Prospective Micro-Encapsulated Fuel with Silicon Carbide Protective Coat

Аннотация

A promising direction in the development of the next-generation fuel is the development of fully ceramic micro-encapsulated fuel (FCM). Such fuel has proven itself well in high-temperature gas-cooled reactors (HTGR). The fuel consists of 200–700 μm in diameter microspheres made from the fuel material coated with a multi-layer ceramic coating. The standard four-layer coating used in HTGR reactors consists of three layers of pyrolytic carbon and a layer of silicon carbide. The technology developed at VNIINM for fabricating protective coatings consisting of only silicon carbide makes it possible to enhance the radiation and heat resistance of the coatings and, correspondingly, increase the fuel life. Calculations have confirmed the main advantages of the micro-encapsulated fuel with a silicon carbide coating over the conventional TRISO coatings. The use of such microfuel elements opens up the possibility of developing fuel elements capable of retaining fission products both under normal operating conditions and in design-basis and beyond-design-basis accidents. Variants of the design of rod-shaped accident-tolerant fuel (ATF) for water-cooled reactors based on micro-encapsulated fuel with silicon carbide coatings and cladding comprised of a composite of the type SiC–SiC are considered.