The paper presents the state of the art for the surveillance of nuclear reactor components by acoustic emission (AE) during hydrostatic tests, as obtained during several inspections made by the Kraftwerk Union (KWU) and Battelle.

The necessary preconditions, wave propagation, calibration method, location accuracy, attenuation of AE signals due to geometrical configurations (nozzles), and the correlation between AE sources and defects as detected by other nondestructive testing methods (NDT) are presented and discussed.

The present results indicate the following:

∎ AE has a high sensitivity for detecting small leakages.

∎ AE signals from inside and outside of a thick reactor component can be located with approximately the same degree of sensitivity and accuracy.

∎ AE is a very sensitive NDT method, able to detect even very small flaws.

∎ AE indications lie preferentially in areas of seam welds, nozzles, welded-on attachments (auxiliary welds), closure studs, or other prominent areas.