Preventive maintenance/repair device and preventive maintenance/repair method for cylindrical structure

A preventive maintenance/repair device for use in maintaining and repairing a cylindrical structure of a cylindrical shape among reactor internal structures installed in a reactor pressure vessel, the preventive maintenance/repair device comprising:

• a device body;
• a holding mechanism connected to the device body, the holding mechanism being configured to hold the device body on an outer circumferential surface of the cylindrical structure;
• a traveling and driving part disposed on the device body, the traveling and driving part being configured to be circumferentially movable along the outer circumferential surface of the cylindrical structure;
• and
• a maintenance/repair mechanism disposed on the device body, the maintenance/repair mechanism being configured to maintain and repair the cylindrical structure;
• wherein the device body is provided with a thruster driving part configured to move the device body in water.

A preventive maintenance/repair method using a maintenance/repair device for use in maintaining and repairing a cylindrical structure of a cylindrical shape among reactor internal structures installed in a reactor pressure vessel, the preventive maintenance/repair device comprising:

• a device body;
• a holding mechanism connected to the device body, the holding mechanism being configured to hold the device body on an outer circumferential surface of the cylindrical structure;
• a traveling and driving part disposed on the device body, the traveling and driving part being configured to be circumferentially movable along the outer circumferential surface of the cylindrical structure;
• and
• a maintenance/repair mechanism disposed on the holding mechanism, the maintenance/repair mechanism being configured to maintain and repair the cylindrical structure;
• wherein
• the device body is provided with an access device configured to bring the device body closer to the cylindrical structure so as to attach the device body to the outer circumferential surface of the cylindrical structure and to detach therefrom the device body, and
• an operation pole is connected to the access device,
• the preventive maintenance/repair method comprising the steps of:
• mounting the access device and the operation pole on the device body;
• sending the device body into the reactor pressure vessel in a hanging manner through the operation pole and bringing the device body closer to the cylindrical structure;
• holding the device body on the outer circumferential surface of the cylindrical body by the holding mechanism;
• removing the access device from the device body, after the device body has been held on the cylindrical structure by the holding mechanism;
• and
• performing a maintenance/repair operation to the cylindrical structure by the maintenance/repair mechanism.