05000530/LER-2024-001, Inoperable Boron Dilution Alarm System(Bdas) with Technical Specification Violation
| ML24157A339 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 06/05/2024 |
| From: | Horton T Arizona Public Service Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 102-08807-TAH/JJM LER 2024-001-00 | |
| Download: ML24157A339 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| 5302024001R00 - NRC Website | |
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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 102-08807-TAH/JJM June , 2024 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Palo Verde Nuclear Generating Station Unit 3 Docket No. STN 50-530 /Renewed License No. NPF-74 Licensee Event Report 2024-001-00 Enclosed, please find the Licensee Event Report (LER) 50-530/2024-001-00 that has been prepared and submitted pursuant to 10 CFR 50.73. This LER reports an event in which Unit 3 had a loss of power to both channels of the Boron Dilution Alarm Monitoring System with subsequent Technical Specification Violation of 3.3.12.
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 Matthew S. Cox, Department Leader, Nuclear Regulatory Affairs, at (623) 393-5753.
Sincerely, TAH/JJM/cr Enclosure: Unit 1 Licensee Event Report 2024-001-00 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: 2024.06.05 11:25:26 -07'00'
ENCLOSURE Unit 2 Licensee Event Report 2024-001-00
Abstract
On 4/9/2024 at 1100, while in a refueling outage at zero percent power, Unit 3 control room experienced an unplanned partial loss of power to annunciator windows in the Control Room due to a planned down power of an electrical power supply for the performance of maintenance. The control room entered Technical Specification (TS) Limited Condition for Operation (LCO) 3.3.12 Boron Dilution Alarm System (BDAS) Condition A and B. Personnel from the Chemistry Department obtained samples until power was restored and the BDAS returned to OPERABLE 4/9/2024 at 1233 when the TS LCO was exited.
On 4/13/2024 at approximately 0630, it was discovered that the sample was obtained from an incorrect sample location.
Further TS LCO 3.3.12 Condition B was not met as redundant samples were not taken. The NRC resident inspectors were notified of this event.
The investigation is on going and a supplemental LER will be submitted once complete.
No similar event has occurred at PVNGS in the last three years.Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050 On 4/13/2024, the Chemistry Supervisor was reviewing the samples and realized that the samples were obtained from a different sample point than specified in plant procedures for the conditions of the RCS system being in Shutdown Cooling (SDC) at the time of the event. Furthermore, the Chemistry Supervisor noticed the samples were not obtained redundantly to validate boron concentration as required by TS LCO 3.3.12 Condition B. The supervisor contacted the control room of the findings.
Units 1 and 2 were unaffected by the event and both remained in MODE 1 at 100% power.
5. ASSESSMENT OF SAFETY CONSEQUENCES
Operability of the BDAS channels are 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 5 on 4/9/2024 when both channels of the BDAS became inoperable. There were no MODE changes and no inadvertent boron dilutions during the time BDAS was inoperable.
An investigation of the event is in progress. Information on the safety consequences will be provided in a supplement to this LER.
6. CAUSE OF THE EVENT
The investigation of the specific causes of this event is in progress. This LER will be supplemented when the investigation is complete.
7. CORRECTIVE ACTIONS
Immediate actions included the restoration of power supplies to the annunciator panels which subsequently restored BDAS to OPERABLE status.
Corrective actions for this event are still being evaluated and will be identified in the supplement to this LER.
8. PREVIOUS SIMILAR EVENTS
No similar events have occurred in the prior three years.
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Palo Verde Nuclear Generating Station (PVNGS) Unit 3 00530 2024 001 00