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[en] A method of monitoring a material for strains and cracks is described comprising attaching a stress detecting member to the material in such manner that elongation of the material imparts a tensile strain on the detecting member, transforming acoustic energy emissions from the member into electrical signals and displaying the signals on an oscilloscope. The stress detecting member may comprise a metallic tube containing compacted ceramic powder, such as Al₂O₃ or SiO₂. (author)

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[en] Acoustic emission has been studied since the early 1960's, particularly with a view to periodic or continuous monitoring of steel pressure vessels. In the years 1970-75 it was realised that ductile steels, used in nuclear vessels, give small amplitude signals which are barely detectable by available instruments. The technique for application in periodic or continuous monitoring and also as applied to leak detection and weld fabrication monitoring is reviewed. It is concluded that manufacturing defects may be detectable during pre-service hydrotest, but that there is insufficient evidence on which to base an estimate of detection probability. In-service hydrotest or continuous monitoring is unlikely to detect growing cracks because of the quiet nature of the material and the noisy reactor background. Both leak detection and fabrication weld monitoring show some promise of successful application in the future. (author)

[en] Developments in acoustic emission are summarised as they relate to the principal applications to nuclear reactors, and light water reactor pressure vessels in particular. Improvement in the understanding of acoustic emission has come from materials tests and these confirm the problems in applying the technique for in-service or periodic proof test monitoring of growing fatique cracks. Applications in LMFBR have confirmed that acoustic emission can be applied in the nuclear environment and the detection of stress corrosion cracking in both BWR and LMFBR seems possible. Some information is included on the developing interest in applying the techniques of acoustic emission for leak detection during shop hydro and in-service monitoring. Acoustic emission is also being developed for weld fabrication monitoring and recently introduced pattern recognition techniques are having a significant impact in this application. (author)

[en] In reviewing the potential of acoustic emission testing of pressurised water reactor vessels the following applications are considered; detection of defects during pre-service and in-service hydrotest, continuous monitoring for crack growth, continuous monitoring for leakage, and fabrication weld monitoring. It is concluded that the technique can detect some of the small manufacturing defects in welds, but there is insufficient evidence to quantify the sizes or types detectable. (U.K.)

[en] The development of the UKAEA acoustic emission monitoring system has continued, directed towards its use to prevent pressure vessel failure in materials of general engineering practice. The acoustic facility, SWEL, can locate sources on large vessels to +- 3 inches and has a two-dimensional display, on line, of the emission sources. Measurements have been made of the location of artifical and natural defects in two experimental ductile steel vessels and on the US EBOR test vessel. Defects of a brittle nature are shown to emit strongly and can be readily detected. Defects in parent plate are shown to be quiet when significant crack growth is occurring, in accord with results from metallurgical specimens. No signals are detected during periods of yielding around defects in vessels in spite of indications from specimens that low level emission occurs. (author)

[en] Acoustic emission measurements have been taken on an experimental mild steel vessel with 4 inserted defects ranging in severity up to 90% of through thickness. The vessel was subjected to a series of pressure excursions of increasing magnitude until failure occurred by extension of the largest inserted defect through the vessel wall. No acoustic emission was detected throughout any part of the tests which would indicate the presence of such serious defects or of impending failure. Measurements of acoustic emission from metallurgical specimens are included and the results of post test inspection using conventional NDT and metallographic techniques are reported. (author)

No abstract available

No abstract available