Acoustic Techniques for Localizing Holdup

Material that does not come out of a process as product or waste is called holdup. When this is fissile material, its location and quantity must be determined to improve safeguards and security as well as safety at the facility. The most common method for detecting and measuring holdup is with radiation based techniques. When using them, one must consider equipment geometry, geometry of holdup, and effects of background radiation when converting the radiation measurement into a fissile material quantity. We are developing complementary techniques that use tiny acoustic transducers, which are unaffected by background radiation, to improve holdup measurements by aiding in determining the above conversion factors for holdup measurements. Thus far, we have applied three techniques, Acoustic Interferometry, Pulse Echo, and Bending Wave Propagation, of which the latter appears most effective. This paper will describe each of these techniques and show how they may ultimately reduce costs and personnel radiation exposure while increasing confidence in and accuracy of holdup measurements.