Session: DA-07-01 Thermal Stresses and Elevated Temperature Design

Paper Number: 62062

Start Time: Thursday, July 15, 2021, 09:00 AM

62062 - Fracture Analysis of Reactor Pressure Vessel Lower Head Considering Core Meltdown Accident 

This paper presents fracture mechanics analysis s for highly loaded reactor pressure vessel of the VVER-440/213 unit during in-vessel core melt retention scenario. In-Vessel Core Melt Retention (IVMR) strategy via external vessel cooling is widely applied for reactors of relatively low power like VVER-440. During the IVRM reactor pressure vessel (RPV) takes huge thermal loading from molted core (a source of heat generation), also internal pressure may be present. To resist these loadings RPV is cooled from the outer surface by the flooding of the reactor cavity. This may lead to thermal shock conditions, as we obtain a huge temperature gradient through the RPV wall, with relative cold water on the outer surface.

The calculations were performed using global 2D RPV model and local 2D sub-model with crack inserted into mesh for J-integral evaluations. First 2D RPV model was used to calculate the global stress-strain state of the RPV. During the calculation plasticity and creep material behavior was considered, as well as melt of the FE during calculation, which were ‘killed’ (excluded) when their temperature was above the melting line. Then a 3D sub-model with crack was calculated, with boundary conditions taken from the 2D axisymmetric analysis. Finally, a J-integral was evaluated according several procedures. Different crack position are compared, as well as different crack axis ratio. Conclusions were drawn about applications of J-integral procedures for such a highly loaded scenario.

Presenting Author: Yaroslav Dubyk IPP-CENTRE

Authors:

Yaroslav Dubyk IPP-CENTRE
Vitalii Antonchenko IPP-CENTRE
Maksym Zarazovskii IPP-CENTRE