Analysis of Pu isotopes in melted fuel by neutron resonance transmission; Examination by linear absorption model

Kitatani, Fumito  ; Harada, Hideo   ; Takamine, Jun ; Kureta, Masatoshi   ; Seya, Michio

Feasibility study of neutron resonance transmission analysis (NRTA) has been started to quantify nuclear materials in particle-like debris of melted fuel formed in severe accidents of nuclear reactor such as Fukushima Daiichi Nuclear Power Plants. The achievable measurement accuracy was examined by NRTA using a linear absorption model for the sample in which substances other than nuclear fuel materials, such as boron, were contained. In this study, boron and iron were considered to be contained in spent nuclear fuel as impurities. The neutron flight path is 5 m, that is the length between the neutron source and a neutron detector. Neutron absorption spectra were calculated using the total neutron absorption cross-section by JENDL-4.0. The absorption spectra together with their errors were evaluated. The achievable accuracy of Pu isotopic density was deduced as a function of neutron intensity and impurity density. This research was supported by JSGO/MEXT.