Remotely Operated Equipments for In-Vessel Inspection in BWRs

This paper describes development and application of remotely operated equipments for reactor internals ultrasonic testing (UT) and visual testing (VT) in boiling water reactors (BWRs) to enhance the availability of operating nuclear power plants. Stress Corrosion Cracking (SCC) in reactor internal components causes relatively low operating rate of BWR as one of the most important issues since the 1990s, and demand to inspect the reactor internals become greater. The remotely operated equipments have been developed for in-vessel inspection of core shrouds, shroud supports, jet pumps and so on. The equipments are evaluated in the point of the positioning precision as an application of a phased array UT technique and visual length measurement system. And as results of application to the actual plants and improvement, a Shroud vehicle, a Crawler vehicle and a Visual position measurement system are enhanced in an aspect of the accessible range and/or positioning precision. Their configurations and functional testing results are shown in this paper. As the other application, micro replication devices are developed for CRD Stub tube and shroud in BWR. This paper indicates the functional testing result using the prototype for the CRD stub tube with observing material microstructure.Copyright © 2008 by ASME