Research Progress and Development Trend of Accident Tolerant Fuel UN Pellets

UN pellet has high uranium density and high thermal conductivity, and is a kind of potential accident tolerant fuel pellet. In this paper, the research progress of UN pellets is summarized from five aspects: preparation process and physical properties, environmental compatibility, irradiation properties, pellet-cladding interaction, economy and safety. The research results show that the advantages of using UN pellets in PWR outweigh the disadvantages, and it is generally beneficial to promote the safety of the reactor under accident conditions. It has the remarkable characteristics of reducing the operating temperature of pellets and reducing the release of energy storage in accidents. The main problems to be solved are poor water corrosion resistance and high cost of 15N enrichment. The possible solutions to improve water corrosion resistance and oxidation resistance include doping or adding antioxidant components, and the high cost problem needs to reduce the cost of 15N enrichment. This review comprehensively summarizes the overall research progress and development trend of UN pellets, and provides reference for understanding its feasibility and existing problems as accident tolerant fuel pellets. © 2024 Atomic Energy Press. All rights reserved.