Performance-based analysis of cylindrical steel containment Vessels exposed to fire

• Safety assessment of cylindrical steel containment vessel exposed to external fire.
• Coupling fluid-thermo-mechanical numerical procedure linking CFD and FEM models.
• Methodology provides reliable analyses ensuring load-bearing-containment functions.

This paper reports the results of a numerical investigation on the structural safety assessment of a nuclear cylindrical steel containment vessel exposed to an accidental external fire condition. A coupling procedure is proposed, linking the modeling of a nearly compressible flow with input energy given by a combustion model (CFD model) and a structural thermo-mechanical analysis (FEM model), allowing an accurate evaluation of a fluid-thermo-mechanical response for the entire duration of the simulated accident. The time-temperature evolution of the burned gases, resulting from the combustion of a hydraulic leakage pool, is performed by the CFD model. The FEM model is used to obtain (i) temperature variation and, (ii) thermo-mechanical behavior and ultimate strength of the vessel. The obtained results indicate that the suggested methodology can provide reliable fire-safety analyses, ensuring that the main safety (load-bearing and containment) functions of the installation are not impaired during accidental events.