05000530/LER-2024-001-01, Inoperable Boron Dilution Alarm System(Bdas) with Technical Specification Violation

Inoperable Boron Dilution Alarm System(Bdas) with Technical Specification Violation

ML24234A332
Person / Time
Site:	Palo Verde
Issue date:	08/21/2024
From:	Horton T Arizona Public Service Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
102-08851-TAH/JJM LER 2024-001-01
Download: ML24234A332 (1)

LER-2024-001, Inoperable Boron Dilution Alarm System(Bdas) with Technical Specification Violation

Event date:
Report date:
5302024001R01 - 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 102-08851-TAH/JJM August 21, 2024 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Subject:

Palo Verde Nuclear Generating Station (PVNGS) Unit 3 Docket No. STN 50-530/Renewed License No. NPF-74 Licensee Event Report 2024-001-01 Enclosed, please find the Licensee Event Report (LER) 50-530/2024-001-01 that has been prepared and submitted pursuant to 10 CFR 50.73. This LER supplement provides additional information that was identified through PVNGS evaluation of the Unit 3 loss of power to both channels of the Boron Dilution Alarm Monitoring System with subsequent Technical Specification Violation of 3.3.12 that occurred on April 9, 2024.

The initial LER 2024-001-00 for the Technical Specification violation was provided to the Nuclear Regulatory Commission (NRC) on June 5, 2024. In this LER, the cover letter and enclosure cover page referenced an incorrect unit. Only Unit 3 was affected. This issue has been documented in the corrective action program.

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 3 Licensee Event Report 2024-001-01 cc:

J. Monninger NRC Region IV Regional Administrator W. T. Orders NRC NRR Project Manager for PVNGS N. Cuevas NRC Acting Senior Resident Inspector for PVNGS Horton, Todd (Z10098)

Digitally signed by Horton, Todd (Z10098)

Date: 2024.08.21 12:45:31

- 07'00'

ENCLOSURE Unit 3 Licensee Event Report 2024-001-01

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.

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. During the time of the event, there were no MODE changes and no inadvertent boron dilutions.

6. CAUSE OF THE EVENT

The direct cause of the event was lack of formality and adequate details in the verbal communications between the Operations and Chemistry departments. The Operations Department and Chemistry Department communications for the LCO required boron samples did not specify all requirements. The apparent cause is that the Chemistry Department procedure did not contain specific sampling requirements necessary to satisfy the required actions of LCO 3.3.12 Condition B.

7. CORRECTIVE ACTIONS

Immediate actions included the restoration of power supplies to the annunciator panels which subsequently restored BDAS to OPERABLE status.

Actions included briefing Operations Staff and Chemistry Staff including expected behaviors regarding control room communication to outside groups and the importance of thoroughly communicating LCO details. Additional actions include procedure revisions for the Chemistry Department to add guidance on sampling locations and other critical task information related to the LCO requirements. The Operations Department will revise the Loss of Annunciators procedure to add steps directing Chemistry to use the guidance.

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 01