Zirconium alloy cladding has been successfully applied to light water reactor (LWR), showing good irradiation-resistance and corrosion resistance. However, a major problem with zirconium reactor applications is that they react strongly with water vapor at high temperatures, releasing large amounts of hydrogen and heat at temperatures greater than 1200 ° c. After the fukushima nuclear accident in Japan, the safety of nuclear power has been put in front of all nuclear workers again. How to further improve the safety and reliability of nuclear fuel elements in light water reactors under accident conditions has become an urgent problem to be solved.
The challenge of light water reactor nuclear fuel elements is the development of accident-resistant fuel to meet the higher safety margin requirements of reactor design for fuel performance. The research direction of the accident-resistant fuel proposed by scientists includes the accident-resistant fuel core and the accident-resistant cladding material. The accident-resistant coating materials are devoted to improving the reaction kinetics of zirconium and water vapor and reducing the hydrogen release rate. The development of accident-resistant coating materials is mainly reflected in two aspects: one is to improve the high temperature oxidation resistance and strength of zirconium alloy coating; The second is to develop non-zirconium alloys with high strength and oxidation resistance. The surface coating of zirconium alloy cladding is studied for the former.
The main benefit of coated zircon cladding applications is economy, which is due to the sustainable production capacity of existing equipment and the ease of commercial application of zirconium based coating coatings. The technical challenge faced by coated zircon shells is to meet the various performance requirements of the fuel cladding and components. The coating cladding does not change the size of the fuel cladding, which is critical for in-reactor performance, especially under normal operating conditions. During long-term operation, the coating should be stable under corrosion, creep and abrasion conditions. Therefore, it is necessary to explore and optimize the surface coating technology of zirconium alloy.
The new technology should make it easier to control the coating quality, especially the coating thickness. The surface coating of zircon shells should maintain long-term stability in the reactor environment.
