Thomas Hartmann, Ph.D.
Associate Professor, Mechanical Engineering/Radiochemistry
Technetium-99 is one of the most abundant, long-lived radiotoxic isotopes in used nuclear fuel (UNF). As such, it is targeted in UNF separation strategies such as UREX +, for isolation and encapsulation in solid waste forms for storage in a nuclear repository. Our research focus on the incorporation of Tc-99 into ternary oxides of different structure types: pyrochlore, perovskite, and layered perovskite. The goal is to determine synthesis conditions of these potential waste forms to immobilize Tc-99 and to harvest crystallographic, thermophysical and hydrodynamic data. Therefore Rietveld structure analysis is applied to allow crystallographic description, while thermophysical properties are determined using a physical property measurement system (PPMS). Our recent studies have revealed superconductivity of Tc-bearing oxide powders through a.c. susceptibility measurements at exceptionally high critical temperatures of 7.8 K, 7.0 K, respectively compared with the ruthenium homolog Tc of Sr2RuO4.