Passage of reactor neutron radiation through non-hydrogenous media

An examination is made of the results of experimental and theoretical studies of the passage of neutrons through non-hydrogenous homogeneous materials and mixtures. The relaxation lengths obtained for neutrons of different energy groups are discussed. It is shown that, with certain assumptions, the magnitude of the attenuation of a flux of neutrons of the upper energy group (E_n ⩾ 3 MeV) in a non-hydrogenous medium can be obtained from fairly simple empirical expressions using wellknown constants: the removal cross section θ_rem, the cross section obtained from the inverse relaxation length (σ1/λ) and the asymptotic cross section. The values of these constants are given.