A fracture mechanic interpretation model for acoustic emission signals caused by thermal fatigue shocking on a reactor pressure vessel nozzle

The analysis of acoustic emission measurements during cyclic thermo-shock tests on a pressure vessel nozzle (HDR) with cracks, indicated a time-dependent emission of signals that partially contradicts the usual fracture mechanic approach (according to Paris). If one assumes a time-dependent corrosion crack growth (normally of secondary importance) as the dominating factor of influence, a qualitatively good agreement between acoustic emission and fracture mechanic is achieved.