DEVELOPMENT AND VALIDATION OF A NEW DIRECT CONTAINMENT HEATING (DCH) MODEL FOR THE INTEGRAL CODE ASTEC

摘要

In this work, a new model for the European integral code ASTEC (Accident Source Term Evaluation Code) to simulate different phenomena related to Direct Containment Heating (DCH) being relevant in pressurized water reactors during severe accidents with reactor pressure vessel failure is presented. The issue of DCH has been subject of the SARNET and SARNET2 research activity as part of the European research framework program and it has been one of the objectives to establish a realistic DCH model for the ASTEC code. The model presented here is a further development of the model already implemented in the GRS containment code COCOSYS. The different phenomena which DCH is composed of, are described within an effective model, e.g. several different phenomena relevant for DCH are not treated as independent processes. To develop a model which is able to yield reliable predictions for the relevant quantities of DCH, the model was thoroughly validated against the experiments of the DISCO facility at the Karlsruhe Institute of Technology (KIT), designed for European Nuclear Power Plants. These are namely the DISCO-C experiments with cold corium simulants to focus on the hydrodynamic effects of pure melt dispersion into the containment, and the DISCO-H experiments which in addition take into account thermal effects of the dispersed high temperature melt.