Use of autoradiography for checking plutonium enrichment and agglomerates in mixed-oxide fuel pellets inside welded fuel pins

Abstract

Autoradiography of nuclear fuel pins containing uranium-plutonium mixed-oxide pellets has been tried as a simple and inexpensive non-destructive technique for assessing plutonium enrichment and detecting the presence of plutonium agglomerates, if any, in the pellets. The optical density of autoradiographs obtained by placing industrial X-ray films in contact with a fuel pin containing pellets of varied PuO2 content has been correlated with the plutonium enrichment of the pellets. Autoradiographs of plutonium agglomerates varying in size from 125 to 2000 μm incorporated in pellets with a nominal composition of UO2 - 4 %wt PuO2 inside welded fuel pins have been analysed. This paper describes the techniques used and the results obtained.