Benchmark evaluation of interacting aluminum cylinders containing uranyl fluoride solution

The re-evaluation of a series of experiments is presented in the paper. The critical experiments, involving aqueous uranyl fluoride (UO2F2) solutions, filled in seven interacting cylinders, were performed in the Oak Ridge National Laboratory in 1955. A Monte-Carlo calculation model to be used with MCNP5 was now developed for the determination of the uncertainties and the effects of various uncertainties on the multiplication factor were studied. The evaluation of the benchmark was performed for validation of calculation techniques and comparison of calculation results with the experimental data.The sensitivity studies include parametric variations of material composition and geometry. The largest care was devoted to the determination of the U concentration levels in the fissile solution and its density since the original experimental data is scarce. Both parameters are also the biggest contributors to the overall uncertainty.

► Reevaluation of older unique experiments. ► Experiments originally performed in 1955, data is incomplete. ► Determination of true experimental conditions and lowering the total uncertainty. ► Successful re-evaluation of experiments – total uncertainty smaller than 1% in keff.