Irradiation Behavior of Submerged Arc Welding Materials with Different Copper Content

摘要

In Germany there are two first generation commercial nuclear power plants in operation, Obrigheim NPP (KWO) and Stade NPP (KKS). The reactor pressure vessels of both plants were fabricated of forged rings, joined with submerged arc welds. These welds were performed with a flux of the first generation, produced in license of Linde, and with copper-coated wires. When the first results of the irradiation surveillance programs were available, it became obvious that the neutron-induced embrittlement of the welding materials would be higher than expected at design of the power stations in the late sixties. To evaluate the neutron irradiation response, additional irradiation programs were performed. In the scope of these programs, submerged arc test welds were produced, corresponding in chemical composition, mechanical properties and Charpy toughness in the unirradiated condition of the core-welds of the two NPPs concerned. It was intended to assess also K_IC, T-curves of the welding material established on fracture toughness tests of large specimens.