Closed Projects

 

Behaviour of the Reactor Pressure Vessel during Core Melt Down Scenarios

By means of coupled thermal and mechanical Finite-Element-Simulations the behaviour of the reactor pressure vessel of light water reactors during an assumed core melt down accident is investigated. The numerical models are validated against medium scaled experiments. The aim is the evaluation of failure modes and times and their impact to the further accident progression or an assessment of possible safety margins against failure. What are possible conclusions for severe accident management measures?

 

Fracture mechanical analysis of a thermal shock scenario for a VVER-440 RPV

This page describes the analytical work done by modelling and evaluating a thermal shock in a VVER-440 reactor pressure vessel due to an emergency case. An axial oriented semi-elliptical underclad/surface crack is assumed to be located in the core weld line. Three-dimensional finite element models are used to compute the global transient temperature and stress-strain fields. By using a three-dimensional submodel, which includes the crack, the local crack stress-strain field is obtained. The determination of the stress intensity factor, which is a measure for the loading of the crack, follows the VERLIFE code. With a subsequent postprocessing using the J-integral technique the stress intensity factors along the crack front are obtained. The results for the underclad and surface crack are provided and compared, together with a critical discussion of the VERLIFE code.