A new approach for the solution of multi-dimensional neutron kinetics equations in LWR's

The intent of this study is to develop an efficient calculation method which can be used to analyze the heterogeneous time-dependent reactor problems. By using the nodal theory one can not only reduce the calculational efforts, but accurately determine the group dependent flux densities averaged over the entire homogeneous nodes. This method uses correction factors(called 'discontinuity factors') in a rigorous manner to obtain the relationship between the node-averaged flux and the surface-averaged fluxs and currents. The discontinuity factors are calculated from the node-averaged fluxes, diffusion coefficients, and the discontinuity factors of the previous time step. The test results for two benchmark problems demonstrate the accuracy and efficiency of the method developed for the transient application in which assembly-size nodes can be used. (Author)