A spacer grid for use in a nuclear fuel assembly has double-deflected vanes that guide an axial flow of coolant around fuel rods and thereby generate swirl flow. The flash memory device is adapted to terminate the program interval in accordance with when the program voltage has been restored to the target voltage after dropping below the target voltage. This design makes possible an extremely simple and reliable variable fastening of a hand-retaining device on the stickpole grip. The controller is programmed to only release the rinse aid when the temperature is above a predetermined threshold value.