A new approximation method for solving three dimensional neutron diffusion equation by neutron leakage iteration technique

A new computation method named ''Leakage Iteration Method'' has been developed for calculations neutron flux in large nuclear reactors with small computer core memory and short computing time. In this method, a reactor core is devided into channels and layers and three dimensional neutron flux in the core is obtained by interating one dimentional channel and two dimensional layer calculations one after the other as intermediation of neutron leakage. For developing this method, fundamental equations, convergence criteria for the iteration were introduced and the factors affecting the convergence were cleared up. By this method, a standerd three dimensional diffusion code named DIFFUSION-ACE has been developed with one and two dimensional finite difference method, and a few computer codes have been also developed for analysing light water power reactors and research reactors. Comparing the computed results by this method with those of detail computer codes or measured data, the effectiveness of this method for analysing the above mentioned type reactors was shown. (author)