ChEMS Seminar: Progress in Pyroprocessing Technology for Used Nuclear Fuel Reprocessing Toward Material Detection and Accountability for Safeguards

McDonnell Douglas Engineering Auditorium (MDEA)
Supathorn Phongikaroon, Ph.D., P.E.
Department of Mechanical and Nuclear Engineering
Virginia Commonwealth University
Richmond, Virginia

Abstract: Pyroprocessing technology has a promising potential for used nuclear fuel treatment. At the heart of this process lies the electrorefiner (ER), which electrochemically dissolves uranium from the used fuel at an anode and deposits it on a cathode. Through normal operation of the ER, transuranic elements (such as plutonium and uranium), fission product chlorides and rare earth chlorides accumulate in the molten salt electrolyte (LiCl-KCl) over time.  These contaminants change the physical properties of the salt, which influences the overall efficiency of the separation process. Thus, from an operational perspective, it is paramount that exact compositional information is available on the salt in order to adjust and ensure a proper operation.  In addition, buildup of transuranic elements in the salt presents criticality and safeguard concerns; this only increases the need for precise concentration data from the salt. Currently, salt composition is obtained via sampling, digestion, and analysis using Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). However, this technique for measuring the composition of the salt is cumbersome; furthermore, it requires significant time to provide accurate results under a safe operational envelop. With the ER running continuously, it is important to have current salt composition data for material detection and accountability, which is extremely crucial for nuclear safeguards.

This work presents the progress in pyrochemical projects at the Virginia Commonwealth University.  The focus areas will be on developments of (1) molten salt aerosol via laser-induced breakdown spectroscopy for near real time concentration detection and (2) electrochemical studies on liquid cadmium cathode (LCC) in molten salt eutectic for measurements of physical and electrochemical properties.  These research areas show significant advancements, which can impact and improve the process basis of the nuclear fuel cycle, and help enabling nuclear safeguards toward this technology.

Biography: Supathorn Phongikaroon earned his Ph.D. and B.S. degrees in chemical engineering and nuclear engineering from the University of Maryland, College Park in 2001 and 1997, respectively.  Prior joining the Virginia Commonwealth University (VCU) in January 2014, he held academic and research positions at University of Idaho in Idaho Falls, ID; Idaho National Laboratory in Idaho Falls, ID; and Naval Research Laboratory, Washington, D.C.  During his research career, Phongikaroon has established chemical and electrochemical separation of used nuclear fuel through pyroprocessing technology and extended his expertise toward material detection and accountability in safeguarding applications.  These developments include kinetics in ion exchange process, advanced chemical separation routines via cold fingers and zone freezing, electrochemical methods, laser induced breakdown spectroscopy, and computational modeling for electrorefiner.  This effort has led to establishing strong Radiochemistry and Laser Spectroscopy Laboratories at VCU.  Phongikaroon’s work has been published in over thirty papers in peer-reviewed journals and presented at over fifty international and national conferences and workshops.