Benchmark Calculations of the ESADA Single-Region Mixed-Oxide Critical Experiments

In 1967, a series of critical experiments were conducted at the Westinghouse Reactor Evaluation Center under the joint sponsorship of the Empire State Atomic Development Associates (ESADA) and Westinghouse using mixed-oxide (MOX) fuel. During the experimental program, both single- and multiregion critical core configurations were constructed for different fuel types and lattice pitches. Two types of MOX fuels and a low-enriched UO₂ fuel were used. A description of selected single-region ESADA experiments with criticality benchmark calculation results for those experiments as well as sensitivity analysis results on some configurations is given. Criticality calculations were performed using MCNP-4A with both ENDF/B-V and ENDF-B/VI cross-section libraries. The calculational results show that the calculated eigenvalues with ENDF/B-V cross-section libraries are higher than calculated eigenvalues with ENDF/B-VI cross-section libraries for all types of fuel. Calculational results also indicate that there is an increase in k_eff with increasing lattice pitch with both cross-section libraries. The uncertainties in k_eff value due to some uncertainties in the measured data are also calculated.