Abstract: A shut-off device for a nuclear reactor component duct is provided that includes a plurality of elastic sealing rings, each radially expandable with respect to a common longitudinal axis between a retracted position at a distance from a wall of the duct and an expanded position for leaktight contact with the wall of the duct; a device provided for selectively moving the sealing rings between their retracted positions and their expanded positions; at least one member for locking in position the shut-off device in the duct to be shut off, distinct from the sealing rings, radially expandable with respect to the central axis between a retracted position in which the locking member is moved away from the wall of the duct and a locking position in which the locking member bears against the wall of the duct; a device provided for selectively moving the locking member between its retracted position and its locking position.

Abstract: A method of conditioning and stress relief for superalloy components includes vibrating the component during welding at a subharmonic frequency. The proper frequency is selected to be below a harmonic frequency, and to produce an amplitude in the range of ? to ½ the amplitude produced by a harmonic frequency. The component to be repaired is vibrated during and after welding at this frequency.

Abstract: An apparatus and method is provided for heat treating a tubular type heat exchanger. A heat fluid is passed through the tube bundle in order to heat the exchanger from within.