Separation of actinides by extraction chromatography prior to X-ray fluorescence measurement for analytical control of a PUREX test

摘要

Five separation methods by Eichrom column extraction chromatography were developed and implemented for performance control of a PUREX (Plutonium, Uranium Refining by EXtraction) test. Four of them, concerning the separation between actinides, are described in this work. The latest, concerning the separation of actinides from fission products in a main raffinate is described in another article submitted to the same journal. For the production of U, Pu and Np streams following the "main extraction" step in the PUREX process, it is necessary to determine the concentration of the two residual actinides in the third actinide stream: i.e. determine the Pu and Np concentrations in the U flow, the U and Np concentrations in the Pu flow, and the U and Pu concentrations in the Np flow. The predominance of any of these three actinides in solution impedes direct L-line X-ray fluorescence LXF: chromatographic separation ensures quantitative separation efficiency for each of the two residual actinides prior to the LXF measurement, and is therefore performed in each case. A final separation method was developed to quantify the residual U in a Pu/Np flow for the Np/Pu partitioning step of the PUREX process. This separation is a prerequisite for LXF to eliminate any interference due to Pu and Np when measuring the U concentration. These separation methods necessary upstream from the LXF measurement were applied during the PUREX test in 2005 in ATALANTE (French acronym for "Alpha facilities and analysis laboratories, transuranics and reprocessing research").