Coexistence of americium in four oxidation states in sodium carbonate-sodium bicarbonate medium

The crystal structures and mechanical properties of the uranyl carbonate minerals roubaultite, fontanite, sharpite, widenmannite, grimselite and čejkaite

The structure, hydrogen bonding, X-ray diffraction pattern and mechanical properties of six important uranyl carbonate minerals, roubaultite, fontanite, sharpite, widenmannite, grimselite and čejkaite, are determined using first principles methods.

Separation of oxidized americium from lanthanides by use of pillared metal(IV) phosphate-phosphonate hybrid materials

Closing the nuclear fuel cycle in the US poses many challenges, one of which is found in the waste streams, which contain both trivalent lanthanides and actinides. The separation of americium from the raffinate will dramatically reduce the long-term radiotoxicity of the waste. The sorption of americium in both the tri- and pentavalent oxidation states was observed for four M(IV) phosphate-phosphonate ion exchange materials in nitric acid at pH 2. High selectivity was observed for reduced Am(III) with K d values ca. 6×105 mL/g, while the K d values for Am(V) were much lower. A new method of synthesizing and stabilizing AmO2 + to yield a lifetime of at least 24 h in acidic media using a combination of sodium persulfate and calcium hypochlorite will be described.

Padiolytically Induced Oxidation Reactions of Actinide Ions in Concentrated Salt Solutions

The autoradiolytic oxidation of Pu(IV) and Am(III) has been investigated in saline solution of different NaCl concentrations, pH and specific α-activities. The high linear energy transfer (LET) property of α-radiation in solution enhances the oxidation of the Cl ion and thus increases the redox potential (Eh) of the NaCI solution system to a value of more than +1000 mV vs. NHE. Radiolytic reaction products are found as being comparable with those from the Cl2 saturated NaCl solution 'and create a metastable system consisting of C12/HCl0/Cl0−/Cl−. The oxidation of Pu(IV) and Am(III) in such solutions is dependent on the NaCl concentration, pH and specific a-activity involved. The quantitative oxidation to Pu(VI) and Am(V) is ob- served in the concentrated NaCl solution at pH > 7 with a moderately high specific activity (> 1 Ci/L).