In most of nuclear water reactors,heavy section components made in low alloy steel are connected with stainless steel piping systems.These junctions are carried out between ferritic nozzle ends and austenitic pipes,following a special manufacturing procedure.The high level of residual stresses due to manufacturing process is greatly reduced by a post weld heat treatment as mitigation against the risk of stress corrosion cracking.During welding defects may arise and the weld metal resistance reduced.Furthermore,the difference of yielding properties concentrates strain along the interface,making this region sensitive to ductile fracture.Therefore the integrity of Dissimilar Material Weld junctions has to be guaranteed.The ADIMEW (Assessment of aged piping Dissimilar MEtal Weld integrity) project aims to quantify the accuracy of structural integrity procedures used in the European nuclear industry to ensure the safety of defect-containing dissimilar metal welds in aged PWR Class 1 piping.A 16 inch diameter DMW weld junction containing a large machined crack has been tested successfully under bending at 300°C to determine the actual behaviour of cracks close to the interface.This paper presents design calculations and an analysis of ductile tearing initiation in the tested pipe.
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