Efficient Dynamic Monte Carlo Simulation in Multi-Physics Coupling Calculation

If particle transport is included in some multi-physics calculation, Monte Carlo method is often used to simulate it and occupies the largest amount of calculation time. So, efficient dynamic Monte Carlo simulation for time-dependent particle transport problem is important, which is inevitably relied on large-scale parallel calculation. Two methods are proposed in this paper. The one is a tally-reduce algorithm which is used in the coupling of transport simulation and burn-up calculation. By reduces the amount of data which should be reduced necessary, this method can decrease the tally-reduce time largely. It can be seen as a new coupling mode for these two processes in MPI environment and will has larger value in cases when model scale is larger relatively compared to sample size. The other method is an adaptive method for setting the sample size of Monte Carlo simulation. Relying on the generalization of the Shannon entropy concept and an on-the-fly diagnosis rule for a entropy value sequence, the adaptive method proposed in this paper can decrease the original huge sample scale to a reasonable level. By numerical test for some non-trivial examples, both algorithms can decrease the calculation time largely while make the results almost unchanged.