On 3/3/2017 at 1705 [CST], during the Byron Station Unit 1 refueling outage, it was determined that the results of a planned
Liquid Penetrant (
PT) examination performed on a previous overlay repair of the reactor vessel head did not meet applicable acceptance criteria. The penetration overlay weld indication will be addressed prior to returning the vessel head to service. The examination was being performed to meet the requirements of
10 CFR 50.55a(g)(6)(ii)(D) and
ASME Code Case N-729-1 to ensure the structural integrity of the reactor vessel head pressure boundary. Ultrasonic examinations have been performed and no ultrasonic indications were identified.
This event is being reported under 10 CFR 50.72(b)(3)(ii)(A) for 'Any event or condition that results in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded.'
The licensee has notified the NRC Resident Inspector.
