Non Destructive Evaluation of the durability and damages of concrete in nuclear power plant
Résumé
The “Non Destructive Evaluation of containment nuclear plant structures” project (ENDE) is a French project developed with 8 partners. Its aims are to control the containment of structures by Non Destructive Testing with ultrasonic, electromagnetic and electric techniques. The results are than combined together to consolidate the final evaluation. Two different objectives are proposed, the first is to estimate concrete properties and the second to follow concrete damages and cracks. The 4 years project was carried out in two steps (in laboratory and on site). The first step consists in realizing two sets of tests on concrete specimens in the laboratory. Objectives of the first set are to characterize the material and to quantify the sensitivity of the Non Destructive Evaluation (NDE) to durability indicators (elasticity modulus, strength, porosity, water content) of the concrete. Two new indicators (thermal damage and stress applied) are tested in order to take into account a possibility of an accident (LLCA). Such accident induces relatively very severe conditions (pressure=4.2 bar and temperature T=180°C) inside the containment The second set was developed to evaluate damaged zones and cracks. The data fusion of measured NDE parameters is applied and developed for each result with two specific processes. It allows to select most sensitive and efficient approaches. The second step consists in an investigation of selected non destructives parameters on a real structures that is containment structures under varying pressure. The presented results were obtained on a mock-up of a containment wall realized in a 1/3 scale and constructed by EDF (Electricity of France) within the VeRCoRs program. These tests are realized in 2017 and simulate the ten-year nuclear power plants control in which the two functions regularly tested are: the concrete mechanical properties and the containment walls leakage. This paper presents the ENDE project and some of in site obtained results.