Abstract: A pressurized water nuclear reactor comprises a normally vertical main vessel externally duplicated by a confinement enclosure. The main vessel contains a simplified primary circuit essentially incorporationg the reactor core and an annular steam generator arranged in such a way that the circulation of water, pressurized once and for all during the sealing of the vessel, takes place by natural convection. All the auxiliary circuits, conventionally ensuring cooling on shut down of such a reactor are eliminated, said cooling being ensured by a special arrangement of the space formed between the vessel and the enclosure and by the fact that the latter is immersed in an external cooling liquid, no matter what the slope of the reactor. The shut down of fission reaction in the core is ensured by systems of absorbing elements and by the automatic displacement of part of the reflector in the case of a slope of the reactor.

Abstract: In order to automatically initiate without any intermediate instrumentation chain the drop of absorbing members into the core of a nuclear reactor, in the of a drop in the cooling liquid level to below a given threshold and, optionally, a rise in the pressure to beyond a maximum permitted value, between each absorbing member and the bar supporting said member is provided an apparatus, which comprises tongs formed by at least two fingers, said tongs normally being locked in a gripping position by locking members, such as balls. A float mounted in the bar controls the unlocking of the tongs in either of the two conditions requiring the dropping of the absorbing members.

Abstract: The invention relates to a standby or emergency cooling device for the core of a pressurized water reactor.A high pressure reservoir filled with boric acid solution is permanently connected to the reactor vessel via two pipes, preferably arriving at the same level. However, one of these pipes is extended within the vessel by a downwardly directed bend in order to issue below the other pipe. These two pipes have horizontal portions which are intended to prevent any natural circulation under normal operating conditions.Application to the improvement of the safety of pressurized water nuclear reactors.

Abstract: An emergency cooling device for a water-cooled nuclear reactor comprises a heat exchanger integrated into a reactor vessel and submerged in the reactor water. One of the ends of the circuit of this exchanger is connected by means of a three-way valve to the upstream valve, while its other end is connected across a downstream valve and a second untreated water-operated cooling exchanger to the cold water tank.

Abstract: The present invention relates to a device making it possible to detect variations in the height of the free level of a liquid in an enclosure.The device comprises a vertical short tube issuing into the upper part of the vessel and whose upper end issues into a first condensation pot, a long tube whose long end issues into the vessel at a level below that at the end of the short tube, the end of the long tube being provided with a hydraulic seal, while the upper end of the long tube issues into a second condensation pot, a differential manometer indicating any pressure differences between the two condensation pots.Application to the measurement of the level of the water contained in the vessel of a pressurized water nuclear reactor.

Abstract: The invention relates more particularly to a pressurized water nuclear reactor in which the heat exchange between the primary and secondary circuits takes place by means of steam generators.A reserve tank is placed in the secondary circuit parallel to the steam generator and inside or outside the latter. It is pressurized directly by the secondary fluid in the gaseous phase leaving the generator, so as to form a reserve increasing the inertia of the generator in the case of closing the steam and supply valves without significantly increasing it in the case of a fracture of the steam piping.Application to pressurized water nuclear reactors.

Abstract: Apparatus for the separaton of the liquid and vapor phases of a fluid incorporating an open ended cylinder in which are arranged blades. Each blade is in the form of a curvilinear triangular surface, whereof a first side contiguous with the cylindrical wall of the cylinder defines a helix whose axis coincides with the cylinder axis, an apex opposite to said first side is arranged substantially at the axis and the remaining sides define a leading edge substantially perpendicular to the cylinder axis and a trailing edge inclined with respect to said axis. A number of blades are joined together at their apices to define the blade arrangement within the cylinder.The invention also relates to a steam generator having an outer casing, a first circuit in which circulates a hotprimary fluid and a second circuit in which circulates a secondary fluid, whereby the latter incorporates at least one group of two separation apparatuses connected in series.

Abstract: Each heat-exchange bank consists of at least two groups of flat, adjacent compartments provided for the circulation of a second fluid and separated by spaces for the circulation of a first fluid. Each compartment has lateral extensions placed in identical and opposite manner in two adjacent groups. The extensions are connected respectively in each group to a common admission manifold and to a common discharge manifold for the second fluid.

Abstract: A reactor vessel filled with coolant fluid is divided by a wall into an upper region and a lower region which contains the reactor core, part of the coolant fluid in the upper region being injected into the lower region. The injection flow rate is regulated as a function of the variations in pressure in the lower region by means of a baffle-plate container which communicates with a leak-tight chamber and with a storage reservoir, a flow of fluid from the chamber to the reservoir being established only at the time of a reduction in the rate of injection into the container. The reactor can be employed for the production of hot water which is passed through a heat exchanger and supplied to a heating installation.

Abstract: The plate exchanger comprises a plurality of flat parallel compartments formed between adjacent plates which are maintained in spaced relation by means of rings each having a T-shaped cross-section. The side arms of the T are welded to opposite edges of orifices formed in adjacent plates and the outwardly directed stem of the T is disposed between the plates. The interior of the array of spacer rings forms a header for the low-pressure fluid which flows through the compartments and a cylindrical tube extends through all the spacer rings in order to serve as an internal support.

Abstract: The steam generator is provided with a vertical cylindrical enclosure having a bundle of U-shaped tubes therein connected to inlet and outlet collectors through a tube plate at the bottom. An inner casing surrounding the tubes defines an annular chamber which communicates with the tube chamber adjacent the tube plate. A heater is provided about the outlet portion of the tubes within the tube chamber. An ejector pump supplying a secondary fluid is located in the annular chamber adjacent the heater for pumping secondary fluid through the heater. A portion of the heated secondary fluid is recirculated through the pump and the remainder is directed into the tube chamber. Vapor phase separators are provided on top of the inner casing to allow the passage of the vapor phase through an outlet in the enclosure while returning the liquid phase to the annular chamber.

Abstract: In a tube-type heat exchanger which produces superheated steam directly while being of the once-through type, the tubes permit recycling of the vapor of the secondary fluid which is circulated within them. A coaxial sleeve mounted within the annular space between an intermediate tube and the pressure tube delimits an annular zone filled with heat-insulating stagnant vapor so as to isolate the vapor produced from the fluid in liquid phase.