DIFFERENCE IN THE COMPRESSIVE STRENGTH BETWEEN THE SURFACE AND THE CENTER OF CONCRETE MEMBERS IN A NUCLEAR REACTOR BUILDING AFTER LONG-TERM USE

Abstract

A research project on the aging concrete of Hamaoka nuclear power plant (NPP) Unit 1―it is currently decommissioning―, was started in 2016. The objective of this project is to create a concrete database of material properties, and employ non-destructive evaluation (NDE) method to construct a better soundness method. For this purpose, approximately 200 core samples were obtained from various concrete structural members, exceed 1.0m owing to seismic performance requirements. It was that the compressive strength of thick members showed a convex-shaped trend, indicating that the center of the cross-section was larger than the surface (Ref. [1]). In ordinary environmental conditions, the average compressive strength of all specimens obtained from seismicresistant 1.0 ~ 1.5m thick walls is approximately 10% larger than the average compressive strength of surface element regardless of these surface coatings.