Highly selective two-step laser ionization schemes for the analysis of actinide mixtures

Nina Kneip,Dominik Studer,Reinhard Heinke,Sebastian Raeder,Vadim Gadelshin,Christoph Mokry,Christoph E Düllmann,Felix Weber,Jörg Runke,Klaus Wendt,Norbert Trautmann

doi:10.1007/s10751-020-01712-4

Abstract

Resonance ionization mass spectroscopy has proven to be a very efficient and selective method for the spatially resolved ultratrace determination of actinide contaminations, and the analysis of specific element and isotopic distributions on surfaces and environment particles. We report on the identification of highly element-selective optical excitation schemes identified for this purpose, with a particular focus on the precise determination of the isobaric ratios of 235U to 239Pu as well as 243Am to 241Pu. The chosen two-step ionization schemes were characterized with respect to their element selectivity on synthetic multi-element actinide mixtures, with an element ratio Pu : Am : U of 1 : 10 : 104, a composition which is typical, e.g., for spent nuclear reactor fuels.

Highlights

The determination of ultra-trace amounts of actinide elements in environmental samples is of major relevance for the investigation of the chemical and migratory behaviour of actinidesThis article is part of the Topical Collection on Proceedings of PLATAN 2019, 1st International Conference, Merger of the Poznan Meeting on Lasers and Trapping Devices in Atomic Nuclei Research and the International Conference on Laser Probing, Mainz, Germany 19-24 May 2019 Edited by Krassimira Marinova, Michael Block, Klaus D.A
The experimental approach is based on resonant laser ionization in combination with mass spectrometry [1]
The samples were composed of 1016 atoms of uranium with a 1 : 1 ratio of 235U : 238U, 1013 atoms of americium with a 1 : 1 ratio of 241Am : 243Am and 1012 atoms of plutonium in total with a ratio of 1 : 0.13 : 0.56 : 0.15 for 239Pu : 240Pu : 241Pu : 242Pu, which resembles a realistic composition of spent nuclear fuel in the ratio of elements [2]

Summary

Introduction

The determination of ultra-trace amounts of actinide elements in environmental samples is of major relevance for the investigation of the chemical and migratory behaviour of actinidesThis article is part of the Topical Collection on Proceedings of PLATAN 2019, 1st International Conference, Merger of the Poznan Meeting on Lasers and Trapping Devices in Atomic Nuclei Research and the International Conference on Laser Probing, Mainz, Germany 19-24 May 2019 Edited by Krassimira Marinova, Michael Block, Klaus D.A. The determination of ultra-trace amounts of actinide elements in environmental samples is of major relevance for the investigation of the chemical and migratory behaviour of actinides. The experimental approach is based on resonant laser ionization in combination with mass spectrometry [1]. For this technique, an efficient and element-selective laser ionization step is required for each investigated chemical element. By the use of a fullyautomated tuning unit within a grating-based Ti:sapphire laser with intra-cavity frequency doubling, individual ionization schemes of different elements can be addressed one after the other. The specific goal of this study was the demonstration of resolving the different isobaric interferences on the masses 238 and 241, which hamper the application of the majority of competing analytical techniques

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Methods

Conclusion