Thermodynamic analysis on the Np-Zr-H system

The thermodynamic data base of the Np-Zr-H ternary system was developed based on the description of its binary constituents, coupling with the calculated enthalpies of formation obtained using the Miedema model and the Griessen-Driessen model. The provisional isothermal sections of the Np-Zr-H phase diagram were calculated using the data base. It was found that the Np-Zr-H ternary system at 972 K includes the liquid phase in the region of low hydrogen to metal ratio. It is pointed out that the composition of the Np-Zr-H hydride should be selected to avoid the hydride fuel melting in designing of a nuclear reactor fuel element.