Effects of Piping Supports Failure to Main Steam Line Integrity under Steam Explosion Condition

In order to mitigate hypothetical severe accident scenarios in an advanced light water reactor, either a core catcher is placed or an ERVC (External Reactor Vessel Cooling) strategy is adopted during design stage. However, when molten core penetrates RPV (Reactor Pressure Vessel) lower plenum and contacts with water in the reactor cavity, serious structural damage may occur. For instance, the dynamic loads on the reactor cavity and the reactor lower plenum could potentially lead to failure of the MSL (Main Steam Line) connected to the steam generators. In addition, since the MSL extends to the containment wall, failure of the containment building may occur. The goal of this research is to examine structural integrity of MSL piping under typical ex-vessel steam explosion conditions through FE analyses. In this paper, parametric numerical analyses of the MSL due to the supports failure were carried out under typical steam explosion condition and the following conclusions were derived. (1) The highest maximum stresses were calculated at liner plate under both failure condition. The all stress values did not exceed their yield strengths. (2) The displacements were high under both failure conditions