A Model for Structural Response to Hydrogen Combustion Loads in Severe Accidents

The response of structures to different pressure histories from hydrogen combustion is analyzed using the model of a linear undamped oscillator. The effective static pressures from a slow deflagration, a fast turbulent flame, a deflagration-to-detonation transition (DDT) and a stable detonation are calculated as functions of oscillator frequency. The response of components with a low natural frequency, such as the outermost shell in a large dry containment, is governed by the long-term pressure after combustion. Detonation peak pressure and impulse are not important. For structures with low frequencies, fast flames have a damage potential very similar to detonations. For the investigated pressure loads, the normally reflected detonation provides the bounding effective static pressure for oscillators up to 500 Hz. Fully confined DDT events can exceed the detonation load near the transition location for structural frequencies above ∼40 Hz.