(401f) 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.