Progress in the geomicrobiology of radioactive waste disposal

Over the past 20 years, radioactive waste microbiology has included a variety of analyses of disposal options for High Level (HLW) and Low/Intermediate Level (L/ILW) waste. Projects have covered a wide range of areas including: fundamental microbiology of geological formations; microbial tolerance to extreme conditions; biodegradation of repository materials and the interaction of radionuclides with microbes and their by-products. The work has included field sampling, laboratory studies, natural analogue investigations and development of mathematical models. Progress in the topic is considered by evaluating each part of the repository system in terms of microbial presence, possible microbial influence on the performance of the engineered and natural barriers, and how such influences can be quantified. From this perspective, priorities for future work in this area are identified.