Parametric Study of Iron Oxide Deposition on Fuel Cladding Surface for Pressurized Water Reactors

Abstract

Nowadays, energy is widely used in industry. Oil and coal are the main fuels that are used for energy source. However, these are unlimited and it will be depleted very soon. Alternate energy sources have been studied by many people and such energy is nuclear energy. Nuclear energy is produced from nuclear reactor. Nuclear fuels generally is UO2. The reaction in the core, where nuclear fuel is contained, will produce heat energy. Heat energy then will be changed to electricity which are used in everyday life. There are lots of compartments in the nuclear reactor. Steam generator (SG) and reactor core are the main components in nuclear reactor. Different reactors exist, such as Pressurized Water Reactors and Boiling Water Reactors. Only PWRs are used in Korea throughout country. Nuclear plants have been used for tens of years, and the power input has been increased compared to the past. It will bring higher output; in contrast, some disadvantages are found. Fuel crud is one of the adverse effects due to higher power input. Crud (Chalk Rivers Unidentified deposits) is the corrosion products that deposit on the fuel cladding surface. Bad influences of fuel crud are unexpected shift in axial power distribution (AOA phenomena), fall in neutron flux in fuel crud region, and crud acts as heat barrier preventing heat flow from cladding to coolant. In order to mitigate fuel crud deposition, chemical studies have to be conducted. Main sources of fuel crud are from the SG and primary pies. Corrosion first starts by oxidation of tubes, and some corrosion products will be released into the coolant. These corrosion products will be deposited on fuel cladding. Some major composition of fuel crud are iron, nickel, and boron. Iron and nickel come from tubes and boron comes from coolant. Boron deposition occurs during crud layer growth. Iron and nickel are also involved in this growth process, however they are normally involved in fuel crud deposition initiation. In order to understand fuel crud, initiation is important to study. Normally, iron has larger portion compared to nickel. Iron or iron oxide deposition experiments have been conducted to obtain dependence on various parameters. Among iron oxide crud deposits, hematite (Fe2O3) has been analytically studied by different researchers. Deposition rate of hematite depends on various parameters such as heat flux, particle diameter, and concentration. In this research, parametric study and obtain correlation equations are major goals