Reactor Critical Experiments at the Rensselaer Polytechnic Institute Reactor Critical Facility with Noteworthy Non-fissile Stainless Steel Elements Sensitivity

This paper describes critical experiments performed between 2016 and 2018 at the Rensselaer Polytechnic Institute (RPI) Reactor Critical Facility (RCF) and their potential for inclusion in the International Criticality Benchmark Evaluation Project (ICSBEP) handbook. The RCF is a pool-type reactor fueled with Special Power Excursion Reactor Test (SPERT)-type 4.807 wt% enriched UO2, stainless-steel-clad fuel rods. The RCF is highly flexible and was used to perform critical and reactor physics experiments involving a pipe composed of stainless steel placed at the center of the core, and a new 408 pin configuration was created to compensate for the reactivity loss. These critical experiments were already evaluated, and some experimental uncertainties were obtained by performing a thorough dimensional and material characterization of different components of the RCF associated with Monte Carlo calculations to determine the perturbation sensitivity and impacts of uncertainties on the keff. Based on these results, the RCF experiments show good potential as a benchmark for inclusion in the ICSBEP handbook. These fully characterized critical configurations will be evaluated and submitted for publication in the ICSBEP handbook, with potential cross listing in the International Reactor Physics Evaluation Project (IRPhEP) handbook of additional reactor physics experiments. The RCF is not currently evaluated in either handbook, so this evaluation would provide a new uncorrelated assembly for use in the validation of low enriched uranium applications and non-fissile structural materials such as stainless steel, recently highlighted as a need for fuel casks validation by the Organisation for Economic Co-operation and Development Nuclear Energy Agency.