On April 3, 2015, during the Braidwood Station Unit 1 refueling outage (A1R18), an in-service Liquid Penetration examination was performed on the previously repaired
control rod drive mechanism (
CRDM) penetration 69. During the examination on the weld build up for
CRDM penetration 69, a 3/8 inch rounded indication was discovered located at 0 degrees on the reactor head portion of the weld build up, and it is 4 inches from the transition of the head to penetration. 0 degrees is located at the outermost portion of the penetration on the
flange side. The transition is the point where the vertical portion of the penetration meets the horizontal area of the reactor head.
Rounded indications that exceed 3/16 inch are rejectable per ASME Code Case N-729-1.
This is reportable pursuant to 10CFR50.72(b)(3)(ii)(A), 'Any event or condition that results in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded' since the as found indication did not meet the applicable acceptance criteria referenced in ASME Code Case N-729-1 to remain in-service without repair.
The NRC Resident Inspector has been informed.
