05000528/LER-2023-003, Control Room Essential Filtration Actuation Signal (CREFAS) Actuation with Essential Spray Pond Pump Start
| ML24032A443 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 02/01/2024 |
| From: | Horton T Arizona Public Service Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 102-08726-TAH/JJM LER 2023-003-00 | |
| Download: ML24032A443 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(iv)(B)(9) 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 5282023003R00 - NRC Website | |
text
10 CFR 50.73 A member of the STARS Alliance, LLC Callaway
- Diablo Canyon
- Palo Verde
- Wolf Creek Todd A. Horton Senior Vice President Nuclear Regulatory & Oversight Palo Verde Nuclear Generating Station P.O. Box 52034 Phoenix, AZ 85072 Mail Station 7605 Tel: 623.393.6418 102-08726-TAH/JJM February 01, 2024 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Palo Verde Nuclear Generating Station Unit 1 Docket No. STN 50-528 /Renewed License No. NPF-41 Licensee Event Report 2023-003-00 Enclosed, please find the Licensee Event Report (LER) 50-528/2023-003-00 that has been prepared and submitted pursuant to 10 CFR 50.73. This LER reports an event in which Unit 1 had a valid balance of plant engineered safety features actuation system (BOP-ESFAS) Control Room Essential Filtration Actuation Signal (CREFAS) on December 06, 2023, with Essential Spray Pond Pumps starting.
In accordance with 10 CFR 50.4, copies of this LER are being forwarded to the Nuclear Regulatory Commission (NRC) Regional Office, NRC Region IV, and the Senior Resident Inspector.
No new commitments are being made to the NRC by this letter. Should you need further information regarding this submittal, please contact Michael DiLorenzo, Department Leader, Nuclear Regulatory Affairs, at (623) 393-3495.
Sincerely, TAH/JJM/cr Enclosure: Unit 1 Licensee Event Report 2023-003-00 cc:
J. Monninger NRC Region IV Regional Administrator W. T. Orders NRC NRR Project Manager for PVNGS L. N. Merker NRC Senior Resident Inspector for PVNGS Horton, Todd (Z10098)
Digitally signed by Horton, Todd (Z10098)
Date: 2024.02.01 12:24:02
- - 07'00'
ENCLOSURE Unit 1 Licensee Event Report 2023-003-00
Abstract
Palo Verde Nuclear Generating Station (PVNGS) Unit 1
00528 3
Unit 1 Control Room Essential Filtration Actuation Signal (CREFAS) Actuation with Essential Spray Pond Pump Start 12 06 2023 2023 003 00 02 01 2024 1
100
Michael DiLorenzo, Department Leader, Nuclear Regulatory Affairs 623-393-3495 X
IL ECDB KAMAN No
On 12/6/2023 at 1857, the Control Room (CR) staff observed a significant electronic spike, exceeding the alarm setpoint, on Unit 1 RU-29 (Train "A Control Room Intake Air Monitor) resulting in a balance of plant engineered safety features actuation system (BOP-ESFAS) Control Room Essential Filtration Actuation Signal (CREFAS). During the CREFAS actuation, the Essential Spray Pond Pumps started as designed. RU-29 was declared INOPERABLE and placed in bypass.
CREFAS actuation is reportable pursuant to 10 CFR 50.73(a)(2)(iv)(A) due to the start of the Essential Spray Pond Pumps which serve as the ultimate heat sink pursuant to 10 CFR 50.73(a)(2)(iv)(B)(9): Emergency service water systems that do not normally run and that serve as ultimate heat sinks.
Troubleshooting efforts resulted in the replacement of the power supply for RU-29 and the monitor returning to service. Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050 On 12/6/2023, at 1857, a significant electronic spike occurred beyond the high-high alarm set-point, triggering a complete BOP-ESFAS CREFAS actuation. Effluent assessments confirmed the absence of any detectable radiological activity. At 2238, RU-29 was placed in bypass mode and declared INOPERABLE.
On 12/7/2023, at 1520, troubleshooting efforts resulted in the successful replacement of the power supply for RU-29.
On 12/8/2023, at 0902, RU-29 was removed from bypass mode and declared OPERABLE.
5. ASSESSMENT OF SAFETY CONSEQUENCES
RU-29 and RU-30 are redundant monitors to detect radiation levels. Although RU-29 was placed in bypass, RU-30 remained OPERABLE and able to detect radiation levels to initiate an actuation of CREFAS. All Technical Specification and Technical Requirements Manual conditions were met during this event.
There were no thresholds exceeded in Unit 1 under the risk management program. The quantifiable risk accrued in Unit 1 was negligible, meaning that there were no nuclear safety, radiological safety, or industrial safety significant consequences as a result of this event. Therefore, this condition did not result in a safety system functional failure as described in 10 CFR 50.73(a)(2)(v).
6. CAUSE OF THE EVENT
The direct cause of this event was electronic spiking of RU-29, train "A" control room intake air monitor, due to a failing power supply.
7. CORRECTIVE ACTIONS
The RU-29 monitor was placed in bypass and the failed power supply was replaced under a corrective maintenance work order. Upon completion of the replacement power supply, the monitor was placed back in service.
8. PREVIOUS SIMILAR EVENTS
No similar event of BOP-ESFAS actuation that resulted in the starting of the Essential Spray Pond Pumps has been reported by PVNGS in the past three years.
3 3
Palo Verde Nuclear Generating Station (PVNGS) Unit 1 00528 2023 003 00