Thermal expansion of TRU nitride solid solutions as fuel materials for transmutation of minor actinides

Takano, Masahide ; Akabori, Mitsuo; Arai, Yasuo; Minato, Kazuo 

Lattice thermal expansions of the TRU nitride solid solutions were measured to investigate the composition dependence. The single phase solid solution samples of (NpAm)N, (PuAm)N, (NpPuAmCm)N and (PuAmZr)N were prepared by carbothermic nitridation of the respective TRU dioxides and nitridation of Zr metal through hydride. Lattice parameters were measured by the high temperature X-ray diffraction method from room temperature up to 1478 K. The average thermal expansion coefficients over the temperature range of 293 to 1273 K for the solid solution samples were 10.1, 11.5, 10.8 and 8.810 K, respectively. Comparison of these values with those for the constituent nitrides showed that the average thermal expansion coefficients of the solid solution samples could be approximated by the linear mixture rule within the error of 2-3%.