Fabrication, characterization and property evaluation of mixed carbide fuels for a test Fast Breeder Reactor

The Fast Breeder Test Reactor (FBTR) at Kalpakkam, India is operating successfully since October 1985 with high plutonium content hyperstoichiometic mixed carbide as driver fuel. The reactor was first made critical with a small core containing (Pu0.7U0.3)C fuel (MKI) and the core is now being progressively enlarged with addition of fuel containing (Pu0.55U0.45)C (MKII). Comparison of out-of-pile experimental data generated on thermal expansion, hot hardness, thermal conductivity, solidus temperature and fuel clad coolant chemical compatibility predicts similar in pile behaviour for both the fuels. Progressive post irradiation examination carried out on MKI fuel estimates a conservative burn up capability of 150 GW d t−1 for the fuel.