To address the inefficiency inherent in traditional pressurized water reactor irradiation surveillance theoretical calculation methods, which require multiple physical modeling and particle transport calculations, this study introduces an accelerated approach of neutron fluence calculation for pressure vessel irradiation surveillance capsules. The method is based on the Forward-Weighted Consistent Adjoint-Driven Importance Sampling (FW-CADIS) technique, coupling the Monte Carlo (MC) method with the Discrete Ordinates (SN) method. A comprehensive investigation into the influencing factors of computational accuracy and speed was conducted for a CPR1000 pressurized water reactor, validating the applicability of the proposed method under various core parameters and providing recommended values for SN transport simulation parameters. Verification and validation of the proposed method were performed on a CPR1000 pressurized water reactor. The results show that the Figure of Merit (FOM) of neutron fluence rate calculations is improved by approximately 95 to 181 times compared with the direct MC method, with a relative deviation between the calculated neutron fluence and measured values not exceeding 8%. Consequently, the irradiation surveillance theoretical calculation method presented in this study effectively enhances computational efficiency while meeting the precision requirements for engineering applications. © 2024 Atomic Energy Press. All rights reserved.
