Study of the impact of decay heat on the in-containment temperature and pressure evolution following a hypothetical severe accident in a SFR

Abstract

We study the relative contribution of decay heat compared to sodium fire and solar radiation to the temperature and pressure evolution in the containment of a medium-size SFR following a postulated severe accident. This is an important problem for containment design concerning source term assessment. Sodium fire model, gamma transport of released radiation and solar heat flux model have been integrated to arrive at the results. Further, sensitivity studies are performed with respect to major dependent parameters. From the study, it is observed that decay heat contribution is significant as substantially higher values of pressure and temperature are sustained in the containment for a longer duration. This has implications for long term radiation release from the containment. The sensitivity study shows that in-containment release fraction, operating power and core inventory are the most sensitive parameters for the temperature and pressure rise in the containment.