isotopic constituency 基本例句 同位素成分 Since Monte Carlo code cannot be applied to calculate the isotopic composition of burned fuel, a new algorithm combined with the depletion code is proposed to calculate burnup.针对蒙特卡罗程序不能计算燃料的同位素成分变化,提出将它和燃耗计算程序耦合以完成燃耗计算。