The importance of understanding Technetium environmental chemistry- research at Institute of Resource Ecology

Technetium (Tc) is a radioactive element, 99-Tc being its most abundant isotope. 99-Tc is mainly generated by anthropogenic sources like nuclear power plants, nuclear weapon detonations (99-Tc is the fission product of 235-U and 239-Pu), and hospitals due to its use in radiodiagnostics (99-Tc is the daughter of 99m-Tc). The emission of 99-Tc is of environmental concern since it is a b- emitter with a long life time (0.213 million years) and a high mobility in groundwater under oxic conditions. Therefore, a deep understanding of the environmental behavior of Tc is crucial to ensure a safe Tc storage in a nuclear waste repository and the protection of the environment.

The environmental behavior of Tc, its bioavailability, and its mobility in groundwater are ruled by environmental conditions like redox conditions, pH, presence of ions or minerals, and temperature among others. The knowledge about basic Tc chemistry helps to identify and understand the environmental conditions under which Tc migration is limited. Additionally, it allows for the development of possible Tc scavengers for remediation of polluted sites.

At the Institute of Resource Ecology (IRE) we study Tc immobilization by various natural materials such as pyrite (FeS₂) and materials found in nuclear waste repositories, such as green rust (Fe(II)-Fe(III) hydroxide). To answer the question, how Tc interacts with these materials, we employ a multitude of experimental techniques including X-ray diffraction, X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), Raman microscopy, scanning electron microscopy (SEM), and geochemical modeling approaches. This allows us to obtain an in-depth understanding of Tc chemistry, which can be used to develop and improve Tc scavengers and to build a safe nuclear waste repository.