The Diagnostic Method of Inner Parts of Welded Joints at Nuclear Power Plant

摘要

There is no possibility to check any inner part at real welded joint at nuclear power station (NPS) during operation because any destructive test cannot be used. In practice there is checked surface of weld. There are used four methodical instructions for the check of real welds: 1. The visual inspection, 2. The measurement of hardness, 3. The chemical composition checking and 4. The microstructure replica analysis. It is necessary to know how these information of weld surface are in accordance with characteristics of inner parts of weld. If there is not any difference between surface weld microstructure and internal weld microstructure of experimental weld it is supposed to that there is not any difference in other measured properties of welds. If is changed structural characteristics of microstructure, it is changed also hardness, chemical analysis etc. It was observed that the microstructure of real welds is almost the same with simulated weld and also the surface microstructure of experimental weld is in accordance with microstructure of inner parts of this weld. It can be supposed extension of lifetime of NPS if there is not any difference between replicas microstructure taken after six year operation of NPS and microstructure of inner parts of simulated weld is almost the same with surface microstructure.