Patent ID: 7178485

Claim:
Steam generator comprising: an outer shell of cylindrical general shape placed with its axis vertical; a bundle of exchange tubes that are fastened inside a bundle wrapper of cylindrical general shape placed coaxially inside the outer shell so as to define, with one of the outer shell and of a skirt coaxial with the outer shell, an annular space for water from the steam generator to flow axially; a feedwater delivery device, at an upper axial end of the annular space, having a header of toroidal general shape approximately coaxial with the outer shell and with the annular space; at least one feed pipe for the header passing through the outer shell; means for distributing the feedwater in the upper part of the annular space, these distributing means being formed by a plurality of openings that pass through an upper wall of the toroidal header and are distributed circumferentially on the wall of the header; the distributing means further including a plurality of substantially vertical distribution tubes that are fixed at a respective lower end thereof to a corresponding opening in the wall of the toroidal header; wherein the tubes of the feedwater distribution means are straight and placed vertically and wherein each of the tubes of the feedwater distribution means has, in an upper ends section: (a) at least one water passage opening passing through the wall of the tube; and (b) a cap that is fastened to the tube and has a lateral surface of substantially cylindrical shape and a top sealing the open upper end of the tube, in an approximately coaxial arrangement, surrounding with a radial clearance, the upper end part of the tube through which the water passage opening passes, one dimension of the opening being less than a characteristic dimension of foreign bodies contained in the feedwater of the steam generator.