Thermophysical properties of urania-zirconia (U,Zr)O2 mixed oxides by molecular dynamics

Thermophysical properties of liquid (U, Zr)O2 by molecular dynamics

“…In this work, we compare two existing potentials: the CRG (Cooper-Rushton-Grimes) potential [6,7,10] and a modied iteration of the Yakub et al potential [8] by Alderman et al [9]. Both were initially designed to model pure UO 2 structures in the solid phase, and later extended for (U, Zr)O 2 systems.…”

“…The Cooper-Rushton-Grimes (CRG) potential [3] was proven to accurately reproduce lattice parameter, thermal expansion and heat capacity of solid UO 2 . This potential was originally designed to model actinide oxides, and later adapted by Liu et al for U Zr interactions in the solid phase by tting data obtained from defect formation energies from DFT calculations of cubic-phase ZrO 2 [6,7]. Although here we will focus on "pure" (U, Zr)O 2 matrices, choosing CRG (Liu) allows for later consideration of ssion products in our systems, or extension to mixed oxides (MOX) fuels.…”

“…Integration timestep was set to 2 fs, thermostats and barostats relaxation times to 0.1 ps. These values have been widely used in previous work with the CRG potential form [6]. For high temperatures, each supercell was heated to 5000 K, for thermal quenching and ensuring proper melting of the atomic structure (avoiding unrealistic crystalline structure above the melting point).…”

“…In recent work, Frost et al [6] used the CRG model proposed by Liu et al [7] to describe the interaction between the solid UO 2 pellet and zirconium cladding. Their set of parameters successfully predicts several thermophysical properties up to the melting point, but fails for liquid phases.…”

A molecular dynamics method to identify the liquidus and solidus in a binary phase diagram

“…However, binary systems will not have one melting point, but a two-phase region bound by a liquidus and a solidus. When those methods are applied to a binary mixture a "pseudounary" melting point is found [10][11][12], but it is not clear whether these melting points correspond to the solidus, the liquidus or somewhere in between. On the other hand, current methods to predict solidus and liquid of binary systems from atomic scale simulations rely on assumptions of ideal mixing to extrapolate the results from the end members.…”