Opinion of the IRSN on the safety of 900 MWe reactors equipped with steam generators with bottoms presenting an abnormally high carbon content

After an anomaly detected on some parts of the EPR Flamanville reactor vessel, it appeared that some primary bottoms of steam generators had been fabricated by the same producers and could present the same anomaly which could result in major residual positive segregations of carbon. This report states the opinion of the IRSN (asked by the ASN) about the defect size, the material mechanical properties, loads on defects in steam generators of 900 MWe reactors, and the risk analysis for a sudden failure of these steam generators