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

Ishimi, Akihiro ; Katsuyama, Kozo ; Miwa, Shuhei  ; Osaka, Masahiko  

The passive -ray spectrometry is under development as one of the non-destructive measurement for nuclear material accountancy for the fuel debris in the Fukushima-Daiichi Nuclear Power Station. In this technology, the amounts of nuclear materials are derived from the determined -emitting fission products by the -spectrometry by using predetermined relationships between FPs and the nuclear materials considering burnup, and so on. Based on the results of TMI-2 accident, Eu and Ce were selected as the candidate nuclides which are expected to accompany to nuclear material. The accompanying behavior of Ce to the nuclear material was investigated by the high temperature heating test and the chemical equilibrium calculation. This test was carried out under the simulated condition of severe accident that the irradiated fuel was liquefied by the high temperature reaction with molten zircaloy. Ce was found to exist in high concentration at the boundary of reaction layer between unreacted fuel and molten zircaloy.