Stress Corrosion Monitoring System of Vessel Penetrating Members and Degradation Evaluation Method of Penetrating Members

摘要

Stress-corrosion damage is tracked in the through structure 32 across the wall 40 of the vessel containing the electrolyte 50. Such a container refers to something like a reactor pressure vessel containing a coolant. The wall 40 of the vessel has control rod guides and through tubes 32 such as cables and sensor signals for coupling the external devices to the vessel's internal structure while maintaining the pressure barrier wall. The through structure 32 is stress-corrosion damaged, especially near the weld that attaches the through structure to the vessel head. One or more of the through structures 32 consists of a sensor probe that forms an electrochemical sensor cell with the through structures, which are exposed to the electrolyte 50 together with the surface of the walls 82 of the through structures 32. An electrode 74 is provided. The electrode 74 and the surface are otherwise insulated, and a plurality of electrodes 64 can be arranged to track separate local areas. The electrodes 72, 74 are connected to a detection circuit that generates a signal as a function of electrochemical activity due to stress and corrosion, indicating corrosion of all through structures. Electrochemical potentials, impedances, currents and specific noise levels of these signals are detected and read out to assess aging of the through-structure wall as a function of electrochemical activity.