The Influence of porosity on thermal conductivity of low-density uranium oxide

Morimoto, Kyoichi ; Ogasawara, Masahiro*

In MOX fuel fabrication, the mitigation of specifications on fuel design is considered from a viewpoint of improvement of economic efficiency. As the one of the mitigations of specifications, the tolerance expansion of the density specification is considered. In this consideration, it is necessary to confirm the applicability of the porosity correction equation to the thermal conductivity in a low density region. In this study, UO pellet was adopted as test specimen for the following reasons. The stability of O/M ratio of UO pellets in the thermal conductivity measurement is superior to that of MOX pellets. The densities of the specimens were adjusted in the wide range by using crystalline cellulose. The thermal conductivities of these specimens were measured and the applicability of the porosity correction equation to the thermal conductivity in a low density region was evaluated.