No description available.

No description available.

Fissile materials in the form of aqueous homogeneous solutions are used during the chemical processing of nuclear materials. In this form there exists the possibility of an accidental criticality. A one-dimensional multi-region model was developed for simulating fast power excursions in a cylinderical homogeneous aqueous fissile solution. The model includes a novel method for computing reactivity feedback that accounts for the axial distribution of power and solution density. The feedback method is based on the change in neutron leakage due to a change in solution density. The model also includes an equation of state derived from quasi-static thermodynamic theory for a solution containing gas bubbles. The model was compared to the KEWB-5 (Kinetic Experiments on Water Boilers) series of experiments. The model could approximate the values of peak power and pressure found in the experiments, but the pressure curves did not match the shapes of the experimental pressure traces.

No description available.

No description available.

No description available.

The R6 procedure is used for the prevention and prediction of crack behaviour and other defects in the reactor pressure vessel(RPV). The RPV material is an upper-bainitic, low alloy steel structure, which deforms inhomogeneously when yielding. The current codes that are used to design and calculate the fracture, within an RPV, assume that the material yields continuously as the size of the L¨uders strain is less than 2%. However, the work of Wenman et al[1] has shown that the inclusion of a L¨uders band during calculations can reduce the residual stress in a material, when compared to standard work-hardening models and, consequently, reduces the amount of conservatism. The objective of the research was to determine whether Wenman’s finding could be generalised and therefore initiate a re-evaluation of R6 procedure, when looking into materials that yield discontinuously. This required further investigation into L¨uders bands, such as using failure assessment diagrams (FADs). The findings from FADs showed that at the temperature range for an RPV steel at -155±C for different micro-structures (assuming that the material deforms homogeneously), this reduced the amount of conservatism. However, at fracture toughness values more representative of room temperature behaviour, the converse was true. That is, assuming a discontinuous yield point reduced the amount of conservatism. It was also shown that the tempered martensite structure could be used as an alternative to the current upper bainitic, low alloy steel that is used in RPVs. Further insight is gained into the nature of a L¨uders band, by developing a theoretical model that showed explicit relations between L¨uders strain and the mean free-path(ferrite path), dislocation density and the grain-size. It was also shown that an explicit relation between the L¨uders strain and carbon content was possible from known data, which a new parameter Á was derived, and is the derivative of the work-hardening exponent with respect to the lower yield stress.

This thesis presents the design and analysis of photo-electro catalytic oxidation technology for its potential use in water treatment applications. Doping titanium dioxide can effectively improve oxidative reactions. Using minute reactor design adjustments, such as electrolysis, the bases of degrading soluble organic compounds can be improved within the reactor. Applications of doping and secondary catalysis are effective in increasing the process of photoactivity within the catalytic reactor, theoretically increasing the production of sacrificial electron acceptors. Higher degradation's were accomplished using doped chromium titanium dioxide photocatalyst, which degraded significantly larger amounts of organics compared with pure titanium dioxide. Techniques used to accomplish the increased photo-reactivity were doping chromium (III) ion into titanium dioxide crystal lattices and silver ions into the photocatalytic coat. Degradation curves were determined by total organic carbon and the chemical oxygen demand. Calculations of the final rate constants show that lighter molar concentrations have higher rates of degradation.

Finding the most cost-effective and environmental friendly way to treat and disinfect wastewater has been raising concerns around the world. Failure in performing disinfection of wastewater before returning it to the environment could have terrible consequences to human health and the ecosystem. The risks associated to continue with current practices have led to the creation of stringent regulations. In this research the HYDROPATH technology is tested while attaching a HydroFlow 60i unit to a reactor that works as a closed recirculation system. To determine the feasibility of the HydroFlow 60i unit as an alternative method to chlorine, the EPA method 1306 is used being Escherichia coli the unit of quantification. After performing several experiments modifying parameters such as conductivity and detention time, it was concluded that the HydroFlow 60i unit by itself would not able to replace current disinfection technologies, to meet EPA standards of E. coli removal.

Typescript. / Digitized by Kansas Correctional Industries