Perpustakaan Digital ITB

Molten salt reactor (MSR) is the fourth-generation nuclear reactor that has advantages compared to light water reactors (LWRs). MSR operates at atmospheric pressure minimizing the risk of explosion. However, the main problem with MSR is tank material durability to corrosion. One of the material candidates is iron-based alloy. Therefore, most of the corrosion product formed is iron (II) fluoride. Thermodynamic modeling can predict a stable phase under certain conditions. This method can predict the chemical property of eutectic mixture of salt LiF-NaF-KF (FLiNaK) in the presence of FeF2. To make such prediction, thermodynamic data of the FeF2-LiF-NaF-KF system needs to be evaluated and optimized. However, evaluation on the FeF2-LiF-NaF-KF system is not available in literatures. Therefore, the aim of this study is to measure thermodynamic data and optimize the FeF2-LiF-NaF-KF system. In addition, the result of the initial evaluation showed that the FeF2-NaF system requires optimization to fit the actual experimental data. This study began with measurement of the heat capacity using the physical property measurement system (PPMS) for solid FeF2, LiF, and NaF. The data obtained along with thermodynamic data from other literatures were used in modeling the FeF2- LiF-NaF-KF system with a focus on optimizing the FeF2-NaF binary system. The thermodynamic model to describe the salt system is the Modified Quasi-Chemical Model (MQM). The optimized database can be utilized to study the interaction of FeF2 with melted FLiNaK salt. Based on the measurements, the heat capacities data were obtained for FeF2, LiF, and NaF. Further data processing shows that the standard entropy data for NaF and LiF are 53.4 J.mol-1K-1 and 37.6 J.mol-1K-1, respectively. The phase diagram optimization results showed an improvement on the liquidus temperature line in the FeF2 mole fraction area of less than 0.5. The optimized database was used to predict the solubility limit of FeF2 in FliNaK salt. Prediction of the solubility of FeF2 in FLiNaK salt has been carried out for various temperatures. The FLiNaK salt mixture has the ability to dissolve FeF2 up to 52% by weight at a temperature of 973 K in thermodynamic equilibrium.