Markus Piro1 Bernard Fitzpatrick1 Srdjan Simunovic2 Theodore Besmann3 Emily Moore3

1, University of Ontario Institute of Technology, Oshawa, Ontario, Canada
2, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
3, University of South Carolina, Columbia, South Carolina, United States

There is an increased interest in integrating thermodynamic calculations in multi-physics codes to predict various aspects of nuclear fuel behaviour in a mechanistic framework. For oxide fuels, progress has been made in providing thermodynamic properties computed by Thermochimica such as chemical potentials, thermochemical activities, and speciation of various phases to the nuclear fuel performance code bison. Furthermore, the output provided by Thermochimica has been used to predict oxygen transport in bison in a more fundamentally correct manner than conventional approaches that do not account for the effects of irradiation. In addition to work in oxide fuels, work is on-going in investigating thermochemical behaviour of molten salt fuels. Here, a great difficulty is that the fuel is liquid and the fission products are not physically separated from the coolant; therefore, the transport of fission product containing phases depends strongly on the state of secondary phases. This presentation will cover a number of recent developments in algorithm and code development in Thermochimica and the coupling to multi-physics codes simulating the behaviour of oxide and molten salt fuels.