Abstract: A nuclear reactor is provided with an emergency cooling water injection device, comprising a vessel through which pass not only the cooling water inlet and outlet pipes under normal operating conditions but also a conduit for injecting pressurized water coming by an emergency reservoir, should a breakage of the primary circuit occur. A thermally insulated duct of the side wall of the vessel, at least at the level of the core, conveys the injected water below the core support plate.

Abstract: A pressurized water nuclear reactor with solid partitioning comprises a core formed by assemblies of prismatic shape disposed side by side inside a vertical cylindrical casing. A space between the core and the casing receives a solid partitioning structure. The partitioning is formed as a vertical stack of rings each completely surrounding the core, whose external periphery is engaged with a clearance in the casing and whose internal periphery matches the external contour of the core. The rings are centered and indexed with respect to the core casing by keys fixed to the casing and projecting into vertical grooves formed in the rings and they are formed with vertical mutually aligned holes defining cooling channels. Plugs in the channels define restricted water flow passages.

Abstract: Device for locking a guide ring on a plate having an orifice comprising a tubular intermediate piece (22) fastened rigidly to a plate (20) so that its central orifice (36) is coaxial with the orifice (32) in the plate (20), receptacles (28) machined radially in the intermediate piece (22) and separated by passages open towards one end of the intermediate piece, and attachment parts (39) which match the receptacles (28) of the intermediate piece (22) and which are associated with the guide ring (21). The invention is used particularly for locking the guide ring of an extension piece on a guide tube of a light-water nuclear reactor.

Abstract: In the device, over at least a portion of the length of the internal guide passage (5) of the tubular conduit (15) extends a retaining tube (16) exhibiting radial undulations (17) such that the cylinder having straight generatrices which is inscribed in the tube (16) corresponding to the free passage in a straight line, within this tube, has a diameter less than the diameter of the tubular conduit (15). In the case of a pressurized water nuclear reactor, the retaining tube (16) is preferably placed, at least in part, within the lower core plate (2).