Development of Fuel Pin with Uranium-Plutonium Nitride Fuel and Liquid-Metal Sublayer

The status of development work on fuel pins with fast-reactor nitride fuel and a liquid-metal sublayer, which is being considered in Project Breakthrough (Project Proryv) together with fuel pins with a helium sub-layer, is presented. Such fuel pins are shown to have the potential to improve the core characteristics of the advanced high-power reactors BR-1200 and BN-1200. The basic results for the development and fabrication of experimental nitride-fuel pins with different variants of the lead sublayer and the results of their tests in the BOR-60 reactor and post-reactor studies are presented. The problems of fabricating fuel pins with a lead sublayer are noted, possible solutions are discussed, and the required additional studies are indicated.