Performance analysis of UO₂-SiC fuel under normal conditions

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. (author)