Method of characteristics with a new Macro-track transport acceleration for complex general geometry

The method of characteristics is a flexible method in heterogeneous geometry and has been widespread use for reactor physics lattice calculation and whole core simulation. However, many acceleration methods commonly used in traditional lattice code and nodal method are not applicable to or inefficient to heterogeneous-geometry, high-dominance-ratio problems. This paper presents a new macro-track transport acceleration method which makes the acceleration without geometrical limitations a reality. The new macro-track transport acceleration method specially designed for the MOC does not use all the parallel tracks as macro-tracks and reduces the computational time without MOC sweeps increment. According to the parametric study, the maximum speedups of 38 relative to unaccelerated MOC transport sweeps and 16.7 relative to unaccelerated MOC runtime were achieved in the C5G7 2D problem.