Direct containment heating calculations for Ringhals 3

The Swedish nuclear power program consists of 12 power reactors. Nine of these are BWR:s and three are PWR:s. At the Ringhals site on the west coast of Sweden we have one BWR and three PWR:s (three-loop Westinghouse design). Direct Containment Heating (DCH) is a severe accident scenario in which a significant part of the core debris after melt-through of the reactor vessel is dispersed into the containment causing a rapid increase of the temperature and pressure in the containment atmosphere. Under certain assumptions concerning the accident sequence DCH is predicted to be a threat to the integrity of the PWR containment. However, the results of such DCH analyses are dependent on the choice of key modelling parameters in the calculations. Finally different plants must be treated individually mainly due to different failure pressure of the containment but also specific design of the containment. (author). 6 refs., 2 tabs., 2 figs