COMPREHENSIVE INVESTIGATION OF SELECTED METAL OXIDES WITH APPLICATION FOR CLEAN ENERGY

点击翻译按钮获取中文摘要

This proposal concerns the application of multi-scale modeling at both nuclear and atomistic levels. This work is unique because it combines nuclear simulations with materials modeling. Although the techniques to be used are well established, they have never been coupled together as proposed here. This work will apply state of the art, first principles (predictive) and improved modeling to investigate structural, optical, mechanical, and thermo-physical properties of novel and nuclear materials. The overall objective of this research is to develop a fundamental understanding of the properties of novel and nuclear materials. The short-term objectives over the next three years focus on (1) use of combined simulation of the radiation sources and atomistic molecular dynamics modeling of nuclear materials to achieve a better, fundamental understanding of the effects of radiation; (2) use of ab initio, predictive, and semiempirical methods to study the effect of radiation induced defects on the properties of materials on a large scale; (3) determining structural, mechanical, and thermo-physical properties for various nuclear fuels from simulations; (4) investigating optical and electronic properties of actinide oxides (with emphasis on U3O8); and (5) preparing interactive code for a reactor safety course. The semiconductive properties of uranium oxides are of interest since these oxides have dielectric constants much higher (e ~ 20) than SiO2 (3.5). Depleted uranium oxides can be recovered from nuclear waste and have potential application in solar cells and electronics. They are also a by-product of the production of enriched uranium. U3O8 is the most stable uranium oxide but there are no experimental data available about optical band gap. We have the required expertise to investigate the electronic structure and the band gap of U3O8, both experimentally (at Canadian Light Source) and theoretically. Cameco Inc. in Saskatoon can provide us with samples of depleted U3O8 that can be safely examined. Once the band gap has been determined both the optical and mechanical properties will be accurately determined from first principles calculations. They will be used to evaluate the potential application of U3O8 in solar panels. It will lay the groundwork for new applications for uranium oxides in the province of Saskatchewan beyond the current export of uranium ore. Accurate data on the mechanical and structural properties of U3O8 would allow the prediction of stresses when urania volume increases due to oxidation during an accident in a reactor or waste storage compartment. We have studied various nuclear fuels theoretically, especially inherently safe thoria with high thermal conductivity that prevents fuel melting by more efficient heat dissipation. However the experimental data for thermal conductivity of fuel show big differences and implications of burn-up-induced degradation is not well known. Monte Carlo code will be used to simulate the atoms displacements in fuels in operating fuel rods and a physical burnup will be evaluated. The parameters in classical molecular dynamics code will be tuned up using the first principles calculations and it will be used to evaluate the degradation of the thermal conductivity by the physical burnup. The comparison between urania and thoria fuel behaviours will be investigated. The developed thermal conductivity correlations for pure fuel and with inclusion of defects will be used in the new interactive software for multidisciplinary investigation of nuclear reactor safety and investigation of fuel melting in an accident similar to Fukushima. It is critical for the design of safer reactors to have access to new methods of simulating the properties of uranium oxides and new safer fuels (thoria, UC).