Fission Gas Release Comparison for PWR Duplex Fuel Pellets

Current research has identified Duplex pellets as an effective strategy for decreasing the centerline temperature of the fuel. However, before this design can be widely utilized several areas, including fission gas release, need to be better characterized. Therefore, this paper seeks to ascertain the relative difference in fission gas release between a standard solid UO2 reference design and a duplex design with Zircaloy and UO2. Although the central area in the duplex doesn’t produce any fission gas, it is not well known if the higher temperatures in the outer annulus (when compared to the equivalent area in the solid design) will cause overall more or less fission gas release. Interestingly, this study concluded that the duplex fuel actually exhibits a 4.4% higher overall fission gas release when compared to the solid fuel. Due to the very approximate treatment of several important input variables it was concluded that while the duplex design does have lower average temperatures, the fission gas release is comparable to that of the solid fuel design.