APPLICATION OF A DUAL VARIATIONAL FORMULATION TO FINITE-ELEMENT REACTOR CALCULATIONS

A number of improvements have been made to the nodal collocation metho d in order to obtain a high-order nodal technique capable of solving t he neutron diffusion equation over full-core three-dimensional pressur ized water reactors. First, the nodal collocation method is derived fo rmally from a dual variational principle, using Gauss-Lobatto quadratu res. Analytical integration and Gauss-Legendre quadratures are next ap plied to the same dual functional in order to obtain more accurate dis cretizations. An efficient ADI numerical technique with a supervectori zation procedure was set up to solve tile resulting matrix system. Val idation results are given for the IAEA 2-D, Biblis and IAEA 3-D benchm arks and for a typical full-core 3-D representation of a pressurized w ater reactor at the beginning of the second cycle.