To successfully perform this inspection, the team used WesDyne's T-crawler robot family, together with a novel time-saving nondestructive testing solution. This solution contributed to completing the work several hours ahead of the planned outage window. This was the fourth such inspection the global team has performed for KKM since 2011.

Meeting the inspection requirements for this core shroud's weld seams is an accomplishment that speaks to the collaboration between utility, WesDyne and Westinghouse personnel to share needed information, plan, design and implement a solution to an access puzzle that is both effective and economic.

During the 1990s, the weld seams of some boiling water reactor core shrouds were found to have intergranular stress corrosion cracking. This discovery prompted organizations around the world, including the Electric Power Research Institute Boiling Water Reactor Vessel Integrity Program and the Swiss Federal Nuclear Safety Inspectorate ENSI to require that the weld seams of some boiling water reactor cores be thoroughly inspected. For KKM, this requirement must be satisfied every two years.

THE CHALLENGE

Determining the extent of indications in the weld seams of core shrouds requires that inspection tools are able to maneuver in and around the reactor core to access the weld seams and acquire accurate and thorough data. The indications can include both axial and transverse (off-axial) intergranular stress corrosion cracking. KKM added a requirement in 2015 to detect transverse indications. The inspections are performed under water - to depths of up to 80 feet (~25 meters).

Read the full article at Power Engineering.