Studies on Methods for Detecting, Locating, and Characterizing Metallic Loose Parts in Nuclear Reactor Coolant Systems

摘要

A research program, largely experimental in character, was conducted to explore the fundamental phenomena and the relationships governing the detection, characterization, and location of loose metallic parts in nuclear reactor coolant systems by means of the sounds produced by their impacts with the reactor vessel walls, internal structures, and piping. Methods for generating impacts of reproducible character and for sensing and analyzing the resultant transient acoustic signals were studied in simple flat-plate geometry in the first phase of this research. In the second phase, deleterious effects on signal detection produced by various sensor misinstallations were quantified, the variation of sensor output with projectile angle of incidence was studied, wave speeds in the medium were measured, and several techniques for ascertaining the location of impacts were developed and tested. In the last phase, tests were performed on a large metallic structure of complex geometry (the reactor vessel of the nonoperating experimental gas-cooled reactor (EGCR) at the Oak Ridge National Laboratory) to assess two impact location techniques under conditions (including simulated interfering background noise) approximating a commercial power reactor.