Abstract: A pressurized-water nuclear reactor with inherent safety comprises a pressurized vessel filled with borated water within which is the body of the reactor. The latter includes an upper part and a lower part within which is the reactor core. The upper part includes a first tubular cavity, a second tubular cavity coaxial with and outside the first cavity and a plurality of helical tube bundles extending between respective pairs of connectors for the inlet and outlet of water circulating in the tube bundles.

Abstract: A diagrid for a nuclear reactor core, of the type with two disc-like plates, for a series of parallel chandelles, and a cylindrical shell fitted with heat-exchanging fluid input and output ducts. A forced fit between the edges of said plates (10,11) and said shell (12) consists of a thick welded joint. The upper ends of each of the chandelles (30) protrudes above the upper surface of the upper plate. The two ends of each of the chandelles are welded to the plates.

Abstract: An intrinsic-safety nuclear reactor of the pressurized water type, having:a reactor vessel (2) equipped with a core (4), a lower header (5) and an upper header (6), at least one heat exchanger (3) with a secondary fluid, means of hydraulic connection (9, 10) between said headers and said heat exchanger and at least one circulation pump (11),a pressurized container (1) surrounding the reactor vessel (2) and which defines a tank (15) full of a cold, neutron-absorbing liquid;pipes (20) allowing communication between the lower area of said tank and the lower header of the vessel, as well as pipes (21) allowing communication between the upper area of said tank and the upper header,in which the pressure drop in the primary fluid across the core is substantially equal to the difference in head between the cold column of said tank and the hot column of the vessel.The pressurized container (1) is immersed in a pool (18) containing a neutron-absorbing liquid at atmospheric pressure.

Abstract: The invention refers to a solution for the reactor block of a sodium-cooled fast reactor, fitted with an inner cylindrical vessel. This forms the mechanical structure for hydraulic separation 7 between the primary sodium hot header 2 and the cold header 3. The hot header is located in the area above the core, and the cold header, having a larger volume and an annular shape, is located all around the hot header. According to the invention the primary pumps and intermediate exchangers 8 are immersed in the cold header 3. The intermediate heat exchangers 8 are of the straight tube bundle type, with primary sodium outside the tubes, and they are hydraulically connected to the hot header by a transverse duct 13, solid with the inner cylindrical vessel 7, and mechanically sealed where it interfaces with the heat exchanger. This mechanical sealing system is made as close against the heat exchanger, as possible, so that the heat exchanger is removable.

Abstract: The subject-matter of this invention is a device for locating rods buried in high-density reinforced concrete. The device envisages an inductor coil (10) which generates a magnetic field, and at least one detector coil (1) able to detect the variations in the magnetic field induced by the presence of steel rods. The device is associated with marking equipment (4), which may be controlled either manually or automatically, depending on the strength of the signal emitted by the detector coil(s).

Abstract: The object of the invention is an automatic servo-controlled valve with high speed opening wherein the shutter is a hinged cover (20). Suitable locking means (30, 50) keep the cover (20) in a locked position up to the time when the pressure difference on the two faces of the cover exceeds a pre-determined minimum level. After the said locking means have moved to an open position, an actuator (40) operates the opening of the said cover at high speed (FIG. 1).

Abstract: A process and an apparatus for continuously welding large high gauge sheets, according to which the position of a torch is defined by a feeler bearing on the root and on a wall of a chamfer. After carrying out a first weld line a switch means signals the end of the first line and moves the feeler to the other side of the chamfer while still dragging along the welding torch, and during its movement measuring the chamfer width at that particular level of the joint. The feeler and torch remain in the same plane parallel to the chamfer axis and contains both of them. The sensed width is then compared with stored widths, thus deciding how many weld lines have to be deposited in that layer, at the same time carrying out the second weld line with the feeler and torch adjacent the other side of the chamfer, and still arranged in a plane parallel to the above mentioned plane.

Abstract: In order to prevent a false signal being given in a circuit arrangement for detecting the presence of rolling stock on a track section, when a rail is grounded or fractured, a detecting circuit (31) is provided for detecting unbalance of the traction current. The unbalance detecting circuit is for association with a transmitter (20) for transmitting a track circuit current and an associated receiver (21). The unbalance detecting circuit has two current sensors (TA) which are connected to the ends of the rails (1, 2) adjacent to the receiver (21) for transmitting respective signals to the unbalance detecting circuit (31), and the unbalance detecting circuit transmits the track circuit signal to the receiver only when the signals detected by the current sensors are equal or when their difference is such as not to cause undue excitation of the receiver, and a pole change switch (30) for connection between the track circuit current transmitter and the ends of the rails associated therewith.