The Impact of americium target in-core loading on reactivity characteristics and ULOF response of sodium-cooled MOX FBR

Amターゲット炉内装荷がNa冷却MOX高速炉に及ぼす反応度特性及びULOF応答特性への影響

山路 哲史; 川島 克之; 大木 繁夫 ; 水野 朋保; 大久保 努

Yamaji, Akifumi; Kawashima, Katsuyuki; Oki, Shigeo; Mizuno, Tomoyasu; Okubo, Tsutomu

MA均質装荷炉心(3wt%MA)を参照炉心として、MAターゲット装荷法(20wt%MA)が炉心の反応度特性及びULOF応答特性に及ぼす影響を評価した。本研究のMAターゲット装荷法は、炉心径方向反応度分布を平坦化し、ULOF時の投入反応度を低減し、出力上昇速度を遅くできる。ターゲット領域の燃料最高温度は内側炉心のそれに比べて高くなることはなく、融点を十分に下回っている。このターゲット装荷法は炉心反応度特性及びULOF応答特性の観点から優れているといえる。

The homogeneous MA loading core with 3wt% MAs is used as a reference design to evaluate the impact of the americium target in-core loading (20wt% MAs) on reactivity characteristics and ULOF response of sodium-cooled MOX-FBR. The Am target loading method of this study can flatten core radial reactivity worth distributions and effectively reduce reactivity insertion into the core during ULOF. As the result, the core power increase speed during ULOF is reduced. The maximum fuel temperature of the target region does not become particularly high compared with that of the inner core and it is much lower than the melting point. It is promising from the viewpoints of the reactivity characteristics and ULOF response.