Preliminary evaluation of the Compact Nuclear Power Source (CNPS) critical experiments as a VHTR physics benchmark

An evaluation of the Compact Nuclear Power Source (CNPS) experiments conducted at the Los Alamos National Laboratory (LANL) in the 1980's has been done using information available in the open literature. The Monte Carlo results for critical test configurations have been quite good with keff values within 0.5% of the critical value of unity. The calculated total and differential rod and material worths were found generally close to measurement values. The lack of information on design data uncertainties and the inconsistency in the design data from different sources make it difficult to quantify the uncertainty in the core integral parameters arising from data uncertainties. The evaluated configurations could however be useful as numerical benchmarks that are based on the currently available information. (authors)