Coating development for fuel claddings in advanced nuclear reactors

Coating development for fuel claddings in advanced nuclear reactors A recap of a 20-year journey in the exploration of coating applications for advanced nuclear reactors. Thin films and coatings are a thin layer of materials coated on a surface to serve certain functions that are different from the surface material. Thin films and coatings are extensively applied in functional layers in integrated circuits for microelectronics, optical layers in optics and lenses, superhard or corrosion-resistive coatings for machineries under extreme environments, just to name a few. The film thickness usually ranges from a few nanometres in microelectronics to a few micrometres in superhard and protective coatings. Because of their thin thicknesses and concerns on potential adhesion challenges, thin films were not immediate materials options in nuclear reactors considering the severe environments the materials experience. In 2007, Haiyan Wang from Texas A&M University then and Purdue now, and Jian Gan from Idaho National Lab pioneered a new innovative coating development initiative under the support of the U.S. DOE Nuclear Fuel Initiatives.1-4 Since then, multiple coating applications in nuclear reactors have been demonstrated and adopted by industries, including coatings for fuel claddings.1-9. Fuel cladding is a critical part of the fuel systems for the safe operation of nuclear reactors. Fuel cladding chemical interactions (FCCI) and cladding-coolant interactions could severely affect the cladding integrity and lead to premature failure of the fuel components. It is very challenging to have a cladding-base material to meet all the requirements including neutron transparency, good thermal conductivity, high radiation tolerance properties, mechanical integrity, and thermal and chemical inertness to fuels and/or coolants. This review highlights some of the major breakthroughs for advanced fuel cladding applications of transition metal nitrides in nuclear reactors and future outlooks.