Abstract: A heat exchanger, in particular for a nuclear reactor steam generator, comprising a U-tube bundle and a stabilizing system composed of anti-vibration bars inserted between the tubes of the bundle in the upper tube U-bend region. The anti-vibration bars have portions that protrude from the tube bend region, and the stabilizing system comprises elements which connect the aligned portions of the ends of the anti-vibration bars and are composed of a comb with slots designed to receive the ends of the anti-vibration bars, and a comb cover attached with fastening means. All the connecting elements are attached to supports that are joined to the bundle wrapper, while allowing limited movement of the set of anti-vibration bars and connecting elements.

Abstract: In a heat exchanger, such as a steam generator equipping a nuclear power station, the intermediate inwardly curved parts (14c) of the U-tubes (14) grouped into a bundle forming parallel layers are maintained by antivibration bars (36a, 36b', 36c') placed between each pair of adjacent layers, these bars being interconnected outside the bundle by connecting pins (38a, 38b, 38c). To prevent the fly-off of the assembly formed by the antivibration bars and the connecting pins, at least part of the bars (36a, 36b', 36c') are placed in slots formed in an elongated structure (40) fixed to the spacing plate (34a) closest to the inwardly curved part of the tubes.

Abstract: A pin (101) for alignment of two elements (1, 3) each comprising at least one orifice (2, 4) to be positioned coaxially with each other, the first element (1) being stationary and the second element (3) being radially displaceable. The alignment pin comprises a cage (11) having a diameter smaller than the diameter of the orifices (2, 4) of the two elements (1, 3) and intended to be placed in these orifices (2, 4). The cage (11) comprises radial expansion blocks (13) for centering the pin (10) in the orifice (2) of the first stationary element (1) forming a reference and for displacement of the second element (3) in relation to the first element (1). The pin is used for centering a cover on a nuclear reactor vessel.