Material property and weldability of primary containment vessel steel plate for nuclear plant

Steel plates for primary containment vessels of nuclear power plants are described. As the nuclear power plants are getting larger with severe safety design requirement, it is necessary to use a high strength steel having a higher tensile strength than ordinary SGV49 steel or to use a SGV49 steel plate thicker than 38 mm. For these purposes, various properties have been investigated of high tensile, 38 mm thick SPV50 and 45 mm thick SGV49 steels. The mechanical properties, weldabilities and fracture toughness of these steel plates and their weld joints are proved safe enough to be used for containment vessel without stress relief heat treatment as well as the conventional SGV49 steel. (author)