Microbial Degradation Processes in Radioactive Waste Repository and in Nuclear Fuel Storage Areas

Purpose ofthe Workshop In the spirit of enhancing developments in science and technology by facilitating international scientific cooperation, the Science Committee of NATO is sponsoring AR W's in several selected priority areas. The objective of this workshop was to discuss what microbial mediated problems have been experienced in the area of nuclear waste management and spent fuel storage. Long term storage of high-level wastes in repositories is just starting in some countries. However, low and medium level wastes have been stored for several decades. In the area of spent fuel interim, storage has been extended at many locations far beyond the intended time. It was a priority of the workshop to examine and discuss what deleterious effects have been observed under these storage conditions or under conditions used in simulated trial tests for predicting material performance under the storage conditions. For example, one chronic problem that was discussed was possibility that microbial influenced corrosion (MIC) could be taking place in the wet storage of spent fuel thereby initiating or accelerating the process of corrosion. Another discussion in the area of waste forms, focused on the presence ofbiofilms which may be breaking down the structure of the waste form and thereby jeopardizing its integrity. The meeting focused on discussing the observations and data collected relating to problems encountered in the storage of these types of wastes, and sharing this information with others that have not monitored their facilities for similar problems.

Policy and Nuclear Waste Management.- Research and Development Priorities in the Hungarian Waste Management Program.- Spent Nuclear Fuel and High Level Radioactive Waste Management in Hungary.- Fundamental Issues.- Activities of Microorganisms and Transfers of Trace Elements of Radionuclides in Microhabitats.- Electrochemical Characteristics of Anticipated MIC in Deep Geologic Nuclear Waste Storage Environments at Yucca Mountain, Nevada, USA.- Assessment of Microbially Influenced Corrosion.- A Procedure to Evaluate the Potential for Microbially Influenced Degradation of Cement-Solidified Low-Level Radioactive Waste Forms.- Microbiologically Influenced Corrosion in Nuclear Waste Storage Environments.- Influence of the Microbiological Processes in Soil on Vertical Migration of Radionuclides.- Influence of Microorganisms on ‘Sr and “’Cs Speciation in Soils.- The Role of Microorganisms in the Mobility of Radionuclides in Soil.- Basic Radiation Microbiology.- Interim Storage of Spent Fuel.- General and Specific Perspectives on Biological Impacts in Wet Storage Facilities for Irradiated Nuclear Fuel.- Corrosion Problems in the Research Reactor “RA” Spent Fuel Storage Pool.- Corrosion in a Spent Fuel Storage Basin.- Wet Storage of Spent Nuclear Fuel: Corrosion Process Investigations.- The Potential for Microbiologically Influenced Corrosion in the Savannah River Spent Fuel Storage Pools.- Biofilm Development and the Survival of Microorganisms in Water Systems of Nuclear Reactors and Spent Fuel Pools.- Predicting the Effects of Microbial Activity on the Corrosion of Copper Nuclear Waste Disposal Containers.- Overview of the Interim Storage Systems for Spent Fuel at Swierk Centre.- Safety Aspects of a Dry Interim Storage Facility for Spent Fuel Cernavoda NPP.-Microbial Aspects of Radioactive Waste Disposal.- The Microbiology of Radioactive Waste Disposal.- 25 Years Experience in Experimental Shallow Land Disposal of Bituminised Radioactive Waste.- Microbial Aspects of LLW Disposal at the UK Low Level Radioactive Waste Disposal Site.- Determination of the Physical and Chemical States of Actinoids (Th, U, Np, Pu, Am) and Fission Fragments (Cs, Sr, Tc, Nd, Sm, Eu, Gd) Resulting from the Microbial Processes.- Gas Generation from Low Level Radioactive Waste: A Comparison of Model Derived and Experimental Data.- Microbial Degradation of Eurobitum Waste Form Under Anaerobic Repository Conditions.- Biodegradation, A Non-Problem if Radioactive Raw Wastes are Properly Conditioned into a Final Solid Disposal Form?.- In Vitro Evaluation of Microbial Effects on Bitumen Waste Form.- Author Index.