Experience with fuel handling system of FBTR

Fast Breeder Test Reactor (FBTR) is a 40 MWt.13.2 MWe sodium cooled mixed carbide fuelled reactor. Fuel handling in FBTR is a group of operations, consisting of charging of fresh fuel, and discharging of irradiated fuel from the reactor. These operations were done with the help of charging and discharging flasks. There is a provision for in-pile transfer of subassemblies using transfer flask. Transfer of subassemblies is done for storage of irradiated fuel subassemblies in periphery for cooling, prior to discharging. During fuel handling, to provide guiding the gripper tube a guide tube of about 6 m long is introduced in to the fuel-handling canal. To approach any position in the grid plate, a system of two rotatable plugs, located eccentric to each other and a fuel-handling canal located in smaller plug is used. Fuel handling is carried out with the reactor in shut down state. In May 1987 during fuel subassembly transfer operation from core to periphery, an incident of jamming of the fuel sub-assembly in fuel handling guide tube was encountered. This paper summarizes the activities carried out to normalize the fuel handling system after the fuel handling incident, modifications carried out and experience with the fuel handling system since then. (author)