Coffinite formation from UO_2+x.

ABSTRACT: Most of the highly radioactive spent nuclear fuel (SNF) around the world is destined for final disposal in deep-mined geological repositories. At the end of the fuel's useful life in a reactor, about 96% of the SNF is still UO₂. Thus, the behaviour of UO₂ in SNF must be understood and evaluated under the weathering conditions of geologic disposal, which extend to periods of hundreds of thousands of years. There is ample evidence from nature that many uranium deposits have experienced conditions for which the formation of coffinite, USiO₄, has been favoured over uraninite, UO_2+x, during subsequent alteration events. Thus, coffinite is an important alteration product of the UO₂ in SNF. Here, we present the first evidence of the formation of coffinite on the surface of UO₂ at the time scale of laboratory experiments in a solution saturated with respect to amorphous silica at pH?=?9, room temperature and under anoxic conditions.

SUBMITTER: Szenknect S 

PROVIDER: S-EPMC7376029 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature