A database for AVLIS - U method

Uranium enrichment is a critical step in transforming natural uranium into nuclear fuel to produce energy. Enrichment services are sold as separative work units (SWU), which represent the level effort required to increase the concentration of 235 U isotope in natural uranium. Higher levels of 235 U require more SWUs. Two technologies are currently used to commercially enrich uranium for nuclear power plants: gaseous diffusion and gas centrifuge. Both use UF6 as the chemical form of uranium for processing, in part because UF6 becomes readily a gas when heated. Both rely on the mass differences between 235 U and 238 U to achieve separation either through a semiporous membrane (diffusion) or by spinning at high speed (centrifuge). Enrichment accounts for about one third of the cost of nuclear fuel and about 10 % of the total cost of the electricity generated. Atomic vapor processes make use of photo-ionization whereby a powerful laser is used to ionize particular atoms present in a vapor of uranium metal. The positively charged 235 U ions are then attracted to a negatively charged plate and collected. The main molecular processes which have been studied are based on photo-dissociation of UF6 to solid UF5 by means of a tuned laser radiation as above. Any process using UF6 fits more readily within the conventional fuel cycle than the atomic process. The newest molecular laser process is SILEX, an Australian development which also utilizes UF6 and tuned laser radiation as above. Any process using UF6 fits more readily within the conventional fuel cycle than the atomic process. These two new methods have been the focus of interest for some time. They promise lower energy inputs, lower capital costs and lower tails assays, hence significant economic advantages. None of these processes is yet ready for commercial use, though one is well advanced. The paper describes the atomic vapor laser isotope separation (AVLIS-U) with its five stages implied: vapor production using electron gun; - production of laser light; - selective ionization of 235 U separation and collection of tails and product; - engineering of laser light facility. An AVLIS - U database is introduced as based on 20 ITIM internal reports. A dedicated comprehensive reference list on uranium enrichment by laser method is added covering the following subject matters: A. Laser method: physical technical, and economical aspects; B. Uranium spectroscopy; C. Lasers; D. Laser-atom interaction; E. Thermal properties of uranium