First principles Candu fuel model and validation experimentation

摘要: Many modeling projects on nuclear fuel rest a quantitative understanding of the co- existing phases at various stages burnup. Since fission products have considerably different abilities to chemically associate with oxygen, and O/M ratio is slowly changing as well, chemical potential (generally expressed an equivalent oxygen partial pressure) function Concurrently, well-recognized small fractions new such inert gas, noble metals, zirconates, etc. also develop. To further complicate matters, dominant UO2 phase may be non-stoichiometric most minor variable composition dependent temperature possible contact coolant in event sheathing defect. A Thermodynamic Fuel Model predict partially burned CANDU containing many major has been under development. This model capable handling non-stoichiometry fluorite phase, dilute solution behaviour significant solute oxides, metal inclusions, second solid U(Pd-Rh-Ru)3, zirconate uranate solutions well other phases, volatile gaseous species. The treatment melding several thermodynamic dealing isolated aspects this important multi-component system. simplify computations, number elements limited twenty representative known appear spent fuel. proportion must first generated using SCALES-5. Oxygen inferred from concentration elements. Provision study disposition very included within general but these are introduced only needed basis for particular purpose. building blocks standard Gibbs energies formation compounds temperature. data added mixing terms associated appearance component species phases. validate model, coulometric titration experiments relating moles SIMFUEL underway. description apparatus oxidize reduce samples controlled way H2/H2O mixture presented. Existing measurements irradiated fuel, both defected non-defected, being incorporated into validation process.