Components and Structures under Severe Accident Loading (COSSAL)

NEA/CSNI/R(2019)2
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In the face of severe accident scenarios with melted core material, such as those that occurred at Three Mile Island-2 in 1979 and at Fukushima Daiichi in 2011, the integrity assessment of primary circuit components requires special consideration. The Nuclear Energy Agency (NEA) Working Group on Integrity and Ageing of Components and Structures (WGIAGE) thus established an international initiative to investigate the integrity of Components and Structures under Severe Accident Loading (COSSAL), which is led by Gesellschaft für Anlagen- und Reaktorsicherheit (GRS). The objective of the COSSAL project is to compare structure mechanical analysis methods for integrity assessment of metallic components under severe accident loading, especially under high temperatures, which may occur during core melt scenarios. The two main safety-related issues to be treated from a generic point of view are: i) which metallic component of the pressure boundary loaded by selected severe accident scenarios with high temperatures will fail first, and ii) what are the uncertainties for the integrity assessment and the quantification of safety margins against failure.