05000530/LER-1992-004-02, :on 921009,containment & Fuel Bldg Ventilation ESF Actuations Occurred Due to Personnel Error.Reactor Operator Disciplined
| ML17306B097 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 11/02/1992 |
| From: | Bradish T ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | |
| Shared Package | |
| ML17306B096 | List:
|
| References | |
| LER-92-004-02, LER-92-4-2, NUDOCS 9211090105 | |
| Download: ML17306B097 (18) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(x) |
| 5301992004R02 - NRC Website | |
text
LICENSEE EVENT REPORT (LER)
FACILITYNAME(I)
Palo Verde Unit 3 TITLE(4)
Invali C
n r R
m C
i F
8 DOCKET NUMBER (2)
PACE 3 osooo5301OF09 EVENT DATE (5)
LER NUMBER (6)
RE RT DATE (7)
OTHER FACIUTIES INVOLVED (6)
MONTH 1
0 DAY YEAR YEAR 099292 NUMBER 004 I'~ NUMBER 0
0 MONTH DAY 0
2 9
2 FACILITYNAMES N/A N/A DOCKET NUMBER(S) 0 5
0 (j
0 0
5 0
0 0
OPERATINO MODE(0)
POWER LEVEL p
p p
NAME 20A02(b) 20.405(ay)(l) 20A05(a)(t gii) 20.405(a)(I)(IT) 20A05(ay)(lv) 20AOS(a)(1 j(v) 20.405(c) 5036(c)(1) 5046(cj(2) 50.73(a)(2)0) 50.73(a) (2)(ii) 50.73(a) (2)(ltl) 50.73(a)(2) Ov) 50.73(a)(2)(v) 50.73(a)(2)(v5) 50.73(a)(2)(vil)(A) 50.73(a)(2)(vti)(B) 50.73(a)(2)(x)
UCENSEE CONTACT FOR THIS LER (12)
THIS REPORT IS SUSMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR f: (Check one or more ol tha (allowing) (11) 73.71(b) 73.71(c)
OTHER (Spectty InAbsb ect below <<viln TetrL NRC Fcnn 366A)
TELEPHONE NUMBER Thomas R. 8radish.
Compliance Manager 602 39 3
5421 COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCR BED IHTIES REPORT (13)
CAUSE SYSTEM COMPONENT MANUFAC-TURER E PORTABLE TO NPRDS
CAUSE
SYSTEM COMPONENT MANUFAC-TURER EPORTAB TO NPRDS
.;vi@gei:~jj&~~e7Aes@gg SUPPLEMENTALREPORT EXPECTED (14)
EXPECTED SUBb5$ SIOH DATE(15) k'jgj<@1vjl:r'gg'(
w'~:.k~<a:(':s; ces MONTH DAY YEAR YES (I/yes, complete EXPECTED SUBMISSION DATE)
NO ABSTRACT(Iinitto 1400 epacea Ie.. epproiirnately Eheen ahBlespace typewrftten Bnes) (16)
At approximately 1653 MST on October 9,
- 1992, Palo Verde Unit 3 was in its third refueling outage with the core offloaded to the spent fuel pool when inadvertent Train A Containment Purge Isolation Actuation System (CPIAS),
Train A Control Room Essential Filtration Actuation System (CREFAS), Train A Control Room Ventilation Isolation Actuation System (CRVIAS), and Train A Fuel Building Essential Ventilation Actuation System (FBEVAS) Balance of Plant (BOP) Engineered Safety Feature Actuation System (ESFAS) actuations occurred.
The actuations were the result of a loss of power to the Train A BOP ESFAS Cabinet (SAA-C02A) (i.ers relays deenergize to actuate) which occurred when a reactor operator inadvertently deenergized the wrong Train A Class 1E 480V Switchgear Load Center.
Most of the Train A equipment:
was tagged out and unavailable.
The available Engineered Safety Feature system equipment (e.g.,
ventilation system components) operated as expected.
Control Room personnel (utility, licensed) responded to the alarms and verified that the BOP ESFAS actuations were not the result of valid signals.
The cause of the event was due to cognitive personnel error.
As corrective
- action, the reactor operator was disciplined.
There have been no previous similar events reported pursuant to 10CFR50.73.
9211090105 921102 PDR ADOCK 05000530 S
LlCENSEE EVENT REPORT (LER) TEXT CONTINUATlON FACILITYNAME Palo Verde Unit 3 DOCKET NUMBER SEQUENTIAL B " REVISION NUMBER I: NUMBER PAQE TEXT DESCRIPTION dF WHAT OCCURRED:
osooog 0, OF A,
Initial Conditions:
On October 9, 1992, Palo Verde Unit 3 was in its third refueling outage with the core (AC) offloaded to the spent fuel pool (ND).
The Reactor Coolant System (RCS)
(AB) was at approximately 77 degrees'ahrenheit and at atmospheric pressure.
Unit 3 was in a Train A outage with most of the Train A equipment tagged out and unavail'able.
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 1653 MST on October 9, 1992, inadvertent Train A Containment Purge Isolation Actuation System (CPIAS) (VA)(JE),
Train A Control Room Essential Filtration Actuation System (CREFAS) (VI)(JE), Train A Control Room Ventilation Isolation Actuation System (CRVIAS) (VI)(JE), and Train A Fuel Building Essential Ventilation Actuation System (FBEVAS) (VG)(JE) Balance of Plant Engineered Safety Feature Actuation System (BOP ESFAS)
(JE) actuations occurred.
The actuations were the result of a loss of power to the Train A BOP ESFAS Cabinet (SAA-C02A)
(JE)(CAB) (i.e., relays deenergize to actuate) which occurred when a reactor operator (utility, licensed) inadvertently deenergized the wrong Train A Class lE 480V Switchgear Load Center (ED).
Most of the Train A equipment was tagged out and unavailable.
The available ESF system equipment (e.g., ventilation system components) operated as expected.
Control Room personnel (utility, licensed) responded to the alarms and verified that the BOP ESFAS actuations were not the result of valid signals.
On October 9, 1992, prior to the event, Operations personnel (utility, licensed) were in the process of realigning plant equipment as necessary to support a bus (BU) outage for the Train A Class 1E 480V Switchgear Load Center (PGA-L31) [Refer to Figure on Page 7].
A bus outage for PGA-L31 would interrupt power to the Channel A Control Room Ventilation Intake Radiation Monitor (RU-
- 29) (VI)(IL) and actuate the Control Room Essential Filtration Units (VI).
Therefore, Train A CREFAS was placed in bypass.
Battery Charger C (PKC-H13)
(EJ)(BYC) which is powered by the 480V Class 1E Motor Control Center (MCC) (PHA-M31) (ED) was taken out of service and the Train C 125V Class lE DC Power (PK) (EJ) bus was realigned to Battery Charger AC (PKA-H15) which is powered by
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITYNAME Palo Verde Unit 3 TEXT DOCKET NUMBER osooo5 3092 LER NUMBER BEOUENTIAL NUMBER 0 04 K< REVIBION g~
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the 480V Class 1E MCC (PHA-M33).
The Train A 125V Class lE DC Power (PK) bus was being powered by Battery Charger A (PKA-Hll).
Battery Breakers (BKR)(BTRY) A and C remained open for electrical maintenance (i.e.,
super charge using an external battery charger) on Battery A (PKA-Fll) and Battery C (PKA-F13).
Following plant equipment realignment necessary to support the Train A Class 1E 480V Switchgear Load Center (PGA-L31) outage, the reactor operator (utility, licensed) responsible for deenergizing PGA-L31, inadvertently deenergized another Train A Class lE 480V Switchgear Load Center (PGA-L35).
This resulted in a sequence of power interruptions from PGA-L35 to the 480V Class 1E Motor Control Center (MCC)
(PHA-M35) to Battery Charger A (PKA-Hll) and to 480V/120V AC Voltage Regulator (PNA-V25) (RG).
Since Battery Breaker A was open and Battery Charger A (PKA-Hll) was deenergized, the Train A 125V Class 1E DC Power bus (PK) and Inverter A (PNA-Nll) (INVT) were deenergized and unavailable.
Also, since the Voltage Regulator (PNA-V25) was deenergized, the automat'ic transfer capability from the normal DC source (PK) to the backup AC source (PH) via the static transfer switch was disabled.
This resulted in a loss of power to the Train A 125V DC Class 1E Power System Distribution Panel (PKA-D21) (EJ) and Train A 120V AC Class lE Instrument and Control Power System (PNA-D25)
(EF),
and subsequent loss of Channel A 120V AC Class 1E Instrumentation and Control power to Channel A Reactor Protection System (RPS)
(JC) and Train A BOP and Nuclear Steam Supply System (NSSS)
ESFAS control systems.
Since most of the Train A equipment was tagged out and unavailable, the only automatic actuations resulted when the BOP ESFAS Cabinet (SAA-C02A) was deenergized.
Train A CPIAS,
- CREFAS, CRVIAS, and FBEVAS actuations (i.e., relays deenergize to actuate) occurred.
The designed cross trips of Train B CPIAS,
- CREFAS, CRVIAS, and FBEVAS did not occur as expected since the Train A cross trip jumpers had been installed in the Train B BOP ESFAS Cabinet (SAB-C02B) to facilitate scheduled maintenance in the Train A BOP ESFAS Cabinet (SAA-C02A).
[Technical Specification Limiting Condition for Operation (TS LCO) 3.9.12 ACTION b was entered at approximately 0450 MST on October 5, 1992, for no Fuel Building Essential Ventilation System (VG) OPERABLE due to the inability of the Train A FBEVAS to initiate a cross trip of the Train B FBEVAS.)
The available Train A ESF system equipment (e.g., ventilation system components) operated as expected.
The only Train A ESF system equipment that started was the Fuel Building Essential Ventilation Unit.
This unit was powered by an unaffected 480V Class 1E MCC (PHA-M37) and did not rely upon the Train A 125V
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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITYNAME Palo Verde Unit 3 DOCKET NUMBER LER NUMBER SEQUENTIAL NUMBER REVISION NUMBER PACE 0o053092 004 0004 OF 0 9
Class 1E DC Power (PK) to actuate.
Train A Control Room, Fuel Building, and Auxiliary Building ventilation dampers (DMP) repositioned in response to the loss of Train A 125V Class 1E DC Power (PK), as designed.
Control Room personnel responded to the alarms and verified that the ESFAS actuations were not the result of valid signals.
At approximately 1701 MST, Battery Breaker A was closed to restore Train A 125V Class lE DC Power (PK).
The reactor operator reenergized PGA-L35, PHA-M35, and PHA-M19.
At approximately 1719 MST, Battery Charger A was returned to service, and the Train A 120V AC Class 1E Instrument and Control Power System (PN) bus was energized.
At approximately 1732 MST, Train A CPIAS and FBEVAS were placed in bypass (CREFAS was already bypassed and CRVIAS was not required to be placed in bypass) in accordance with the restoration procedure following the loss of 120V AC Class 1E Instrument and Control Distribution Panel (PNA-D25).
At approximately 1744 MST, PNA-D25 was returned to service, and Train A 125V Class 1E DC Power (PK) and 120V AC Class 1E Instrument and Control Power (PN) were restored.
At approximately 1747 MST on October 9, 1992, Train A Class 1E 480V Switchgear Load Center (PGA-L31) was deenergized and the bus outage work initiated.
At approximately 1810 MST, CPIAS,
- CREFAS, CRVIAS, and FBEVAS were reset to restore normal ventilation lineups.
By approximately 1818 MST, Fuel Building, Auxiliary Building, and Control Building ventilation systems were returned to normal.
At approximately 0903 MST on October 10,
- 1992, PGA-L31 and PGA-M31 were restored to service following the completion of the bus outage.
C.
Status of structures,
- systems, or components that were inoperable at the start of the event that contributed to the event:
Although most of the Train A equipment was tagged out and unavailable, and Battery Breaker A was opened for electrical maintenance, as described in Section I.B, 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.
E.
Failure mode, mechanism, and effect of each failed component, if known:
Not applicable
- - no component failures were involved.
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITYNAME Palo Verde Unit 3 DOCKET NUMBER TEAR gZ SEQUENTIAL Py
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F.
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:
Not applicable
- - there have been no component or system failures or procedural errors identified.
Cause of Event
An independent investigation of this event was conducted in accordance with the APS Incident Investigation Program.
The investigation determined that the reactor operator responsible for deenergizing Train A Class lE 480V Switchgear Load Center (PGA-L31) had the appropriate procedures available and in use and had properly completed the requirements necessary to deenergize the PGA-L31 bus.
- However, due to a momentary lapse of self-verification techniques, specifically, to verify that the labeled component number and the noun name are identical to that listed in the procedure, the reactor operator inadvertently deenergized PGA-L35 by operating the incorrect handswitch (SALP Cause Code A:
Personnel Error).
No unusual characteristics of the work location (e.g., noise, heat, poor lighting) directly contributed to this event.
There were no procedural errors which contributed to this event.
Safety System Response:
The following safety system responses occurred:
Fuel Building Essential Ventilation System, Train A; Channel A Control Room Normal Air Handling Unit Isolation Dampers repositioned; and Channel A Fuel Building Normal Air Handling Unit Isolation Dampers repositioned.
Due to the Train A outage, most of the Train A equipment was tagged out and unavailable, and therefore did not actuate.
I I
LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITYNAME Palo Verde Unit 3 DOCKET NUMBER osooo530 9
2 LER NUMBER BEOUENTIAL A:
NUMBER 004 REVIBION NUMBER 0
0 0
6 PAOE DF0 9
Failed Component Information
Not applicable
- - no component failures were involved.
II.
ASSESSMENT OF THE SAFETY CONSEQUENCES AND IMPLICATIONS OF THIS EVENT:
The Train A BOP ESFAS actuations were not the result of conditions requiring system actuations.
The event did not result in any challenges to the fission product barriers or result in any releases of radioactive materials.
Therefore, there were no adverse
safety consequences
or implications resulting from this event.
This event did not adversely affect the safe operation of the plant or the health and safety of the public.
III.
CORRECTIVE ACTION
A.
Immediate:
A night order and shift briefing was presented to the Unit 3 Operations personnel emphasizing the importance of self-verification.
The event was also discussed at the Unit 3 Supervisor's meeting in order that lessons learned are relayed to the Unit 3 work groups.
The reactor operator was disciplined in accordance with the PVNGS Positive Discipline Program.
B.
Action to Prevent Recurrence:
This event will be included by the Training Department in industry events training for Control Room personnel.
This training is expected to be completed by February 26, 1993.
IV.
PREVIOUS SIMILAR EVENTS
Although previous similar events involving a momentarily lapse of self-verification techniques by a reactor operator have been reported, no events have been reported pursuant to 10CFR50.73 which involved the same
cause
and sequence of events (i.e., deenergization of the Channel A BOP ESFAS Cabinet and subsequent Train A BOP ESFAS actuations of CPIAS,
- CREFAS, CRVIAS, and FBEVAS).
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UCENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITYNAME Palo Verde Unit 3 TEXT osooo53092 g~> SEQUENTIAL NUMBER 004 i'j REVISION I'. NUMBER 0
0 PAGE 0 SoF 0 9
V.
ADDITIONALINFORMATION:
Effective October 13,
- 1992, the Nuclear Regulatory Commission (NRC) amended its regulations to make minor modifications to the current nuclear power reactor event reporting requirements.
These events include invalid actuations, isolation, or realignment of a limited set of ESFs including systems, subsystems, or components (i.e.,
an invalid actuation, isolation, or realignment of only the reactor water clean-up
- system, or the control room emergency ventilation system, reactor building ventilation system, fuel building ventilation system, auxiliary building ventilation system, or their equivalent ventilation systems).
The event reported in this LER (530/92-004) occurred on October 9, 1992, prior to the new regulations'ffective date.
A similar event occurred again in Unit 3 on October 14, 1992.
Although the October 14, 1992 event is no longer reportable under the new regulations, an event description is provided below due to the similarities and close proximity of both events.
On October 14,
- 1992, Palo Verde Unit 3 was in its third refueling outage with the core offloaded to the spent fuel pool.
The Reactor Coolant System (RCS) was at approximately 82 degrees Fahrenheit and at atmospheric pressure.
At approximately 1809 MST on October 14, 1992, inadvertent Train B CPIAS, Train B CREFAS, and 'Train B FBEVAS BOP ESFAS actuations occurred.
The actuations were the result of a loss of power to several Radiation Monitoring System (IL) monitors fi.e., Channel B Control Room Ventilation Intake Radiation Monitor (RU-30) (VI)(IL)(RI)initiates a
CREFAS signal, Channel B Fuel Building Ventilation Exhaust Radiation Monitor (RU-145) (VG)(IL)(RI) initiates a FBEVAS signal, and Channel B
Power-Access Purge Area Radiation Monitor (RU-38) (VA)(IL)(RI) initiates a CPIAS signal] which occurred when a reactor operator (utility,
'icensed) deenergized the Train B 120V AC Class lE Instrument and Control Power System (PNB-D26) (EF).
PNB-D26 was deenergized as part of a planned Train B 120V AC Class 1E Instrument and Control Power System bus outage.
Contrary to a caution statement in an approved procedure, the reactor operator responsible for deenergizing PNB-D26 did not ensure that the Train B BOP ESFAS relays had been placed in bypass.
The available ESF system equipment operated as expected for the current plant alignment.
Control Room personnel (utility, licensed) responded to the alarms and verified that the BOP ESFAS actuations were not the result of valid signals.
The designed cross trips of Train A CPIAS,
- CREFAS, and FBEVAS did,not occur as expected since the Train B cross trip jumpers were installed in the Train A BOP ESFAS Cabinet (SAA-C02) to facilitate scheduled maintenance.
[TS LCO 3.9.12 ACTION b was entered at approximately 1730,MST on October 14, 1992, for no Fuel Building Essential Ventilation System OPERABLE due to the inability of
LICENSEE EVENT REPORT (LER) TEXTCONTINUATION FACILITYNAME Palo Verde Unit 3 DOCKET NUMBER LER NUMBER
<4a SEQUENTIAL
>N NUMBER
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the Train B FBEVAS to initiate a cross trip of the Train A FBEVAS.]
At approximately 1825 MST, Train B CPIAS,
- CREFAS, and FBEVAS were placed in bypass in accordance with the restoration procedure following the loss of 120V AC Class 1E Instrument and Control Distribution Panel (PNB-D26).
An independent investigation of this event was conducted in accordance with the APS Incident Investigation Program.
The investigation determined that the reactor operator responsible for deenergizing Train B 120V AC Class 1E Instrument and Control Power System (PNB-D26) had the appropriate procedures available and in use.
However, contrary to a caution statement in the procedure, the reactor operator did not ensure that the Train B BOP ESFAS relays were placed in bypass, The investigation also determined that a contributing cause of the event was that an action statement was embedded within a caution statement of the procedure in use.
As corrective action, the reactor operator was disciplined in ac'cordance with the PVNGS Positive Discipline Program.
In addition, the appropriate procedures will be modified such that the specific actions to place the BOP ESFAS actuations in bypass are incorporated into the procedure,
I