Analysis of Pressurized Water Reactor Pin-by-pin Homogenization

Homogenization performances for pin cells in 2D geometry are analyzed in order to facilitate pin-by-pin core calculation. There are different choices for spatial homogenization, energy homogenization and the corresponding core calculation methods. Two spatial homogenization methods were investigated including the generalized equivalence theory (GET) and the super-homogenization (SPH) method. Energy groups were condensed from the 69 WIMS-D4 structure to either 2 or 7 together with spatial homogenization. Both P1 and SP3 were employed as pin-homogenized core calculation methods. The pin-homogenized core calculation results were compared with the original heterogeneous core calculation. In addition, the traditional two-step calculation with assembly homogenization and pin-power reconstruction was employed as a comparison. The numerical results revealed encouraging conclusions. (1) The pin-by-pin calculation scheme can provide more accurate results than the traditional two-step calculation. (2) Different spatial homogenization techniques can provide results with similar accuracy. (3) Energy groups has to be increased together with spatial homogenization zone refinement.