Abstract: A device for radially holding the envelope of a tube bundle and spacer plates of a steam generator, constituted by abutments traversing the wall of the bundle envelope and fixed to the wall level with the spacer plates. The said abutments being distributed on the periphery of each spacer plate in order to radially separate the bundle envelope from the pressure envelope of the steam generator. Each abutment comprises a first part (37) fixed to the bundle envelope (6) and contacted with the inner face of the pressure envelope (1), as well as a second part (32) exerting rigid holding stress on the spacer plate.

Abstract: In a preheating steam generator, the secondary water is introduced into a preheating space (34) by deformable extensions (52) from inverted J tubes (50) fixed to a semi-torroidal supply collector (48). The structure may be in the form of three tubular segments interconnected by swivel connections or couplings. The fitting of the extensions (52) between the tubes (50) and a plate (54) partly upwardly sealing the preheating space (34) is ensured by dismantable fixing members, without any welding.