Remote metallographic examination of mixed carbide fuel of fast breeder test reactor in radiometallurgy laboratory

Fast breeder test reactor (FBTR) uses unique, indigenously developed mixed carbide of plutonium and uranium (70% PuC + 30% UC) as fuel. The performance of the fuel was studied at different burn-ups by carrying out post-irradiation examinations (PIE) to facilitate prediction and extension of life for the indigenously developed fuel. As a part of PIE, remote metallography was carried out to study the swelling behaviour of the fuel, estimate the fuel-clad gap and examine the fuel and clad microstructures. Results of the metallographic examinations were used to increase the limit of FBTR fuel burn up and linear heat ratings. This paper describes in detail the remote metallographic techniques adopted during PIE of fuel after a burn-up of 25 GWd/t and 50 GWd/t.