New Approximations of Anisotropic Scattering in Neutron Transport and Diffusion Equations

A systematic approach to the problem of defining effective scattering cross sections for neutron diffusion equations is presented. In our analysis, anisotropic scattering of the second order is assumed for the one-speed transport equation, and criterion of preserving both the diffusion length and the total absorption serves as a basis for the derivation of effective isotropic scattering cross sections for both transport and diffusion equations.