Development of Fuel Failure Detection System for a High Temperature Gas Cooled Reactor

A high-sensitive fuel failure detection (FFD) method for a high-temperature gas-cooled reactor has been studied. A FFD system was developed and tested using an irradiation rig of the JMTR. A special irradiation capsule which contains both intact fuels and failed fuels of coated fuel particles was loaded in the irradiation rig. The primary helium gas with fission products was led to the FFD system. The response of the FFD system and the behaviors of gaseous fission products released were compared the failed fuels to the intact fuels in the various operation conditions. Counting rates of the FFD system due to the fission products released from the both fuel samples showed different behaviors at the fuel temperature over 1200 C. Gamma-ray spectra of the primary helium gas were also monitored for identification of the nuclides.