[en] In our conditions, having available the computers of medium-size capabilities only, the easiest way to obtain faster and more accurate results in nuclear reactor calculations is to apply more efficient numerical methods. The principal goal of these methods is to reduce the number of degrees of freedom (the number of unknowns) in the problem, and still retain sufficient accuracy. A new method for multidimensional diffusion calculations of nuclear reactors is developed and presented in this paper. On the basis of a priori implemented geometrical properties in the approximate solution, in this method the solution of diffusion equation can be obtained with a drastically reduced number of unknowns compared to the other methods. (author)