[en] The SKI has from the Atomic Energy Research Establishment (AERE) at Harwell, U.K., acquired the computer model NAMMU for groundwater hydrology calculations. This code was first implemented on an AMDAHL 470, an IBM compatible computer, and then modified to get integrated with HYPAC which is a program package for pre- and postprocessing finite element data, development by KEMAKTA Consultants Co. The NAMMU code was then transferred to a CYBER 205 by Control Data AB. This report describes the implementation of HYPAC on CYBER 205, enhancement of NAMMU performance on CYBER 205 and a study of the influence of spatial discretization on groundwater flow calculations. (author)