ML17263A563

LER 94-005-00:on 940217,turbine Runback Occurred Due to Lost Offsite Power Circuit 751 Causing Low Voltage on Safeguard Busses 14 & 18.Circuit 751 Restored by Automatic Reclosure of Transformer breaker.W/940321 Ltr

ML17263A563
Person / Time
Site:	Ginna
Issue date:	03/21/1994
From:	Mccredy R, St Martin J ROCHESTER GAS & ELECTRIC CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-94-005, LER-94-5, NUDOCS 9403290326
Download: ML17263A563 (12)

Text

ACCj"-'LBRA"I"BD DlSTRlBUTluN DEMON&"I'RA'i'los SYS l'UIvl l,

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9403290326 DOC.DATE: 94/03/21 NOTARIZED: NO DOCKET FACIL:50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G 05000244 AUTH. NAME AUTHOR AFFILIATION ST MARTIN,J.T. Rochester Gas & Electric 'Corp.

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

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 94-005-00:on 940217,turbine runback occurred due to lost offsite power circuit 751 causing low voltage on safegaurd D busses 14 & 18.Circuit 751 restored by automatic reclosure of transformer breaker.940321 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 PD 1 1 JOHNSON,A 1 1 INTERNAL: AEOD/DOA 1 1 AEOD/DS P/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRIL/RPEB 1 1 NRR/DRSS/PRPB 2 2 1 1 NRR/DSSA/SRXB 1 1 1 1 RES/DSIR/EIB 1 1 1 1 EXTERNAL EG&G BRYCE g J ~ H 2 2 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POORE,W. 1 1 NUDOCS FULL TXT 1 1 D

D S'OTE D

TO ALL "RIDS" RECIPIENTS:

'S PLEASE HELP US TO REDUCE WARM CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 27 ENCL 27

'1 ROCHESTER GAS AND ELECTRIC CORPORATION e 89 EAST AVENUE, ROCHESTER N. Y. 14649-0001 ROBERT C MECREDY TEt.EPk<ONB Vice Ptetldent aAEA COnE 7 te 546-2700 Cinna tcvctear pcodoction March 21, 1994 U.S. Nuclear Regulatory Commission Document Control Desk Attn: Allen R. Johnson Project Directorate I-3 Washington, D.C. 20555

Subject:

LER 94-005, Loss of Offsite Power Circuit 751, Due to Loss of Power to

¹2 34.5 KV Bus at Station 204, Causes Automatic Actuation of RPS System (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 a manual or automatic actuation of any engineered safety feature (ESF), including the reactor protection system (RPS) ", the attached Licensee Event Report LER 94-005 is hereby submitted.

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

Very truly yours, go(

Robert C. Mecredy xc: U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Ginna Senior Resident Inspector 940329032b 940321 PDR ADOCK OS000244 8 PDR

NRC FORH 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150 0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY 'WITH THIS INFORHATION COLLECTION REQUEST: 50.0 MRS.

LICENSEE EVENT REPORT (LER) FORWARD COMMENTS REGARDING BURDEN ESTIHATE TO THE IHFORHATION AND RECORDS HANAGEHENT BRANCH (HNBB 7714), U.S. NUCLEAR REGULATORY COMHISSION, (See reverse for required number of digits/characters for each block) WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF HANAGEHENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAME (1) R. E. Ginna Nuclear Power Plant DOCKET NUMBER (2) PAGE (3) 05000244 10F9 TITLE (4) Loss of Offsite Power Circuit 751, Due to Loss of Power to ¹2 34 ' KV Bus at Station 204, Causes Automatic Actuation of RPS System (Turbine Runback)

EVENT DATE (5) LER NUHBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (B)

SEQUENTIAL REVISION FACILITY NAHE DOCKET NUMBER MONTH DAY YEAR YEAR HONTH DAY YEAR NUHBER NUMBER 02 17 94 94 --005-- 00 03 21 FACILITY NAHE DOCKET NUHBER OPERATING N

THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5: (Check one or mor e) (ll)

HODE (9) 20.402(b) 20.405(c) X 50.73(a)(2)(iv) 73.71(b) 20 '05(a )(1)(t) 50.36(c)(1) 50 '3(a)(2)(v) 73.71(c)

POWER 09B LEVEL (10) 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) OTHER 20 '05(a)(1)(iii) 50.73(a)(2)(i) 50 '3(a)(2)(viii)(A) (S pe cify ln 20.405(a)(1)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) Abstract and in Text, below 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) NRC Form 366A)

LICENSEE CONTACT FOR THIS LER (12)

NAHE John T~ St. Martin - Director, Operating Experience TELEPHONE NUMBER (Include Area Code)

(315) 524-4446 COHPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

REPORTABLE REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER CAUSE SYSTEM COMPONENT HANUFACTURER TO NPRDS TO NPRDS SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR YES SUB HIS SION (lf yes, complete EXPECTED SUBHISSION DATE).

X ND DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

On February 17, 1994, at approximately 1421 EST, with the reactor at approximately 98l. steady state power, a turbine runback occurred when offsite power 34.5 KV Circuit 751 was lost, causing low voltage on safeguards busses 14 and 18.

The Control Room operators performed the appropriate actions of AP-TURB.2, "Turbine Load Reduction", and verified that the plant was stabilized at approximately 93% power after the runback signal cleared.

The underlying cause of the loss of power to offsite 34.5 KV Circuit 751 was loss of power to N2 34.5 KV Bus at offsite Station 204. (This event is NUREG-1022 (C) Cause Code.)

Corrective action to preclude repetition is outlined in Section V (B).

NRC FORH 366 (5-92)

NRC FORH 366A U.S. NUCLEAR REGULATORY COHHISSION APPROVED BY OMB NO. 3150-0104 (5.92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COHPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

FORWARD COMMENTS REGARDIHG BURDEN ESTIHATE TO LICENSEE EVENT REPORT (LER) THE INFORHATION AND RECORDS HANAGEMENT BRANCH TEXT CONTINUATION (MNBB 7714), U.ST NUCLEAR REGULATORY COHMISSION, WASHINGTON, DC 20555-0001 AND TO THE PAPERWORK REDUCTION PROJECT (31/0-0104), OFFICE OF MANAGEMENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAME (1) DOCKET NUHBER (2) LER NUMBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION R.E. Ginna Nuclear Power Plant 05000244 2 OF 9 94 005 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

I. PRE-EVENT PLANT CONDITIONS The plant was at approximately 98~ steady state reactor power. The "A" emergency diesel generator (D/G) was in operation for the monthly periodic test of D/G performance, procedure PT-12 "Emergency Diesel Generator lA." The "A" D/G was in Manual voltage control,'nd electrically loaded, per PT-12.1, to approximately two thousand (2000) kilowatts (KW), supplying power to 480 volt AC safeguards busses 14 and 18. The D/G was synchronized to the offsite distribution system, and was backfeeding some power to the offsite electrical distribution system.

The offsite power to the plant was as follows:

~ Offsite power 34.5 KV Circuit 751 was lined up to supply power to safeguards busses 14 and 18 through 12A 34.5 KV/4160V transformer and through the safeguards busses 4160V/480V transformers. In parallel with offsite power, the "A" D/G was also supplying power to these busses.

~ Offsite power 34.5 KV Circuit 767 was supplying power to safeguards busses 16 and 17 through 12B 34.5 KV/4160V transformer and through the safeguards busses 4160V/480V transformers.

NRC FORM 366A (5-92)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150 ~ 0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS IHFORMATION COLLECTION REQUEST: 50.0 HRS.

FORWARD COMMENTS REGARD IHG BURDEN ESTIMATE TO LICENSEE EVENT REPORT (LER) THE INFORMATION AND RECORDS MANAGEMENT BRANCH TEXT CONTINUATION (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001 AND TO THE PAPERWORK REDUCT ION PROJECT (3110-0104), OFF ICE OF MAHAGEMENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SEQUENTIAL REVISION R.E. Ginna Nuclear Power Plant 05000244'EAR 3 OF 9 005-- 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

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

~ February 17, 1994, 1251 EST: Monthly test of the "A" D/G was started, per PT-12.1 P

~ February 17, 1994, 1421 EST: Offsite 34.5 KV Circuit 751 was isolated from the electrical distribution system.

~ February 17, 1994, 1421 EST: Turbine runback. Event date and time.

February 17, 1994, 1421 EST: Discovery date and time.

V February 17, 1994, 1422 EST: Control Room operators performed the appropriate actions of AP-TURB.2, "Turbine Load Reduction," and stabilized the plant.

~ February 17, 1994, 1444 EST: Safeguards busses 14 and 18 resupplied from offsite power 34.5 KV Circuit 751.

~ Febiuary 17, 1994, 2210 EST: Plant was restored to approximately 98~ steady state reactor power.

B. EVENT:

On February 17, 1994, a problem was identified in the Rochester Gas and Electric (RGEE) electrical distribution system. An air tank on a 34.5 KV circuit breaker was leaking.

At approximately 1420 EST, RGEE Energy Operations checked the bus voltages at two offsite electrical distribution stations (Station 204 and Station 13A) and opened the affected circuit breaker (5X20452). This was a standard switching operation that has been performed a number of times. Upon opening breaker 5X20452, ¹2 34.5 KV Bus at Station 204 experienced a high voltage condition. After receiving the high voltage alarm, ¹2 34.5 KV Bus transformer breaker (2T20452) unexpectedly tripped, isolating ¹2 34.5 KV Bus from the rest of the electrical distribution system.

NRC FORM 366A (5-92)

NRC FORH 366A U.S. NUCLEAR REGULATORY COHHISSION APPROVEO BY OHB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIHATED BURDEN PER RESPONSE TO COHPLY WITH THIS INFORMATION COLLECTIOH REQUEST: 50.0 HRS ~

FORWARD COMMENTS REGARDING BURDEN ESTIHATE TO LICENSEE EVENT REPORT (LER) THE INFORMATION AND RECORDS HANAGEHENT BRANCH TEXT CONTINUATION (HNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001 AND TO THE PAPERWORK REDUCTION PROJECT (3140-0104), OFFICE OF MANAGEMENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUHBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION R.E. Ginna Nuclear Power Plant 05000244 94 -- 005-- 00 4 OF 9 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

The g2 34.5 KV Bus supplies Circuit 751, one of the two 34.5 KV transmission circuits that supplies offsite power to Ginna Station.

Therefore, a partial loss of offsite power to Ginna occurred, as Circuit 751 was now isolated from the rest of the electrical distribution system. The other offsite power supply, from 34.5 KV Circuit 767, was unaffected and continued to supply power to 480V safeguards busses 16 and 17. Circuit 751 and the N2 34.5 KV Bus with their connected loads remained energized by the Ginna "A" D/G, since the D/G had been paralleled to the offsite electrical distribution system via Circuit 751. However, with the "A" D/G in Manual voltage control, the "A" D/G voltage output was reduced by the electrical loads on N2 34.5 KV bus, which resulted in a low voltage condition on busses 14 and 18. This voltage reduction resulted in actuation of undervoltage relays, which tripped the normal supply breakers to 480V busses 14 and 18. Tripping of the normal supply breakers to busses 14 and 18 isolated the "A" D/G and busses 14 and 18 from Circuit 751. The "A" D/G voltage (and the voltage on busses 14 and 18) recovered to above the undervoltage relay actuation setpoints. Coincident with the low voltage on bus 14, low voltage occurred on the "B" Instrument Bus. Low voltage on the "B" Instrument Bus existed for approximately four (4) seconds. I At approximately 1421 EST, with the reactor at approximately 98%

steady state reactor power and low voltage on the "B" Instrument Bus, the Control Room received numerous annunciator alarms. The Control Room operators immediately determined that a turbine runback had occurred. This runback was caused by one of four Overtemperature Delta Temperature (OT Delta T) channels and one of four Overpower Delta Temperature (OP Delta T) channels runback

'signals. This runback decreases turbine load when the relays drop out.

The Control Room operators responded to the annunciators, and immediately performed the appropriate actions of abnormal operating procedure AP-TURB.2, "Turbine Load Reduction". The operators observed that the normal supply breakers for busses 14 and 18 had opened, and that the "A" D/G was supplying power to busses 14 and

18. Load on the "A" D/G stabilized at approximately 500KW.

NRC FORH 366A (5 92)

l NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150.0104 (5-92) EXPIRES 5/3'1/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO LICENSEE EVENT REPORT (LER) THE INFORMATION AND RECORDS MANAGEMENT BRANCH TEXT CONTINUATION (MHBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001 AND TO THE PAPERWORK REDUCTION PROJECT (3140-0104), OFFICE OF MANAGEMENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION R.E. Ginna Nuclear Power Plant 05000244 5 OF 9 94 -- 005-- 00 TEXT (If more space is required, use additional copies of HRC Form 366A) (17)

At approximately 1422 EST, Energy Operations personnel telephoned the Ginna Control Room, and notified the Operations Shift Supervisor of the switching operations that had occurred at Station 204 and of the unexpected loss of power to Circuit 751. Circuit 751 had been isolated for approximately ninety (90) seconds. The Control Room operators stabilized the plant at approximately 93% reactor power after the runback signal cleared.

At approximately 1439 EST, the operators referred to emergency restoration procedure ER-ELEC.1, "Restoration of Offsite Power". At approximately 1444 EST, using this procedure, the Control Room operators closed the normal supply breakers to busses 14 and 18, restoring offsite power to busses 14 and'18. The "A" D/G was then shut down and returned to normal standby status.

Due to the reactor power decrease from the turbine runback, axial flux difference in the reactor core exceeded "penalty" limits of Technical Specification (TS) 3.10.2. The operators subsequently reduced reactor power to below 90~ to comply with the action requirements of TS 3.10.2 for limits on axial flux difference.

At approximately 1511 EST, a power increase back to 98'. reactor power was initiated, and the reactor was at approximately 98~ steady state reactor power at approximately 2210 EST on February 17, 1994 '

INOPERABLE STRUCTURES i COMPONENTS OR SYSTEMS THAT CONTRI BUTED TO THE EVENT:

None D. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None E. METHOD OF DISCOVERY:

This event was immediately apparent due to Main Control Board annunciator alarms and other indications in the Control Room.

NRC FORM 366A (5-92)

NRC FORM 366A U.S. NUCLEAR REGULATORY COHHISSION APPROVED BY OHB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESI'IMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REOUEST: 50.0 HRS.

FORWARD COMMENTS REGARDING BURDEN ESTIHATE TO LICENSEE EVENT REPORT (LER) THE IHFORHATION AHD RECORDS MANAGEMENT BRANCH TEXT CONTINUATION (MHBB 7714), U.ST NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0'104), OFFICE OF MANAGEMENT AND BUDGET WASHINGTOH DC 20503.

FACILITY NAHE (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEOUEHTIAL REVISION R.E. Ginna Nuclear Power Plant 05000244 6 OF 9 94 -- 005 00 TEXT (If more space is required, use edditionat copies of HRC Form 366A) (17)

F. OPERATOR ACTION:

The Control Room operators immediately performed the appropriate actions of AP-TURB.2 and verified that the "A" D/G was operating properly and that busses 14 and 18 were energized from the D/G. The operators restarted necessary equipment, including the "A" service water pump. The operators notified higher supervision and the NRC Resident Inspector.

Subsequently, the operators restored offsite power to busses 14 and

18. They transitioned to procedure 0-5.1, "Load Reductions," and reduced power below 90 ' due to axial flux difference in the reactor core. The operators terminated the test of the "A" D/G, and the. "A" D/G was shut down and returned to normal standby status per procedure T-27.4, "Diesel Generator Operation."

G. SAFETY SYSTEM RESPONSES:

Electrical loads on busses 14 and 18 deenergized as designed, due to an undervoltage condition on the busses. The operators manually restarted necessary loads, including the "A" service water pump, at approximately 1422 EST.

The "A" D/G continued to supply power to busses 14 and 18 until restoration of offsite power to busses 14 and 18. Offsite 34.5 KV Circuit 767 continued to supply power to safeguards busses 16 and 17 during the event.

CAUSE OF EVENT A. IMMEDIATE CAUSE:

The immediate cause of the turbine runback was receipt of turbine runback signals from one of four OT Delta T and OP Delta T channels.

B. INTERMEDIATE CAUSE:

The intermediate cause of receipt of turbine runback signals was low voltage on the "B" Instrument Bus, which caused the turbine runback relays associated with the "B" Instrument Bus to drop out. The low voltage on the "B" Instrument Bus was due to low voltage on MCC-1C, which supplies power to the "B" Instrument Bus. The low voltage on MCC-1C was due to low voltage on Bus 14, which supplies MCC-1C.

HRC FORH 366A (5-92)

NRC FORH 366A U.S. NUCLEAR REGULATORY COHHISSION APPROVED BY OHB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COHPLY lllTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

FORllARD COMMENI'S REGARDING BURDEN ESTIMATE TO L'ICENSEE EVENT REPORT (LER) THE INFORMATION AND RECORDS HANAGEMENT BRANCH TEXT CONTINUATION (HNBB 7714), U.S. NUCLEAR REGULATORY COHHISSION, IIASHINGTON, DC 20555-0001 AND TO THE PAPERllORK REDUCTION PROJECT (3140-0104), OFFICE OF HANAGEMENT AND BUDGET lJASHINGTON DC 20503.

FACILITY NAME (1) DOCKET NUHBER (2) LER NUHBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION R.E. Ginna Nuclear Power Plant 05000244 7 OF 9 94 -- 005-- 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

C. ROOT CAUSE:

The underlying cause of the low voltage on Bus 14 (and Bus 18) was loss of power to 34.5 KV Circuit 751, due to loss of power to g2 34.5 KV bus at Station 204. (This event is NUREG-1022 (C) Cause Code, External Cause.)

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 a report of, "Any event or condition that resulted in a manual or automatic actuation of any engineered safety feature (ESF), including the reactor protection system (RPS) " The turbine runback was an automatic actuation of the RPS, and

~

the manual start of the "A" service water pump was an actuation of an ESF.

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

~ All reactor control and protection systems performed as designed, thus limiting the overall effects of the turbine runback transient.

~ The "A" D/G operated as designed by supplying power to safeguards busses 14 and 18.

~ The Control Room operators expeditiously stabilized the plant after the transient.

~ Offsite power 34.5 KV Circuit 767 was still in operation supplying power to safeguards busses 16 and 17.

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

it can be concluded that the public's health and NRC FORH 366A (5-92)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OHB NO. 3150.0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATIOH COLLECTION REQUEST: 50.0 HRS.

FORWARD COMMENTS REGARDIHG BURDEN ESTIMATE TO LICENSEE EVENT REPORT (LER) THE INFORMATION AHD RECORDS MANAGEMENT BRANCH TEXT CONTINUATION (MHBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555.0001 AND TO THE PAPERWORK REDUCTION PROJECT (3140-0104), OFFICE OF MAHAGEMEHT AND BUDGET WASHINGTON DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

YEAR SEOUEHTIAL REVISION R.E. Ginna Nuclear Power Plant 05000244 94 00 8 OF 9 005 TEXT (If more space is required, use additional copies of HRC Form 366A) (17)

V. CORRECTIVE ACTION A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:

~ Offsite power 34.5 KV Circuit 751 was restored by automatic reclosure of transformer breaker 2T20452 at Station 204 '

The Ginna Control Room operators restored offsite power to safeguards busses 14 and 18 from 34.5 KV Circuit 751.

~ The "A" D/G was shut down and returned to normal standby status.

~ Reactor power was restored to approximately 98~ steady state reactor power after restoring axial flux difference to within operating limits.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

~ Energy Operations has reviewed the applicable offsite electrical distribution drawings and switching orders.

~ Energy Operations has made changes in the switching orders to minimize the probability of a loss of power to Circuit 751 '

Energy Operations has made changes to the notification procedures of the switching orders to ensure these activities are communicated to the Ginna Operations Shift Supervisor.

~ Procedures affecting Circuit 767 and/or Circuit 751 will be identified and revised, as necessary, to ensure appropriate activities are communicated to Energy Operations.

NRC FORM 366A (5-92)

NRC FORH 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150.0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COHPLY WITH THIS INFORMATION COLLECTIOH REQUEST: 50.0 HRS.

FORWARD COMMENTS REGARDIHG BURDEN ESTIHATE TO LICENSEE EVENT REPORT (LER) THE INFORMATION AHD RECORDS MAHAGEMEHT BRANCH TEXT CONTINUATION (HHBB 7714), U.S. NUCLEAR REGULATORY COHMISSION, WASHINGTOH, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF HANAGEHENT AHD BUDGET WASHINGTON DC 20503.

FACILITY NAHE (1) DOCKET NUHBER (2) LER NUHBER (6) PAGE (3)

YEAR SEQUENTIAL REVISION R.E. Ginna Nuclear Power Plant 05000244 9 OF 9 94 005 00 TEXT (If more space is required, use additional copies of HRC Form 366A) (17)

VI. ADDITIONAL INFORMATION A. FAILED COMPONENTS:

There were no failed components at Ginna Station.

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 Nuclear Power Plant could be identified.

However, LER 92-007 and LER 91-002 were similar events with different root causes.

C. SPECIAL COMMENTS:

None HRC FORH 366A (5-92)