Critical Measurements on Near-Homogeneous BeO—Moderated, Enriched-Uranium Fueled Systems

A series of critical measurements on unreflected systems, fueled by thin enriched uranium (93.2%) foils, is described. Fuel density is varied by use of different foil thicknesses and spacings between foils. Five fuel densities have been used which correspond to atomic BeO/U²³⁵ ratios from 246 to 7660. For three of these ratios, the fuel foil thickness was varied to find effects of self-shielding and flux depression on the critical dimensions.