Abstract
A new resonance calculation method, SDGM (Spatially Dependent Gray-Resonance-Shielding Method), is developed for calculating spatially dependent effective cross sections within fuel pellet. The present method has been implemented to GALAXY, which is the MHI's new lattice physics code. SDGM accurately generates burnup dependent radial power profiles within pellet. The formulation of SDGM is carried out by extending the resonance self-shielding method of GALAXY with the combination of Stoker-Weiss method and SDDM. If pellet is not sub-divided, SDGM is completely consistent with the method used in the basic design calculations of GALAXY. For verifications and validations of SDGM, Monte Carlo benchmark and post irradiation examination (PIE) analysis are carried out. In Monte Carlo benchmark, reaction rate distributions within pellet are compared between GALAXY with SDGM and continuous energy Monte Carlo code MVP. On the other hand, for the PIE analysis, burnup and nuclide composition distributions within irradiated UO2 pellet are compared between GALAXY with SDGM and measurements. From these calculations, the applicability of SDGM is totally confirmed. SDGM is so efficient and practical method for generating power profiles within pellet (used in fuel integrity evaluation), accurate neutronics analyses for fuel with spatially high gradient of neutron flux and nuclide compositions, etc.
