ML17306A335
| ML17306A335 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 12/13/1991 |
| From: | Bradish T, James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 192-00763-JML-T, 192-763-JML-T, LER-91-010-01, LER-91-10-1, NUDOCS 9112230253 | |
| Download: ML17306A335 (28) | |
Text
ACCELERATED D ATTRIBUTION DEMONS RATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION,NBR.9112230253 DOC DATE. 91/12/13 NOTARIZED. NO DOCKET g FACIL:STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 05000530 AUTH. NAME , AUTHOR AFFILIATION BRADISH,T.R. Arizona Public. Service Co. (formerly Arizona Nuclear Power LEVINE,J.M. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION R'
SUBJECT:
LER 91-010-00:on 911115,mobile crane came in contact w/
energized 13.8 kV power line, resulting in deenergization of offszte power. Caused by personnel error. Crane operating D engineer site access revoked.W/911213 ltr.
DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR 1 ENCL ! SIZE:
TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.
NOTES:Standardized plant. 05000530 A RECIPIENT D COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD D 1 1 TRAMMELL,C 1 1 THOMPSON,M 1 1 INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DS P 2 2 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB8H3 1 1 NRR S~N LB8Dl 1 1 NRR/DST/SRXB 8E 1 1 LE 02 1 1 RES/DSIR/EIB 1 1 RGN5 Fl LE 01 1 1 EXTERNAL: EGGG BRYCE,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 NOTES: .1 1 D
D NOTE TO ALL "RIDS" RECIPIENTS:
D PLEASE HELP US TO REDUCE O'ASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOihI 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 35 ENCL 35
Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P.O. BOX 52034 ~ PHOENIX, ARIZONA85072-2034 JAMES M, LEVINE 192-00763-JML/TRB/KR VICE PRESIDENT NUCLEAR PRODUCTION December 13, 1991 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Mail Station Pl-37 Washington, D.C. 20555
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Unit 3 Docket No. STN 50-530 (License No. NPF-74)
Licensee Event Report 91-010-00 File: 91-020-404 Attached please find Licensee Event Report (LER) 91-010-00 prepared and submitted pursuant to 10CFR50.73. In accordance with 10CFR50.73(d), a copy of this LER is being forwarded to the Regional Administrator, NRC Region V.
If you have any questions, please contact Thomas R. Bradish, Compliance Manager, at (602) 393-2521.
Very truly yours, JML/TRB/KR Attachment cc: W. F. Conway (all with attachment)
J. B. Martin D. H. Coe INPO Records Center
?ii2230253 I- DR Pii2ig ADOCK 05OI.ICI530 8 F'DR
NRC Form 345 U.S. NUCLEAR REOULATORY COMMISSION (0-53 I APPROVED,OMB NO, 31504101 EXPIRES! 5/31/SS LICENSEE EVENT REPORT ILER)
DOCKET NUMBER (2l PA E FACILITY NAME (11 Palo Verde Unit 3, 0 5 0 0 0 () 3 0 1 OF]
TITLE (4)
ESF Actuations Caused by Manual Deenergization of Offsite Power EVEN1'ATE IS) LER NUMBER (5) REPORT DATE (71 OTHER FACILITIES INVOLVED (Sl MONTH DAY YEAR YEAR <X~yr. SEQUSNTrAL Vrrr'C rrsvrsroN MONTH DAY YEAR FACILITYrrAMES DOCKET NUMBER(SI
<r r NUMBER. y. 3 NUMBER N/A 0 5 0 0 0 1 5 9 1 010 0 0 1 2 1 3 9 1 THIS REPORT IS SUBMITTED PURSUANT T0 THE REOUIREMENTS OF 10 cF R (I! ICneck one or more
'N/A of the follorvinf/ (ll 0 5 0 0 0 OPERATINO MODE (0) 20.402(Ii) 20.405(cl 50.73( ~ l(2l(iv) 73.71(tr)
POWER 20A05 (e) (I)(i) 60.35(cHI) 60.73(e)(2Hvl 73.7 1(c)
LEVEL P Q Q 20.405(eH(HEI 50.35(c)('2) 50.73(eH2HYS) OTHER (Specify In A(re!rect Oeloyr end ln Tent, HIIC Fohn 20.405( ~ ) (I l(iii) 50.73(e) (2)(il 50,73(e)12Hviii) (A) 3ESA/
20A05(eH1 Hivl 50.7 3(e) (2) IS) 50 73( ~ ) (2) (vLS) (5) 20.405( ~ l(1 l(v) 60.73(el (2) (Iii) 50.73(e) (2)(cl LICENSEE CONTACT FOR THIS LER (12)
NAME TELEPHONE NUMBER AREA CODE Thomas R. Bradish, Compliance Manager COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13) 602393-2521 CAUSE SYSTEM COMPONENT MANVFAC.
TURER CAUSE SYSTEM COMI'ONENT MANUFAC TURER EPORTABLE TO NPRDS
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SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED SUBMISSION DA E (15)
YES Ill yeL complete EXPECTED Sr/Bkr/SSIOII DA TEI NO 9 ABSTRACT ILimlr to f400 rpecet, I e., epproelmetely filreen rlnole rpece rypervritten linn/ (15) 2'n November 15, 1991, at approximately 0913 MST, Palo Verde Unit 3 was in Mode 3 (HOT STANDBY) when Control Room personnel, responding to a report that a mobile crane was in contact with an energized 13.8 kV overhead power line, secured power to the'rain B 13.8 kV non-Class lE intermediate switchgear bus (NAN-S06). This resulted in the expected loss of power to the Train B Class 1E 4.16 kV bus, and a Loss of Power (LOP) Engineered S'afety Feature Actuation System (ESFAS) actuation. The Train B Emergency Diesel Generator (EDG) started and loaded per design. At approximately 0914 MST, the Control Room was notified that the line the crane was in contact wi.th was still energized and that the Train A 13.8 kV non-Class 1E intermediate switchgear bus (NAN-S05) needed to be deenergized. Control Room personnel proceeded to reenergize the NAN-S06 bus prior to deenergizing the NAN.-S05 bus. At approximately 0922 MST, Control Room personnel deenergized the NAN-S05 bus which resulted in the expected loss of power to the Train A Class 1E 4.16 kV bus and a Train A LOP ESFAS actuation. The Train A EDG started and loaded per design. All equipment functioned as designed. No other safety system responses occurred and none were required.
Based on investigation results, the cause of the crane coming in contact with an energized 13.8 kV power line was determined to be personnel error.
There have been no previous similar events reported pursuant to 10CFR50.73.
NRC Form 345 (94)3)
t LICENSEE EVENT REPORT {LER) TEXT CONTINUATION .
FACII.IEY IIAME IIOCKET IIUMEEII LEII IIIIMEEII ~ ACE U 5 N 5 I *5 YEAA,re 5 5 C"IUM05 A 5 V l 5 lO ll A NUll~ FA Pa1o Verde Unit 3 0 5 0 0 0 g 3 0 9 1 0 00002 OF 1 1 2 DESCRIPTION OF WHAT OCCURRED A. Initial Conditions:
At 0913 MST on November 15, 1991, Palo Verde Unit 3 was in Mode 3 (HOT STANDBY) at normal operating temperature and pressure following an automatic reactor (AC)(RCT) trip which occurred on November 14, 1991 (LER 530/91-008).
B. Reportable Event Description (Including Dates and Approximate Times of Major Occurrences):
Event Classification: An event or condition that resulted in an automatic actuation of an Engineered Safety Feature (ESF)
(JE) .
At approximately 0913 MST on November 15, 1991, Unit 3 Control Room personnel (utility, licensed), responding to a report that a mobile crane was in contact with an energized 13.8 kV overhead power line,'secured power to the Train B 13 ' kV non-Class 1E intermediate switchgear bus (NAN-S06) (BU)(EA). This resulted in the expected loss of power to the Train B Class 1E 4.16 kV bus (PBB-S04) (BU)(EB) and a Loss of Power (LOP) Engineered Safety Feature Actuation System (ESFAS)(JE) actuation. The Train B Emergency Diesel Generator (EDG) (FG) started and loaded per design.
At approximately 0914 MST, Control Room person'nel were notified that the line, which the crane was in contact with, was still energized and that the Train A 13.8 kV non-Class 1E intermediate switchgear bus (NAN-S05) (BU)(EA) needed to be deenergized.
Control Room personnel proceeded to reenergize the NAN-S06 bus prior to deenergizing the NAN-S05 bus, thereby maintaining the availability of offsite power. At approximately 0922 MST, Control Room personnel deenergized the NAN-S05 bus which resulted in the expected loss of power to the Train A Class lE 4.16 kV bus (PBA-S03) (BU)(EB) and a Train A LOP ESFAS actuation. The Train A EDG started and loaded per design. All equipment functioned as designed. No other safety system responses occurred and none were required.
Prior to the event, on the morning of November 15, 1991, work was in progress to perform evaluations and maintenance on the Phase A Main Transformer (XFMR)(EL) following a lightning induced electrical fault and automatic reactor trip which occurred on November 14, 1991 (LER 530/91-008). A 35 0on mobile crane was 99419-OSUA RCV. 9-89
LICENSEE EVENT REPORT ILERI TEXT CONTINUATION FACILITY NAME POCKET NVMEEII L'Ell NVMEEII I'ACE YE*A +Ca.': SSPVSNTIAI r'gy 1SytSIOH HVVS ~ A F'u uuuSSA P
Palo Verde Un.it 3 0 5 0 0 0 5 3 0 91 01 0 0 0 0 3 OF required to allow maintenance personnel to perform pre-installation checks on the replacement bushing for the
-transformer. At approximately 0710 MST, Control Room personnel had been contacted by a senior mechanic (utility, nonlicensed) to obtain the status of the overhead power lines in the area of the transformer. The Assistant Shift Supervisor (utility, licensed) cautioned the senior mechanic about the energized 13.8 kV overhead power lines and the impact on the plant if contact was made by the crane with the energized lines (e.g., tripping of reactor coolant pumps). The crane operating engineer (contractor, non-licensed),
cognizant of the energized overhead power lines, drove the crane into the area near the transformer and positioned the replacement bushing laydown area. The crane's front it in front of outriggers were extended to stabilize the crane. With the help of a second crane operating engineer as a signalman (contractor, nonlicensed), the crane operating engineer lifted the replacement bushing from the shipping container for doble testing and subsequently lowered the bushing back into the shipping container.
The signalman removed the rigging slings from the bushing. The crane operating engineer. exited the crane cab to inquire about additional crane support that may be required at that time.
Prior to exiting the crane, the operating engineer raised the crane hook and turned off the engine. The crane operating engineer knew that he should set the friction brake before leaving the cab, and he believed that he had set the brake. The crane boom was approximately 23 feet from the nearest energized overhead power line. After the crane operating engineer exited the cab, the boom rotated toward the energized overhead power lines, brushed the middle line, and came to a final resting position against the outside energized 13.8 kV overhead power line. This resulted in the arcing of the crane outrigger pads to ground and the burning of the asphalt area immediately in contact with the pads. At the time, a light breeze (i.e., approximately 12 miles per hour) was blowing out of the south in generally the same direction that the boom moved. At approximately 0910 MST, the
'site Fire Department was notified of the fire inside the protected area.
A single phase-to-ground fault of approximately 140 amps resulted when the crane came in contact with the 13.8 kV overhead power line. The fault was insufficient to trip the NAN-S05 feeder breaker (BKR) or to cause control board electrical system alaim (ALM)(IB) indications in the Control Room (NA). APS engineering determined that the circuit breaker (52) supplying the 13.8 kV overhead power line (NAN-S05) would have tripped when the crane came in contact with the line, if the crane had been properly PV419-OSUA RCY. 9-89
II 1
LICENSEE EVENT REPORT fLERI TEXT CONTINUATION FACILITY NAME POCKET NUMOEII LEK NUMEEII ~ ACE YEAA g( 5 5 QU 5 N 5 I A L NUQ55A AIVNKIN UUUOIA Pa1o Verde Unit 3 0 5 0 0 0 5 3,0 9 10 0 0004 OF 1 1 2 grounded in accordance with PVNGS procedures and the PVNGS Accident Prevention Manual, At approximately 0913 MST on November 15, 1991, the Control Room Shift Supervisor (utility, licensed) was notified by an electrical foreman (utility, nonlicensed) via telephone that the crane had come in contact with an energized 13 ' kV overhead power line; that a fire was in progress, and that the line required deenergization. No control board electrical system alarm indications related to this event were received in the Control Room. The electrical foreman identified the. line that required deenergization as NAN-S06 to NAN-S04 (i.e., Train B 13.8 kV switchgear bus). Because of his concern for personnel safety, the Shift Supervisor questioned the electrical foreman on the geographical location of the line to be deenergized rather than sending an operator to verify the information. The Shift Supervisor was confident that the electrical foreman was cognizant of the correct 13.8 kV line to be deenergized. The electrical foreman stated that he realized at the end of the telephone conversation that he had identified the wrong line to deenergize and corrected his mistake, but apparently the correction was not heard by the Shift Supervisor.
At approximately 0913 MST, Control Room'personnel deenergized the overhead power line by securing power to the NAN-S06 bus which resulted in the expected loss of offsite power to the Train B 4 kV Class lE bus and a Train B LOP ESFAS actuation. 'The ESF, signal
'6 automatically load shed .the Class 1E bus and started the Train B Emergency Diesel Generator (EDG). The Train B EDG started and assumed the loads as designed. In addition, securing the power to .
the NAN-S06 bus resulted in the deenergization of the Train B switchgear bus (NAN-S02) which supplies power to Train B reactor coolant pumps (AB)(P) (RCPs 1B and 2B), two (2) circulating water pumps (NN)(P) (CWPs), and non-essential load centers. The Control Room entered Technical Specification Limiting Condition for Operation (TS LCO) 3.8.1.1 ACTION a (i.e., one offsite circuit inoperable) and TS LCO 3.4.1.2 ACTION a (i.e., one reactor coolant loop in operation).
Subsequently, at approximately 0914 MST, the Control Room was notified'hat the 13.8 kV overhead power line in contact with the crane was still energized (i.e., arcing of the crane outrigger pads to ground was still in progress) and that the immediate personnel safety concerns were reduced because all personnel were clear of the crane. At this time, Control Room personnel determined that the crane was actually in contact with the Train A 13.8 kV overhead power line supplied by the NAN-S05 bus. Contr'ol 4
PV419.0SVA RCY. 9-89
LICENSEE EVENT REPORT ILER) TEXT CONTINUATION.
FACILITY NAME DOCKE't NUMIEII LEII IIUMIEII AACE YEAN CQ SSOVSNSIAI NUMSSA yS s'V ASVISION NMMSS 1 Palo Verde Unit 3 o 5 o o o 5 3 0 9 1 0 0 0 0 0 5o"1 1 2 Room personnel proceeded to reenergize the NAN-S06 .bus prior to deenergizing the NAN-S05 bus, thereby maintaining the availability of offsite power; At approximately 0915 MST, the Fire Department response team (i.e., personnel, fire engine, and command vehicle) arrived at the scene of the fire.'t approximately 0922 MST, Control Room personnel deenergized the NAN-S05 bus which resulted in the expected loss of offsite power to the Train A 4.16 kV Class 1E bus and a Train A LOP ESFAS actuation. The ESF signal automatically load shed the Class 1E bus and started the Train A EDG. The Train A EDG started and assumed the loads as designed. In addition, securing the power to the NAN-S05 bus resulted in the deenergization of the Train A switchgear bus (NAN-S01) which supplies power to Train A reactor coolant pumps (RCPs 1A and 2A), two (2) circulating water pumps (CWPs), and non-essential load centers. The Control Room entered TS LCO 3.8.1.1 ACTION d (i.e., two offsite A.C. circuits inoperable) and TS LCO 3.4.1.2 ACTION b (i.e., no reactor coolant loop in operation). Control Room personnel verified that heat removal was maintained via natural circulation in the reactor coolant system (AB) (RCS).
At approximately 0928 MST, the Shift Supervisor received information from the Fire Department Incident Commander that the fire was out and that there were no apparent injuries. PVNGS Emergency Plan Implementing Procedures require the declaration of a Notification of Unusual Event (NUE) for a fire in the protected area lasting longer than 10 minutes. At approximately 0928 MST, the Shift Supervisor declared a Notification of Unusual Event.
Subsequent to the deenergization of the 13.8 kV overhead power line (NAN-S05)', the crane operating engineer reentered the cab and positioned the right rear outrigger against the ground in order to stabilize the crane.
At approximately 0945 MST, TS LCO 3.4.3.1 ACTION b was entered when the maximum steady-state water level in the pressurizer, (PZR)(AB) exceeded 56 percent. This occurred due to a delay in restoring letdown (CB) with charging and seal injection in service. Initial attempts to open the letdown isolation valve (CB)(ISV) were not successful. Since nuclear cooling water (NCW)
(CC) flow is required to enable the opening of the letdown isolation valve,'the letdown isolation valve is interlocked with the NCW flow switch (FS)(CC) ~ However, following the deenergization of the 13.8 kV busses, power had not been restored to the NCW flow switch. Power is required to activate the NCW flow switch'hich in turn will allow the opening of the letdown PV419-OSUA Rev. 9-89
LICENSEE EVENT REPORT ILER) TEXT CONTINUATION 5ACII,ll'Y NAME OOCKEZ NUMIKII LEII NIIMItll ~ AOK y5*A d5~'5QU5NT>AI.
v 5 NUIT~ 51 l
'CV~5ION I NUM051 Palo Verde Unit 3 o 5 o o o 5 3 0 91 010 00 0 6 OF isolation valve. The reactor operator (utility, licensed) observed proper NCW flow on a control board NCW flow indicator (FI)(CC) in the Control Room and determined that the letdown isolation valve could be opened. However, the operator did not recognize that the NCW flow switch was deenergized. Subsequent investigation by Control Room personnel revealed that power to the NCW flow switch had been secured when the 13.8 kV busses had been deenergized.
At approximately 0950 MST, forced circulation was restored to the RCS when reactor coolant pump 2B was restarted. The Control Room entered TS LCO 3.4.1.2 'ACTION a (i.e., one reactor coolant loop in operation) ~ At approximately 1002 MST on November 15, 1991, the NUE was terminated in accordance with EPIP-03 when the Control Room Supervisor (utility, licensed) determined that the incident involving the crane was under control.
At approximately 1050 MST, RCP 1B failed to start from the Control Room. An auxiliary operator (AO) was dispatched to investigate the problem with RCP 1B. During the AO's investigation of RCP 1B, the AO heard a relay chattering or a clicking noise in the cubicle adjacent to the breaker for RCP 2B and placed his hand on the RCP 2B breaker switch. At approximately 1057 MST, the AO inadvertently tripped RCP 2B when he accidently turned RCP 2B's local breaker control switch in the open direction while simultaneously inspecting the RCP 1B cubicle breaker. The Control Room reentered TS LCO 3.4.1.2 ACTION b (i.e., no reactor coolant loop in operation). At approximately 1103 MST, RCP 2B was successfully restarted, restoring forced circulation. The Control Room entered TS LCO 3.4.1.2 ACTION a (i.e., one reactor coolant loop in operation).
The Shift Supervisor determined that the unsuccessful attempt to start RCP 1B was due to a preexisting problem with the oil lift pump switch. RCP start circuitry is interlocked with the oil flow switch contact. The oil flow switch contact remained open disabling the RCP starting interlock. At approximately 1106 MST, RCP 1B was started but tripped on a low speed signal fourteen (14) seconds later. In addition, an RCP reverse rot'ation alarm was observed in the Control Room. In accordance with an approved procedure, local verification 'is required to ensure that the RCP is not rotating in reverse. A reactor operator (utility, licensed) made a containment entry and verified that RCP 1B was not rotating backwards. Subsequent investigation by Control Room personnel revealed that RCP 1B tripped because power to the speed probe circuit had been secured when the 13.8 kV busses had been deenergized.
IV419.0SUA Rcv. 9-89 P
I 11
LICENSEE EVENT REPORT ILERI TEXT CONTINUATION FACILITY NAME OOCIIKT NVMSEFI LCII HVM84II ~ AOK Y SAIS SSOMSlt TIAL ~~'I DIVISION HUTS ~ % V NUMSSA Palo Verde Unit 3 osooo5309.1 0 1 0 0 0 07o"12 At approximately 1118 MST, pressurizer level was restored to less than 56 percent following the restoration of power to the NCW flow switch and the subsequent opening of the letdown isolation valve.
The highest pressurizer level reached before letdown flow was restored was 68 percent. The Control Room exited TS LCO 3.4.3.1 ACTION b.
At approximately 1309 MST, the loads on the Train B Class 1E bus were transferred to the Train B offsite power supply, and the Train B EDG output breaker was opened, exiting TS LCO 3.8.1:l.
ACTION d (i.e., two offsite A.C. circuits inoperable) ~
At approximately 1436 MST, once the power to the RCP 1B speed probe circuit was restored, RCP 1B was successfully restarted.
Both reactor coolant loops were operable and TS LCO 3.4.1.2 ACTION
- a. was exited.
Following the completion of the maintenance of the Phase A Main Transformer, at approximately 0900 MST on November 17, 1991, Control Room personnel reenergized the NAN-S05 bus, restoring offsite power to Train A 4.16 kV Class lE bus and Train A 13.8 kV switchgear bus (NAN-S01). At approximately 0916 MST on November 17, 1991, the loads on the Train A Class lE bus were transferred to the Train A offsite power supply, and the Train A EDG output breaker was opened, exiting TS LCO 3.8.1.1 ACTION a (ice., one offsite circuit inoperable).
Status of structures, systems, or components that were inoperable at the start of the event that contributed to the event:
Not applicable - no structures, systems, or components were inoperable at the start of the event which contributed to this event.
D. Cause of each component or system failure, if known:
Not applicable - no component or system failures were involved.
Failure mode, mechanism, and effect of each failed component, if known:
Not applicable, - no component failures were involved.
PV419-OSUA ROY. 9-89
LtCENSEE EVENT REPORT {LER) TEXT CONTINUATlON FACII.ICY IIAMC OOCKCT IIUMCCII CCII IIIIMCCII ~ ACC TCAA SCOVSIITI*l. 15TISIOII
~~i@
~ IVII~ 5 A >r<r'ruII ~ SA Palo Verde. Unit 3 osooo53091 0 1 0 0 0 0 8 OF For failures of components with multiple functions, list of systems or secondary functions that were also affected:
Not applicable - no failures of components with multiple functions were involved.
G. For a failure that rendered a train of a safety system inoperable, estimated time elapsed, from the discovery of the failure until the train was returned to service:
Not applicable - no failures that rendered a train of a safety system inoperable were involved.
H. Method of discovery of each component or system failure or procedural error:
There have been no component or system failures identified. The procedural errors which contributed to this event are discussed in Section I.I.
Cause of Event:
An independent investigation into this event was conducted in accordance with the APS Incident Investigation Program. The cause of the first LOP ESFAS actuation was determined to be the manual deenergization of the Train B 13.8 kV non-Class 1E intermediate switchgear bus (NAN-S06) by Control Room personnel responding to a call from an electrical foreman that a mobile crane was in contact with an energized 13.8 kV overhead power line. This resulted in the expected loss of power to the Train B Class 1E 4.16 kV bus.
No control board electrical system alarm indications related to this event were received in the Control Room. The electrical foreman identified the line that required deenergization as NAN-S06 to NAN-S04 (i.e., Train B 13.8 kV switchgear bus). Because of his concern for personnel safety, the Shift Supervisor questioned the electrical foreman on the geographical location of the line to be deenergized rather than sending an operator to verify the information. The Shift Supervisor was confident that the electrical foreman was cognizant of the correct 13.8 kV line to be deenergized. The electrical foreman stated that he realized at the end of the telephone conversation that he had identified the wrong line to deenergize and corrected his mistake, but apparently the correction was not heard by the Shift Supervisor.
The second LOP ESFAS actuation was determined to be the manual deenergization of the Train A 13.8 kV non-Class 1E intermediate switchgear bus (NAN-S05) by Control Room personnel responding to a PVC19.0SUA Rcv. 9-89
n LICENSEE EVENT REPORT ILERI TEXT CONTINUATION FACILITY HAMf f POCK T IIUMff II LfllIIIIMffll FAOf yfAA gQ.TTQUCIITIAL HUUFTA
'Tg AfVISIOII IIUUFF A Palo Verde Unit 3 osooo530 91 01 0 00 0 9 OF 1 2 report that the line the crane was in contact with was still energized.
A single phase-to-ground fault of approximately 140 amps resulted when the crane came in contact with the 13,8 kV overhead power line. The fault was insufficient to trip the NAN-S05 feeder breaker or to cause control board 'electrical system alarm indications in the Control Room. APS engineering determined that the circuit breaker supplying the 13.8 kV overhead power line (NAN-S05) would have'ripped when t'e crane came in contact with the line, if the crane had been properly grounded in accordance with PVNGS procedures and the PVNGS Accident Prevention Manual.
On November 18, 1991, the crane was configured in its as-found condition to determine the cause of the boom swinging into the energized overhead power line. The simulation could not duplicate the event with the friction brake engaged. Disassembly and inspection of the friction brake on November 20, 1991, indicated that the brake was in good mechanical condition and functioned
.properly. Based on the results of the investigation, the cause of the crane coming in contact with the energized 13.8 kV overhead power line was dete'rmined to be due to personnel error by the crane operating engineer who used poor work practices during the operation of the crane (i.e., crane was not grounded, crane was not level, friction brake was not set, and crane was left unattended) (SALP Cause Code A: Personnel Error).
The investigation also concluded that other actions involving the use of the 35 ton mobile crane contributed to the crane coming in contact with the energized 13.8 kV overhead power line:
the work order did not identify t'e need for crane usage to perform the doble testing or to install the bushing, the guidance for the control of mobile crane operations is provided in multiple procedures and documents (i.e.,
Accident Prevention Manual and Engineering Evaluations).
Site standards for crane operation (i.e., use of boom, use of outriggers, getting out of cab with boom extended) do not exist,-
the pre-job briefing was inadequate in that the various work groups did not have a clear understanding of the job scope, nor were the various group activities coordinated, the crane operating engineer did not receive a formal pre-job briefing as to the scope of the crane support necessary PV419-OSUA Rey. 9-89
LICENSEE EVENT'EPORT,(LER) TEXT CONTINUATION FACILISY HAMS OOCKKT HUMISII Ltll HUMICII IIAOK TSAA I SHTIAL SOU ASVISlOH HVL4~ I A HUMSS A Pa1o Verde Unit 3 osooo53091 0 1 0 0 0 1 0 oF'-1 2 to perform the work (i.e, doble testing and not installation of the bushing),
the crane operating engineer was certified as a crane operator in accordance with the APS crane operator qualification procedure, however there is no requirement for refresher or continuing training for crane operating engineers, and weaknesses were identified pertaining to supervisory involvement during the crane operation., A senior electrician acting in a supervisory capacity was not at the job site at the time of the event.
The cause of the inadvertent. tripping of RCP 2B was due to personnel error when the auxiliary operator (AO) accidently turned RCP 2B's local breaker control switch in the open direction: The AO did not remove his hand from the RCP 2B breaker switch aEter checking Eor chattering as he leaned over to check the adjacent RCP 1B breaker cubicle indications.
The cause of the unsuccessful attempt to start RCP 1B was that the operator was not cognizant oE a preexisting problem with the oil lift pump switch. The cause of the operator not being cognizant of the previously identified problem with the starting interlock for RCP 1B lift oil pump flow was due to the unavailability of procedural guidance that documented the special process required to start the pump.
The cause of RCP 1B tripping on a low speed signal was due to the power not being available to the speed probe circuit prior to attempting to start RCP 1B. Once the power was restored to the speed probe circuit, RCP 1B was successfully restarted. However, the operators did not, veriEy that power to the speed probe circuit was available as required by procedure (Reactor Coolant Pump Operation) prior to attempting to start the RCP.
The cause of pressurizer level exceeding 56 percent was due to the delay in the restoration. of letdown flow with charging"and seal injection in service. Since nuclear cooling water (NCW) flow is required'o enable the opening of the letdown isolation valve, the letdown isolation valve is interlocked with the NCW flow switch.
However, following the deenergization of the 13.8 kV busses, not been restored to the NCW flow switch. Power is required power'ad to activate the NCW Elow switch which in 'turn 'will allow the opening of the letdown isolation valve. The reactor operator observed proper NCW flow on a control board NCW flow indicator in PV419 OSVA Rcv. 9.89
LICENSEE EVENT REPORT {LER) TEXT CONTINUATION FACILITY NAME POCKET NUMEEII AMMED LEII NIIMEEII ~ APE T EI II 8I,"gv SEQUENT>AL SA AS VISION MlJM ~ S A Palo Verde Unit 3 osooo530 9 1 0 1 0 00.1 1 OF 1 2 the Control Room and determined that the letdown isolation valve could be opened. However, the operator did not .recognize that flow switch was deenergized. At t'e time of the event, the the'CW operators were in an abnormal operating procedure for loss of letdown flow, which did not offer the appropriate guidance to assist the operators in restoring letdown flow in a timely manner (i.e., requirement for power to the NCW flow switch)..
Safety System Response:
Following the loss of power to Trains A and B Class 1E 4.16 kV busses, the Trains A and B Emergency Diesel Generators started and energized the Trains A and B ESF busses within the Technical Specification time requirement. The load sequencer initiated a Load Shed signal and subsequently resequenced the following safety systems on the respective busses as required by design:
Control Room Essential Ventilation (VI), Trains A and B, Diesel Generator Essential Ventilation (VJ), Trains A and B, Essential Battery Chargers and Voltage Regulators reenergized (BYC)(EI),
Containment Normal Air Handling Units restarted (AHU)(NH),
Control Element Drive Mechanism Normal Air Handling Units restarted (AHU)(AA)
Auxiliary Feedwater Pump (P)(BA), Train B (on Train B LOP),
Essential Cooling Water Pumps (P)(BI), Trains A and B, Essential Spray Pond Pumps (P)(BI), Trains A and B, and Essential Chillers (CHU)(KM), Trains A and B, K. -
Failed Component Information:
Not applicable - no component failures were involved.
II. ASSESSMENT OF THE SAFETY CONSEQUENCES AND IMPLICATIONS OF THIS EVENT:
Both trains of the Emergency Diesel Generators started properly and assumed the loads on both trains of the Class lE 4.16 kV busses. All components operated as designed with no abnormalities. An assessment was performed in accordance with the APS Incident Investigation Program and it was determined that no safety limits were violated and that the event (i.e., loss of offsite power causing loss of forced circulation) is bounded by previous'nalyses contained in the Updated Final Safety Analysis Report Chapters 6 and 15.
The event did not result in any challenges to fission product barriers or result in any'releases of radioactive materials. Other than the PV419 OSUA RCY. 9-89
1 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME OOCIIET IIUMEEII LEII IIUMEEII ~ ACE
,YEAII jYg ! EQUEHTIAL g'p A(VISION aVMI(A :. F euuOTA Pa1o Verde Unit 3 osooo53091 0 1 0 0 0 1 2oi1 2 personnel safety concerns, there were no safety consequences or implications as a result of this event. This event did not adversely affect the health and safety of the public.
III. CORRECTIVE ACTION:
A. Immediate:
'er plant management directive, all crane usage at Palo Verde stopped until appropriate crane operation guidance was established.
An action plan was developed, approved, and implemented to remove the mobile crane from the bushing laydown area to a quarantined location where a root cause investigation'could be'afely performed.
An inspection of the 13.8 kV overhead power lings was performed and "it was determined that the lines sustained minimal damage that would not affect reenergization or structural integrity of the lines.
B. Action to Prevent Recurrence:
APS revoked the crane operating engineer's site access'n investigation team was formed and an investigation was initiated in accordance with the APS Incident Investigation Program. As part of the investigation, corrective actions to prevent recurrence are being developed. The investigation is expected to be completed by December 31, 1991. The corrective actions and a schedule for implementation will be submitted in a supplement to this report. The supplement is expected to be submitted by January 31, 1992.
IV. PREVIOUS SIMILAR EVENTS:
There have not been other 'previous similar events reported pursuant to 10CFR50.73. Although there have been other events in which a loss of power to the Class 1E 4.16 kV bus resulted in a LOP ESFAS actuation, there have been no similar events in which the cause was due to a mobile crane being in contact with an energized 13.8 kV overhead power line.
PV419.0SUA RCY. 9.89
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