ACOUSTIC EMISSION TECHNIQUES.

In this chapter the author reviews the principles and development of surveillance techniques based on acoustic emission (AE) as they relate to the nondestructive examination of pressure circuit components. In the first sections he considers the propagation of acoustic waves from a source, examines how signals may be detected in the presence of noise, and how with multiple sensors the source position is mapped. He later treats the conditions under which emissions may be generated, and examines AE surveillance appropriate to proof testing and in-service operation with subcritical crack growth by fatigue, creep and stress corrosion. He concludes that AE is an important technique in NDE since it increases assurance in component integrity and can be applied remotely, without operator involvement and in adverse environments during plant operation.