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作为三维全堆芯非均匀输运计算的基础,基于扩散近似提出了三维非均匀变分节块法,能够采用节块内部的等参有限元和节块轴向表面的分片常量精细描述燃料棒的非均匀几何结构,消除均匀化过程.同时,为了降低计算代价,相应地提出了平源加速方法(FS).数值结果表明,该方法具有可靠的精度,且FS能够在不影响精度的前提下有效地降低计算内存和计算时间.“,”As a foundation of three-dimensional whole-core heterogeneous transport calculation, a 3D heterogeneous variational nodal method is proposed, which employs iso-parametric finite elements within each node and piecewise constants along nodal interfaces to explicitly describe the pin-resolved heterogeneous geometry. This means full elimination of the homogenization approximation. Meanwhile, the flat source acceleration method is proposed accordingly to reduce the computational costs. Numerical results show that the method is accurate and the flat source region acceleration method can effectively decrease the memory storage and computational time without degrading the accuracy.