ASSOCIAÇÃO BRASILEIRA DE ENERGIA NUCLEAR – ABEN 2019 International Nuclear Atlantic Conference - INAC 2019 Santos, SP, Brazil, October 21-25, 2019 PERFORMANCE ANALYSIS OF UO2-SiC FUEL UNDER NORMAL CONDITIONS Daniel de Souza Gomes and Antonio Teixeira e Silva Instituto de Pesquisas Energéticas e Nucleares (IPEN / CNEN - SP) Av. Professor Lineu Prestes 2242 05508-000 São Paulo, SP, Brazil dsgomes@ipen.br, teixeira@ipen.br ABSTRACT This study aims to investigate a fuel mixture of silicon carbide (SiC) and uranium dioxide (UO2) and analyze performance when this fuel applies to light-water reactors (LWRs). Utilization of the licensing code, FRAPCON, with UO2 helped to determine the fuel response under normal conditions initially. High thermal conductivity could permit the use of UO2-10 vol% SiC fuel, showing thermal conductivity values that are far superior to the UO2 alone, exceeding 50% at 900 °C. Ultimately, the formulation should reduce gaseous fission products, avoid fuel cracking, and improve safety margins. SiC has excellent physical properties such as chemical stability, a cross-section with low absorption, irradiation resistance, and a higher melting point. There are some benefits for fuels that use carbon composites such as UO2-carbon nanotube (CNT), and UO2-diamonds. The pellets containing fractions of the carbon limit the amount of fissile U-235 and require additional enrichment to produce the same energy. In the past, there have been various attempts to increase the thermal conductivity of UO2. High conductivity is present in uranium nitride (UN), uranium carbide (UC), and UO2 mixed with beryllium oxide (BeO). The production method of UO2-SiC fuels should include the spark plasma sintering (SPS) technique. Advantages of SPS include a lower manufacturing temperature of 1050°C, better results, and reduced processing time of 30 s. SPS can help produce more tolerant fuels, such as UO2-SiC, UO2-carbon nanotube, and diamond powder dispersion in the UO2 matrix. The thermal conductivity of SiC can decrease substantially under irradiation. UO2-diamond has some drawbacks because of graphitization phenomena. INTRODUCTION Uranium dioxide is the most common fuel material used in nuclear power reactor fleets. Uranium dioxide has a low thermal conductivity of 2.8 W/m-K at 1000 °C. During regular reactor operation, after the densification phase, the thermal gradient into the pellet increases and induces the pellet cracking and relocations phenomena. These combined effects are undesirable features when considering risk management of the nuclear unit. The Fukushima disaster also prompted the start of accident tolerant fuel (ATF) initiatives. 5056