Heat and mass transfers in a concrete wall with composite liner under accidental conditions

• Published in: Nuclear engineering and design 2004-03, Vol.228 (1), p.261-272
• Main Authors: Billard, Y, Shekarchi, M, Debicki, G, Granger, L, Chauvel, D
• Format: Article
• Language: English
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Heat transfer; Installations for energy generation and conversion: thermal and electrical energy; Theoretical studies. Data and constants. Metering
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2003.06.027

The aim of this work was to study the behaviour of a concrete wall, covered with a composite liner and exposed to accidental conditions leading to high temperatures and pressures on a face of the material. In the laboratory, two practical levels of accidental situations (beyond design) have been considered. Firstly, the “SC1” scenario (accidental conditions) consisted of a rise from ambient conditions to a saturation point of 160 °C, and a pressure of 0.75 MPa in 12 h, using the maximum increase possible with the apparatus. This rise was then followed by cooling, leading to 0.22 MPa and 120 °C in 24 h. These conditions were maintained for several days. Secondly, a “SC2” scenario (severe accident conditions) consisted of a rise to a saturation point of 173 °C and a pressure of 1 MPa, these conditions were maintained for 24 h before cooling. A cylindrical specimen of 1.3 m of thickness was used. Thermocouples, pressure taps and moisture gauges were implemented before concreting. These devices provided local information, and were mostly distributed in the first 0.30 m of the concrete. The concrete composition (high performance concrete) was the same as that used for the construction of the CIVAUX 2 nuclear power station. Typical experimental results for the evolution of temperature, pressure and water content as functions of time are shown for the two test conditions. The concrete attached to the back of the composite dried, and a mass transfer was induced towards colder zones in the centre of the specimen. The liner acted as a heat insulator and the pressure acting on the back of the composite remained lower than that applied on the composite. The residual adhesion of the liner to the concrete was measured. Finally, the overall results allowed the comparison of situations where the wall was lined and unlined, during exposure to SC1 and SC2 conditions.