Corrosion influenced by biofilms during wet nuclear waste storage

In this work, effects of microbial populations within a nuclear waste repository were studied. Consequences of biofilm formation, bacterial biosorption of metals, and bacterial radioresistance must be assessed. Water samples taken during the interim storage of spent fuel at the Atomic Energy Research Institute in Budapest were examined. Six morphologically different bacteria were isolated from the samples. The radiosensitivities of the isolates and the biosorption of Cd, Co, Sr and Cr cations were also investigated. Biofilm development on stainless steel was examined by atomic force microscopy. After one 3-week incubation period, bacterial attachment was detected on the surface. After 5 weeks individual bacteria were not observed: they were enmeshed within the exopolysaccharide matrix. The surface of the stainless steel was studied after removal of the biofilm, and biocorrosion-induced pits (depth: 100 nm) were found.