Nuclear Energy Agency Committee on the Safety of Nuclear Installations Oecd-nea Workshop on the Evaluation of Defects, Repair Criteria & Methods of Repair for Concrete Structures on Nuclear Power Plants

Aging of concrete structures occurs with the passage of time and has the potential, if its effects are not controlled, to increase the risk to public health and safety. Activities have been conducted to address factors related to quantifying the effects of age-related degradation on nuclear power plant concrete structures and components. Environmental effects that can lead to age-related degradation of reinforced concrete structures and their manifestations are described. Current regulatory in-service testing and inspection requirements are reviewed. Techniques commonly used to inspect nuclear power plant concrete structures to assess and quantify age-related degradation are identified. An approach for conduct of condition assessments is presented, as well as criteria, based on visual indications, for use in classification and assessment of concrete degradation. Materials and techniques for repair of reinforced concrete structures are noted and guidance provided on repair options available for various forms of concrete degradation (e.g., cracking, spalling, and steel reinforcement corrosion). Nuclear power plant degradation and repair experience is summarized. In-service inspection/repair strategies to maintain the probability of failure of a concrete component at or below a target value are discussed.