A novel reactivity-equivalent physical transformation method for homogenization of double-heterogeneous systems. (July 2020) - Lou, Lei
Highlights: The traditional RPT method has been studied and verified for its effectiveness and limitations. An novel method named Ring RPT method for Double-heterogeneous system is developed. The Ring RPT method has wider scope of usage and higher accuracy than traditional RPT method. Abstract: Because of the double heterogeneity of dispersed particle-type fuel and burnable poison, the traditional volumetric homogenization method (VHM) on double-heterogeneous (DH) systems will bring unacceptable calculation deviation, and then Reactivity-Equivalent Physical Transformation (RPT) method is introduced to transform the DH systems into single-heterogeneous systems which can be modeled by traditional reactor physical calculation programs. In this paper, it's pointed out that RPT method becomes invalid for some DH systems with dispersed particle-type burnable poison whose absorption cross section is very large but the absorption cross section of whose depletion child nuclides is very small, and large reactivity deviation will appear during the depletion. After an analysis and extension of the RPT method, a novel RPT method named Ring RPT method is born. Results of depletion calculations for different types of dispersed particle-type fuel and burnable poisons and the comparison with Monte Carlo results of grain models prove the validity of Ring RPT method, preliminary conclusion can be obtained that Ring RPT method has wider scope of usage and higher accuracy than traditional RPT method.