Interaction of clay-relevant microorganisms with radionuclides and investigation of the microbial influence on the corrosion of container materials
Prof. Dr. Thorsten Stumpf, Dr. Andrea Cherkouk (HZDR)
Besides salt and crystalline rock, clay formations are potential host rocks for the long-term storage of high-level radioactive waste in a deep geological repository in Germany. Therefore, a multi-barrier system is favored, consisting of the container with the waste as the technical barrier, the sealing and backfilling material (e.g. compacted bentonite) as the geotechnical and the host rock as the geological barrier. This system aims to isolate the radioactive waste from the biosphere.
Different studies showed that Desulfosporosinus spp. are present in various clay formations, as well as in bentonites. Desulfosporosinus hippei DSM 8344 is an anaerobic sulfate-reducing microorganism and a close phylogenetic relative of the sulfate-reducing microorganisms occurring in clay rock. This work focuses on the interactions of uranium and other actinides with this microorganism, to give proof of a possibly occurring reduction process. Therefore, different microscopic and spectroscopic methods, e.g. TEM, XAS, TRLFS and UV/VIS shall provide reliable data.
Another part of this Ph.D. thesis is the investigation of the corrosion of copper and steel coupons. In the course of this work, the influence of individual sulfate-reducing microorganisms as well as the effects of different microbial communities on the corrosion process will be examined. Different characterization methods, e.g. Raman spectroscopy and SEM will help to investigate the coupons before and after the corrosion process and to determine dissolution rates.
This work is part of the iCross project (Integrity of nuclear waste repository systems – Cross-scale system understanding and analysis), which is funded by the Federal Ministry of Education and Research under contract number 02NUK053B and by the Helmholtz Association of German Research Centers under contract number SO-093.