Evaluation of temperature-dependent critical experiments at the Walthousen reactor critical facility for benchmark development

Abstract

Development of benchmark libraries based on accurate experimental measurements is crucial for validation of computational toolkits in nuclear reactor design and analysis. A benchmark library is developed based on the low-power isothermal critical experiments conducted at the Walthousen Reactor Critical Facility ranging in temperatures between 16 and 46 Celsius. Sensitivity analysis was performed to evaluate uncertainties in reactivity and its temperature coefficient due to core geometry, material composition, and temperature based on the temperature-dependent experimental data. A comprehensive sensitivity study of the effect of nuclear data on criticality was also performed. The total combined uncertainty in criticality of the benchmark model due to geometry and material parameters is determined to be 144 pcm. Prediction of criticality from sample calculations lies within the benchmark model combined uncertainty from measurements, demonstrating the acceptance of these datasets for use as a benchmark for validation of simulation toolkits and evaluation of nuclear data libraries.