Speciation of Uranium and Plutonium From Nuclear Legacy Sites to the Environment: A Mini Review

Abstract

The row of 15 chemical elements from Ac to Lr with atomic numbers from 89 to 103 are known as the actinides, which are all radioactive. Among them, uranium and plutonium are the most important as they are used in the nuclear fuel cycle and nuclear weapon production. Since the beginning of national nuclear programs and nuclear tests, many radioactively contaminated nuclear legacy sites, have been formed. This mini review covers the latest experimental, modeling, and case studies of plutonium and uranium migration in the environment, including the speciation of these elements and the chemical reactions that control their migration pathways.

High-energy resolution X-ray spectroscopy at actinide M4,5 and ligand K edges: what we know, what we want to know, and what we can know

“…More beamlines at various synchrotron facilities made an effort to construct the experiment stations for the tender X-ray range and to equip them with X-ray In this article we show how the XANES, HERFD and RIXS methods at the actinide M 4,5 edges and ligand K-edge can provide an unprecedented amount of detail regarding the actinide oxidation state, speciation, defects, nature of the actinide chemical bonding, 5f occupation and degree of the 5f localization. Such fundamental knowledge is a key step towards solving the extreme complexity of the chemistry problems with radionuclides [17][18][19][20][21][22][23][24][25][26] , safe disposal of nuclear wastes and prediction of the radionuclide behaviour in the environment 17,[27][28][29][30][31] .…”

From EXAFS of reference compounds to U(VI) speciation in contaminated environments

“…requires a detailed study of individual U species under controlled laboratory conditions. In environmental systems, technogenic U is usually present as a mixture of various UO 2 2+ compounds or as UO 2 particles (Kr ˇepelova ´et al, 2008;Qafoku & Icenhower, 2018;Marshall et al, 2015;Romanchuk et al, 2021). Along with surface complexation with minerals and incorporation into solids like calcite, an essential mechanism of U immobilization is the formation of intrinsic U(VI) phases.…”

Successive Crystallization of Organically Templated Uranyl Sulfates: Synthesis and Crystal Structures of [pyH](H3O)[(UO2)3(SO4)4(H2O)2], [pyH]2[(UO2)6(SO4)7(H2O)], and [pyH]2[(UO2)2(SO4)3]

“…Microporous uranium compounds formed upon the oxidation of spent nuclear fuel (SNF) attract essential interest due to their non-trivial crystal chemistry [1], and they also are promising materials for ion exchange and catalysis [2][3][4][5][6]. For instance, framework uranyl phosphates selectively absorb 90 Sr and 137 Cs nuclides [7][8][9]. The largest structural diversity is observed among compounds containing tetrahedral and pseudo-tetrahedral oxo-anions, e.g., molybdates [10][11][12][13][14][15][16], phosphonates [17], phosphates [18][19][20][21], and vanadates [22,23].…”