ML17223B285

LER 91-006-00:on 910918,generator Output Breaker Closed Out of Phase,Resulting in Instantaneous Overcurrent Condition on Control Element Drive Mechanism Bus.Caused by Personnel Error.Individuals counseled.W/911015 Ltr

ML17223B285
Person / Time
Site:	Saint Lucie
Issue date:	10/15/1991
From:	Sager D, Snyder M FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-91-272, LER-91-006-01, LER-91-6-1, NUDOCS 9110250031
Download: ML17223B285 (6)

Text

ACCELERATED DIS BUTION DEMONSTRATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR: 9110250031 DOC. DATE: 91/10/15 NOTARIZED: NO DOCKET FACIL:50-335 St. Lucie Plant, Unit 1, Florida Power & Light Co. 05000335 AUTH. NAME AUTHOR AFFILIATION SNYDER,M.J. Florida Power & Light Co.

SAGER,D.A. Florida Power & Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 91-006-00:on 910918,generator output breaker closed out of phase, resulting in instantaneous overcurrent condition on control element drive mechanism bus.Caused by personnel error. Individuals counseled.W/911015 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ( ENCL 1 SIZE:

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

NOTES' RECIPIENT COPIES RECIPIENT COPIES D ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-2 LA 1 1 PD2-2 PD 1 1 NORRIS,J 1 1 D INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB 7E NRR/DLPQ/LPEB10 NRR/DREP/PRPB11 1

1 2

1 1

2 NRR/DLPQ/LHFB10 NRR/DOEA/OEAB NRR/DST/SELB 8D 1,

1 1

1 1

1 NRR/DST/SICBBH3 1 1 QEGF/R)BT7'S'B8 D1 1 1 NRR/DST/SRXB 8E 1 1 RX& F 02 1 1 RES/DSIR/EIB 1 1 GR2 FILE 01 1 1 EXTERNAL EG&G BRYCE i J ~ H 3 3 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POOREiW 1 1 NUDOCS FULL TXT 1 1 D

D D

NOTE TO ALL "RIDS" RECIPIENTS:

S.

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK ROOM P 1-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 33 ENCL 33

P.O. Box 128, Ft. Pierce, FL 34954-0128 OCT15 $ 91 L-91-272, 10 CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:

Re: St. Lucie Unit 1 Docket No. 50-335 Reportable Event: 91-06 Date of Event: September 18, 1991 Reactor Trip During CEA Motor-Generator Set Synchronization Due to Personnel Error The attached Licensee Event Report is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.

Should there be any questions on this information, please contact Use Very truly yours, Oi45 D. A ager Vice esident St. Lucie Plant DAS/JJB/kw Attachment cc: Stewart D. Ebneter, Regional Administrator, USNRC Region Senior Resident Inspector, USNRC, St. Lucie Plant II DAS/PSL 4536-91 9il025003l 9il0i5 PDR ADOCK 05000335 PDR an FPL Group company

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, FACILITYNAME (1) DOCKET NUMBER (2) PAGF- 3 St. Lucie Unit 1 050003351 0 4

( ) REACTOR TRIP DURING CONTROL ROD DRIVE MOTOR-GENERATOR SET SYNCHRONIZATION DUE TO PERSONNEL ERROR EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED(8)

DAY YEAR YEAR S IAL MONtH DAY FACILITYNAMES DOCKET NUMBER(S)

N/A 5 0 9 1891 9 1 0 0 6 0 0 1 0 1 5 9 1 N/A 05 0 0 0 THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR:

OPERATING Check one or more of the followin (11)

MODE (9) 20.402(b) 20.405(c) X 50.73(a)(2)(iv) 73.71(b)

POWER 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)

LEVEL (10) 1 0 0 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vil) OTHER (Specify in Abstract 20.405(a)(1 )(iii) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) below and in Text 20.405(a)(1)(iv) 50.73(a)(2)(viii)(B) NRC Form 366A) 50.73(a)(2)(ii) 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LER 12 NAME TELEP ONE NUMBER AREA CODE Michael J. Snyder, Shift Technical Advisor 4 0 7 465.3550 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 13 MANUFAC- REPORTABLE MANUFAC- REPORTABLE CAUSE SYSTEM COMPONENT TURER TO NPRDS CAUSE SYSTEM COMPONENT TURER TO NPRDS X S B T R P A 4 8 5 I I I SUPPLEMENTAL REPORT EXPECTED 14 EXPFCTED MONTH DAY YEAR SUBMISSION YES (lfyes, complete EXPECTED SUBMISSION DATE) X NO DATE (15)

ABSTRACT (Limit to 1400 spaces. i e. approximately fifteen single-space typewritten lines) (16)

On 18 September, 1991, with Unit 1 in mode 1 at 100%, operators prepared to return the 1A Control Element Drive Mechanism (CEDM) Motor Generator (MG) set to service following maintenance on its flywheel bearing. At 1043, while a utility non-licensed operator was manually synchronizing the 1A MG set to the CEDM bus, the generator output breaker was closed out of phase with the running MG set. This resulted in an instantaneous overcurrent condition on the CEDM bus. The overcurrent condition opened 7 Trip Circuit Breakers (TCBs) and removed power to the CEDMs. AII Control Element Assemblies (CEAs) then fully inserted. The main turbine automatically tripped upon sensing an undervoltage condition on the CEDM bus and the 2 remaining TCBs opened. The operators then implemented Standard Post Trip Actions, and the normal Reactor Trip Recovery procedure.

The root cause for the out of phase synchronization of the MG set was that a non-licensed operator made a personnel error while attempting to manually synchronize the 1A MG set to the CEDM bus. The non-licensed operator closed the generator output breaker out of phase while he was in an incorrect section of the procedure.

Contributing factors to this event included: on the scene supervision of this load threatening activity was absent, a lack of specific technical knowledge by the operator, no pre-evolution brief between maintenance and operating personnel was held, and the procedure for MG set operation contained some human factor deficiencies.

Corrective actions were to: counsel the individuals involved on this event, emphasize the importance of on the scene supervision and pre-evolution briefings, provide additional training on MG set operation to non-licensed operators, revise the procedure for CEDM MG Set Operation, and verify the proper operation of the 1A MG set.

FPL Facsimile of NRC Form 366 (6-89)

F PL Faceimle ol .S. NUCLEAR REGULATORY COMMlSS ION FFFICFHO CAHIICA 01 1001 01 NRC Form X6 CIHTHTNcreele

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YEAR EQUENTIAL REVISIO St. Lucie Unit 1 NUMBER NUMBER 0 500 0335 9 1 0 0 6 0 0 0 2 0 4 TEXT (Ifmore spaceis regufred, use additional NRC Form 366A's) (17)

On 18 September, 1991, with Unit 1 in mode 1 at 100%, operators prepared to return the 1A Control Element Drive Mechanism (CEDM)(EIIS:AA) Motor Generator (MG)(EIISJA) set to service following maintenance on its flywheel bearing. At 1043, while a utility non-licensed operator was manually synchronizing the 1A MG set to the CEDM bus, the generator output breaker was closed out of phase with the running MG set, resulting in an instantaneous overcurrent condition on the CEDM bus. The high current condition opened 7 Trip Circuit Breakers (TCBs)(EIIS~) and removed power to the CEDMs. AII Control Element Assemblies (CEAs) then fully inserted. The main turbine automatically tripped upon sensing an undervoltage condition on the CEDM bus, generating a loss of load Reactor Protection System (EIIS:JC) signal, and the remaining 2 TCBs opened. The operators then implemented EOP-1, During the post trip recovery, water level in the 1A Steam Generator (SG)(EIIS:SG) was regained to normal level by using the 1A 15% Feedwater Regulating Valve(EIIS:JB). Auxiliary Feedwater Actuation System-2 (AFAS)(EIIS:BA) actuated due to the 1B SG water level reaching its initiation setpoint (19.5% narrow range). As a precaution, the Main Steam Isolation Valves were shut after a minor steam leak at a steam trap was noted post trip. The Atmospheric Dump Valves were used to remove decay heat. Normal SG levels were regained, AFAS was reset, two sets of Safety Function mode 3, Hot Standby.

The root cause of this event was a personnel error by a utility non-licensed operator while not adequately following an approved procedure. The cause for the out of phase synchronization of the MG set was that the non-licensed operator was using the wrong section of the procedure for placing a MG set in service. While attempting to manually synchronize the 1A MG set to the CEDM bus, the operator closed the generator output breaker out of phase.

A contributing factor to this event was that there was no operations supervisory oversight present at the 1A MG set during this evolution. Also, testing indicated a weakness among other non-licensed operators in the area of MG set theory. Another contributing factor was that a pre-evolution brief between maintenance and operations personnel on returning the 1A MG set to service was not

'.* " ' ' HNlRlhL Qg~rttigg, OP 1-0110020 Rev 9. For example, the title for section 8.2 "Single MG Line-up" did not indicate that this section is to be used when the unit is shutdown.

There were no unusual work location characteristics that directly contributed to the error.

FPL Facsimile of NRC Form 366 (6-89)

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YEAR EQUENTIAL REVISIO .

St. Lucie Unit 1 NUMBER NUMBER 0 500 0335 9 1 0 0 6 0 0 0 30 0 4 TEXT (Ifmore spaceis required, use additional NRC Form 366A's) (1 7)

This event is reportable under the requirements of 10CFR50.73.a.2.iv as an event that resulted in a manual or automatic actuation of any Engineered Safety Feature.

The plant response during this event was bounded by section 15.2.9 of the St. Lucie 1 FUSAR, "Loss of Offsite Power." The plant response was much more conservative than that described in the FUSAR for several reasons. 1) Offsite power was not lost to auxiliary equipment, only power to all CEDM holding coils was removed. 2) RCS temperatures did not go above normal operating temperatures because the Steam Bypass Control System operated post trip.

The health and safety of the public were not at risk at any time during this event.

1) Senior Plant and Operations management personally counseled the crew involved in the event on the failure of the team to perform to departmental expectations. These expectations were transmitted to the remaining operating crews through a departmental letter.

2) Operations management emphasized the importance of on the scene supervision for potentially load threatening activities. Procedures will be identified and changed to require a Senior Reactor Operator's presence during critical non-licensed operators (NLOs) activities.

3) Diagnostic testing validated a weakness among NLOs in the area of MG set theory. Additional training is now being given on that subject to NLOs.

4) Operations management emphasized the importance of pre-evolution briefings between maintenance and operations personnel before performing potentially load threatening activities.

5) The Operations department has revised OP to human factors considerations. The St. Lucie 1-0110020,,

2 equivalent procedure has been with respect similarly revised.

6) A Human Performance Enhancement Study review was performed on this event and validates the conclusions of this LER.

7) The 1A MG set generator, voltage regulator, synchronization circuitry, and output breaker were verified to be functioning properly. The 1A MG set was then returned to service.

8) FPL Engineering has been directed to prepare a design change for the installation of a MG set synchronization check circuit for an additional level of unit reliability and protection.

I FPL Facsimile of NRC Form 366 (6-89)

FPL FacCIITTID or NRC Form 366 (6.89I LICENSEE EVENT REPORT (LER)

TEXT CONTINUATlON

.S. NUCLEAR REGULATORY COMMISSION CDCNATTO 100YXN TTII ~ 00ICIITO CADI I00 $ 1 $ 0010I f

EXPIRES: AODTT TO DODTY TIITHTI00 00CYYAATON CCAACCTION IYY100T:NIT ITIC CHNAIICCAANNT0 IOAAOHeAT IAAYXN CDTDAATE TO TIO ICCOIYT0 NO IC0CTITD MNACCANNTWINCH f04000 IAL IANACNIIKTAAATCIIYCI0000NCK TYANANOICN,DC 000$ A AIOTo TIO

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YEAR EQUENTIAL REVISIO St. Lucie Unit 1 NUMBER NUMBER 0 500 0335 9 1 0 0 6 0 0 0 4 0 0 4 TEXT (lfmore space is required, use additional NRC Form 366A's) (17)

No. 216 Steam Trap Armstrong Machine Works LER 335-84-003, describes a reactor trip during a startup following refueling when an operations trainee improperly paralleled the 1B MG set to the CEDM bus.

FPL Facsimile of NRC Form 366 (6-89)