Luminescence Analysis of Actinides: Instrumentation, Applications, Quantification, Future Trends, and Quality Assurance

Since the discovery of uranium, the impact of actinides has dramatically increased in our everyday life, firstly through the naturally occurring elements Th, Pa, and U (that were first used mainly as color pigments or for cancer treatment) and secondly through the artificial ones, produced in all steps of the nuclear power process (mostly Pu, Np, Am, and Cm). Considering the huge problem of providing safe and sustainable energy in order to supply the fast increasing world demand, nuclear power will be one of the major concerns of this century. It is therefore of tremendous importance to tackle associated problems, which are related to the remediation of old mining and milling sites, to the control of fissile products throughout the nuclear power production cycle, and finally to the long term disposal of generated wastes. In this field, and according to public concern, quantification and quality assurance are of utmost importance. However, owing to the radioactive properties of actinides, these objectives are liable to even more difficulties than for other more stable elements. Other problems that need to be overcome are mainly related to the complexity of the chemical behavior of actinides, which display numerous oxidation states, a large tendency to hydrolysis, and, for the short-lived ones (mostly elements above Cm), handling problems. Furthermore, the range of concentration of these elements found in the environment (mainly as a consequence of mining, milling, nuclear bomb testing, and accidents) limits the use of speciation techniques, which need to be safe, fast, reliable, and very sensitive. Fortunately, some major actinides display luminescence, which can be used for the determination of complex stabilities as well as for the direct detection of the formed species in different environments over a wide concentration range, from ultra-traces to chemically usable concentrations up to reprocessing conditions.