Related Experiment Video
Updated: Jan 3, 2026

Preparing an Isotopically Pure 229Th Ion Beam for Studies of 229mTh
Published on: May 3, 2019
Challenging the thorium-immobility paradigm
Haylea Nisbet1,2, Artas A Migdisov3, Anthony E Williams-Jones4
1Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA. haylea.nisbet@mail.mcgill.ca.
Abstract:
Thorium is the most abundant actinide in the Earth's crust and has universally been considered one of the most immobile elements in natural aqueous systems. This view, however, is based almost exclusively on solubility data obtained at low temperature and their theoretical extrapolation to elevated temperature. The occurrence of hydrothermal deposits with high concentrations of Th challenges the Th immobility paradigm and strongly suggests that Th may be mobilized by some aqueous fluids. Here, we demonstrate experimentally that Th, indeed, is highly mobile at temperatures between 175 and 250 °C in sulfate-bearing aqueous fluids due to the formation of the highly stable Th(SO4)2 aqueous complex. The results of this study indicate that current models grossly underestimate the mobility of Th in hydrothermal fluids, and thus the behavior of Th in ore-forming systems and the nuclear fuel cycle needs to be re-evaluated.
Related Concept Videos
Nuclear Transmutation
Nuclear Stability
To hold positively charged protons together...
Nuclear Power
Nuclear Fuels
Nuclear fuel consists of a fissile isotope, such as uranium-235, which must be present in sufficient quantity to provide a...
Nuclear Fission
Directionality of Nuclear Transport
Nuclear Fusion
A helium nucleus has a mass that is 0.7% less than that of four hydrogen nuclei; this lost mass is converted into energy during the fusion. This reaction produces about...

