MOUNTING SEAT CHECKING METHOD FOR WATER CHAMBER PIPING NOZZLE CLOSING COVER, MOUNTING SEAT INNER CIRCUMFERENTIAL SURFACE CHECKING TOOL AND MOUNTING SEAT INNER DIAMETER CHECKING TOOL

PROBLEM TO BE SOLVED: To check the integrity of a mounting seat to which a piping nozzle closing cover is mounted.SOLUTION: A mounting seat checking method for water chamber piping nozzle closing cover is provided for checking an annular mounting seat regarding a steam generator comprising the mounting seat to which a piping nozzle closing cover is mounted, the piping nozzle closing cover being provided to surround a water chamber side opening of a piping nozzle provided in a water chamber for closing the piping nozzle. The mounting seat checking method includes the step of draining primary cooling water in the water chamber (step S1), the step of next disposing a mounting seat inner peripheral surface checking tool with which imaging means is provided rotatable, within the water chamber in such a manner that the imaging means faces an inner peripheral surface of the mounting seat (step S7), and the step of then rotating the imaging means of the mounting seat inner peripheral surface checking tool to image the inner peripheral surface of the mounting seat (step S8).