Critical Experiments and the 2200 m/sec Neutron Parameters

The analysis of critical volumes of aqueous homogeneous solutions of uranium to aid in defining the 2200 m/sec neutron parameters for ENDF/B has been examined. The parameters for ²³³U and ²³⁵U are constrained by relating to the constant K obtained from the analysis of the critical systems. Here K is directly proportional to the hydrogen capture cross section at 2200 m/sec. This Note suggests that the capture cross section of hydrogen be removed from K and that a new constant K/σ_aH be defined by the critical systems. This new constant is the hydrogen-to-uranium ratio for an infinite critical system populated with neutrons having a Maxwellian energy distribution.