Thermodynamic Assessments Of Phase Diagrams In U-Th Based Alloys

Nuclear energy is an important kind of new energy,and nuclear materials are an important guarantee for the secure and highly efficient operation of the nuclear actors. U-Th based alloys are the vital part of nuclear materials.However,due to the rigorous restriction of the experimental conditions for the nuclear material,the traditional trial and error method is not useful for the investigation of the nuclear materials.In order to design high-powered nuclear material,knowledge of phase diagrams and thermodynamic data of the involved systems are crucially necessary.In this paper thermodynamic calculations(CALPHAD) on the phase relations of U-Th-X(X:Pu, Cr,Cu,Mg,Mn,Nb,Zr) systems are carried out,and the U-Th based thermodynamic data base is built,which is described in the following.(1) Thermodynamic description of the U-X(X:Mn,Nb,Th,Cr,Cu,Mg) binary systems were firstly optimized by using the CALPHAD method based on critically evaluated experimental data.Calculated results from the obtained thermodynamic parameters were in good agreement with the available experimental data.(2) Thermodynamic description of the Th-X(X:Pu,Cr,Mn,Nb,Zr) binary systems were firstly optimized by using the CALPHAD method based on critically evaluated experimental data.Calculated results from the obtained thermodynamic parameters were in good agreement with the available experimental data.(3) Based on the optimized parameters in this work or literature for the U-X and Th-X binary systems,the U-Th-X(X:Mn,Zr) ternary systems were firstly assessed according to the experimental data.The calculated phase equilibria and thermodynamic properties were in good agreement with the experimental data.(4) By combining with the optimized parameters in this work or literature for the U-X and Th-X binary systems,the U-Th-X(X:X:Pu,Cr,Cu,Mg,Nb) ternary systems were extrapolated for the first time.The isothermal sections of the U-Th- X(X:X:Pu, Cr,Cu,Mg,Nb) ternary systems at and 350℃and 1000℃were calculated.According to the calculation of this work,the binary systems of U-X(X:Mn,Nb, Th,Cr,Cu,Mg) and Th-X(X:Pu,C,Cr,Mn,Nb,Zr) were assessed,as well as the U-Th-X(X:Pu,Cr,Cu,Mg,Mn,Nb,Zr) ternary systems,and the U-Th based thermodynamic database for nuclear materials is built,which will provide important messages for the design of nuclear materials.