Development of a new solvent extraction system for the separation of americium from spent nuclear fuels

SCK•CEN Mentor

Van Hecke Karen, kvhecke@sckcen.be, +32 (0)14 33 32 75

Expert group

Radiochemistry

SCK•CEN Co-mentor

Verguts Ken , kverguts@sckcen.be , +32 (0)14

Introduction

A partitioning and transmutation strategy aims to reduce long term radiotoxicity and heat load of the nuclear waste. In this strategy, U and Pu are recycled via the well-established PUREX process1 and refabricated into nuclear fuels (MOX fuels). The minor actinides (Np, Am, Cm) are separated (“partitioned”) and transmuted into short-lived or stable nuclides. To separate the minor actinides from a so-called PUREX raffinate, several partitioning processes were developed in the context of European projects (ACSEPT, SACSESS, GENIORS).2,3 However, the selective extraction of Am remains a big challenge.

Objective

In this project, solvent extraction systems will be developed to selectively extract Am from a PUREX raffinate (i.e. nuclear waste stream of the PUREX process from which U and Pu have been removed). Currently, AmSel (Americium Selective separation) is one of the promising processes to extract Am from this raffinate.4 Here, Am(III), Cm(III) and all Ln(III) are co-extracted to the organic phase in a first step. In a second step, Am(III) is selectively stripped from the organic phase using a water soluble extractant.

The objective of this project is to replace commonly used solvents by ionic liquids, which are more resistant to ionizing radiation, and to develop an ionic liquid based extraction system selective for americium. Batch extractions will be performed to study the influence of several parameters like temperature, extractant concentration, pH, time, and phase ratio on the extraction process. These data are required to calculate distribution ratios, separation factors and construct extraction isotherms. Non-radioactive experiments will be performed first, in order to buildup knowhow and train lab-skills in a regular chemical lab environment. In the second stage of this project, tracer amounts of radionuclides will be used to assess the extraction system in a more realistic way.

 

(1)  Anderson, H. H.; Mass, N.; Asprey, L. B. Solvent Extraction Process for Plutonium. 2924506, 1947.
(2)  Modolo, G.; Geist, A.; Miguirditchian, M. Minor Actinide Separations in the Reprocessing of Spent Nuclear Fuels: Recent Advances in Europe; Elsevier Ltd., 2015.
(3)  GENIORS – GEN IV integrated oxide fuels recycling strategies http://www.geniors.eu/.
(4)  Wagner, C.; Müllich, U.; Panak, P. J.; Geist, A. AmSel, a New System for Extracting Only Americium from PUREX Raffinate. In Sustainable Nuclear Energy Conference; 2014.

 

The minimum diploma level of the candidate needs to be

Academic bachelor

The candidate needs to have a background in

Chemistry