Proposal Defense – Bryn Merrill

About the event

Speaker: Bryn Merrill

Group: Dr. Xiaofeng Guo

Title: Elemental mixing in uranium chloride molten salt systems: thermodynamic studies of line compound formation and melt interactions

Abstract:

Molten salts have many applications in the modern energy landscape, as they find use in both thermal energy storage and nuclear energy. In nuclear power production, molten salts can act as either a coolant medium for fissile material in nuclear fuel or in the pyroprocessing of spent metallic nuclear fuel. The varying compositions of molten salt systems provide different advantageous thermodynamic properties, such as low vapor pressure and high vaporization temperature, that make some molten salt systems good candidates for certain technological applications. Understanding the thermodynamic properties of molten salt systems is vital to designing and maintaining molten salt infrastructure, such as molten salt reactors (MSRs). This proposed project aims to explore the thermodynamic properties, including Gibbs energy and heat capacity, of select chloride molten salt systems identified in the literature as good candidates for molten salt nuclear fuel: XCl-UCln (X = Li, K, Na; n = 3, 4). These systems will be investigated both experimentally and with thermodynamic mixing models. Experimental work will combine high temperature drop calorimetry and X-ray total scattering to gain information about the energetics and local structure of the molten salt melts. Modeling work will be accomplished using a computer coupling of phase diagrams and thermochemistry, also known as CALculation of PHAse Diagrams (CALPHAD), by means of the pycalphad python library. The resulting combinatory approach will result in information on chemical equilibrium which will aid in future chloride MSR designs.