Development of 3-D parallel first-collision source method for discrete ordinate code JSNT-S

Abstract

A new three-dimensional parallel first-collision source code named JSNT-FCS is developed to alleviate the ray effect in discrete ordinate method. JSNT-FCS applies the ray trace method to obtain uncollided flux both for the Cartesian and cylindrical geometry. Parallel calculation is implemented based on spatial domain partition algorithm. The ray trace is performed in each domain based on the entire meshes to avoid parallel communication between domains. To decrease the error of FCS method, source region is automatically refined. The reflection boundary condition is handled by adding a symmetric source region at the opposite side of reflection boundary. Several benchmarks are calculated, and all results of calculation prove that the accuracy of JSNT-FCS is high enough. Response calculation of source range detector is performed based on the geometry of HBR-2, and the calculation results indicate that JSNT-FCS code can effectively eliminate the nonphysical oscillations of flux spatial distribution.