In-service inspection of nuclear power plant components: An opportunity to perfect ultrasonic non-destructive test methods

The need for specialized ultrasonic non-destructive techniques for in-service inspection has been a strong incentive to development in this field. Not only have new or improved ultrasonic methods and procedures been established, but there have also been changes in some philosophical aspects of the planning and execution of ultrasonic testing inspections and the evaluation of the results. This refers to the basic information sources in the use for the evaluation, the sensitivity setting and the detection probability. These aspects are discussed in the paper. A survey of possible ultrasonic testing-methods is given for near and far surface defects and for coarse grain structures. The problems of coupling fluctuatuions, of the sensitivity setting in connection with the detection probability and the catalogue of possible defects and the evaluation of the results are described. (author)