Non destructive monitoring of mechanical stress in concrete for the survey of nuclear power plants
Résumé
To prevent consequences of damage in case of accident, some barriers of pre-stressed concrete are included in the nuclear power plant structures. Hence, to insure the nuclear security, it is important to control these structures. The nuclear accident induces pressure and temperature increases. This case is studied in a French Project involving eight academic and industrial laboratories with skills in NDE (Non-Destructive Evaluation) methods. In this paper, we focus on the synthesis for the results with different techniques in relation with the evolution of stress in the structure. Experiments tests have been conducted on slabs 0.5 m x 0.25 m x 0.12 m submitted to compressive load, for one concrete mix formulated to be representative of nuclear containment. In situ NDE measurements have been done during a test simulating nuclear accident. These experiments were realized on the Vercors mock-up which is a 1/3 scaled concrete power plant (ϕ 16 m x h 30 m cylinder, with 0.40 m thick walls) submitted to internal pressure up to 4 bars. This study includes electromagnetic techniques such as radar, capacitive, resistivity, permeability and ultrasonic measurements (impact echo, ultrasonic pulse velocity for volume and surface waves, diffuse waves, coda wave interferometry, nonlinear acoustics, etc.). Good agreements are observed between laboratory and in situ measurements. Industrial and research perspectives are presented.
Mots clés
Non-Destructive Evaluation Concrete Nuclear power plant Mechanical stress Ultrasonic Electromagnetic
Non-Destructive Evaluation Concrete Nuclear power plant Mechanical stress Ultrasonic Electromagnetic
Non-Destructive Evaluation
Concrete
Nuclear power plant
Mechanical stress
Ultrasonic
Electromagnetic
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