Autoradiographic inventory methods

Described are autoradiographic techniques which can verify the number and SNM content of plutonium- and uranium-containing fuel elements. These techniques are applied to fast critical assembly fuel elements and to low-enriched uranium in LWR fuel assemblies. Autoradiographic images are formed by the spontaneously emitted X- and gamma-rays from the fuel elements striking X-ray film in contact with the fuel elements of their containers. Autoradiography allows a large number of items to be examined in a minimum inspection time and with minimum effect on the facility. Results are presented for fast critical assembly fuel in a variety of storage modes as well as in fast critical assemblies themselves. Results are also presented for low-enriched uranium rods in unirradiated LWR fuel assemblies. In all cases, missing fuel elements or substitution of elements containing inert material or depleted uranium were detected. (author)