Thermalhydraulic phenomena governing the quenching of hot rods, and existing models

After a core dry-out and a period of rod clad overheating, which might occur in some postulated accidental sequences in a PWR, the actuation of safety injections allows to quench the hot rods. Both thermal and mechanical processes control the phenomenon of quenching. Quenching first requires that liquid water is present to release the heat stored in the rod. When water is present, a pre-cooling of the clad is also required before quenching. (author)