Automatic generation method for right window parameter based on free path pretreatment

The present invention discloses an automatic generation method for right window parameter based on free path pretreatment. The method comprises: firstly performing pre-simulation transport according to distribution and location of a radiation source and geometric complexity of problem space, and performing statistics to obtain the free path with the change of particle type, energy and material change; then automatically and effectively dividing a right window mesh boundary in the entire model space by a mean value of the free path obtained by calculation; and finally, performing simulation transport again to generate a corresponding parameter value of minimum right window of mesh automatically, so as to ensure the particle to collide in each mesh for appropriate times. Therefore. the variance of an estimator is reduced, and the computational efficiency is improved. The method disclosed by the invention avoids using of an experience-based traditional variance reduction technique by manually dividing meshes to generate the minimum right window so as to achieve a fast and accurate calculation effect of radiation shielding.