Application of Three-Dimensional Discrete Ordinatesand Monte Carlo Coupling Method on Fast Neutron Fluence Rate Calculation

A three-dimensional discrete ordinates and Monte Carlo coupling method（the SN-MC coupling method） is applied on Pressurized Water Reactor（PWR） pressure vessel Fast Neutron Fluence rate（FNF） calculation, and the results of the SN-MC coupling method are compared with those of the discrete ordinates method（the SN method）, the Monte Carlo method（the MC method） and the measurements. Numerical results show that the difference between the calculated FNF by the SN-MC coupling method and the measured FNF are less than 20%, which satisfies the requirement of the difference for FNF calculated methods in Regulatory Guide（RG） 1.19 promulgated by Nuclear Regulatory Commission（NRC）. The speed of the SN-MC coupling method is 2~10 times faster than that of the MC method when the two methods obtain the same tally errors.