Effective method for realization of generalized perturbation theory in the JARFS programme set

The report outlines an algorithm that uses effective calculation procedures to solve two- or three-dimensional diffusion equations for hexagonal geometric arrangement. Essentially, the algorithm is based on a generalized perturbation theory. The 'coarse mesh method' has previously been proposed for solving a multidimensional diffusion equation at a point in a hexagonal cell. It contains a term which accurately expresses the characteristics of neutron leak in the neiborhood of the cell. The algorithm has been developed by using such a neutron balance equation as above that incorporates an improved macroscopic constant. In the present study, the algorithm is applied to developing a set of programmes that are based on the generalized perturbation theory. A form of three-dimensional diffusion equation to be employed for calculation is derived and adjoint equations to be used in carrying out the generalized perturbation algorithm are described. Discussions are made on the stability of calculation results. Such stability evaluation is indispensable to determine the performance of a calculation procedure. Some calculation results for two- or three-dimensional breeder reactor models are presented and the performance of the calculation procedures are discussed. (Nogami, K.)