Microstructural evaluation of thermal and fast reactor fuels

Radiometallurgy Division has been entrusted with the task of developing plutonium based fuels for different type of reactors. Microstructural evaluation using the optical microscope has been effectively employed for the characterization of various ceramic and alloy fuels. Metallography of these fuel materials are carried out in specially designed alpha leaktight glove boxes. Standard ASTM metallographic practices have been adopted for the preparation of these fuels. These specimens have been examined microscopically for the pore shape, size and distribution, average grain size, presence of inclusions and second phase. Chemical and cathodic etching methods are adopted for revealing the grain boundary structure. Evaluation of these parameters play an important role as the microstructure of the fuel dictates the fuel performance. This paper summarizes typical microstructures of different fuels of the following reactors: 1) PURNIMA (PuO2), 2) FBTR (Pu,U)C, 3) BWR (4%PuO2-UO2), 4) AHWR (ThO2-4%PuO2), 5) KAMINI (UAl, PuAl alloys). (author)