Maintenance standards and defects evaluation of pressure equipment

Defects evaluation which was the most important object in fracture dynamics was concretely described. A defects evaluation method is regulated in Sec. XI, ASME Boiler and Pressure Vessel Code. This method is widely applied in the world not only to nuclear power plant, but also to general appliances. In Japan, technical standard on maintenance of the nuclear power plant components is also recently prepared by using Sec. XI of ASME standard for a model. In this technical maintenance standard, a defects evaluation method in response to actual condition in Japan is regulated. Here are described concretely on defects evaluation by using the defects evaluation method of maintenance standard in Japan for a base. (G.K.)