Abstract: The flow distribution baffle (14) is placed inside the bundle wrapper (7) of the steam generator, at its lower part,-near the steam generator tube plate. Passing through the flow distribution baffle (14) are openings (17, 18) for the passage of tubes of the steam generator bundle and feedwater. The flow distribution baffle (14) comprises a central zone (15) of more or less circular shape with, as its axis, the axis of the steam generator and a radius (R1) smaller than 40% of the internal radius (R) of the bundle wrapper (7), and a more or less annular peripheral zone between the central zone and the outer edge of the flow distribution baffle (14). In the central zone (15) the openings (17) for the passage of tubes and feedwater in the flow distribution baffle have a cross section (S1), the cross-sectional area of which is greater than the cross-sectional area of the cross section (S2) of the openings (8) for the passage of tubes and feedwater in the peripheral zone.

Abstract: A fluid control valve having a valve body, a cage, and a flexible elastomeric diaphragm with a formed convolution to fully open the cage opening. An elastomeric diaphragm regulator with a flow diverter in the fluid flow path to reduce fluid flow separation and thereby reduce the required flow recovery area before pressure throttling. A raised knife edge seat located on the cage top in a position of stagnant fluid flow to reduce the build-up of contaminants on the seat. An elastomeric diaphragm regulator with a valve actuator coupled to a guided valve stem attached to the regulator diaphragm.

Abstract: The secondary water supply for a steam generator is provided by a toroidal or semitoroidal collector (38) placed in the bottom of the annular recirculation space (32) of the generator, in a larger diameter part (36) of the outer envelope. The collector (38) has holes (40) ensuring a vertical mean flow of the secondary water into the annular space (32). The cross-section of the holes is chosen in such a way as to trap in the collector the migrating bodies or members from the secondary water circuit and which could damage the steam generator tubes. At least one access orifice makes it possible to extract these migrating bodies from the collector during maintenance operations.

Abstract: Device for the emergency removal of the heat dissipated by a fast breeder nuclear reactor when shut down, comprising a liquid-liquid heat exchanger immersed in the vessel of the reactor and a liquid-air exchanger for the cooling of the secondary liquid of the latter exchanger. The liquid-liquid comprises a casing composed of a sleeve (18,19) having openings (21,22) for the natural circulation of the cooling fluid of the reactor in contact with the tubes (25) of a nest (20) disposed in the casing of the exchanger. Each of the tubes (25) includes a straight input section and a long straight return section, separated by a helically wound section forming a loop with a low number of turns, inclined to a small extent with respect to the horizontal plane. The coil diameter of the tubes (25) is constant and identical for all the tubes and very slightly less than the interior diameter of the sleeve (18,19).The invention applies in particular to liquid sodium-cooled fast breeder nuclear reactors.

Abstract: The apparatus comprises an annular cup (5) solid with the component (1) and surrounding its outer wall, a frusto-conical support surface (9) having as axis the vertical axis (2) of the component (1) fixed at the perimeter of its large base to the passage (4) into which the component (1) passes and a closure element (14) with rotational symmetry. The closure element (14) has an upper part (15) which rests on the support surface (9) so as to totally close the annular space (18) at the top and a part directed downwards constituted by a sleeve whose lower part goes into the cup (5). The cup (5) fills up with liquid metal (17) which condenses when the reactor is operating, which ensures sealing between the sleeve (4) and the cup (5).The invention is particularly applicable to fast neutron nuclear reactors cooled by liquid sodium.