05000530/LER-2024-002, Invalid Specified System Actuation of Train B Emergency Diesel Generator
| ML24177A322 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 06/25/2024 |
| From: | Harbor C Arizona Public Service Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 102-08821-CDH/CWD LER 2024-002-00 | |
| Download: ML24177A322 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 5302024002R00 - NRC Website | |
text
'
<6,A A
%"A <*4,(9A!,/<4(;79@A7551::176A
$ A 7*<5,6;A76;974A,:3A
'(:016/;76A A A
"<)2,*;A
!)#)& #) #% ) %% ! ) %))
) )
)
$$ ! "$
"$ " !$
$ #$$
#$ $
$
$"" $ $
$ $
! %)!)) ) () $)!)
)
$) ' %)"!#%))
6*47:,+A 84,(:,A-16+A;0,A 1*,6:,,A=,6;A!,879;A !A
A;0(;A0(:A
),,6A89,8(9,+A(6+A:<)51;;,+A8<9:<(6;A;7AA!A A
A#01:A !A9,879;:A(6A,=,6;A16A
>01*0A%61;A A0(+A(A(<;75(;1*A(*;<(;176A7-A;0,A%61;A A#9(16AA5,9/,6*@A1,:,4A,6,9(;79A
A(6+A;0,A%61;A A#9(16AA::,6;1(4A"89(@A 76+A <58A"
6A(**79+(6*,A>1;0AA!A A *781,:A7-A;01:A !A(9,A),16/A-79>(9+,+A;7A;0,A <*4,(9A
!,/<4(;79@A7551::176A !A!,/176(4A .1*,A !A!,/176A&A (6+A;0,A",6179A!,:1+,6;A
6:8,*;79A
7A6,>A*7551;5,6;:A(9,A),16/A5(+,A;7A;0,A !A)@A;01:A4,;;,9A"07<4+A@7<A6,,+A-<9;0,9A 16-795(;176A9,/(9+16/A;01:A:<)51;;(4A 84,(:,A*76;(*;A (;;0,>A"A7?A ,8(9;5,6;A
,(+,9A <*4,(9A!,/<4(;79@A--(19:A (;A
A
A "16*,9,4@A
'*9A
6*47:<9,A
%61;A A 1*,6:,,A=,6;A!,879;A A
- A
A 76616/,9
'A#A 9+,9:A
A ,93,9
!A!,/176A&A!,/176(4A+5161:;9(;79A
!A !!A 972,*;A (6(/,9A-79A & "A
!A",6179A!,:1+,6;A6:8,*;79A-79A & "A
Harbor, Cary (Z16762)
Digitally signed by Harbor, Cary (Z16762)
Date: 2024.06.25 10:18:51 -07'00'
Abstract
Palo Verde Nuclear Generating Station (PVNGS) Unit 3 00530 3
INVALID SPECIFIED SYSTEM ACTUATION OF UNIT 3 TRAIN B EMERGENCY DIESEL GENERATOR 4
27 24 24 002 00 06 25 24 6
0%
Matthew S. Cox, Department Leader, Nuclear Regulatory Affairs (623)393-5753 On 27 April 2024, at 10:18 Mountain Standard Time (MST), during clearance restoration for the Unit 3 Train B Spray Pond (SP) system, an invalid actuation of the the Unit 3 Train B Emergency Diesel Generator (EDG) occurred. The EDG inadvertently started when the EDG hand switch was taken to REMOTE as part of the restoration activities. The start of the Unit 3 Train B EDG resulted in an automatic actuation of the Unit 3 Train B SP pump, as designed. The automatic start of the EDG was caused by a Loss of Power (LOP) signal that had not been reset as part of previous clearance work. There was no loss of voltage on any required bus. No Technical Specifications (TS) were entered due to Unit 3 being in Mode 6 with the Train B equipment not being necessary to meet TS or safe shutdown requirements. Corrective actions include restoring the system lineups and implementing procedure changes to minimize recurrence. The NRC residents were notified at the time of the event.
No similar events have occurred at PVNGS in the last three years.Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050
5. ASSESSMENT OF SAFETY CONSEQUENCES
There were no inoperable structures, systems, or components that contributed to this event. The Unit 3 Train B EDG responded as designed to the invalid LOP signal. The Unit 3 B Train SP pump actuated to support the running EDG.
This event did not result in any challenges to the fission product barriers or result in the release of radioactive materials. This event did not prevent the fulfillment of a safety function, as described by 10 CFR 50.73(a)(2)(v).
6. CAUSE OF THE EVENT
The direct cause of the invalid emergency start of the Unit 3 Train B EDG was the presence of an invalid LOP signal that had not been reset after de-energization of Train B BOP-ESFAS.
The apparent cause of the invalid emergency start of the Unit 3 Train B EDG was that the relevant procedure did not appropriately identify the need to reset the Unit 3 Train B EDG circuitry prior to placing the EDG Mode Control Switch in REMOTE.
- 7. CORRECTIVE ACTION(S):
Immediate corrective actions were the securing of the EDG followed by the reset and restoration of the BOP-ESFAS signal, the Unit 3 Train B EDG, and the Unit 3 Train B SP pump.
Planned corrective actions include updates to the associated procedure to incorporate cautions for EDG start signals, instructions to utilize equipment status tags, and modification to steps to ensure proper reset of the system prior to return to service. This will identify the need to reset the EDG circuitry using the appropriate procedure section to prevent an automatic emergency start when the EDG is restored.
8. PREVIOUS SIMILAR EVENTS
No similar events have occurred in the prior three years.
3 3
Palo Verde Nuclear Generating Station (PVNGS) Unit 3 00530 2024 002 00