Uranium and Thorium Resources

Abstract

Glossary Cross section Probability of neutron interaction with a nucleus, expressed in terms of area, in units of barns (b). One barn equals 1.0 Â 10 À24 cm 2. Enrichment The fraction of an isotope, usually fissile 235 U, in a mass of uranium. Enrichment is commonly quoted as the weight percent of the particular isotope. Natural uranium has an enrichment of 0.711 wt%, commercial reactor fuel is 3-5% enriched, and depleted uranium is 0.2-0.3% 235 U. Enrichment tails (also depleted uranium) The uranium remaining after the enrichment of natural uranium into fuel, today about 0.3% 235 U and earlier 0.2-0.25% 235 U. Fractionation Crystallization from a magma in which the initial crystals are prevented from equilibrating from the parent liquid, resulting in a series of residual liquids of more extreme composition than would have resulted from continuous reaction [1]. Geoneutrino An electron antineutrino emitted within the Earth in the b-decay of 232 Th, 238 U, or 40 K and their decay product nuclei. Highly enriched uranium (HEU) Uranium containing more than 20 wt% 235 U. J th Joule (i.e., watt-second) thermal. One British thermal unit (BTU) equals 1,055 J th. Low-enriched uranium (LEU) Uranium containing less than 20 wt% 235 U. Log-normal distribution A distribution of the form f x ð Þ ¼ e À 1n x ð Þ 2