Evaluation of micro-homogeneity in plutonium based nuclear reactor fuel pellets by alpha-autoradiography technique

Alpha-autoradiography is a fast and non-destructive technique which is used at Advanced Fuel Fabrication Facility (India) to evaluate micro-homogeneity of plutonium in uranium and plutonium mixed oxide (U–Pu)O₂ fuel pellets fabricated for both thermal and fast breeder reactors. In this study, various theoretical calculations to understand effect of alpha autoradiography process parameters and limiting conditions for measuring micro-homogeneity of plutonium in the pellets having different concentrations of plutonium were reported. Experiments were carried out to establish the procedure to evaluate micro-homogeneity of plutonium in (U-x%Pu)O₂ pellets where x varies from 0.4 to 44% and to measure the size of agglomerates, if any, present in the pellet. An attempt had been made to measure plutonium content in the agglomerate using alpha-autoradiography. This study can also be useful for carrying out alpha-autoradiography of spent fuel pellets during post-irradiation examination. - Highlights: • Alpha-Autoradiography of (U–Pu)O₂ oxide pellet having 0.4–44% PuO₂ was done. • Exposure and etching time required for alpha-autoradiography was optimized. • Size of Pu agglomerate was measured using micro-homogeneity profiling.