DESCRIPTION OF CRITICAL EXPERIMENTS IN SPHERICAL GEOMETRY CONTAINING UO2F2 SOLUTION

Hundreds of criticality experiments were performed at Oak Ridge Nation al Laboratory in the 1950s. Several sets of these experiments were use d to determine the critical properties of U-233 and U-235. Here, four sets are analyzed to provide benchmark descriptions for validation of computational tools used by nuclear criticality specialists, All four sets were performed in water-reflected spherical geometry and containe d a highly enriched uranyl fluoride solution (93.18% U-235) With the h ydrogen-to-fissile ratio of measurements ranging from 35.8 to 1272. Th e scope of these experiments spans the minimum values of the subcritic al mass limit curve, One experiment was never reported in the open lit erature, and three experiments were performed at elevated temperatures . An uncertainty in the experimental k(eff) was found by sensitivity s tudies on reported measurement uncertainties, inconsistencies, and omi ssions in experimental parameters. To be useful for all computer codes , one-dimensional benchmark configurations were determined for all set s of experiments, The descriptions can be used to find bias values for a code/cross-section package, The k(eff) values for similar configura tions can then be corrected using the bias values, The sensitivity ana lysis of the experiments was performed using ONEDANT with 27-group END F/B-IV cross sections and MCNP with continuous-energy ENDF/B-V cross-s ection data. The k(eff) values for both one-and three-dimensional conf igurations were found using MCNP with ENDF/B-V and ENDF/B-VI cross-sec tion data, The values for k(eff) for the one-dimensional configuration were also found by using ONEDANT and KENO V.a with Hansen-Roach and 2 7-group ENDF/B-IV cross sections.