A New Approach to Comparing Ultrasonic Seal Signatures

Sandia National Laboratories since the late 1970s has been developing ultrasonic sealing systems for international safeguards applications on reactor fuel assemblies. The Seal Pattern Reader (SPAR) is a product of this effort. The SPAR instrument reads the identities of ultrasonic seals such as the Sandia Fuel Assembly Identification Device (FAID), the Atomic Energy of Canada Limited Random Coil (ARC) seal, the Sellafield, UK Multielement Bottle (MEB) seal and the JRC-lspra VAKIII seal. The unique acoustic pattern of an ultrasonic seal, when compared to the previously recorded pattern of the same seal, is used to confirm the identity of the seal. Previously, such comparisons or correlations were pei-formed in the time frame or special configuration unique to the seal. The random start feature of the VAKIII seal required a different approach. The approach chosen was to employ the Fourier transform of the acoustic pattern obtained by the seal pattern reader, rather than the special pattern as it was read, in this case. Other applications of this aproach are presented.