Pressure-induced damage monitoring in prestressed concrete of nuclear containment wall segments using acoustic emission technique – Application to VeRCoRs containment building

Abstract

This paper reports benchmark findings of an experimental study of pressure-induced damage monitoring in a nuclear containment building (NCB) reproducing realistic conditions of internal pressure increase accidents. The leak-tightness of NCBs is assessed every 10 years during integrated leak-rate tests (IRLT). For double-wall containments, which have no metallic liners, the leak-tightness is strongly influenced by the degree of cracking of concrete and opening of the cracks. This paper is focused on assessing the effectiveness of the Acoustic Emission (AE) technique to evaluate the damage evolution of a reinforced concrete containment wall under pressure loading test. Piezoelectric accelerometers were mounted on the internal containment wall of the VeRCoRs mockup, which constitutes the containment building of a Nuclear Power Plant in a 1:3 scale. The Akaike criterion (AIC) as an AE hit picking method and the adaptive meshing algorithm (AMA) as an AE events localization algorithm have been applied for damage and cracking monitoring. A benchmark analysis based on the distribution of AE events and energy is presented for the detection of damages and the monitoring of crack propagation in correlation with the known locations of main cracks. The potential and limitations of the AE technique for in situ damage sources estimation are discussed upon two experimental campaigns (2017 and 2019), and the main conclusions of the benchmark survey are given. The results show that the AE technique is adequate for damage evaluation in large-scale concrete structures. It provides important information about the integrity of the structure and the assessment of damage evolution with time.