U-O Chemical Kintetics and Spectroscopic Modeling

A study of U-O chemical kinetic reactions and species was conducted to aid in developing a tractable reduced chemical mechanism for numerical simulations of larger scale U-O physics such as nuclear fireballs. Such environments contain high pressures, inhomogeneous media, and mixing/diffusion timescales that control the oxidation rates. Modeling atomic and molecular spectra of the U-O kinetics products is a critical tool to help understand uranium gas-phase oxidation reactive pathways, reaction rate dependencies, and U x O y formation. By applying spectral modeling to spatially varying, non-uniform flowfields, important features and unique spectral trends can potentially be linked to critical flow and reaction characteristics in processes such as developing flame fronts and turbulent structures. In this research we will discuss the use of Quasi-Steady State Approximation (QSSA) analysis to reduce the reaction set for more tractable 3D simulations. Analysis was performed using synthetic spectroscopic models to understand the sensitivity of mechanism choice, plasma properties, and the presence of various intermediate product species (UO, U + , etc.) on the resultant spectroscopic features from a temporal and spatial evolution perspective.