The radiation sensitivity of naturally occurring microorganisms in buffer materials vas investigated as veil as the sensitivity of Bacillus subtilis spores and Acinetobacter radioresistens in a buffer matrix. The D10 values obtained in our radiation experiments varied from 0.34 to 1.68 kGy and it vas calculated that the surface of a nuclear fuel vaste container vould be sterilized in 9 to 33 d after emplacement, depending on the type of container, and the initial bioburden. This suggests that formation of biofilms and microbially influenced corrosion vould not be of concern for some time after emplacement. The results also indicated that sterilization throughout a 25 cm thick buffer layer is unlikely and that repopulation of the container surface after some time is a possibility, depending on the mobility of microbes in compacted buffer material.