Depletion, Chemical Reaction and Transport in High Burnup Nuclear Fuel

Abstract

We have developed a formulation and computational model for oxygen transport in Light Water Reactor (LWR) uranium dioxide fuel. The overall model couples the burnup simulation isotopic composition with a thermochemistry model of the fuel phase, and oxygen transport using the driving forces from the thermodynamic calculations. The diffused oxygen is accounted for in the thermochemistry model in order to establish consistent material and thermodynamic conditions in the fuel undergoing burnup. The model has been implemented in the nuclear fuel performance code Bison. The formulation and the model have been successfully demonstrated on fuel burnup data from the open literature. The developed capability enables consideration of complex chemical composition of irradiated fuels beyond available burnup models in Bison.

Thermochemically-Informed Mass Transport Model for Zr in U-Zr Fuel

“…Thermochimica is a software library that determines the equilibrium combination of phases and compositions of those phases given input temperature, pressure, and concentrations of chemical elements. Thermochimica and the development of Thermochimica as well as its integration into the MOOSE/BISON framework have been well-documented in previous technical reports [29,39,38,37,40,34], and journal articles [33,30,32,31], as well as in the Thermochimica documentation (available on GitHub [26]).…”

“…However, the kinetics are driven by variables provided by Thermochimica, such as the chemical potentials of diffusing species. This approach follows previous work in coupling Thermochimica with BISON for calculations of oxygen diffusion in nuclear fuels [39,40,34].…”

“…The coupling of Thermochimica with BISON for Zr transport in metallic fuel builds upon previous efforts to couple Thermochimica calculations into the MOOSE framework [39,38,37,40,34], including the use of the re-initialization algorithm [34]. The classes implemented to complete this work also build on those implemented in those previous efforts.…”

“…This Kernel is based on, and very similar to, the Kernel DiffusionGradChemPotential described in detail in Ref. [40]. In this case the species mobility is provided by an AuxKernel such as MobilityUZrAux that is evaluated at the nodes, rather than from a Material.…”

“…The remainder of the implementation is identical to that of DiffusionGradChemPotential, and details may be found in Ref. [40].…”