The effect of microorganisms on asphaltopropylene concrete in a radioactive waste repository. Part 2

The permeability of asphaltopropylene concrete (APC) was examined after the action of aerobic bacteria and molds, and the changes in its volume, weight and swelling capacity were recorded. APC has been used as a sealing material in low level radioactive waste pits at the Dukovany NPP repository. Results of check-up sampling of microorganisms in the repository are evaluated. Sulphate reducing bacteria, which have been detected in soil near the reactor site, were isolated and their action upon asphaltopropylene (AP) was investigated. The resistance of bitumen layers containing model waste, against the action of aerobic bacteria and molds and against water was also examined. Bitumen samples containing model waste were found to absorb water at low temperatures considerably faster than unfilled bitumen. At elevated temperatures the absorption of water is appreciable, causing high weight losses of the bituminized waste layer due to degradation. The time dependences of the bitumen sample weight at 20 degC and 60 degC in distilled and cement water are given in the Appendix. The results included in the final reports ''Investigation of the effect of microorganisms on asphaltopropylene-based insulating materials employed as sealing in the secondary radioactive waste repository at the Dukovany NPP in relation to the microbial flora present. Bacteria'' and ''Investigation of the impact of biodegradation effects of aerobic and anaerobic microorganisms including molds on asphalt and asphaltopropylene in conditions of the ground repository at the Dukovany NPP'' are also given. (J.B.). 8 tabs., 33 figs