In 2013, the NNSA’s Stewardship Science Academic Alliance Program established the Radiochemistry (Radchem) Center of Excellence at the University of Tennessee-Knoxville (UT). Radiochemistry and nuclear chemistry are key scientific areas that support a number of NNSA mission areas.
The UT Radchem Center involves faculty and students in nuclear engineering, chemistry, chemical engineering, materials science, and UT’s new interdisciplinary PhD program in energy science and engineering. In addition to students directly supported under the Center, students supported through other means are also being influenced by the work of the Radchem Center. For example, US Army officers pursuing advanced degrees under the auspices of the Army’s advanced education programs are participating in Radchem Center research, and one of UT’s senior graduate students just began a National Nuclear Forensics Graduate Fellowship program at Los Alamos to complete his dissertation in actinide measurements by mass spectrometry.
The UT Radchem Center is organized into a set of two major and two minor research thrusts, each selected to develop new scientific understanding in areas of strategic interest and to develop student expertise and interests that overlap with NNSA needs. Those thrust areas are:
Advanced Radiochemical Separations
The goal of this focus is to improve the specificity, timeliness, detection limits, and/or operational suitability of radiochemical separations. Radiochemical separations ultimately underlie all NNSA applications of radiochemistry. This work focuses primarily on exploiting gas-phase chemistry to develop and improve separations, with a particular emphasis on faster and higher specificity separations.
UT’s early work in this area focused on developing the instrument and detection capability to investigate these gas-phase separations and elucidate their controlling thermodynamic parameters. Some recent work on modeling this process indicates substantial improvements in both specificity and timeliness are possible. A key research objective is to better constrain the thermodynamic data regarding the interaction of the gas-phase species with the separation column substrate – current data is sparse and occasionally contradictory.
Radiochemical Probes For Physical Phenomena
Another major research thrust is using imaging technology adapted from nuclear medicine to develop experimental capabilities to assess the performance of turbulent flow computer models. This is an interesting intersection of radiochemistry and engineering model validation needs of NNSA.
The UT Radchem Center is also supporting a small effort in improving the fundamental understanding of relevant nuclear reactions (particularly neutron induced reactions such as (n,xn) reactions) through a variety of means, including high-resolution measurements using inverse kinematics. This approach, if successful, will provide a capability with broad applicability to neutron induced reactions. The Radchem Center is also collaborating with another SSAP center – the Rutgers-led Center of Excellence for Radioactive Ion Beam Studies for Stewardship Science – in aligning the UT approach to neutron induced measurements with other SSAP activities.
Bulk Actinide Oxide Materials Processing and Behavior
The other small effort supported under the Radchem Center is improving the understanding of bulk actinide separation and solidification processes, with a special focus on understanding the complete behavior of trace chemicals and byproducts. Processes that are relevant to current or new NNSA efforts, such as the Uranium Processing Facility (UPF) and the Mixed Oxide (MOX) fuel plant, are high priority. This work, led by Professors Kirk Sickafus (Materials Science) and Brian Wirth (Nuclear Engineering) will focus on computational materials science coupled with experiments to assess new materials synthesis and formulation options for better performance.