Abstract
Many known defects that develop in concrete over time threaten the safety and security of the infrastructure in nuclear power plants (NPPs). These defects also exist in other concrete infrastructures, but the harsher nuclear environment adds significant difficulty to their detection and correction. To monitor the structural health of a concrete facility, coring and other destructive testing methods are typically employed, but this is not the ideal solution for NPP concrete infrastructure. Developing a reliable nondestructive evaluation (NDE) method to evaluate the damage in these structures will greatly improve the long-term operation and safety of NPPs. The University of Tennessee, in collaboration with Oak Ridge National Laboratory, developed a large-scale experiment to study one known defect due to the reaction between hydroxyl ions of the alkalis in cement paste and the siliceous minerals present in some aggregates known as alkali-silica reactions (ASRs). Alkali-silica gel forms and swells due to its hygroscopic characteristic, causing cracking and material failure. This paper discusses the NDE measurements performed on the large concrete specimens and the reconstructed images from these measurements.
