Critical Experiments with Interstitially-Moderated Arrays of Low-Enriched Uranium Oxide. Topical Report on Reference Critical Experiments

摘要

The critical separation between two tables supporting arrays of cans containing low-enriched uranium oxide has been measured for twenty-one (21) reflected configurations having interstitial layers of moderating material between cans. The critical separation varied between 0.23 and 1.84 cm. The uranium oxide (U3O8) is enriched to 4.46% 235U, compacted to a density of 4.7 g/cu cm, and adjusted to an H/U atomic ratio of 0.77 by the addition of water. Each can weighs 16 kg and is a 15.3 cm cube. Interstitial plastic moderator 1.0, 1.3, or 2.5 cm thick separates cans of the three-dimensional array. Some experiments include thin sheets of neutron absorbing materials, such as mild steel or polyvinyl chloride, surrounding each can.