Benchmark Experiments/Calculations of Neutron Environments in the Annular Core Research Reactor

Abstract

Benchmark experiments using spherical test objects were performed in the central cavity of Sandia National Laboratories' Annular Core Research Reactor. The experiments were performed with 10.16 cm and 17.78 cm diameter aluminum (AI6061) and high-density polyethylene spheres that were essentially solid with cavities scrolled out along the equator to allow the insertion of activation foils and/or sulfur pellets. The neutron monitor foils were selected to cover a wide range of reaction energies. The reactor environments were modeled in detail using Monte Carlo N-Particle eXtended (mcnpx). The experimental results were compared to the Monte Carlo calculations of the reaction rates of each of the foils at various depths in the spheres produced by mcnpx. The comparison includes a complete treatment of the uncertainties.