Selection matrix for non-destructive testing of NPP concrete structures

In general, the deterioration factors affecting concrete structures may be divided into (i) physical, (ii) chemical, and (iii) mechanical factors including also (iv) defects. Deterioration can result in loss of strength and unsafe conditions of the structures. NPP contain a variety of concrete structures that their structural performance of which is essential to the safety of the plant. Early detection of concrete structural deterioration in NPP is critical issue considering the consequence that they can eventually lead to. To ensure the safety and integrity of NPP, non-destructive testing (NDT) is carried out during the in-service life time. However, current NDT faces several challenges: (i) the NDT can be performed only during the revision time and the test process is time limited, (ii) the accuracy of the test devices, (iii) the compatibility of different NDT methods to the concrete structures and their deterioration mechanisms, (iv) the global uniformity of the NDT test methods and (v) the creditability of the test results and analysis. This paper is critically assess the NDT techniques currently in use to build a selection matrix for non-destructive testing of NPP concrete structures for the needs of NPP infrastructure evaluation in Finland. The results will specify the means for the assessment of suitability of different NDT methods for the NPP concrete structures. The results will also provide the nuclear power companies and utilities with reliable non-destructive test techniques to ensure the safety of the nuclear power plant facilities.