Development of fission gas measurement technique in the irradiated fuel pellet

Hatakeyama, Yuichi; Sudo, Kenji; Kanazawa, Hiroyuki

The amount of fission gas (Kr, Xe) in irradiated fuel pellet increases with extending the burn up and that exerts a serious influence upon thermal and mechanical properties of light water reactor fuel. Therefore, the accumulation of the data on the release behavior of fission gas is important in the investigation program of safety and reliability for extended burn up fuel. In the post irradiation examination at the Reactor Fuel Examination Facility in JAERI,the fission gas which released into the plenum region from UO pellet during irradiation has been measured by puncturing test of irradiated fuel rod. The results of puncturing test show the most of fission gas remained in the pellet. It can be seen that the additional release of fission gas might occur under higher burn up and accident conditions. To know the fission gas release behavior from irradiated fuel, the Out Gas analyzer(OGA)which has the performance to heat up the UO pellet stepwise up to 2300C and to measure the released fission gas instantly from the pellet has been developed and installed at RFEF.