Monte Carlo Few-Group Constant Generation for CANDU 6 Core Analysis

The current neutronics design methodology of CANDU-PHWRs based on the two-step calculations requires determining not only homogenized two-group constants for ordinary fuel bundle lattice cells by the WIMS-AECL lattice cell code but also incremental two-group constants arising from the penetration of control devices into the fuel bundle cells by a supercell analysis code like MULTICELL or DRAGON. As an alternative way to generate the two-group constants necessary for the CANDU-PHWR core analysis, this paper proposes utilizing a B1theory augmented Monte Carlo (MC) few-group constant generation method (B1MC method) which has been devised for the PWR fuel assembly analysis method. To examine the applicability of the B1MC method for the CANDU 6 core analysis, the fuel bundle cell and supercell calculations are performed using it to obtain the two-group constants. By showing that the two-group constants from the B1MC method agree well with those from WIMS-AECL and that core neutronics calculations for hypothetical CANDU 6 cores by a deterministic diffusion theory code SCAN with B1MC method generated two-group constants also agree well with whole core MC analyses, it is concluded that the B1MC method is well qualified for both fuel bundle cell and supercell analyses.