Irradiation Testing of Structural Materials in Fast Breeder Test Reactor

Fast Breeder Test Reactor (FBTR) at Kalpakkam, India is a sodium cooled fast reactor with neutron flux level of the order of 1015 n/cm2/s and temperature of coolant in the range of 600-720K (330-450°C), which is being used for the development of fuel and structural materials required for Indian Fast Reactor Programme. Irradiation performance testing on structural materials is being carried out by subjecting prefabricated specimens to desired experimental conditions as part of planned irradiation experiments, and by testing of material samples sourced from actual fuel clad tubes / fuel assembly wrapper tubes irradiated to various fuel burn up levels in FBTR. Pressurised capsules of Zirconium alloys and D9 alloy (modified stainless steel type 316 with controlled additions of titanium and silicon) have been developed to determine the in-reactor creep performance of indigenously developed zirconium alloys and D9 alloy. Pressurised capsules made of zirconium alloys were subjected to fluence levels up to 1.1 x 1021 n/cm2 (E> 1 MeV) in FBTR at temperatures of 579 to 592K and diameter measurements were carried out in the hot cell facility to determine the irradiation creep rate. Pressurised capsules of D9 alloy are currently undergoing irradiation at a temperature of 623K in FBTR along with small size tensile test specimens and shear punch test specimens of D9. Non-instrumented gas-gap type irradiation capsule has been developed to achieve higher irradiatio