Development of position detection method for an underwater vehicle used in reactor core internal inspection

An underwater vehicle system to inspect nuclear power plants has been developed. In this work, a function to show the moving vehicle's position to operators is proposed and the new position detection method described. The method consists of a horizontal position detection part and a vertical position detection part. In the former, map matching is used which consists of the cross-sectional shape data cut from a 3-D CAD and the inner surface shape measured by a laser range system. In the latter part, a pressure sensor is used. It was confirmed that the position was detected with an accuracy of 48 mm based on results of a fundamental examination using the sensor unit. Finally, in an experiment using the vehicle- mounted sensor unit, it was confirmed that the position was detected with an accuracy of 60 mm. (authors)