Refueling apparatus for sodium-cooled fast reactor and method for the same

A refueling apparatus for charging a nuclear fuel assembly in a reactor vessel, the refueling apparatus comprising:

• a refueling unit including an extraction unit for extracting the nuclear fuel and a central axis connected to the extraction unit and transferring the extraction unit;
• a first waveguide sensor unit including a first ultrasonic wedge configured to form a Lamb wave, a first waveguide with a first end connected to the first ultrasonic wedge and with a second end configured to transmit the Lamb wave to a bottom of the extraction unit, and a first ultrasonic sensor connected to the first ultrasonic wedge and configured to sense a reflection signal reflected from an inside of the reactor vessel, the first waveguide being formed in a plate shape and mounted in an end of the extraction unit;
• and
• a second waveguide sensor unit including a second ultrasonic wedge configured to form a Lamb wave, a second waveguide with a third end connected to the second ultrasonic wedge and with a fourth end configured to transmit the Lamb wave to a side of the central axis, and a second ultrasonic sensor connected to the second ultrasonic wedge and configured to sense a reflection signal reflected from an inside of the reactor vessel, the second waveguide being formed in a plate shape and mounted in an end of the central axis,
• wherein the first waveguide sensor unit is configured to detect a condition of a bottom of the extraction unit and the second waveguide sensor unit is configured to detect a condition of the side of the central axis while the refueling unit refuels the reactor vessel, and
• wherein the extraction unit has a first space for the first waveguide, and at least a portion of the first waveguide is mounted in the extraction unit, and the central axis has a second space for the second waveguide, and at least a portion of the second waveguide is mounted in the central axis.