A joint approach for PWR core barrel bolt and weld inspection

The outer circumference of the core internals is formed by a cylinder-shaped shell, the core barrel, which are welded together. The enclosed horizontal former plates are connected to the core barrel via support and/or clamping ripples and the support plates. Bolts connections are used to fasten the support plates. In case the integrity of the barrel welds and of the barrel former bolts is not guaranteed, the entire structure of the core barrel would be jeopardized by the external forces which occur according to design and operation loads. It is, therefore, of importance to inspect the barrel former bolts and barrel welds with a non-destructive inspection method and to replace them in case of a failure. Because of the high radiation in this area, all work has to be done by remote controlled manipulators. The first inspection of core barrel bolts and welds was successfully conducted by the joint efforts of Kansai, MHI and ABB Reaktor. This result demonstrated the ability to inspect the core barrel bolts and welds using manipulator system and UT technique. (author)