An apparatus for repairing bent mixing vanes in a nuclear reactor fuel assembly is provided, including a unique tool and a related tool handling device. The tool is an elongated tube with a housing containing two sets of opposing, high-strength blades movable between closed and opened positions. The tool is inserted into a fuel cell detected as having a grid with a bent mixing vane to a location below the damaged grid with the blades in the closed position. The blades are then remotely opened and the tool is withdrawn. As the tool is withdrawn, one blade abuts the bent mixing vane and bends it back close to its original position. The blades are then closed and the tool is fully extracted from the fuel cell. Once the tool is fully extracted, the fuel rod can again be reliably inserted into the repaired fuel cell. The related method includes the steps of: introducing the apparatus below the damaged grid; opening the blades; withdrawing the apparatus so that a blade abuts and straightens the bent mixing vane; closing the blades; and fully extracting the apparatus from the fuel cell.