Determination Method of Through WallNon-Through Wall Cracks and Measurement Method of Through Wall Crack Length on Nuclear Steam Generator Tubes

摘要

PURPOSE: A method for measuring a crack and a length of the crack in a heating pipe of a steam generator are provided to precisely determine the crack in the heating pipe by measuring the number and position of peak points. CONSTITUTION: A motorized rotating coil is spirally rotated while moving along a heating pipe of a steam generator. When the motorized rotating coil passes through a crack portion of the heating pipe, a swirl current signal is detected. The swirl current signal is represented as a graph. The number and position of peak points in the graph are measured so as to determine the crack state of the heating pipe. The motorized rotating coil includes one selected from the group consisting of a pancake coil, a plus point coil, an axial coil and a circumferential coil.