On the significance of modeling nuclear fuel behavior with the right representation of physical phenomena

This work emphasizes the relevance of representation of appropriate mechanisms for understanding the actual physical behavior of the fuel pin under irradiation. Replacing fully empirical simplified treatments with more rigorous semi-empirical models which include the important pieces of physics, would open the path to more accurately capture the sensitivity to various parameters such as operating conditions, geometry, composition, and enhance the uncertainty quantification process. Steady state and transient fuel behavior demonstration examples and implications are given for sodium fast reactor metallic fuels by using FEAST-METAL. The essence of appropriate modeling of the fuel clad mechanical interaction and fuel clad chemical interaction of the metallic fuels are emphasized. Furthermore, validation efforts for oxide fuel pellet swelling behavior at high temperature and high burnup LWR conditions and comparison with FRAPCON-EP and FRAPCON-3.4 codes will be given. The value of discriminating the oxide fuel swelling modes, instead of applying a linear line, is pointed out. Future directions on fuel performance modeling will be addressed.

Research highlights▶ Essence of more physics based modeling approaches to the fuel behavior problem is emphasized. ▶ Demonstrations on modeling of metallic and oxide fuel dimensional changes and fission gas behavior with more physics based and semi-empirical approaches are given. ▶ Essence of fuel clad chemical interaction modeling of the metallic fuel in an appropriate way and implications during short and long term transients for sodium fast reactor applications are discussed.