Patent Number: 043022863
Section: abstract

A reactor vessel in-service inspection assembly (17) having an improved positioning device (80) for properly and repeatedly locating the inspection transducers (75) of the assembly within a hollow portion of the reactor vessel cavity. An acoustic transducer of the positioning device of this invention is affixed to the positioning arm (40) of the inspection transducers (75). The positioning transducer is operable to generate and simultaneously, radially direct acoustic signals around the circumference of the hollow portion of the vessel cavity and receive the signals reflected off of the cavity walls at a location within the hollow cavity. Means are provided for monitoring the received signals as a function of time. The in-service inspection assembly transducer positioning arm is arranged to automatically move in response to the monitored difference in the time of reception of the received signals to locate the positioning transducer at a preestablished location within the hollow portion of the reactor cavity.