In-service testing and monitoring of the enclosure
Containment. Enclosures

Before the unit is commissioned, the PWR 900 enclosure and the inner wall of the PWR 1,450 enclosure are subjected to a test by pressurizing the interior atmosphere with dry air at ambient temperature. The effective pressure is equal to the design pressure p for PWR 1,300-1,450, and 1.15 p for PWR 900, to account for the action of the metal skin in the event of a LOCA, as its expansion is counteracted by the concrete, which remains cold.

In operation, no resistance tests are planned. However, a complete survey of the monitoring devices is carried out during the periodic overall watertightness tests.

In addition, measurements are taken at intervals of around 3 months to monitor the evolution of the structure...