Abstract: An apparatus for supporting and moving tools for fixing a cluster of tubes to the tubular plate (2) of a steam generator, comprising a first running track (25), a carriage (26) movable on this track, a horizontally alignable support (39) resting on the carriage 26, a second running track (43) carried by the support (39) and perpendicular to the track (25), and at least one supporting structure (42) consisting of a base (45) movable on the second running track (43) and carrying a vertical column (46), a tool holder (54) being mounted to move on the column (46) to offer a tool opposite each of the holes in the plate (2) in succession by virtue of a motor driven guiding and displacing elements (53-55) carried by the column (46) and of elements (31, 50,51) for moving the carriage (26) and the structure (42). The invention applies particularly to assembling the steam generator of pressurized-water nuclear reactors.

Abstract: Method and a device for inspecting the operation of a valve. The valve (1, 11) is placed on a test bench (2, 3) capable of applying an opening and closing force to the valve, a representative graph of the movement of the valve as a function of the force applied is plotted, the coordinates of which are measured continuously, and the graph of the test is compared with a reference graph (C.sub.1) in order to detect operating defects according to the positions of the valve. The invention is applicable to the inspection of valves for passing fluids, more specifically in the nuclear industry.

Abstract: A device for guiding a control cluster consisting of several absorbing rods consisting of a casing in which are mounted continuous-guiding sleeves each provided with at least one cylindrical slide suitable for the vertical guiding of a rod, and each open with a vertical slot emerging in the slide. Each guiding slide (631, 641) is associated with two orifices (635, 645) forming a hollow in the two lips (633, 643) of the slot (632, 642) so that, when a rod (31) is in contact with the lips, the interior of the slide communicates with the slot.

Abstract: A tool for the manufacture of a fuel assembly, said tool comprising for each end of an assembly an inner metal plate which can be applied to the bottom of an end member, an outer metal plate which can be displaced, under the action of a jack, along sliding columns fixed to the inner plate, in longitudinal translation with respect thereto and threaded ties traversing corresponding openings in the end member and in the inner and outer plates, able to engage with the internal thread of the guide tubes, and each provided with a head on which is supported a spring for compensating the action of the jack. A method for utilizing the tool is set forth, also.

Abstract: The invention relates to a method of protection of a pressurized-water nuclear reactor, which enables the crisis of boiling and the melting of fuel to be avoided. An emergency shutdown is triggered when a parameter representative of the crisis of boiling or the power released per unit length of the fuel elements exceeds a limiting value. For the determination of these parameters, the most exact representation possible of the distribution of the power in the core of the reactor is employed. This distribution is obtained by measurement of the axial power by ionization chambers, and determination of the radial power by measurement of the positions of the control rods.

Abstract: The exchanger is placed in a fluid of elevated temperature and comprises tubes connected to an inlet header and to an outlet header. The exchanger comprises a plurality of panels (4) constituted by tubes (41 to 48) extending below two inlet headers and two outlet headers, to which they are connected at the upstream and downstream ends, and forming two semi-panels which are imbricated one inside the other, each semi-panel comprising a subheader tube (41 or 42) connected to an inlet header (21 or 22) and being divided into at least one tube (43,44,45 or 46, 47, 48) which is coiled into a laced configuration so that the two sub-header tubes (41 or 42) extend vertically within the envelope of said tubes having a laced configuration and they support them through cantilever supports (411, 421). This exchanger may be in particular employed in a fluidized bed apparatus or for the recovery of the heat of gas or fumes.

Abstract: The disclosure relates to an expanding plug intended for closing a cylindrical aperture provided in a wall and accessible from only one side. In one embodiment, the plug comprises a base which is applied against the front face of the wall, at least two gripping members which are inserted into the aperture with their ends protruding on the other side of the aperture, which are provided with an outwardly extending radial shoulder, and which are mounted for sliding in corresponding recesses provided in a central member, permitting their radial displacement through a pivoting displacement effected in the plane of the radial recesses, a screw control into the central member in order to effect simultaneously their radial displacement towards the outside and their longitudinal displacement in the direction of the rear face of the wall until the shoulders of the gripping members are applied against the rear face of the wall.

Abstract: Device for elimination of vibrations of a valve for decompression of an enclosure containing a fluid under pressure, comprising a lever articulated on the valve body in two parts. The first part is integrally fixed to a spindle mounted to rotate in the valve body. This part comprises a rocker arm and its end opposite the rocker arm is connected to the valve stem. The second part is connected to the moveable armature of an electromagnet and comprises a bearing surface for the tappet. The two parts of the lever are connected through the intermediary of a friction coupling. Movements of the valve beyond the position of locking by the electromagnet are damped by the friction coupling. The invention is applicable in particular to a decompression valve in a pressurized water nuclear reactor.

Abstract: The invention relates to an actuating device for two clusters of control rods movable vertically in one and the same fuel array of the core of a nuclear reactor.The first cluster, used for running the reactor, is connected to a first actuating rod (2), the movements of which are effected by a mechanism (27, 28, 29, 30, 34). This rod (2) carries hooking fingers (41), the operation of which is effected by a device (45) mounted slidingly on the end of the rod (2). The device (45) causes the closing of the fingers by means of a spring (46), or on the contrary their opening by overstroke movement towards the top of the rod (2). The second cluster remaining fully inserted into the assembly during a part of the operating cycle of the reactor is connected to a second actuating rod (3).

Abstract: Device for supporting and rotating a part (1) of large dimensions about its horizontal axis, comprising a frame (5) carrying a plurality of pairs of rollers (6 and 7) including at least one pair (6) of driving rollers, a cylindrical support (4) receiving the part (1) in its interior and adapted to be positioned on the rollers (6 and 7) in such a manner as to be driven in a rotational movement about its horizontal axis when the driving rollers (6) are themselves given a rotational movement. Stop elements (13 and 13') prevent rotational movement of the driving rollers (6) in the event of incorrect positioning of the cylindrical support (4) on the frame (5). The device has particular application in the manufacture of boilermaking equipment.

Abstract: Safety device between a system for the control of a safety actuator and a logic circuit for controlling the actuator.The device comprises sequential circuit for the transmission of logic signals supplied by the control system to the logic circuit, sequential checking circuit for applying to the logic circuit actuator release signals in the case of a failure of the contol system or of the tansmission circuit, the transmission of signals between the system and the logic circuit being carried out after checking the no-failure of the transmission circuit.

Abstract: Fuel assembly for a nuclear reactor comprising at least two guide tubes (6) made of a material metallurgically compatible with the material of the spacer grids (9, 10). The guide tubes (6) are fixed rigidly to the plates (8) and to the spacer grids (9, 10). The other guide tubes (7), made of a material with a low neutron capture cross section, are secured to only one of the end plates and are movably engaged in the cells of the spacer grids (9, 10) so as to be able to move with respect to these under the effect of expansion.The invention is particularly applicable to pressurized water nuclear reactors.

Abstract: The invention relates to an inspection device for the tube plate of a heat exchanger. It comprises a motive part (2) mounted on a support equipped with fixing means to the inlet face of the tube plate. The motive part (2) is driven in rotation and in translation along the axis of the tubes. The device also comprises an active part (1) carrying an inspection probe (10) and guide means (17) for the probe (10) in the tubes. The active part (1) consists of a central shaft (8) and at least one sleeve (14) mounted rotatably on the shaft (8). The sleeve (14) comprises, in its side wall, at least two sets, spaced along the axial direction, of three orifices (15) placed at 120.degree.. Each of the orifices (15) contains a ball (17) projecting outwards. The active part (1) is connected to the motive part (2) by an articulation (3) permitting a disalignment between the active part (1) and the motive part (2).

Abstract: Device for safety injection on a pressurized-water nuclear reactor, including at least two separate injection trains each consisting of at least one set of means (60, 61, 62) for pumping water from a reservoir (58, 59) arranged outside the safety enclosure, and a main injection pipe (64, 65) connected to a distributor drum (70, 70') for the distribution of the water into each of the cold arms of the primary circuit. From each of the main pipes (64, 65) there is tapped off outside the enclosure an auxiliary pipe (84, 85) in which is located a block valve (96, 97). The auxiliary pipes (84, 85) include a branching-off (86, 87, 88, 89) for placing the auxiliary pipe (84, 85) into communication firstly with a cold arm (52, 53, 54, 55) and secondly with a hot arm (56, 56'). The invention is applicable in the event of leakage in the primary circuit of a pressurized-water nuclear reactor.

Abstract: A centrifugal pump for the circulation of fluid, comprising a flow-chamber through which passes an inlet neck and which is bounded at the opposite side from the latter by a cross wall, a rotor mounted at the end of a drive shaft located in prolongation of the axis of the inlet neck, and a stator comprising an outer toroidal shroud located in prolongation of the outer shroud of the rotor, the latter being surrounded by a fixed part for connection between the end of the inlet neck and the outer shroud of the stator. The rotor is guided axially by a hydrostatic bearing consisting of a journal which is arranged on the upstream portion of the outer shroud of the rotor and cooperates with a bearing arranged on the part for connection of the stator to the inlet neck, the bearing comprising a plurality of bearing pockets placed in communication with the flow chamber and thus fed by the fluid flowing through the pump at the pressure prevailing in the flow chamber.

Abstract: A method for regulating the power supplied to a steam turbine by a pressurized water nuclear reactor driving an electric current generator supplying a network by utilizing the movement of control rods in the reactor and the by-passing of a fraction of the steam produced by the reactor out from the turbine circuit. In the case of electrical uncoupling between the generator and the network or load rejection, the parameter determining the position of the control rods is selected as the greater of two values of a reference temperature. The by-passing of the steam is kept in operation and the operation of the reactor remains automatic. The opening signal for the by-pass valves is modified by a gain signal determined from a signal representing the power level. The invention is particularly applicable to the regulation of the power of pressurized water nuclear power stations.

Abstract: The invention relates to a superheated steam generator comprising a bank of U-tubes.It comprises a water drum (1) and a secondary casing (14) which are welded one on each side of the tube plate (5) and a bank of tubes (6) fixed on the tube plate (5) and contained in a casing (12) disposed inside the secondary casing (14) and forming an annular space (15) lying between the casings (12 and 14). Above the tube bank casing (12) a free space (25) is provided inside the secondary casing (14). This free space (25) constitutes a reserve of feed water in communication with the annular space (18). The water capacity thus constituted can be fed by at least one supply means (26).The invention is particularly applicable to pressurized-water nuclear reactors.

Abstract: Machine for monitoring internal equipment of a nuclear reactor, when stored outside the reactor vessel in the swimming pool of the reactor, comprising a first longitudinal carriage (16) movable on rails (14) on the bottom of the swimming pool, a transverse beam (46) movable on the first carriage (16), a second transverse carriage (61) bearing monitoring instruments (65) and movable on the beam (46), and an arrangement for moving the beam (46) in predetermined steps on the first carriage (16), and the second carriage (61) on the beam (46).

Abstract: Method and apparatus for monitoring the movement of the control rods of a nuclear reactor.The number of steps of movement in either direction of the rod from which the control rod is suspended is counted. According to the height of the step, an indication of the position of the suspension rod and of the control rod. The apparatus comprises devices for measuring the speed of movement of the control rod, for logging variations in speed higher than a given value, and for counting such variations according to their sign. The invention is particularly useful in pressurized water nuclear reactors.

Abstract: Apparatus for removing deposit from fuel elements of a nuclear reactor, by scraping the elements C by means of a remote-controlled scraping device entering the pool A of the reactor. The scraped sample is sucked, together with a certain amount of liquid, into an intermediate reservoir (20), the liquid removed with the sample is passed into a detachable filtration chamber (3), which retains the sample, the liquid being led into a buffer reservoir (21), and the filtration chamber (3) is introduced into a storage container (4), all the operations being carried out under the protection of shielded walls.