Consideration of accidents beyond the design stage
Containment. Enclosures

At the end of the 70s, following the publication of the American WASH 1400 report [10] , hypothetical scenarios, which could lead to containment failure through internal overpressure due to a slow rise in pressure beyond the design basis pressure, were applied to French PWRs.

Such scenarios assume, in particular, the total and prolonged loss of the unit's power sources, rendering all backup systems for reactor cooling unavailable. Realistic calculations have made it possible to estimate the pressure limit beyond which the containment system can no longer perform its function:

• for PWR 900, this absolute pressure is 0.9 MPa and...