Model Uncertainty of Empirical Metallic Fuel/Clad Eutectic Predictive Relationships

Sodium-cooled Fast Reactors (SFRs) remain a strong contender amongst the Generation IV reactor concepts. Many U.S. SFR designs utilize binary or ternary metallic fuel with stainless steel cladding. At high temperatures, iron from the cladding will diffuse into the fuel, and uranium, plutonium and rare earth fission products from the fuel will diffuse into the cladding to form a low melting point fuel/clad eutectic. The erosion of the cladding due to this eutectic formation may accelerate creep rupture, thus allowing the radioactive fission products to escape into the sodium coolant. Accurate modeling of this phenomenon may be important to making the SFR more economically competitive, but currently the eutectic formation rate is predicted using only the temperature of the fuel/clad interface. This paper improves the modeling accuracy of eutectic formation through the application of a multivariable linear regression with a database of fuel/clad eutectic experimental results.