Study on Monte Carlo Variance-reduction Method Used for Maze Shielding Calculation

The forced pointing auto-importance sampling (FPAIS) method was presented using multiple variance-reduction methods in this paper, and was realized in MCNP5 code. This method was applied to the calculation of a multiple-bend maze example, and the calculation result was compared with natural Monte Carlo calculation, DXTRAN sphere and point flux methods using MCNP5 code. Besides, the sensitivity for setting the guiding surface and particle number of FPAIS method was analyzed with this example. The results show that the FOM of FPAIS significantly increases with 2.3 orders of magnitude compared with the other three methods in the premise of ensuring high calculation accuracy. FPAIS method is insensitive to the setting of the guiding surface and easy to use, and it is an accurate and efficient solution for the calculation of maze shielding.