Ab initio study of the properties of liquid uranium for temperatures up to 2050 K*

Uranium compounds are used as fissile materials in nuclear reactors. Nowadays the most used nuclear fuel is UO₂, but in generation-IV reactors other compounds are being considered, such as UC and UN [1].

Upon possible loss of coolant accidents, the core of the reactor would get heated up to very high temperatures, and it is essential to understand the behaviour of the nuclear fuel in such conditions for proper risk asessment. UO₂ and UC would eventually melt, but UN would not reach a melting process since at high temperatures it is thermochemically unstable, and decomposes into gaseous N₂ and liquid U.

The experimental study of liquid U is difficult and scarce. For instance, there is no experimental information about its static structure factor. In this contribution we analyze the properties of liquid U, studied through ab initio methods, for three temperatures in the temperature range between its melting point (1405 K) and 2050 K. We show results for the static structure and also for several dynamic properties, including atomic diffusion and viscosity.

References:
[1] www.gen-4.org/gif/jcms/c_9260/public