New Experiment Improves Predictions of Uranium Dispersion

The predictive models that describe the fate and transport of radioactive supplies in the environment following a nuclear incident assume that um-bearing particulates would attain chemical equilibrium throughout vapor condensation.

In new research, commissioned by the Office of Defense Nuclear Nonproliferation Research and Growth (DNN R&D) within the U.S. Department of Energy’s National Nuclear Security Administration and the U.S.

Division of Defense’s Defense Threat Reduction Agency (DTRA) Basic Science Grant, researchers from Lawrence Livermore National Laboratory (LLNL) and the University of Illinois at Urbana–Champaign (UIUC) demonstrated that kinetically driven processes in a system of quickly reducing temperature could result in substantial deviations from chemical equilibrium.

This will cause uranium to condense out in metastable oxidation states that have different vapor pressures than the thermodynamically favored oxides, significantly affecting uranium transport.

The physical and chemical processes that happen through the condensation of a nuclear fireball are approximated utilizing fallout models.

These models assume that atomized elements heated to extraordinarily high temperatures will reach a state of chemical equilibrium as the fireball cools and thermodynamically favored oxides will form as soon as the temperature drops under their boiling points.

Nonetheless, condensation patterns noticed in fallout samples reveal that some fraction of the uranium is held up in the vapor part relative to refractory actinides and fission products.