Nuclear melt glass-derived colloid experiments explain why plutonium is migrating in groundwater

The migration of low levels of plutonium has been observed at the Nevada National Security Site (NNSS) and attributed to colloid-facilitated transport. (A colloid is a mixture in which one substance of microscopically dispersed particles is suspended throughout another substance.) To understand why plutonium is migrating, LLNL scientists performed experiments using mineral colloids produced from nuclear melt glass collected directly from underground nuclear test cavities at the NNSS. They found that the formation of zeolites and clays hydrothermally altered at 200°C leads to a more stable association of plutonium with colloids than previously thoughtand could give rise to more extensive colloid-facilitated transport. These insights help explain why trace levels of plutonium are found downstream from their original source decades after a nuclear detonation.

[C. Joseph, E. Balboni, T. Baumer, K. Treinen, A.B. Kersting, and M. Zavarin, Plutonium Desorption from Nuclear Melt Glass-Derived Colloids and Implications for Migration at the Nevada National Security Site, USA Environ. Sci. Technol., available online on October 7, 2019, doi: 10.1021/acs.est.9b03956.]