Importance of pools, sprays, and ice beds in fission product retention in containment

The retention of fission products, which may become airborne during a postulated severe accident, is an important consideration in risk assessment of nuclear plants. Both natural processes and engineered safety features are characterized by mechanisms which remove and retain fission products. Theoretical and empirical formulations have been developed which show substantial fission product retention by pressure suppression pools, containment sprays, and ice bed condensers. Ice bed data is minimal, and more experiments are necessary for retention model verification. Theoretical trends for pool and spray retention have been verified by available data, but a more extensive data base over a broader range of geometric and thermodynamic parameters would improve model evaluation and verification, and help to minimize conservatisms. This paper provides a summary of the technological state-of-the-art of fission product retention by pools, sprays, and ice beds