.

C. SPECIAL COMMENTS:

None.

VAC rOAU )NA T STI

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,.-'-.;.:"CEIZRATED D %'KBUTION DEMONS A,'DON SYSTEM REGULA Y INFORMATION DISTRIBUTI SYSTEM (RIDS)

ACCESSION NBR:8911200124 DOC.DATE: 89/11/06 NOTARIZED: NO DOCKET FACZL: 50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G 05000244 AUTH. NAME AUTHOR AFFILIATION BACKUSPW.H. Rochester Gas & Electric Corp.

MECREON,R.C. Rochester Gas S Electric Corp.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 89-012-00:on 891007,turbine runback caused by nuclear instrument sys rod drop circuitry.W/891106 ltr.

W/8 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR 4 ENCL 3 TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

SIZE:

NOTES:License Exp date in accordance with 10CFR2,2.109(9/19/72). 05000244 RECIPIENT COPIES RECIPIENT .COPIES h ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD1-3 LA 1 1 PD1-3 PD 1 1 JOHNSON,A 1 1 INTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2 ACRS WYLIE 1 1 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 DEDRO 1 1 NRR/DEST/ESB 8D 1 1 NRR/DEST/ICSB 7 1 1 NRR/DEST/MEB 9H 1 1 NRR/DEST/MTB 9H 1 1 NRR/DEST/PSB 8D 1 1 NRR/DEST/RSB 8E 1 1 NRR/DEST/SGB 8D 1 1 10 NRR/DLPQ/HFB 10 NRR/DOEA/EAB NUDOCS-ABSTRACT ll 1 1

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On October 7, 1987 at 1734 EDST with the Reactor at approximately 994 full power, a turbine runback to approximately 80% reactor power occurred. This turbine runback was caused by Nuclear Instrument System Rod Drop circuitry on power range channel N-44, which occurred during the calorimetric ad)ustment and subsequent changing of position of the rod mode selector switch.

The Control Room operators performed the applicable steps of abnormal procedure AP-TURB.2 (Automatic Turbine Runback) and stabilized the plant.

Subsequently the Control Room operators defeated power range channel N-44 per equipment restoration procedure ER-NIS.3.

The underlying cause of power range channel N-44 causing the turbine runback is undetermined at this time.

NAC Scree

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PRE-EVENT PLANT CONDITIONS The unit was at approximately 994 steady state full power with no major activities in progress. The Control Room operators were performing operating procedure. 0-6.3.2, (Maximum Unit Power Calculation Using the LEFM For Flow Measurement). (Note: "LEFM" is the Leading Edge Flow Meter)

DESCRIPTION OF EVENT A. DATES AND APPROXIMATE TIMES FOR MAJOR OCCURRENCES:

o October 7, 1989, 1734 EDST: Event date and time.

r o October 7, 1989, 1734 EDST: Discovery date and time.

o October 7, 1989, 1734 EDST: Control Room .

operators performed the actions'f abnormal procedure AP-TURB.2 (Automatic Turbine Runback) and stabilized the plant at approximately 804

'ower.

o October 7, 1989, 1922 EDST: Started increasing load to approximately 1004 full power.

B. EVENT:

On October 7, 1989 at 1734, with the reactor at approximately 994 full power, a turbine runback occurred. Prior to the turbine runback, the Control Room operators were adjusting gains on the power range channels per 0-6.3.2 to reflect calculated unit power. As part of this sequence of adjusting gains, the dropped rod mode selector switch was placed from "normal" to bypass thus defeating the turbine runback from this power range channel while the adjustment was being made. After power range channel N-44 bistables verified normal, the dropped rod mode selector switch was placed from "bypass" to "normal".

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~ Pesas ma'sl lln o 5 o o o 2 4 4 8 9 0 1 2 0 0 3o~ 0 6 At this time the turbine runback occurred and the Control Room operators entered and performed the actions of AP-TURB.2 (Automatic Turbine Runback).

The plant was stabilized at approximately 80% power and all systems and equipment performed normally.

During the runback the dropped rod stop bistable on the N-44 channel was observed to be Control Board annunciator E-28 (Power Range Rod Drop, lit and the Main Rod Stop -54/5 sec) was lit.

Subsequently, after the plant was stabilized, power range channel N-44 was defeated per equipment restora-tion procedure ER-NISA3 and higher supervision, the NRC and the Instrument and Control (I&C) Department were notified of the event. The Core Quadrant Power Tilt Ratio (QPTR) was checked to be within operating limits thus verifying that. a control rod had not dropped into the core.

After verifying that all control rods were in their required position the plant,was returned to approxi-mately 1004 full power.

C. INOPERABLE STRUCTURES P COMPONENTS P OR SYSTEMS THAT CONTRIBUTED TO THE EVENT:

None.

D. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None.

E. METHOD OF DISCOVERY:

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

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R.E. Ginna Nuclear Power Plant mCr Ia' Nttt e vN hSC ttee ~'N IIS osooo2449 012 0 0 0 oF 06 F. OPERATOR ACTION:

Immediate operator action was to stabilize the plant at approximately 804 reactor power by performing the applicable steps of AP-TURB.2 Subsequent operator action was to defeat power range channel N-44 per ER-NIS.3, notify Higher Supervision, the NRC and the I&C Department and verify the QPTR was within normal operating limits.

SAFETY SYSTEM RESPONSES:

The turbine generator decreased load automatically to approximately 804 reactor power due to the dropped rod runback circuitry.

III CAUSE OF EVENT A. IMMEDIATE CAUSE:

"The automatic turbine runback was caused by Nuclear Instrument System Rod Drop circuitry on power range channel N-44.

B. INTERMEDIATE CAUSE:

The Nuclear Instrument System Rod, Drop Circuitry event on power range channel N-44 occurred during the calorimetric adjustment of power range channel N-44, and subsequent switching of the rod mode selector switch from "bypass" to "normal".

C. ROOT CAUSE:

The underlying cause of the turbine runback from power range 'hannel N-44 is undetermined at this time. The I&C Department could not duplicate the event during subsequent troubleshooting efforts.

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~I Q A v R.E. Ginna Nuclear Power Plant o s o o o 2 4 4 8 90 1 2 0 0 0 50'6 mrrIr~~e~ ~~IYIIC/awe~'AIIm ZV. ANALVSrS OF ZVZNT The 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 automatic turbine runback was an automatic actuation of the RPS.

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 turbine runback event because:

o The event was immediately apparent.

o The turbine runback was in the conservative direction.

. o All reactor control and protection systems performed as designed thus limiting the overall effects of the transient.

o The Control Room operators stabilized the plant very quickly.

Based on the above, health it can be concluded that and safety was assured at all times.

the public's vAC NOAE t &I l

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R.E. Ginna Nuclear Power Plant hHO ltAttN ~'sJ 117l CORRECTIVE ACTION o s o o o 2 4 8 9 -012 00 06 os 0 6 A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:

o During subsequent troubleshooting efforts, the I&C Department could not duplicate or identify any malfunctions that would have caused the turbine runback from power range channel N-44.

o After all troubleshooting efforts were completed, power range channel N-44 was returned to service.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

As the underlying cause of the event is still undeter-mined, I&C Department is planning to do a further analysis of power range channel N-44 circuitry to identify possible malfunctions that could have caused the event. For possible malfunctions that are identified, these circuits will be monitored during a future calorimetric adjustment, and Z&C will perform appropriate troubleshooting.

Any further corrective action will depend upon conclusions reached from the above planned trouble-shooting.

ADDITIONAL INFORMATION:

A. FAILED COMPONENTS:

None identified.

B. PREVIOUS LERs ON SIMILAR EVENTS:

A similar LER event historical search was conducted with the following results: No documentation of similar LER events with the same root, cause at Ginna Station could be identified.

.C. SPECIAL COMMENTS:

None.

VAC rOttU lliA 0 All

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November 6, 1989 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Subject:

LER 89-012, NIS Dropped Rod Signal Causes Turbine Runback 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 Pro-tection System (RiS)", the attached Licensee Event Report LER 89-012 is hereby submitted.

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

Very truly yours, Robert C. Mecr y General Manager Nuclear Production xc'.S. Region I Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Ginna USNRC Senior Resident Inspector