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The judgment of welds with defects in reactor components is done by nondestructive as well as destructive material testing, stress analysis, and fracture mechanics. The following investigations are required: The kind, position, and size of defects in welds (stress relief cracks, hot tearing) is determined through nondestructive and destructive material testing. Strength, toughness, and subcritical crack-growth data are measured for weld-material, heat-affected zone and base material. The determination of strength, toughness, and subcritical crack growth of the heat-affected zone is very difficult, because the heat-affected zone is small and irregulary distributed. Therefore the heat-affected zone is simulated through suitable heat treatment. From this it is possible to estimate the behavior of original welds. Through the defect, material, and stress data the safety of welds with defects is proved. Additionally the margin of this safety is determined. The experimental verification of the calculations is done through a pulsating test of model under original loading conditions, including all specified loads.

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