MITRad · Assessing microbial impact on trapping of radioactive contaminants from groundwaters by minerals

Assessing microbial impact on trapping of radioactive contaminants from groundwaters by minerals

One of the most serious environmental concerns is the wide occurrence of radionuclides in natural and anthropogenic environments and the safe management of spent nuclear fuel (SNF) and high-level radioactive waste (HLW) generated by nuclear facilities. As of 2016 over 58,000 tons of SNF are required for disposal in repositories as soon as they become operational. The key factor for the safe operation of a geological repository is an oxygen-free environment in groundwaters to retard the degradation of SNF. Essential are the secondary minerals forming directly from the groundwater that act as scavengers for contaminants. For example, uranium (U) - the main constituent of SNF and other important radioactive elements present in SNF can be potentially trapped by secondary minerals in deep surface environments. Natural U in deep groundwater is extensively studied in connection with the search for suitable locations for the final disposal of SNF. The U removal process in deep aquifers depends on environmental and geochemical conditions and is associated with fractionation of the U isotopes (238U and 235U), which serves as an important isotope proxy for redox specific scenarios in local to global temporal and spatial scales. The 238U/235U vary substantially in both magnitude and direction when mediated either by dissolved or solid inorganic species and/or microorganisms. Yet, multiple effects of mineral and microbial species on U retention and isotope fractionation in natural settings are poorly explored. These are crucial parameters for the long-term safety assessment safety of deep SNF repositories and require the integration of reliable geochemical models. The main objective of the MSCA project is to increase a fundamental understanding of U removal pathways during its interaction with various minerals mediated by abiotic and microbial species in deep granitic rock-groundwater systems. The main research tasks were achieved by implementing a comprehensive experimental approach involving U speciation techniques in minerals, U isotope signatures in minerals and deep groundwaters, integration with microbiological studies, and the cross-correlation between natural and laboratory studies. This was achieved by combining the experimental approach with coherent project work packages for a multi-technique study of U in minerals collected after short- and long-term experiments from the engineered facility and from deep drilled boreholes near planned SNF repository in Sweden.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз