Evaluation of ENDF/B-IV

The recently released Version IV of ENDF/B was evaluated by calculating measured integral quantities for eighteen fast critical assemblies. The integral quantities investigated in this study were keff, central reaction rate ratios, and central reactivity coefficients. In addition, to determine how ENDF/B-IV compares with earlier cross section data, calculations were also performed using Versions I, II, and III of ENDF/B and the Bondarenko cross section set. The evaluation indicates that ENDF/B- IV does an excellent job of predicting criticality for a wide range of critical assemblies. However, effort is still required to resolve differences between measured and calculated central reaction rate ratios and to resolve the fissile fuel central worth discrepancy.