The modelling of chugging loads in pressure suppression systems

Chugging occuring during a later period of a LOCA blowdown stems from collapsing steam volumes within the pool. It is supposed that chugging produces high impact loads on the containment structure. Thus for evaluating the structural response one has to know the pressure-time history of such an impact. This paper is concerned with the description of the chugging model KSWING. It is believed that a thermodynamic instability, called spontaneous condensation initializes the chugging event. Comparison between KSWING-results and two different experimental results show good agreement in frequency content and pressure time history. (orig.)