Molecular dynamics simulation of the thermal properties of minor actinides-containing mixed oxide fuels

マイナーアクチニド含有酸化物燃料熱物性のモデリング及びシミュレーション

黒崎 健*; 片山 将仁*; 安達 淳*; 宇埜 正美*; 三輪 周平  ; 逢坂 正彦  ; 田中 健哉; 山中 伸介*

Kurosaki, Ken*; Katayama, Masahito*; Adachi, Jun*; Uno, Masayoshi*; Miwa, Shuhei; Osaka, Masahiko; Tanaka, Kenya; Yamanaka, Shinsuke*

マイナーアクチニド(MA)を0-15%含有する混合酸化物(MOX)燃料の分子動力学計算を実施し、格子定数,熱容量及び熱伝導率を評価した。熱伝導度の計算値は、計算した温度・MA組成範囲においてほぼ一定であったことから、15%までのMA添加においてはMOX燃料の熱伝導度はその影響をほとんど受けないことが示された。本研究により、本手法はMA含有MOX燃料の熱物性予測評価に有効であることがわかった。

The molecular dynamics (MD) calculations were performed on MA-containing mixed oxide (MOX) fuels; in this case MA = Np and Am. The lattice parameter, heat capacity, and thermal conductivity of the MA-containing MOX fuels were evaluated and the effects of the MA content on the properties were studied. The calculated lattice parameter increased with temperature and varied linearly with the MA content. The calculated thermal conductivity data were comparable in MOX at any temperature and any x value, indicating that the thermal conductivity of MA-containing MOX fuels is scarcely influenced by adding MA up to 15 %. This result seems to be reasonable because both the mass and size differences between the ions of uranium and neptunium and/or americium are very small. The present study showed that the MD calculation can be usefully applied to determine the thermal properties of the MA-containing MOX fuels.