Chemical Sciences and Engineering Division Technical Seminar
Wednesday, January 9, 2008
3:00 p.m.
Y-Wing Auditorium
Building 205
Conversion of Uranium Hexafluoride (UF6) with Improved Requirements for an Existing Process System
Presented by: Alan Rothman
Abstract
The U.S. DOE has elected to convert a 40 to 50-year stored inventory of depleted-UF6 waste from its past uranium enrichment operations to UO2, together with HF for sale to the private sector. That conversion involves high-temperature treatment of UF6 with steam and hydrogen, similar to a two-stage fluidized-bed Westinghouse process described in U.S. Patent 3,547,598. Experimental studies described in this presentation were carried out at the ACL and the Bochvar Institute in Moscow in determination of process requirements for an alternative system to convert UF6 to ammonium polyuranate and high-grade CaF2. Such an alternative process system would involve treatment of the aqueous dissolution products of UF6 with aqueous NH3 to precipitate ammonium polyuranate and purify the filtrate for treatment with Ca(OH)2 to produce CaF2. Its process requirements could be applied directly in improvements of a Westinghouse process system described in U.S. Patent 3,758,664, for production of (low-enrichment) ammonium polyuranate prior to converting it to UO2 fuel for commercial reactors.
Depleted or enriched ammonium polyuranate from the alternative process can be decomposed to either UO3, U3O8 or UO2, for existing needs or disposal, by heating it as required to temperatures lower than or as high as those Westinghouse has used for the production of UO2 fuel.