Dynamic Loads from Reactor Pressure Vessel Core Melt-Through Under High Primary System Pressure

Estimates are presented of the thermal-hydraulic load acting on a pressurized water reactor pressure vessel and its support girder after lower head failure at high pressure (17 MPa). The estimates are based on onedimensional calculations performed with the RELAP5/MOD3 transient analysis thermal-hydraulics code. The information obtained provides a force-function input for structural dynamic calculations of an increased containment. On the assumption of a global circumferential rupture of the vessel lower head, the computations show a load peak of 340 MN and a continuing load of 160 MN acting on the vessel support ring. The analysis is related to the containment concept of Eibl, Kessler, and Hennies, which is aimed at developing passive mechanisms that can safely confine core-melt consequences.