Development of mechanistic fuel property model and irradiation behavior analysis code for mixed oxide fuel

Ikusawa, Yoshihisa   ; Ozawa, Takayuki   ; Kato, Masato   

MOX is one of the most typical nuclear fuel. MOX fuel is divided into two categories. One is low Pu contained MOX fuel, which is used in light water reactors, with Pu content of less than 15 wt%. The other is high plutonium contained MOX fuel, which is used in fast reactors, with Pu content of more than 20 wt%. The physical properties of MOX fuel are depended on Pu content. In addition, the irradiation behavior of MOX fuel is significantly different between LWRs and FRs due to the difference in these operating environments. Therefore, various studies of MOX fuel have been conducted separately for LWR and FR. In our facility, MOX physical properties, such as thermal conductivity, melting point, and specific heat, have been measured using various MOX fuel samples. Based on these measurements, a mechanistic MOX fuel property model has been developed. This model can evaluate the physical properties of MOX fuel for any specification. Irradiation behavior analysis codes developed based on this property model might have the potential to be a general-purpose code that can evaluate the behavior of any MOX fuel. In this study, as a first step of development of a general-purpose irradiation behavior analysis code, the fuel temperature analysis function of the irradiation analysis code "DIRAD" was confirmed by using the data of high Pu contained MOX fuel irradiated in JOYO and low Pu contained MOX fuel irradiated in Halden. As the result, it was confirmed that the fuel temperature of low to high Pu contained MOX fuel could be evaluated by using DIRAD code adopting the property model.