05000423/LER-2023-006, Pressurizer Power Operated Relief Valve Failed to Stroke Open During Surveillance Testing Resulting in a Condition Prohibited by Technical Specifications

Pressurizer Power Operated Relief Valve Failed to Stroke Open During Surveillance Testing Resulting in a Condition Prohibited by Technical Specifications

ML24123A227
Person / Time
Site:	Millstone
Issue date:	05/02/2024
From:	O'Connor M Dominion Energy Nuclear Connecticut
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
24-160 LER 2023-006-00
Download: ML24123A227 (1)

LER-2023-006, Pressurizer Power Operated Relief Valve Failed to Stroke Open During Surveillance Testing Resulting in a Condition Prohibited by Technical Specifications

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
4232023006R00 - NRC Website

Abstract

On October 20, 2023 at 0240 hours0.00278 days <br />0.0667 hours <br />3.968254e-4 weeks <br />9.132e-5 months <br />, with Millstone Power Station Unit 3 at O percent reactor power in Mode 4, the "B" pressurizer power operated relief valve (PORV), 3RCS*PCV456, failed to stroke open upon demand during performance of surveillance testing. The failed PORV was replaced with a rebuilt PORV and new pilot solenoid operated valve and passed all required post maintenance tests. The direct cause of the 'B' PORV failure to stroke was a failed pilot solenoid operated valve (SOV). Although it could not be determined when 3RCS*PCV456 became inoperable, it was likely not capable of stroking open in Mode 1-3 for a period exceeding the 72-hour allowed outage time of Technical Specification. This report is being submitted pursuant to 10 CFR 50.73 (a)(2)(i)(B), as an operation or condition that was prohibited by the plant's Technical Specifications.