05000530/LER-2024-003, Violation of Technical Specifications 3.9.2 and 3.3.12
| ML24347A138 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 12/12/2024 |
| From: | Spina J Arizona Public Service Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 102-08883-JLS/CWD LER 2024-003-00 | |
| Download: ML24347A138 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| 5302024003R00 - NRC Website | |
text
Spina, Jennifer (Z08962)
Digitally signed by Spina, Jennifer (Z08962)
Date: 2024.12.12 07:21:35 -07'00'
Abstract
Palo Verde Nuclear Generating Station (PVNGS) Unit 3 00530 3
VIOLATION OF TECHNICAL SPECIFICATIONS 3.9.2 and 3.3.12 4
13 2024 2024 003 00 12 12 2024 6
0%
Matthew S. Cox, Department Leader, Nuclear Regulatory Affairs (623) 393-5753 A
SE IG W120 Y
On April 13, 2024 at approximately 18:00 Mountain Standard Time (MST), Unit 3 was in a refueling outage conducting core offload when alarms were received in the control room indicating an issue with excore startup range channel 2. The excore startup range channel 2 was declared inoperable, Technical Specifications (TS) Limiting Conditions for Operation (LCOs) 3.9.2.A and 3.3.12.A were entered, and core offload was suspended. On April 13, 2024 at approximately 21:00, Operations personnel declared the channel OPERABLE, exited TS LCOs 3.9.2.A and 3.3.12.A, and resumed core offload. On October 22, 2024 during the third quarter integrated inspection exit, PVNGS was notified that a Green Non-Cited Violation (NCV) would be issued for failing to follow station procedure, "Operations Operability Determination Process," to properly evaluate operability of the Unit 3 excore startup range channel 2 during fuel movement. This resulted in a violation of TS 3.9.2 and 3.3.12 when Operations exited the LCOs and recommenced core alterations. Corrective actions include power supply repair, Operations personnel event briefing, and a Training Needs Analysis to address a knowledge gap. No similar events have been reported by PVNGS in the last three years due to the same initial cause.Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050
5. ASSESSMENT OF SAFETY CONSEQUENCES
Operability of the BDAS channels is necessary to meet the assumptions of the safety analyses to mitigate the consequences of an inadvertent boron dilution event as described in the UFSAR Chapter 15, Revision 22. Unit 3 was in MODE 6 on April 13, 2024 when the Unit 3 excore startup channel 2 failed resulting in the inoperability of BDAS channel
- 2. Although the instrument was providing counts, it was degraded and was not evaluated to have reasonable expectation of operability because the instrument's reduced reliability was not considered. There were no inadvertent boron dilutions during the time BDAS channel 2 was inoperable and fuel integrity was not challenged. Loss of Safety Function was not challenged as excore startup channel 1 and BDAS channel 1 remained OPERABLE at all times.
6. CAUSE OF THE EVENT
The direct cause of the event was degraded components in the high voltage power supply for excore startup channel 2.
Subsequently, use of station procedure, "Operations Operability Determination Process," failed to properly consider reduced reliability when evaluating reasonable expectation of operability of the Unit 3 excore startup range channel 2 detector. The apparent cause of the event was a knowledge gap for implementation of the operability determination procedure.
7. CORRECTIVE ACTIONS
Immediate corrective actions included replacement of the excore startup range channel 2 high voltage power supply and channel calibration. Additional corrective actions identified during the evaluation of the event included an Operations newsflash with the relevant operating experience issued to all operating crews and a Training Needs Analysis to address knowledge gaps in the affected training programs.
8. PREVIOUS SIMILAR EVENTS
No similar events have been reported by PVNGS in the last three years due to the same initial cause.
3 3
Palo Verde Nuclear Generating Station (PVNGS) Unit 3 00530 2024 003 00