Microbiology in nuclear waste disposal

The objectives of the lectures will be on how life processes can influence the safety and performance of future repositories for nuclear wastes. Microbiological systems are alive and thus not in thermodynamic equilibrium because living organisms preserve their internal order by taking free energy from their surroundings in the form of organic nutrients, reduced inorganic compounds or sunlight, and they expel an equal amount of energy as heat and entropy to their surroundings. This means that order is increased in the microorganisms and decreased in their surroundings, i.e. living systems strive to move away from thermodynamic equilibria. Consequently, by excluding microbial processes that may control reactions rates, too optimistic assumptions may be introduced in the safety and performance assessment of the repositories. This is because uncertainties and technical issues related to microbial processes that could undermine the repository safety case, such as microbially induced corrosion, gas formation, radionuclide transformation and migration and barrier degradation may remain overlooked.