Restructure behavior analysis in fast breeder reactor MOX fuel by X-ray CT

X線CTによるFBR MOX燃料の組織変化挙動解析

石見 明洋 ; 勝山 幸三 ; 古屋 廣高*

Ishimi, Akihiro; Katsuyama, Kozo; Furuya, Hirotaka*

高速実験炉「常陽」にて高・低密度MOX燃料ペレットを照射した。照射後、X線CT撮像を実施し、中心空孔の形成挙動について評価した。本評価では、中心空孔径と照射初期、末期における燃料ペレット温度を解析した。低密度燃料ペレットの中心空孔は、同じ線出力で照射された高密度燃料ペレットと比較して大きいことが分かった。また、中心空孔が形成された線出力と温度は、高密度燃料と比較して低密度燃料が低いことが分かった。

Both high and low density MOX fuel pellets of uranium and plutonium oxides were irradiated in the experimental fast reactor JOYO. After irradiation, these fuel pellets were examined by X-ray CT and their irradiation behavior was evaluated for formation of the central void. In particular, the central void size and temperature of fuel pellets at the beginning and end of irradiation were analyzed. The central voids in the low density fuel pellets were bigger than those of the high density fuel pellets at the same linear heating rate (LHR), and the threshold LHR and temperature at which the central voids were formed were lower than those of the high density fuel pellets. It was understood from these results that the irradiation behaviors of high and low density fuel pellets were different.