Chemical and radiological assessment of deep brine-type geothermal groundwaters

Elevated activities of naturally occurring radionuclides (NORs) detected in deep geothermal groundwaters, as well as the high salt concentrations observed in these groundwaters, pose several challenges to the successful exploitation of deep geothermal energy. As a result of changing conditions in the surface installations of the geothermal power plant (temperature, pressure,…), minerals become oversaturated in the brine and will start precipitating. This scale formation can cause clogging of the wells and heat exchanger. Moreover, it will decrease the productivity of the geothermal system. It is observed that several naturally occurring radionuclides (such as 226Ra, 228Ra, 212Pb and 210Po), will precipitate together with these scales. The high amount of accumulated radionuclides requires the expensive disposal of radioactive waste. An increased insight into the radiological and chemical aspects inherently associated with deep geothermal installations, is necessary. It will allow for system optimization to minimize contamination of installations and equipment with NORM-associated radionuclides. Lab experiments, radionuclide measurements and geochemical modeling of reactions and scale formation will allow to propose mitigating strategies in case such contamination would occur.

Publication year:2021

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