Advances in actinides radiochemistry at the Centro Nacional de Aceleradores
Dr Mercedes López Lora1, Elena Chamizo2, Grzegorz Olszewski3, Isabelle Levy4, Victoria Lérida2, Mats Eriksson1
1Linköping University, Linköping, Sweden, 2Centro Nacional de Acleradores, Sevilla, Spain, 3University of Gdansk, , Poland, 4International Atomic Energy Agency, , Monaco
The Centro Nacional de Aceleradores (CNA, Sevilla, Spain) has hosted since 2005 a 1MV multi-elemental AMS system allowing the analysis of an assorted group of traditionally targeted AMS radionuclides, being among them the actinides. The measurement techniques for Pu isotopes (i.e. 239Pu, 240Pu, 241Pu), 236U and 237Np have been implemented, consolidating this facility for actinide measurements, and, very recently, the possibilities of this system for 233U analysis have been explored . A key part has been the development of radiochemical procedures meeting the requirements of the CNA 1 MV AMS system which features a compact design. Important efforts have been devoted in order to develop simple and reliable methods allowing the sequential extraction of Np, U and Pu fractions from marine samples in order to analyze 239Pu, 240Pu, 241Pu, 236U and 237Np by AMS at our facility. 237Np has been specially challenging because of the limitations imposed by the lack of a long-lived isotopic tracer to control both radiochemical procedure and AMS analysis. A new simplified method for the sequential extraction of U, Pu and Np from small-volume seawater samples (<10L) was successfully set up at the CNA . This procedure is based on the use of 242Pu as tracer for both Pu and Np, and the U and Np+Pu final purified fractions are extracted using TEVA® and UTEVA® resins. To expand the target matrixes to sediments and seaweed and include 233U among the measurable U isotopes, the former procedure has been adapted and tested during the last few years. The necessity of enhancing the removal of Th from the U fraction to analyze 233U forced the introduction of an additional TEVA® resin in the procedure. The pretreatment step was modified to quantitively recovering U, Pu and Np when solid samples are prepared. These modifications will be discussed and the results for reference materials provided by the International Atomic Energy Agency will be presented and evaluated.
 E. Chamizo, M. López-Lora, M. Christl, Possibilities of the 1 MV AMS system at the CNA to analyse 233U in natural samples, in: The 15th international conference on Accelerator Mass Spectrometry (AMS-15), 2021.
 M. López-Lora, I. Levy, E. Chamizo, Simple and fast method for the analysis of 236U, 237Np, 239Pu and 240Pu from seawater samples by Accelerator Mass Spectrometry, Talanta. 200 (2019) 22–30. https://doi.org/10.1016/j.talanta.2019.03.036.
Mercedes López-Lora finished her PhD thesis in December 2019 in the group of AMS at the Centro Nacional de Aceleradores (CNA, University of Seville, Spain). Currently, she holds a postdoctoral position at the Linköping University. Therein, she is part of the radioecology group at the Department of Health, Medicine and Caring Sciences. Her research focuses on the analysis of actinides by AMS in environmental samples. Now, she is involved in different projects for the study of Baltic Sea. She works in the different stages along this kind of studies: sampling, sample preparation, AMS technique and discussion of the results.