Thermodynamic assessment of the Fe-Ni-Te system

For the purpose of modeling internal corrosion of the stainless steel fuel pins in fast nuclear reactors, the present work presents a thermodynamic description of the Fe-Ni-Te system modeled via the Calphad method. The liquid phase was modeled using the ionic 2-sublattice liquid model. Only binary parameters were optimized in the beta 2, delta and tau solid phases, to fit the isothermal section at 600 degrees C. The liquid did not require much adjustment from the extrapolation from the binary Fe-Te, Ni-Te and Fe-Ni systems. The paper presents a re-optimization of the Fe-Te liquid description in order to remove inverted liquid miscibility gaps at high temperatures. The resulting phase diagrams reproduce experimental isothermal sections well, and fits liquidus and solidus data very well. The description will be incorporated into the Thermodynamics of Advanced Fuels - International Database (TAF-ID). This will then be coupled with the Germinal system code to model the fission-product induced corrosion in nuclear fuel pins. (authors)