Press release of September 14, 2022
A closer look at hidden interactions
New BMBF young investigator group sheds light on technetium
With a half-life of about 210,000 years, the radioactive isotope technetium-99 (99Tc), which is produced in nuclear reactors by fission of the uranium isotope 235U, plays a central role in the question of safe final disposal of radioactive materials. Nevertheless, it is still largely unclear how technetium behaves in the environment after release. A new young investigator group called "TecRad" led by Dr. Natalia Mayordomo Herranz of Helmholtz-Zentrum Dresden-Rossendorf (HZDR) now aims to close this gap with a variety of advanced methods. The German Federal Ministry of Education and Research (BMBF) is funding the project with 1.87 million euros over the next five years.
In addition to spent fuel elements, medicine is also a strong source of the radioactive isotope 99Tc: Because the metastable technetium-99 (99mTc), which decays into 99Tc after only six hours, is very good at detecting tumors in the human body. For this reason, it is used around 40 million times each year worldwide for imaging and functional examinations of the brain, heart muscle, thyroid, lungs, liver, gall bladder, kidneys, skeleton and blood. "As a result, technetium-99 enters municipal wastewater on a daily basis, albeit at very low concentrations," explains Mayordomo Herranz.
Nevertheless, according not only to the Spanish native, who has been working at the HZDR Institute of Resource Ecology since 2017, the emission of technetium poses risks to health and the environment because it is highly mobile in groundwater and could enter the food chain. "Technetium transport in the environment is highly dependent on chemical conditions such as pH, presence of ions and redox potential. The risk of dispersal would decrease enormously if technetium is immobilized by interaction with reactive surfaces such as minerals or microorganisms," Mayordomo Herranz concludes.
Substantial risks but hardly any data
Currently, there is little data that can be used to evaluate technetium transport, particularly when it comes to the formation of inorganic and organic complexes at various oxidation states. "Therefore, the overall goal of the project is to gain a comprehensive understanding of the environmental behavior of technetium. We will study both the technetium in water and the reactions with minerals and microorganisms," Mayordomo Herranz describes.
The HZDR researchers plan to use an interdisciplinary approach that combines physical as well as radio-, geo- and biochemical methods to fill these critical knowledge gaps. At the same time, they want to improve experimental methodology to study processes in solution and at interfaces in situ. "We will expand the experimental tools previously used in this research area by coupling electrochemistry with infrared and nuclear magnetic resonance spectroscopy," says Mayordomo Herranz, highlighting an innovation her team will introduce.
Impact on repository research expected
The results of this project will be used not only to develop strategies for remediating contaminated sites, but also help to prevent technetium emissions to the biosphere from engineered environments such as repositories, as well as to assess the long-term safety of nuclear waste storage. "We will use the thermodynamic data obtained to develop and apply biogeochemical models. These models are theoretical tools that we need to predict the environmental behavior of technetium both in solution and at interfaces. Until now, this has hardly been possible for redox-active systems such as plutonium, arsenic or selenium," summarizes Mayordomo Herranz.
The innovative approach of this project is expected to advance the fundamental understanding of the (bio)geochemical behavior of other redox-active contaminants in the repository and in further contamination scenarios, such as for uranium, plutonium, selenium, arsenic or chromium. Natalia Mayordomo Herranz's team is composed of three graduate students and one technician. It is one of four young investigator groups funded by the BMBF through a program that aims at preserving and further developing nuclear expertise in Germany.
This research and development project is funded by the German Federal Ministry of Education and Research (BMBF) within the funding measure Kreativer Nachwuchs forscht für die Nukleare Sicherheits-, Strahlen- und Rückbauforschung (NukSiFutur) (funding number: 02NUK072) and managed by the Project Management Agency Karlsruhe (PTKA).
Dr. Natalia Mayordomo Herranz
Institute of Resource Ecology at HZDR
Phone: +49 351 260 2076 | Email: firstname.lastname@example.org
Simon Schmitt | Head
Communications and Media Relations at HZDR
Phone: +49 351 260 3400 | Cell: +49 175 874 2865 | Email: email@example.com