APPROXIMATE SOLUTIONS OF THE TWO-DIMENSIONAL INTEGRAL TRANSPORT EQUATION BY COLLISION PROBABILITY METHODS.

A set of approximate solutions for the isotropic two-dimensional neutron transport problem has been developed using the interface current formalism. The method is applied to regular lattices of rectangular cells containing a fuel pin, cladding, and water, or homogenized structural material. The cells are divided into zones that are homogeneous. A zone-wise flux expansion is used to formulate a direct collision probability problem within a cell. The coupling of the cells is effected by making extra assumptions on the currents entering and leaving the interfaces. Two codes have been written: The first uses a cylindrical cell model and one or three terms for the flux expansion, and the second uses a two-dimensional flux representation and does a truly two-dimensional calculation inside each cell.