Speakers
Description
At the Centro Nacional de Aceleradores (CNA, Seville, Spain), research efforts are being devoted to exploring the limits of the 1 MV AMS system to analyse several radioisotopes present in nuclear waste that pose serious analytical challenges to radiometric techniques. The focus has been placed on 41Ca, 36Cl, and actinides radionuclides (239,240,241Pu, 236,238U, 237Np, 241,243Am and 244,245,246Cm). 41Ca and 36Cl have stable isobars, 41K (6.73% isotopic abundance) and 36S (0.0158% isotopic abundance), respectively, which cannot be fully suppressed in our system using techniques based on stopping power difference as is done in conventional AMS facilities. Our alternative approach is based on i) the removal of K (41K) or S (36S) through optimised radiochemical methods and ii) the indirect control of the 41K or 36S count rates mimicking the detector signal of 41Ca and 36Cl, respectively, using other stable K and S isotopes with well-known isotopic abundances. The obtained results this way point out to minimum atomic ratios of 10-12 for 41Ca/40Ca (3 mBq/g of Ca), and 10-9 for 36Cl/35Cl (0.1Bq/g of Cl). It has been observed that the interference from 36S and 41K originates from the metallic matrix of the cathode rather than from the samples. As for actinides, efforts have been devoted to simplifying the existing radiochemical methods and the measurement techniques for environmental samples. Using one UTEVA® and one DGA® resin in tandem, the U, Np and Pu species on the one hand, and Am and Cm on the other, respectively, are sequentially separated from nuclear waste matrixes. Subsequently, the target nuclides for each fraction (236,238U, 237Np, and 239,240,241Pu for the U+Pu+Np AMS sample; 241,243Am and 244,245,246Cm for the Am+Cm AMS sample) are analysed on the 1 MV AMS system. In this work, the status of the AMS analysis on nuclear waste at the CNA and first results for samples from the decommissioning of a Spanish nuclear reactor (i.e. resin, sludge, and concrete) will be presented and discussed.
| Student Submission | Yes |
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