The fabrication of nano-scale engineered surfaces to investigate the enhancement of boiling heat transfer and CHF in nuclear reactors

Abstract

This work looks into the feasibility of utilizing nanotechnology in order to improve the performance of pressurized water reactors (PWRs) in the nuclear industry. Through growing zinc oxide nanowires (ZnO NW) on the surface of zircaloy, which clads the uranium oxide fuel, the project aims to increase the heat flux limit, i.e., the critical heat flux (CHF), resulting in a boiling crisis. That allows for improvement on the safety margins and operation at higher power. The exact procedure for growing the nanowires will be delineated such that the results can be replicated exactly. A variety of ZnO NW structures will be fabricated based on the characteristic size of the features and characteristic spacing among the structures. This goal will be achieved by controlling the fabrication steps at various stages. Utilizing the Scanning Electron Microscope (SEM) and Focused Ion Beam (FIB), we will be able to geometrically describe the properties of the nanowires. Heat transfer performance of ZnO nanostructured surfaces will be characterized through flow boiling at atmospheric pressure and under pressurized conditions, using state-of-the-art diagnostic systems consisting of high-speed video and infrared (IR) thermometry. The post processing of the IR data will allow us to determine spatial and temporal evolution of heat flux and temperature across the heated surface to the point of CHF. This will all culminate into a numerical result termed the enhancement, which will describe the improvement from modern standards. These results will provide useful insights into designing the future generation nuclear fuel claddings as well as economic, feasible, and scalable nanofabrication techniques.