ML17305A373
| ML17305A373 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 10/31/1989 |
| From: | James M. Levine, Shriver T ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LER-89-006-01, LER-89-6-1, NUDOCS 8911090074 | |
| Download: ML17305A373 (26) | |
Text
ACCELERATED ITRIBUTION DEMONSATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:8911090074 DOC.DATE: 89/10/31 NOTARIZED: NO DOCKET FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 AUTH. NAME AUTHOR AFFILIATION SHRIVER,T.D. Arizona Public Service Co. (formerly Arizona Nuclear Power LEVINE,J.M. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION
SUBJECT:
LER 89-006-01:on 890731,inadvertent ESF actuation.
W/8 DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:
TITLE: 50.73/50.9 Licensee Event Report (LER), Inciden Rpt, etc.
NOTES: 05000528 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 CHAN,T 1 1 DAVIS,M. 1 1 INTERNAL: ACRS MICHELSON 1 1' ACRS MOELLER 2 2 ACRS WYLIE 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 1 1 NRR/DLPQ/PEB 10 1. 1 NRR/DOEA/EAB 11 1 1 NRR DR 0 2 2 NUDOCS-ABSTRACT 1 1 ILE 02 1 1 RES/DSIR/EIB 1 1 RGN5 1 1 EXTERNAL: EG&G WILLIAMS,S 4 L ST LOBBY WARD 1 1 LPDR 1 1 NRC PDR 1 1 NSIC MAYS,G 1 1 NSIC MURPHY,G.A 1 1 NUDOCS FULL TXT 1 1 N9TES "1 1 NOTE TO ALL "RIDS" RECIPIENIS:
PLEASE HELP US TO REDUCE WASTE! 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 40 ENCL 40
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Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P 0 BOX 52034 ~ PHOENIX, ARIZONA 85072-2034 192-00544-JML/TDS/JEM October 31, 1989 U. S. Nuclear Regulatory Commission NRC Document Control Desk Washington, D.C. 20555
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Unit 1 Docket No. STN 50-528 (License NPF-41)
Licensee Event Report 89-006-01 File: 89-020-404 Attached please find Supplement Number 1 to Licensee Event Report (LER) No.
89-006-00 prepared and submitted pursuant to the requirements of 10CFR 50.73.
In accordance with 10CFR 50.73(d), we are herewith forwarding a copy of this report to the Regional Administrator of the Region V Office.
If you have any questions, please contact T. D. Shriver, Compliance Manager at (602) 393-2521.
Very truly yours,
. M. Levine Vice President Nuclear Production JGH/TDS/JEM/kj Attachment cc: W. F. Conway (all w/a)
E. E. Van Brunt, Jr.
J. B. Martin T. J. Polich M. J. Davis A. C. Gehr INPO Records Center
- q. g9.103i ADOCK O~OOO528 Ob @Dc" /~g&
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FACILITY NAME (II DOCKET NUMBER (2) PACE 3 TITLE ( ~ I Palo Verde Unit 1 o 5 o o o 5 2810F] 3 Inadvertent Engineered Safety Feature Actuation EVENT OATK (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (SI MONTH OAY YEAR YEAR SEQUENTIAL o'.X tleVISION MONTH OAY YEAR FACILITYNAMES DOCKET NUMBERIS)
NVMSEA NUMBER N/A 0 5 0 0 0 0 7 31 8 9.89 006 0 1 1 0 3 1 8 9 N/A 0 5 0 0 0 OPERATINC THIS REPORT IS SUBMITTED PURSUANT 7 0 THE REQUIREMENTS OF 10 CF R (): IChech one or more ol the foliowinpl (ill MODE (9) 20A02(5) 20.405(cl 50.73(el(2) (wl 73.710I)
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LICENSEE CONTACT FOR THIS LER (12I NAME TELEPHONE NUMBER AREA CODE Timothy D. Shriver, Compliance Manager 6 02 39 3 25 21 COMPLETE ONE LINE FOA KACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
MANUFAC MANUFAC. EPORTABLE CAUSE SYSTEM COMPONENT SYSTEM COMPONENT TURER TVRER TO NPRDS >
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SVPPLEMENTAL REPORT EXPECTED (14) MONTH OAY YEAR EXPECTED SUBMISSION DATE II5)
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On July 31, 1989, Palo Verde Unit 1 was in a refueling outage with the core off-loaded to the Spent Fuel Pool.
On the night shift of July 31, 1989, Unit 1 personnel were making preparations for an outage of all the Train HBH Class 1E electrical switchgear. Auxiliary Operators were stripping Train RBR loads when at approximately 0115 MST on July 31, 1989, there was a loss of power to panel lE-PNB-026 which caused a loss of power to the Remote Indicating and Control (RIC) unit for radiation monitor RU-38 thus initiating a Train AB" Containment Purge Isolation Actuation Signal (CPIAS). The CPIAS cross-tripped Train HBH Control Room Essential Filtration Actuation Signal (CREFAS) which in turn cross-tripped CREFAS "A", all in accordance with design. Due to the planned electrical outage, all safety equipment for CPIAS and CREFAS was in its actuated condition prior to the event with the exception of the Train ABR Control Room Essential Air Handling Unit which started as designed. Approximately one (1) minute after the event initiation, power was restored to lE-PNB-D26 and
.RU-38 was placed back on line and at approximately 0221 MST on July 'U-38.
31, 1989, the CPIAS and CREFAS were reset.
An investigation of the event has been completed. Attempts to recreate this event, interviews with all involved personnel, and troubleshooting of the electrical equipment could not identify the root cause of the event.
NRC Forth 366 (54)9)
IJ NRC FORM 35SA U.S. NUCLEAR REGULATORY COIAMISSION APPROVED OMB NO. 3(500'(04
. (SJISI EXPIRESI 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REQUEST: 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P030I, U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3(504/104). OFFICE OF MANAGEMENT ANO BUDGET, WASHINGTON. OC 20503.
FACILITY NAME (ll DOCKET NUMBER (2) LER NUMBER (Sl SEQUENTIAL gin>~REVISION NUMSER ':4I NUMBER Palo Verde Unit 1 o s o o o 5 2 8 8 9 0 0 6 01 0 2 OF 1 3 TEXT ///mors spsoo /4 rsqIr/rsd. oss sddio'ons/ A'RC form 3054'4/(17>
DESCRIPTION OF WHAT OCCURRED:
A. Initial Conditions:
On July 31, 1989, Palo Verde Unit 1 was in a refueling outage with the core (AC) off-loaded to the Spent Fuel Pool (ND).
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).
On the night shift of July 31, 1989, Unit 1 personnel were making preparations for an outage of all the Train "8" Class lE electrical switchgear (SWGR)(EB)(ED)(EJ). Nuclear Operators (utility, non-licensed) were stripping Train RBR loads when at approximately 0115 HST on July 31, 1989, there was a loss of power to panel lE-PNB-D26 which caused a loss of power to the Remote Indicating and Control (RIC)(IL) unit for the Containment Power Access Purge Exhaust Radiation Monitor (RU-38)(MON)(IL) thus initiating a Train "8" Containment Purge Isolation Actuation Signal (CPIAS)(JE)(VA).
The CPIAS cross-tripped Train "BU Control Room Essential Filtration Actuation Signal (CREFAS)(JE)(VI) which in turn cross-tripped CREFAS "A", all in accordance with design.
Prior to the event on the night shift of July 31, 1989, Unit 1 personnel were preparing for an outage of all the Train "BR Class 1E electrical switchgear to perform preventive maintenance. One exception to the outage was the Class lE 120 Volt (EF) distribution
.panel (PL)(EF) 1E-PNB-D26 being supplied by temporary power from 480 Volt (EC) Motor Control Center (MCC)(EC) H10 through the normal supply breaker (BKR) on HCC 36 and voltage regulator (RG)(EF)
PNB-V26. Another exception was the HDR Battery (BTRY)(EJ) Bus (BU)(EJ)(1E-PKD-M44) and its respective loads which were being supplied by temporary power from HCC H10 via the B-D Battery Charger (BYC)(EJ).
Nuclear Operators (utility, non-licensed) had been dispatched to strip the loads from MCC's 20, 32, 34, 36, 38 and 72 and were making progress on that evolution. The RBR Battery Charger was then taken off the HB" Bus (lE-PKB-M42) leaving the bus powered by the RBR Battery to supply power for breaker operation.
During this same time frame, the Reactor Operator (utility, licensed) involved with the downpower was at the Balance of Plant Engineered Safety Feature Actuation System (BOP ESFAS)(JE) panel NRC Form 35SA (SSS(
NRC FORM 3SSA U.S. NUCLEAR REGULATORY COMMISSION (54)9) APIIROVED 0MB NO, 31504)(04 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REOUESTl 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P.530). V.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON. DC 20555. AND TO THE PAPERWORK REDUCTION PROJECT (31500104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, DC 20503.
FACILITY NAME (I) DOCKET NUMBER (2) LER NUMBER (5)
SEQUENTIAL rPS> RSYISlON NUMSSR vPXS NVMSSR Palo Verde Unit 1 o s o o o 52 88 9 0 0 6 0 1 0 3 OF 1 3 TEXT ///mere 4/rsceis reea(red, lrse sddr)rails/IVRC farm JSSA's/ (17) where he was placing the Loss of Power (LOP)(JE) modules in bypass in preparation for the downpowering of the Train "BH Class 1E electrical switchgear (IE-PBB-S04), and the area 4 Nuclear Operator was stripping loads from HCC H-34.
The area 4 Nuclear Operator had a question concerning stripping breakers with temporary power and made a call to the Control Room which was received at approximately 0115 HST the same time the loss of power occurred to distribution panel IE-PNB-026. The loss of power to distribution panel 1E-PNB-026 was identified by annunciator (ANN)(IB) and computer (CPU)(IB) alarms (ALH)(IB).
This resulted in de-energizing the RIC for RU-38 which then initiated the Containment Purge Isolation Actuation Signal (CPIAS)
Train RB". In accordance with system design, CPIAS RBR cross-tripped Control Room Essential Filtration Actuation Signal RBR (CREFAS) which in turn cross-tripped CREFAS RA". 0ue to the planned electrical outage, all equipment associated with CPIAS and CREFAS was in its actuated condition" prior to the event with the exception of the Train RBR Control Room Essential Air Handling Unit (AHU)(VI) which started as designed.
The Reactor Operator who had just returned from the BOP ESFAS panel took the call from the area 4 Nuclear Operator and informed the area 4 Nuclear Operator that he should not open any breakers supplied with temporary power and that they had an ESF actuation which could be connected with HCC N36.
After the telephone (TEL)(FI) conversation the Reactor Operator and the Shift Supervisor (utility, licensed) researched electrical prints to find the supply breaker for distribution panel 1E-PNB-026 as the area 4 Nuclear Operator continued with stripping loads.
. After approximately one (1) minute and two (2) seconds after the loss of power to distribution panel IE-PNB-026, the power returned with no apparent operator action.
The area 4 Nuclear Operator then contacted Control Room personnel and questioned wheather to open the RBR Battery Charger supply breaker. The Reactor Operator told the area 4 Nuclear Operator to wait on opening the RBR Battery Charger supply breaker until he heard from the area 5 Nuclear Operator. The Reactor Operator then dispatched the area 4 Nuclear Operator to HCC H36 to check breaker N3626 closed. The area 4 Nuclear Operator checked the breaker and reported it closed to the Reactor Operator.
The on-shift personnel made all required notifications and contacted Radiation Protection personnel (utility, non-licensed) to reset Radiation Honitor RU-38. The Radiation Protection personnel placed RU-38 back on line. At approximately 0221 NST on July 31, NRC Fona 35SA (5 59)
NRC FORM 388A US, NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 31500104 (585),
EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP830), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON. OC 20503.
FACILITY NAME (1) DOCKET NUMBER I2) LER NUMBER (5) PAGE (3) 55OVSNTIAL Il5 V l5 IO N NVM SII NVMesa Palo Verde Unit 1 o s o o o 52 88 9 0 0 6 01 04 1 3 TEXT /I/mors sOsos /4 rsh)hh/rsC lhss sdCh5onul NRC Form 38//A'/ (It) 1989, the Reactor Operator reset the CPIAS and CREFAS actuations and continued with the Train HBR downpower without further incident.
C. 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 that have been determined to have contributed to the event.
D. Cause of each component or system failure, if known:
Not applicable - no component or system failures have been identified.
E. Failure mode, mechanism, and effect of each failed component, if known:
Not applicable - no failed components have been identified.
For failures of components with multiple functions, list of systems or secondary functions that were also affected:
Not applicable - no component failures have been identified'or G. failures 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 have been identified.
H. Method of discovery of each component or system failure or procedural error:
Not applicable - no component or system failures or procedural errors have been identified.
Cause of Event:
, The cause of the CPIAS ESF actuation was a loss of power to the RIC for RU-38 due to a loss of power to distribution panel IE-PNB-D26.
After having investigated the apparent potential causes for the event there has been no single reproducible occurrence that could cause the MCC Breaker M3626 contactor to open then reclose without manual operation.
NRC Form 388A (84)5)
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION
)669) APPROVE'D OMB NO. 31500104 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION REOUFSTI 50.0 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P430). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT 131500104). OFFICE OF MANAGEMENTANO BUDGET WASHINGTON, OC 20503r FACILITY NAME 11) DOCKET NUMBER )2) LER NUMBER )6) PAGE )3I SEQUENTIAL II6 V IS IO N NUM 6 II NVMSSA Pal o Verde Uni t 1 o s o o o 52 889 0 06 0 1 05oF13 TEXT ///mors cess /s>>r/cr'rsC Ir>> 4CChooos/HRC Form 3664's/ Ill)
A loss of power to H10 or load shedding by BOP ESFAS relay K202 would have resulted in the loss of other equipment and distribution panels which was not evidenced by the alarm readout.
A ground fault tripping H3626 would not reset .without an operator closing the breaker and the contactor.
Shifting of the transfer switch to off on lE-PNB-V26 would cause a loss of panel 1E-PNB-026 but would not interrupt power to the voltage regulator and the alarm point RPNB-026 STBY SPLY LOST" would not be actuated.
The Nuclear Operator's statement of how he conducted the load stripping and the Reactor Operator's statement that the Nuclear Operator was on the phone as the actuations occurred, also verified by the RHS alarm typer and walk through reenactment gives credence to the statement by the Nuclear Operator that he was not at the breaker H3626 when the loss of power to lE-PNB-D26 did occur.
Due to the indeterminate nature of the specific cause of the event, two types of potential causes have been identified; control equipment malfunction and operator actuation of electrical supply breakers.
Equipment Halfunction Action Plan
- 1. Research alarm PNB-D26 STBY SPLY LOST alarm to ensure a power loss did indeed occur.
~
- 3. Check continuity of BOP,-ESFAS relay (RLY) K232 (start sequencing relay)
- 4. Perform inspection of breaker H3226 to ensure proper operation.
- 5. Perform reenactment of plant conditions and evolutions at the time of the event.
Operator Error Action Plan
- 1. Review alarm typers (TPM) in regard to statements and attempt to establish chronology of events and fill in any missing information.
NRC Form 366A )64)9)
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NRC FOAM 35SA U,S. NUCLEAR REGULA'TORY COMMISSION (6$ 9) APPAOYED OMB NO. 3150010S EXPIRES: o/30/92 ESTIMATED BURDEN PEA RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILERI INFORMATION COLLECTION AEQUESTI 500 HRS. FORWARD COMMENTS AEGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION ANO REPORTS MANAGEMENT BRANCH (F430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON. OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3)504104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, OC 20503.
FACILITYNAME (1) DOCKE)'UMBER (21 LER NUMBER (Bl YEAR ssQUENTIAL rsdE IIsvlsION NVMSSR PPrr NVMBSR Palo Verde Unit 1 o s o o o 52 88 9 0 0 6 01 06 OF 1 3 TEXT Ii/moro spooois nquired. Irss sddrriorMI NRC Farm 3/JIJA's/ (IT)
- 2. Walk through operators'tatements to obtain information for questions for personnel interview.
- 3. Conduct personal interviews to attempt to collect additional information and clarify previously gathered information, 4, Perform test of RBR Charger alarm to determine validity and whether additional information can be drawn from it.
- 5. Perform operator reenactment to correlate information and determine missing items.
Equipment Malfunction Action Plan Results Equipment Malfunction of the equipment which could have resulted in the loss of power alarm Due to the unusual nature in which power to lE-PNB-D26 was lost and returned it was necessary to determine that a loss of power on lE-PNB-D26 had occurred and that the loss was due to the opening of the H3626 breaker or contactor and not a downstream problem with the inverter (INVT) or transfer switch.
The alarm PNB-D26 STBY SPLY LOST only indicates when'the contact associated with the M3626 contactor is open; therefore, the H3626 contact was open during the duration of the alarm and then reclosed approximately 1 minute later.
- 2. Equipment Malfunction of the BOP ESFAS relay K202 to load shed M3626 BOP ESFAS relay K202 was scrutinized to determine the possibility that it was momentarily moved to its actuated condition causing the loss of power to the RBH 120 AC inverter.
It was determined that the K202 relay, had it pulsed would have also caused a loss of standby power to the RCH 120 AC inverter and the alarm RC INV STBY SPLY LOST" to be received.
Inspection of the Plant Monitoring System (PHS) alarm typer showed that it was not received at that time. Receipt of the alarm later that following day, during a separate evolution, showed that the alarm was functioning and in a non-alarming state at the time of the incident and would have come in if K202 had indeed caused a shedding of H3626.
N RC FonII 36BA (689)
NAC FORM 388A US. NUCLEAR REGULATORY COMMISSION (569) APPAOVED OMB NO. 3'I500104 EXPIRES: 4/30/92 ESTIMATED BURDEN PER AESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LERI INFORMATION COLLECTION REQUEST: 500 HAS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECOAOS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P 530). V.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555. ANO TO THE PAPERWORK AEOVCTION PROJECT (3'I500104), OFFICE OF MANAGEMENTANO BUDGET. WASHINGTON, OC 20503, FACILITY NAME (I) DOCKET NUMBER (2) LER NUMBER (8)
YEAR (g$ SEQUENTIAL III'u
.ii ( REVISION NVMEEII NVMOEII Palo Verde Unit 1 0 S 0 0 0 5 2 Q 8 9 0 0 6 01 07 OF 1 3 TEXT ///nhoro 4/rooo /4 roo~, uro odCh(/ono////IC Form 388AS / (17)
Inspection was made of a Potter Br urnfield relay identical to the one in question to determine if it could have actuated and displayed only part of its assigned was feasible that K202 functions and it was determined by the System Engineer that due to the construction of the relay ,it was unlikely that that could occur and had no history of that type of failure.
- 3. Equipment Halfunction of the BOP ESFAS relay K232 to restore power H3626 K232 was checked by removing the contact leads and measuring resistance across the contact. It was determined that K232 was in its normal configuration implying that if power were lost to the breaker H3626, the contactor pushbutton would have to be depressed to restore the path in the control circuitry to allow the inverter to be reenergized.
It was determined that the close pushbutton should be inspected to ensure it was not stuck closed also potentially providing a path for inappropriate contact operation.
During performance of an authorized work order, the close pushbutton was verified to be functioning properly, and is required to be pushed to close the contactor.
- 4. Equipment Halfunction of the H3626 Breaker could have temporarily lost and restored power to IE-PNB-D26 Inspection of breaker H3626, power supply breaker to RBA 120 AC inverter, was performed, under an authorized work order, and checked for loose or burnt wiring, burnt or pitted contacts. It performed a functional check of the breaker ensuring it operated normally on a loss of power to the breaker, and that the pushbutton was indeed required to close the contactor after power was restored.
Through the course .of the inspection no problems were detected within H3626 that could account for either the loss or return of power without operator action.
It is necessary to note that this inspection was conducted after the temporary power had been removed and the system had been returned to normal and removed a potential contributor to the event from further investigation; however, it is not believed to be a likely cause.
NRC Form 368A (869)
NRC FORM 388A U.S. NUCLEAR REGULATORY COMMISSION 1889) APPROVED OMB NO.31500104 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION AEOUESTI 500 HRS, FORWARD COMMENTS AEGARDINQ BUADEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (P.530), U.S. NUCLEAR REGULATORY COMMISSION, 'IVASHINQ'TON, OC 20555, ANO TO THE PAPERWORK REDUCTION PROJECT (3)504))04). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON. OC 20503.
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (8) PAGE (3)
YEAR )PA SEQUENTIAL NUMBER REVISION NUMBER Palo Verde Unit 1 o so o o 5 28 89 0 0 6 01 08 OF 1 3 TEXT /rl maro 4/Mao /4 roarr/rad. 444 oddr)/aao/NRC Farm 35/A'4/ I)7)
- 5. Equipment Halfunction of unknown origin A reenactment of the plant conditions and evolutions leading up to the event was performed to determine evolutions and the transferring of power supplying the BOP if different plant ESFAS from its normal AC source to a slightly degraded DC source would cause any peculiar activities or indications to be seen, generated by the BOP ESFAS cabinet.
The reenactment was conducted per an authorized work order, and allowed the HBR Battery Bus to degrade slightly while being powered from its battery alone. With the battery bus degraded, the AC power was then interrupted to the HBH BOP ESFAS and the plant monitored for a response.
Though the cabinet showed no response that could be directly related to the loss of power to the HBR 120 AC regulator, it did provide an unexpected response upon re-energizing AC power.
When AC power was returned to the cabinet, the PHS alarm typer showed that the load sequencer went into the mode associated with a CREFAS, Fuel Building Essential Ventilation Actuation Signal (FBEVAS), Auxiliary Feedwater Actuation Signal (AFAS) 1 and 2, CPIAS and Control Room Ventilation Isolation Actuation Signal (CRVIAS) and then without operator action returned 1 minute later to mode "zero", or normal mode.
The System Engineer evaluated this and determined it would be beneficial to perform a test on the RB" BOP ESFAS cabinets power supplies and ensure they were providing adequate support for the cabinet.
This was performed as stated in the following action plan.
- 6. Equipment Halfunction of the RBR BOP ESFAS power supplies Performance of a test of the RBR BOP ESFAS power supplies was accomplished in order to determine if the supplies were a potential cause of the RBR BOP ESFAS indication seen during the previous test.
The test was run on September 28, 1989 and exposed no malfunctions or abnormalities which have any bearing on the de-energization of 1E-PNB-D26, "BR train 120 volt AC.
NRC Form 388A (84)9)
NRC FORM SSSA V.S. NUCLEAR REGULATORY COMMISSION (SB9) APPROVED 0MB NO. 31500104 5 XP I R 5 S: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMP(.Y WTH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION REQUEST: 50A) HRS. FORWARD, COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND RFPORTS MANAGEMENT BRANCH (PB30). U.S. NUCLEAR REGIJLATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31504)104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON. OC 20503, FACILITY NAME (11 DOCKET NUMBER (2) LER NUMBER (5) PAGE (3)
YEAR ~D SEOVENTIAI NUMBER 2>r REVISION k>2 NV MOOR Palo Verde Unit 1 o s o o o 52 889 00 6 01 09 o" 1 3 TEXT /I/ moro 4/Moo /4 roOu/ror/ u Jo odchr/orM//VRC Form 35//AB/ ()7)
Operator Error Action Plan Results Review alarms to correlate statement Review of the Radiation Monitoring System (RMS) (IL) and PMS alarm typers showed a disparity in the times of the two typers of one minute and eighteen seconds by comparing the times of actuation. Using this as a guide the RMS typer shows that the Nuclear Operator removed power from radiation monitor (RU-34) two minutes and five seconds before the actuations occurred. RU-34 being powered from breaker M3437 would be one of the first breakers to be opened on MCC M34.
The next breaker that should have caused an alarm would have been the H3406 breaker which was supplying power,to RU-146.
This breaker was supplied temporary power that the Nuclear Operator had opened mistakenly and had called the control room to request information. That breaker did not, however, give indication and subsequent research showed that the monitor was Roff the line and unreachable" and therefore would give no indication if the power was interrupted, The next alarm pertaining to the sequence of events occurred 45 seconds prior to the actuations and that was the HBR Battery Charger trouble alarm. Research showed that the alarm could be brought in either from the opening of the AC feeder breaker (M3627), or the AC input breaker at the charger. The shift supervisor states that he remembers having concise communication that the RBR Battery Charger was off the line in accordance with procedure prior to the loss of 1E-PNB-026.
It was also noted that if those breakers had been opened then it is expected that H3628 (the next breaker in the series) would have also been opened and alarmed on RU-143 detector failure but, this alarm was not received.
- 2. Walkdown Sequence of events to correlate statements To gain orientation with the .sequence of events it was necessary for the investigator to walk down the event with the personnel statements to attempt to determine if they accurately described the manner in which the evolutions in progress would have evolved.
Using known times of events from the alarm typer it was found that the manner in which the Nuclear Operator proceeded was normal and appropriate and would take the approximate amount NRC Form 3SSA (54)9)
v NRC FORM 358A U.S;NUCLEAR REGULATORY COMMISSION APPROVEO OMB NO. 31500)04
)309)
EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT (LER) INFORMATION COLLECTION REQUEST? 500 HRS. FORWARD COMMENTS REGARDING BURDEN FSTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH (F430), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500104). OFFICE OF MANAGEMENTAND BUDGET,WASHINGTON. OC 20503,
'ACILITY NAME (11 DOCKET NUMBER (2) LER NUMBER (5)
YEAR +~@ 55005NTIAL ?vri t?Ev?SION NUtsost? :??v NUMSst?
Palo Verde Unit 1 o s o o o 52 88 9 0 0 6 0 1 1 0 oF 1 3 TEXT ///moro s/tsso/1 rsoo/rsd. oss sddd/oos///RC Form 3SSA'5/ ()7) of time stated to strip loads up to H3406 then call the control room and have it be at the same time as the actuations occurred. It also displayed an unlikelihood that the operator would have been able to complete stripping of HCC M34 and proceed to HCC H36 and complete stripping of MCC M36 (M3626 causing the actuation) and call the control room in the time frame as outlined by the alarm typer.
Observation of equipment and breakers in the area showed that there was nothing that would have given the operator indication that anything was actuating, that he may have been the cause of, and led him to call the control room.
Therefore, the statement that he called the control room to question the yellow tag that was on H3406 (the first tag encountered addressing temporary power) is a logical action that correlates into the time restraints. The adverse supposition being that he stripped all of MCC H34 then proceeded to HCC H36 and opened the HBR Battery Charger breaker, in a minute and twenty seconds, then waited 40 seconds and opened the breaker next to it (H3626). Then he would have had to hurry to the phone (3 to 5 seconds, approximately 30 feet away) and call the control room in the middle of the evolution for no reason other than to question a breaker that had been opened moments earlier.
Personal interviews with the operators concerned were conducted through a reenactment of the event with particular emphasis on events leading to and following the loss of power to IE-PNB-026.
- 4. Walk-through of personnel statements On August 26, 1989 a walk-through of the personnel statements was performed to attempt to elicit more facts than those acquired from the personnel statements, personnel interviews and plant data recording mediums; specifically trying to gain more information concerning time between actions and content of communications between operators.
from the Reactor Operator's standpoint it was established that he had entered the control room and started to the Assistant Shift Supervisor's desk to discuss with the Shift Supervisor a concern about leaving CPIAS unbypassed for the evolution of downpowering 1E-PBB-S04. He was speaking while in transit and had not reached the assistant's desk prior to the receipt of the actuation.
NRC Form 35BA (589)
NRC FORM 388A US. NUCLEAR REGULATORY COMMISSION APPROVEO OMB NO. 31500104 (54)9)
EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WtH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION RH)UESTI 50.0 HRS. FORWARD COMMENtS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION ANO REPORTS MANAGEMENT BRANCH (PB30). U.S. NUCI.EAR REGULATORY COMMISSION, WASHINGTON, OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3)504)104), OFFICE OF MANAGEMENTANO BUDGET, WASHINGTON, OC 20503.
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (8) PAGE (3) jg SEQUENTIAL NUMSER REVISION NUMBER Palo Verde Unit 1 5 28 89 0 0 6 0 1 OF 1 3 tEXT /I/ mOro SPSOO iS ror)rrsod. OSS Sddrr/OOS///RC FOrm 3r)r/A'4/ (1 7)
From the time of the actuation until the phone call from the Nuclear Operator the Reactor Operator only had time to silence the alarm using the B07 Main Control Board acknowledge button then answer the phone immediately adjacent.
He spoke momentarily with the Nuclear Operator concerning whether to open temporary powered breakers.
Following the phone conversation the Reactor Operator then proceeded to B06 Main Control Board where he addressed the alarm response for CREFAS. He stated that he knew that CPIAS was not previously in service and considered CREFAS more pertinent.
The alarm response directed the operator to verify equipment actuations, which he then proceeded to do. After verifying that the affected equipment was all either tagged out or had responded properly he went to the system prints to accompany the Shift Supervisor in determining the specific cause of the actuation.
Upon determination of the affected breaker he then believes he contacted the Nuclear Operator by radio and had him call the control room. The Nuclear Operator responded with a call and the Reactor Operator told him to check closed M3626 while he waited on the line. The operator returned information that the breaker was found closed.
The expired time from the actuation until the Reactor Operator made the Nuclear Operator aware of the breaker identification being approximately 1.5-2 minutes.
The walk with the Nuclear Operator was essentially the same as the Nuclear Operator's statement and also did not provide any clarification as to the content of the phone communications.
Based upon this investigation, several potential causes have been identified.
Equipment Malfunctions lE-PNB-D26 became deenergized and reenergized with no operator action.
- 2. Alarm indicating loss of standby supply to lE-PNB-D26 alarms without a loss of lE-PNB-D26.
NRC Form 388A (589)
NRC FORM 35SA U.S. NUCLEAR REGULATORY COMMISSION IErB9) APPAOVEO 0MB NO. 31500104 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION AEQUEST: 500 HRS. FOAWARO COMMENTS REGARDING BURDEN FSTIMATE TO THE RECORDS TEXT CONTINUATION AND AEPORTS MANAGEMENT BRANCH IPB30). U.S. NUCLEAR REGULATOAY COMMISSION, WASHINGTON. OC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (31500104), OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON, OC 20503.
FACILITY NAME (I) DOCKE1'UMBER (2) LER NUMBER (S) PAGE (3)
YEAR $( p seavsNTrAL NVMSSA
~:: FEY
':>> rs~ars NUMSSO Palo Verde Unit 1 52 889 0 06 01 12 OF 1 3 TEXT /Ifmoro spsseis required. use sddr'Sons! /VRC Form 35/(4'4/ Ilt)
Personnel Errors
- 3. Inadequate prebriefing/instruction given prior to stripping of loads for IE-PBB-S04 downpower.
- 4. Inadequate/unclear instructions on yellow tag for H3626 T MOD temporary power.
- 5. Inadequate attention to detail to plant yellow tags and their intended purpose.
- 6. Lack of responsibility in reporting actual plant conditions in the face of potential personnel error.
J. Safety System Response:
As described above in Section I.B the safety systems were in their actuated positions before the event except for the Train ABH Control Room Essential AHU which started automatically.
K. Failed Component Information:
Not applicable - no failed components have been identified.
II. ASSESSMENT OF THE SAFETY CONSEQUENCES AND IMPLICATIONS OF THIS EVENT:
During this event all fuel was stored in the Spent Fuel Pool (ND). All safety systems required to operate were in their actuated positions or actuated as designed when the event occurred. The event did not result in any challenges to fission product barriers or result in any releases of radioactive materials. Therefore, there were no safety consequences or implications as a result of this event. This event did not adversely affect the safe operation of the plant or health and safety of the public.
III. CORRECTIVE ACTIONS:
A. Immediate:
Power was restored to distribution panel IE-PNB-026 which reenergized RU-38. RU-38 was placed back on line and CPIAS and CREFAS were reset.
B. Action to Prevent Recurrence:
Since the root cause of this event is indeterminate corrective actions will address the potential causes.
N AC Form 35SA (BB9)
NRC FORM 366A US. NUCLEAR REGULATORY COMMISSION (L%9) APPROV EO OM 8 NO. 31500104 EXP)RES( 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS LICENSEE EVENT REPORT ILER) INFORMATION COLLECTION REOUEST: 500 HRS. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS TEXT CONTINUATION AND REPORTS MANAGEMENT BRANCH IP-530). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, OC 20555, ANO TO THE PAPERWORK REDUCTION PROJECT (31500104). OFFICE OF MANAGEMENTAND BUDGET, WASHINGTON. DC 20503.
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER I6) PAGE IS) 6 6 Q U 6 NT I A L :R~ rlsvlSION rrvMSsrl rrUM844 Palo Verde Unit 1 o s o o o 52 889 0 0 6 0 1 13o" 1 TEXT /I/moro spsoo /4 rosoirsd. oss sddr)iorrs///RC form 366A'4/ I(ll Ensure all operations personnel are aware of this incident via required reading, use caution during related evolutions, and report any similar types of events to engineering and operations management.
Expected Completion Date: January 31, 1990 The tagging procedure 40AC-90P15 will be revised to require that yellow caution tags specify the position of breakers.
Expected Completion Date: February 28, 1990 The area 4 Nuclear Operator has been counseled regarding the
.responsibilities of plant operations.
If a root cause can be determined a supplement to this LER will be submitted identifying the root cause and any corrective actions to be taken.
IV. PREVIOUS SIMILAR EVENTS:
Other ESF actuations have been previously reported. Since the root cause of this event is indeterminate, it cannot be determined if previously reported events were similar or if previous corrective actions could have prevented this event.
NRC Form 366A (BB9)
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