Improved cross-section modeling methodology for coupled three-dimensional transient simulations

The purpose of this paper is to introduce a more accurate and sophisticated methodology for use in three-dimensional coupled neutronic/thermal hydraulic analysis. The approach described in this paper is an original method of modeling cross-section variations for off-nominal core conditions, which is becoming an important issue with the increased use of coupled three-dimensional neutronic/thermal hydraulic simulations. This proposed method improves the accuracy of the cross-section modeling for transient applications and it is called the adaptive high-order table lookup method (AHTLM). During nuclear power plant (NPP) transient and accident simulations AHTLM interpolates into multi-dimensional cross-sections tables, which form a box envelope bounding the expected range of change of both nominal and off-nominal NPP conditions. This paper further addresses the methodologies for the development of the cross-section libraries and issues that affect the proper formulation of accurate data. The automated generation procedure outlined in this paper gives the user the tools and the ability of generating accurate cross-sections that cover a large range of thermal hydraulic parameters. Further improvements and expansions for future applications are also discussed.