Nuclear concrete structures are typically passive under normal operating conditions. They are, however, play a key role in mitigating impacts of extreme/abnormal operating and environmental events. As structures age, changes in material properties arise from continuing microstructural changes and environmental influences. Changes in environmental conditions anticipated during the original design can sometimes lead to unpredicted effects, which may jeopardize the in-tegrity of the structures.
In order to continue successful operation, continuous integrity of the safety-related concrete structures shall be ensured by controlling and mitigating aging related degradation. A key element of aging management is the systematic and rigorous assessment of structures most commonly referred to as Condition Assessment (CA). Over the years, SNC-Lavalin personnel have assessed containment structures and safety related structures of Nuclear Power Plants (NPPs), research reactor and waste storage facilities.
This paper discusses requirements and approach to aging management for existing as well as new NPP concrete structures, and presents the methodology used to perform the CA.