Acoustic emission measurements on an intermediate size vessel

Abstract

To demonstrate and to extend the performance of acoustic emission testing as a method of detecting and classifying flaws, six institutes conducted acoustic emission measurements in the course of various loading tests on a medium-sized, thickwalled vessel (model of a reactor pressure vessel) containing natural flaws. This paper will present a description of the vessel and the preparation of the flaw patch with 14 natural flaws, the performance of the loading tests to simulate pressure test and operating conditions existing in the primary systems of pressurized water reactors, and especially the conduction of acoustic emission measurements by using various monitoring systems. In the pressure tests conducted with slowly rising pressures, only one flaw was detected unequivocally by the acoustic emission monitoring, although several flaws had grown in the test phases between the pressure tests. Cyclic loading over prolonged periods of time produced clear signals of larger flaws, which calculations and subsequent destructive investigations showed to have grown. The small flaws which, most probably, had not changed, could not be detected.