Finite Element Analysis of a Reactor Pressure Vessel during a Severe Accident.

摘要

Finite element analyses have been conducted to investigate some of the salient features associated with the failure of a pressurized nuclear reactor vessel. In the limited study, the temperature dependent elastic-plastic response of the steel has been considered without regard to any embrittlement or coupled creep phenomena demonstrated by the material. The primary purpose of these calculations is to determine the relative importance of thermal strains in establishing the net time to failure. The presence of molten material in the bottom of the pressure vessel is crudely simulated by a temperature boundary condition. Thermal properties are assumed to be temperature independent and the resulting linear heat conduction problem is solved independently (uncoupled) from the mechanical problem. Although the presence of thermal strains dramatically increases the magnitude of the sag in the bottom of the pressure vessel and changes the transient stress distribution occurring through the thickness of the shell, it does not significantly alter the time to failure.