Exploring Molten Salt Reactor Fuels Through Thermal Property Measurements

Toni Karlsson, Research Scientist, Idaho National Laboratory 

Molten salts are gaining international interest for use in heat transfer systems, as potential energy storage media, and a carrier for nuclear fuels in Molten Salt Reactors (MSRs). Salts exhibit unique properties such as low viscosity, low vapor pressure, and high heat capacity. However, due to their corrosivity and sensitivity to impurities such as moisture, obtaining thermal property measurements with low uncertainties can be a challenge. Significant efforts have been made by Idaho National Laboratory researchers to overcome issues with obtaining thermal property data so it can be used in databases, Multiphysics modeling and simulations, and eventually licensing of MSRs.

Dr. Karlsson is a Research Scientist and is currently the lead scientist for the Molten Salt Thermophysical Examination Capability (MSTEC) a shielded hot cell containing advanced high temperature thermophysical and thermochemical characterization equipment. Her research targets thermal property measurements of actinide bearing salt such as uranium and plutonium chlorides and fluorides. Toni is also working on development of analytical techniques for analysis of salts as well as development of methods and procedures for reducing sampling error. Toni is actively engaged in the development of NQA-1 measurement procedures and adopting those to encompass thermophysical property measurements for research and molten salt reactor vendors.

At INL, Dr. Karlsson has investigated phase stability of molten salts in a uranium electrorefiner and how the build-up of fission products in the salt impacts the thermal properties.  This work made it possible to predict a spent fuel treatment processing scenario under which electrorefining could no longer be performed as a result of increasing liquidus temperatures of the salt. Dr Karlsson has research experience in highly radioactive, remote, and high temperature environments.

One of Dr. Karlsson’s passions is the advancement of current and future researchers. She has a special interest and focus on workforce development through collaborations with other DOE laboratories, DOE campaigns, internships, and educational outreach, and industry.