Analysis of Cross-Section Condensation in PWR Simulations - 310

As computer power has improved in recent years, the nuclear industry has more powerful tools to solve large-scale reactor problems more effectively. Historically, due to limited computing power, has relied on multi-group nodal diffusion methods to solve whole-core problems, which requires cross sections to be homogenized over assemblies and collapsed into a coarse group structure (2-4 groups). However, increased computing power has generated an increased interest in the development of direct transport methods for whole-core analysis. Using continuous-energy or fine-group cross sections in whole-core transport is still beyond the capability of available computers, and in the development of whole-core transport methods, it is desirable to know the degree to which the collapsing of cross sections affects the solution. In this paper, an analysis of the effect of the collapsing procedure is presented for PWR assemblies, with the goal of determining the number of coarse groups necessary to effectively solve whole-core transport problems. (authors)