Proceedings of the CSNI/RILEM workshop on use and performance of concrete in NPP fuel facilities

Reinforced concrete is widely used in construction of facilities for storage of low and intermediate-level waste. Thick-section structures constructed of conventional concrete are often divided into cells that provide both physical and chemical barriers to radionuclide transport. Reinforced concrete also finds applications in structures used for interim and deep disposal storage of high-level waste. The design life of concrete structures used in fuel cycle facilities may extend to several hundred years and hence durability requirements require careful consideration. To maintain performance and function over an extended design life structures must resist deteriorating influences from both the natural environment and the materials they contain. The overall objective of the workshop was to assess the current practices and the state of the art with respect to the use and performance of concrete (over several centuries) utilized for nuclear power plant fuel cycle facilities. Information obtained as a result of this assessment were utilized to identify issues or 'gaps' in the present knowledge for the primary purpose of formulating and prioritizing research needs on this topic. The objective was achieved through 4 technical sessions: 1. Regulatory Considerations; 2. Materials, Degradation Mechanisms, Repair and Decontamination; 3. Instrumentation, Monitoring and Assessment; 4. Damage and Service Life Models. The use of reinforced concrete for construction of waste storage facilities where design life is to be of the order of 300 years provides significant challenges in terms of material behavior, inspection, instrumentation and repairability. Considering the constraints of such structures, the design phase must integrate all these considerations. To ensure that the storage structure will perform its function through time it is important that any strategy for storage accounts for the concrete itself, integrates an ageing management program, is robust and can adapt to new safety goals in the future