Evaluation of accompanying behavior of fission products with nuclear materials for the establishment of nuclear material accountancy method using passive gamma-ray spectrometry

Fukushima Project Team, Oarai Research and Development Center

The passive gamma-ray spectrometry of the fuel debris is under development as one of the candidate technologies for nuclear material accountancy in 1F Nuclear Power Plants. Based on the results of TMI accident, Eu and Ce were selected as the candidates of monitored gamma-ray emitters which were accompanied with nuclear material. The accompanying behavior of Ce with nuclear material under the severe accident was investigated by the high temperature heating test and the chemical equilibrium calculation. The high temperature heating test was carried out under the simulated condition of severe accident that the irradiated fuel was liquidized by the high temperature reaction with molten zircaloy. Ce was found to exist in high concentration at the boundary of reaction between fuel and molten zircaloy.