Inorganic controls on the incorporation of Np(V) and U(VI) in carbonate, sulfate and borate minerals
EMSL Project ID
47892
Abstract
The co-precipitation of actinides in low-temperature mineral phases may exert a significant control on mobility in the subsurface. According to the Department of Energy, Neptunium (Np) is an environmental contaminant of concern, and it is a major dose contributor during the long- term storage of irradiated nuclear fuels in a geological repository. In this BER funded program, we are examining the co-precipitation of Np(V) and U(VI) actinyl ions into several mineral structures. These are the dominant oxidation states for the respective cations in aqueous solution, and there is abundant evidence to support the hypothesis that these two actinyl cations will behave differently in the environment, especially relative to co-precipitation. This study probes incorporation of these actinyl ions into various cation sites in mineral structures. We request time resolved laser fluorescence spectroscopy (TRLFS) access at EMSL to investigate the details of incorporation in our Np and U-bearing synthetic minerals, including information on the coordination environments of the actinide cations. The specimens have already been thoroughly characterized for purity with X-ray diffraction, and chemically by inductively coupled plasma mass spectroscopy (ICP-MS). There are major differences in incorporation levels of Np(V) and U(VI) across our model minerals, thus it is essential to develop an understanding of the incorporation mechanisms to underpin development of a predictive model that can be expanded to other systems.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2013-10-01
End Date
2014-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Balboni E, JM Morrison, Z Wang, MH Engelhard, and PC Burns. 2015. "Incorporation of Np(V) and U(VI) in Carbonate and Sulfate Minerals Crystallized from Aqueous Solution." Geochimica et Cosmochimica Acta 151:133-149. doi:10.1016/j.gca.2014.10.027