Separation of amercium from a concentrated raffinate by liquid-liquid extraction hot tests in the ATALANTE facility

V. Vanel (1) , M. Montuir (1) , V. Pacary (1) , C. Marie (1) , M.J. Bollesteros (1) , L. Corbin (1) , V. Boyer-Deslys (1)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)

Abstract – Recycling americium (Am) alone from the spent fuel is an important option studied for the future nuclear cycle. Since 2008, a liquid-liquid extraction process called EXAm has been developed by the CEA to allow the recovery of Am alone from a PUREX or COEXTM raffinate (already cleared from U, Np and Pu). A mixture of DMDOHEMA (N,N'-dimethyl-N,N'-dioctyl2-(2-(hexyloxy)ethyl)-malonamide) and HDEHP (di-2-ethylhexylphosphoric acid) in TPH is used as the solvent and the Am/Cm selectivity is improved using TEDGA (tetraethyldiglycolamide) as a selective complexing agent to maintain Cm and heavier lanthanides in the acidic aqueous phase (HNO3 5M). Americium is then stripped selectively from light lanthanides at low acidity (pH2.5-3) with a polyaminocarboxylic acid. Since 2011, in order to increase the compactness of this process and future plan associated, additional developments have been studied to adapt the EXAm process to a concentrated raffinate (addition of a TEDGA stripping step, pH in the Mo stripping step more difficult to control, development of a model in low acidic conditions). Following up first cold tests in G1 facility in 2011-2012, a test was carried out in April 2014 in the ATALANTE facility (C17 hot cells) on a surrogate feed solution with trace amounts of americium and curium. This C17 test aimed at consolidating the process flowsheet and ensuring performances achievement in terms of americium recovery and its decontamination towards curium and light lanthanides. An americium recovery rate of 99.3% was obtained. Although the americium flow was not sufficiently decontaminated towards Cm and light lanthanides, several ways of improvement were identified. A simulation of this test was performed with the PAREX code and compared with experimental data, either in transitory situations or at the end of the test. The modelling of main elements was broadly validated. Based on this work, a flowsheet is proposed for a hot test on a genuine PUREX raffinate scheduled in 2015 in CBP hot cells in ATALANTE facility. The recovery of several grams of americium is expected to produce some AmO2 pellets for irradiation experimentations.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Physique Nucléaire Théorique [nucl-th]

V. Vanel, M. Montuir, V. Pacary, C. Marie, M.J. Bollesteros, et al.. Separation of amercium from a concentrated raffinate by liquid-liquid extraction hot tests in the ATALANTE facility. GLOBAL2015, Sep 2015, Paris, France. ⟨cea-02491638⟩