Future Production of Americium-241 Oxide at Los Alamos National Laboratory

Future Production of Americium-241 Oxide at Los Alamos National Laboratory

Mary Ann Stroud, Louis Schulte, David Kimball and Brad Skidmore

Actinide Engineering and Science Group, Los Alamos National Laboratory, Los Alamos, NM

LA-UR-16-23214

Americium-241 oxide has been produced at United States Department of Energy (DOE) sites in the past with specification requirements of chemical purity of > 95 wt% AmO₂ and ²⁴¹ Am isotopic purity > 99 wt%. This stockpile has been depleted and there is currently no domestic supplier of ²⁴¹AmO₂. An ongoing need exists in industry for ²⁴¹AmO₂, to be used primarily as Am-Be neutron sources for oil and gas well logging. The DOE Office of Science Isotope Program has funded Los Alamos National Laboratory (LANL) to re- establish a capability for ²⁴¹ AmO₂ production at the LANL Plutonium Facility (LANL-PF).  

Am rich residues are a readily available by-product of LANL-PF Pu metal purification operations. LANL-PF aqueous chloride operations efficiently separate the bulk of the Pu from these Am rich residues using solvent extraction. LANL-PF is in the process of starting up the CLEAR (Chloride Extraction and Actinide Recovery) glovebox line to produce purified ²⁴¹AmO₂ from the resulting Am rich effluent streams. The CLEAR line will use extraction chromatography (EC) to purify and recovery the ²⁴¹Am from the effluent stream. The EC operation uses di-(4-t-butylphenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (4-t-BuC₆H₄)₂P(O)CH₂C(O)N(i-Bu)₂ as an extractant, along with diamyl amylphosphonate [DAAP, (C₅H₁₁)₂P(O)OC₅H₁₁] as a diluent, on an inert resin bead. The EC columns provide a simple, reusable method of concentrating actinides from HCl waste effluent streams. The new CLEAR line will also add ion exchange (IX) columns using Reillex-HPQ resin to recover and purify Pu. Incorporation of EC and IX requires minor additional equipment, and the processes are relatively straightforward to run. Large scale EC runs on HCl process effluents have demonstrated efficient recoveries (~99%) of Am and Pu from process effluent streams.