PSI - Issue 28

Casper Versteylen et al. / Procedia Structural Integrity 28 (2020) 1918–1929 Versteylen/ Structural Integrity Procedia 00 (2020) 000–000

1921

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The fracture toughness in BCC metals is highly temperature dependent, and also irradiation dependent. This dependence is a function of the chemical composition and is therefore different for SA508gr3cl1 and SA-508gr.4N, see Table 2.

2. Boundary conditions

A finite element analysis of can be used to obtain the stress field of the RPV wall. Thermal stresses play a large role in this analysis. The temperature profiles in the RPV are obtained by CFD simulations. The temperature data is then exported to a FE model in which pre-existing cracks are meshed. 2.1. CFD Analyses The temperature of the RPV wall is calculated using CFD simulations, the simulation methods are described in detail in a previous publication Uitslag-Doolaard et al. (2019). The entire RPV and fluid contents are at 283 ° C for t = 0, when the emergency cooling starts the wall cools unevenly due to the ingress and turbulence of the hot and cold water. The RPV wall temperatures are used as input in a FE-analysis. The cooling transient of 200 seconds seen in the article by Uitslag-Doolaard et al. (2019), was prolonged to 1000 seconds in order to capture more of the PTS. An example of the temperature profile after 100 seconds of cooling transient is seen in Fig. 1.

Fig. 1. Temperature profile (in degrees Celsius) on the inner surface of the RPV wall after 100 seconds of ECCS. The complex fluid mixing simulated with CFD provides a temperature profile which can be used in FE to obtain thermal stresses. Image from ANSYS workbench 19.2. Fig. 1. T mperature profile (in d gre s Celsius) on th inner surface of the RPV wall after 100 seconds of E CS. The complex fluid m xing simulated with CFD provides a temperature profile which can be used in FE to obtain thermal stresses. Image from ANSYS workbench 19.2.

2.2. Geometry and boundary conditions

Reactor pressure vessels have thick walls in order to cope with high pressures of the water inside the reactor. A typical reactor pressure vessel geometry is used in this report. With an outer wall of thickness 250 mm, and a circular