Passive containment cooling by natural air convection and thermal radiation after severe accidents

Abstract

One essential feature of composite containment is its potential to remove decay heat by natural air convection coupled with thermal radiation. Experimental and numerical investigations have been carried out to determine the coolability of such a passive cooling system and to study the contribution of thermal radiation to decay heat removal. A data base has been provided for validating advanced multi-dimensional computer codes and for developing physical models. It has been found that the passive containment cooling by natural air convection coupled with thermal radiation is a promising concept. Both the experimental data and the numerical results show that for intermediate and high wall emissivities, respectively, thermal radiation significantly enhances the entire heat transfer, even at low temperatures of the containment wall. The FLUTAN code combined with the new radiation model developed has been proven to be an accurate and efficient numerical tool for investigating flow and heat transfer behaviour in the system considered.