Thermal expansion of TRU nitrides as the fuel materials for transmutation of minor actinides

マイナーアクチノイド核変換用燃料材料である超ウラン元素窒化物の熱膨張

高野 公秀 ; 赤堀 光雄; 荒井 康夫; 湊 和生 

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

マイナーアクチノイド核変換用燃料材料の物性データベース構築の一環として、超ウラン元素窒化物の熱膨張を高温X線回折法により測定した。まず、単元素窒化物のNpN, PuN及びAmNの格子定数の温度依存性を測定し、線熱膨張を温度の関数として定めた。293Kから1273Kまでの平均線熱膨張係数は、それぞれ8.8, 11.1, 11.210Kであった。次に、窒化物固溶体試料である(Np,Am)N, (Pu,Am)N, (Np,Pu,Am,Cm)N及び(Pu,Am,Zr)Nについて測定を行い、熱膨張の組成依存性を検討した。その結果、これら窒化物固溶体の平均線熱膨張係数は、各成分窒化物の値から線形混合則で近似でき、その誤差は23%以内であることを明らかにした。

As the research activities concerning the nitride fuel for the transmutation of minor actinides, the lattice thermal expansions of the transuranium nitrides were investigated in order to build the material database. The lattice parameters of NpN, PuN and AmN were measured by the high temperature X-ray diffraction method from room temperature to 1478 K. Their linear thermal expansions were determined as a function of temperature. The average thermal expansion coefficients over the temperature range of 293 to 1273 K for these nitrides were 8.8, 11.1 and 11.210 K, respectively. Further, the thermal expansions of the nitride solid solution samples, (Np,Am)N, (Pu,Am)N, (Np,Pu,Am,Cm)N and (Pu,Am,Zr)N, were measured to investigate the composition dependence. It was confirmed that the average thermal expansion coefficients for these solid solution samples could be approximated by the linear mixture rule within the error of 23%.