Extrapolation Distances and Diffusion Parameters via Pulsed-Neutron Analysis

Size-dependent extrapolation distances for pulsed-neutron experiments in light-water, spherical, non-multiplying systems have been determined by calculating the buckling in the B-1, 30-group approximation corresponding to a given decay constant. The decay constants for spheres of various radii were taken from an earlier work which reported 30-group S_n calculations of decay constants as a function of system radius. The same 30-group, B-1 method was also used to calculate pulsed-neutron-decay constants as a function of buckling over a wide range of buckling. The static or poisoning experiment inverse-relaxation length, as a function of concentration of a one-over-v poison, was also computed in the same approximation. The resulting data were combined and fitted to yield values of the neutron-diffusion parameters