Homogenization of the effective cross sections in a periodic lattice

A method of obtaining homogenized neutron cross sections for periodic reactor lattices in the P-1 approximation is described. Some general properties of the neutron distribution in an infinite lattice which do not depend on its specific structure are obtained using conditions of lattice periodicity and symmetry. E xpressions for the neutron distribution in a finite medium much larger than a separate cell are formulated. In this case the homogenized cross sections have proved to depend only on the neutron distribution in an equivalent cell. For the thermal energy range a description is given of the method developed to account for the simultaneously heteroaeneous and thermalization effects on the homogenized diffusion coefficient