A Behavior of O/M Ratio and Its Effect for Material Accountingin High Plutonium Concentration MOX Fabrication Process (2)

A behavior of Oxygen to Metal ratio (O/M ratio) is an important element to manage in MOX fabrication process. In particular, high plutonium concentrated MOX powder may affect material accountancy because the weight of MOX powder and its plutonium concentration are changeable by its decay heat. The studies on the behavior of O/M ratio in the MOX powder using pure PuO, powder as feed material had been therefore carried out in the Plutonium Fuel Production Facility (PFPF) FBR line before and those results \\?rere already reported at the INMM 37th annual meeting. Following to the previous studies, several examinations on an co-converted MOX powder which is another feed material into the PFPF process have been conducted. The drift of O/M ratio for the co-converted MOX powder was confirmed, and the results showed different tendency from the previous studies. Furthermore, a distribution of O/M ratio in the MOX powder accommodated in a container becomes slightly non-uniform because the temperature of the MOX powder depends on its position in the container. Taking this non-uniformity into account, a sample taking procedure to have more accuracy was considered. This paper summarizes the results of these examinations.