Thermodynamic properties of fission products in liquid bismuth

The thermodynamic properties of fission products in molten salt and liquid metal have a great influence on the disposal of nuclear waste in the nuclear fuel cycle industrial system. This paper attempts to extract useful thermodynamic information from the only few experimental activities of lanthanides (Ce, Pr, La) in liquid Bi at different temperatures. The molecular interaction volume model (MIVM) was adopted to model and predict some temperature-dependent thermodynamic functions, including activity, infinite dilute activity coefficient, and molar excess Gibbs energy. The minor average of Δ G ¯ error indicated that assuming εji − εii is a constant is reasonable. On this basis, the natural logarithm of the interaction coefficients and the natural logarithm of the infinite dilute activity coefficient of lanthanides (Ce, Pr, La) in the Bi-based metal melt, these two parameters, show the linear relationship with the reciprocal of temperature. The reasonable agreement of the modeled thermodynamic parameters with the existing experimental data verified that the MIVM is quite convenient and reliable, which can provide guidance for separating fission products from molten salt reactors.

Thermodynamic properties of iron, aluminum, boron and phosphorus in dilute silicon solutions by molecular interaction volume model

The thermodynamic properties of impurity components in silicon solutions play an important role in the chemical removal process to the metallurgical route. In this paper, the component activity coefficients and interaction parameters of dilute silicon solutions were estimated by the molecular interaction volume model (MIVM). The activity coefficients (?i) of component i in dilute binary Si-i and ternary Si-i-j solutions at 1687-1873 K were firstly calculated. The concentration dependences of the interaction parameter and activity coefficient were also obtained. The self-interaction parameters (?i,i) for Si-i system were obtained as ?B,B= -2.728-362.031/T, ?Al,Al = 2.157-1876.776/T, ?Fe,Fe= -4.842+14445.926/T and ?P,P = -2.543+13767.036/T. At the same time, the interaction parameters among components B, Al, and Fe in dilute ternary Sii- j solutions were also derived as ?Fe,B=-1.2758-2946.306/T, ?Al,B = 0.7467-9765.9298/T and ?Fe,Al= -1.39677+3319.6803/T. Most important of all, the temperature dependences of the interaction parameters and activity coefficients in dilute Si-i and Si-i-j solutions with a certain i or j concentration were deduced. The results show that the predicted self-interaction parameters of B, Al, Fe, and P in binary silicon solutions reasonably agree with the experimental data. This further shows that MIVM is of reliability and can be expanded to a multi-component dilute silicon solution.