Framatome & Cie.

Framatome Gmbh

Guy Desfontaines

Jean-Paul Millot

Michel Babin

Patrice Alibran

Gerard Chevereau

Fernand Savary

Jacques Baujat

Claude Leroy

Alain Heuze

Jean Paul Millot

Pol Dejeux

Rene Peletan

Serge Cochin

Dominique Hittner

Jean Damezin

Michel Le Helloco

Bernard Dumortier

The device comprises a mobile probe which can be displaced inside thimbles. A plurality of ducts (20) for the passage and support of a thimble are disposed in the partitioning (6) of the reactor, around the core (4) along an axial direction and substantially over the entire height of the core. The ducts (20) are distributed circumferentially around the core (4). A plurality of feed-through sleeves in the cover of the vessel are each disposed along the axial extension of a duct (20) for the passage of a thimble. Guide columns each disposed along the axial extension of a duct and each engaged in a feed-through sleeve in the cover of the vessel form, with the corresponding duct (20) and feed-through sleeve, a channel for the reception of a thimble. An arrangement for the guidance, displacement, switching and parking of the mobile probe is disposed outside the vessel (1) and fixed on to the cover of the vessel. This arrangement comprises a plurality of guide tubes each connected at one of its ends to the apparatus for displacement, guidance and switching of the mobile probe and, at its other end, to a thimble. The device with mobile probe enables a readjustment to be carried out to the measurements of neutron flux made by a set of fixed instruments comprising in particular external multi-stage fission chambers (40).

Device and method for the measurement of the neutron flux in the core of

Upper internals for a nuclear reactor comprise an upper core plate and a plate which supports cluster guides tubes connecting the two plates together. The cluster guides project above the support plate. A bottom wall of the support plate is situated at a level just higher than the outlet nozzles of the reactor vessel and each guide is supported by the bottom wall of the support plate by abutment of a shoulder formed in a passage of the bottom wall, in the lower half thereof.

Nuclear reactor upper internal equipment with cluster guide devices

The invention relates to a nuclear reactor with improved efficiency. The nuclear reactor comprises a massive partition (18) of material reflecting high energy neutrons at the circumference of the core (7) of the reactor, two layers (19 and 20) of material absorbing low energy neutrons and containing fertile material arranged one at the lower part and one at the upper part of the core (7) and an assembly of neutron energy spectrum variation rods (27). The rods (27) are associated with mechanisms permitting them to be either fully inserted into the core (7), or fully extracted. These rods (27) consist of a material absorbing low energy neutrons and permit a shift of the neutron spectrum towards the high energies. The invention is particularly applicable to pressurized water nuclear reactors.

Nuclear reactor with improved efficiency

Nuclear reactor having upper internal equipments and lower internal equipments with probe guiding means including probe guide ducts for slidably guiding flexible elongated probes into the core. The upper internal equipments include a plenum chamber for collecting the coolant coming out of the core and separating means disposed between the core and the plenum chamber, said separating means including two plates, one upper and one lower, connected at their periphery by an envelope and comprising spacer tubes through which pass the coolant so as to avoid passing through cluster guides for guiding the clusters of control elements into and out of the core. Lower internal equipments placed between the core and the bottom of the vessel include an enclosure and ducts for the passage of the coolant entering the core, said enclosure thus defining a tranquilized volume in which the probe guide ducts are distributed. These probe ducts penetrate into the reactor through sleeves situated above coolant inlet and outlet nozzles means.

Nuclear reactor having a longitudinally elongated vessel

A nuclear reactor has a pressure resistant vertical vessel with inlet and outlet pipes situated at the same horizontal level. It also includes internals having a barrel supporting the core and defining with the vessel a down flow path for the coolant from the inlet pipes towards a space under the core and upper internals defining a flow path for the coolant leaving the core, above this latter, and flowing towards the outlet pipes. The upper internals include dividing walls defining circumferentially distributed volumes located at the common level of the pipes and each over a different angular sector. Some volumes belong to the initial part of the downgoing coolant path and the others force part at least of the coolant leaving the core to follow a path which is successively directed upwardly then curving towards the outlet pipes. The invention is particularly suitable for use in pressurized water reactors.

Nuclear reactor with flow guidance in the upper internals

A device is provided concerning probe guide ducts for allowing a probe to pass for carrying out measurements on the coolant at the outlet of the assemblies (6) of a nuclear reactor (1). It comprises sleeves (9) through which pass upper columns (12) grouping together the guide ducts (10). After running horizontally along the periphery of the reactor, the ducts (10) are grouped together in lower columns (15) in the form of bundles before running towards the outlets of the coolant from the asemblies (6) in contact with the upper plate of the core (7). This device provides an excellent protection of the probe guide ducts with respect of the flow of the coolant.

Probe guide duct device for a nuclear reactor

Mechanism for displacing and securing the rod of a nuclear reactor control bar, comprising an enclosure coaxial with the rod and forming a hydraulic cylinder in which the rod slides while defining a decompression chamber, a device for mechanically securing the rod in its high position, and a positive displacement reciprocating pump inserted between the decompression chamber and the inside of the tank, whose piston is actuated electromagnetically means and causes at each backward and forward movement lifting of given amplitude of the rod and the device for securing the rod in the high position disengagable also electromagnetically.

Mechanism for controlling and securing a control bar in a liquid cooled

A tubular cluster guide for use in a nuclear reactor having upper internals comprising a lower plate formed with flow openings is fixed to an upper plate of the intervals and provided with a device for guiding and centering its lower part in the lower core plate. The centering device has a plurality of rigid blades carried by the lower part of the guide, spaced apart angularly about the axis of the guide and engagable in an opening of the lower plate with a radial clearance and a plurality of flexible blades between the rigid blades. The flexible blades bear on the edge of the opening and exert a radially directed force thereon. Bridges may be formed in the lower plate to retain a broken resilient blade.

Cluster guide with centering and antivibratory positioning device for

A control device for a PWR includes a plurality of clusters arranged for insertion into and removal from the core and each having a plurality of rods connected to a common carrier vertically slidable in a stationary guide structure and connectable to a drive shaft. First clusters contain neutron absorbing material and are each individually associated with electromagnetic actuation means for adjusting the amount of insertion of the associated one of the first clusters. Second clusters contain a different material and are each individually associated with hydraulic actuation means controllable to cause upward and downward movement. A set of one first cluster and one second cluster is associated with some of said fuel assemblies, with the drive shafts of the two clusters in each set being arranged symmetrically with respect to the axis of a single stationary structure located above the associated fuel assembly and arranged for authorizing mutually independent movement of the first and second clusters.

Device for control of the core of a nuclear reactor

A control unit for a nuclear reactor constituted by a plurality of sealed vessels (17) communicating with the inside of the tank of the reactor (15) which they extend upwards above its cover (16); each containing a displacement mechanism for a unit absorbing neutrons in the core of the reactor. The drive motors (18) for the mechanisms are positioned in the upper part of the sealed vessels (17) within vertical aeration ducts (32). The control unit includes a supporting and insulating device for the sealed vessels (17) constituted by a vertical structure (23) fast to the cover of the tank (16), a horizontal strengthening plate (27) fixed to the upper part of the vertical structure (23) and a heat-insulating envelope (36) surrounding the sealed vessels (17) to a level below the level of the motors (18). The invention is particularly applicable to pressurized water nuclear reactors equipped with screw and nut mechanisms.

Control unit for a nuclear reactor

Fuel array for an undermoderated nuclear reactor, comprising rods (6) arranged in a prism-shaped casing (1) parallel to the height of this casing (1). The internal surface of each of the walls (2) of the casing (1) is provided with channels (5) each of the channels (5) is located opposite a rod (6) arranged at the periphery of the array. The projecting parts (9) of the walls (2), between two channels (5), occupy part of the space between two peripheral rods (6). In this way, the moderating level remains constant throughout the cross-section of the array. The invention applies, in particular, to pressurized water reactors.

Fuel array for an undermoderated nuclear reactor

A modular lining for adapting the containment to the core of a pressurized water nuclear reactor, consisting of juxtaposed modular blocks (5) placed between the core containment (1) and the outer surface of the core (3). Arranged between the adjacent faces of the blocks (5), there are thin packing pieces (8) maintaining a certain gap between the undrilled solid blocks (5). The blocks (5) are fixed non-contiguously to the core containment (1) by screw devices (10) cooled by water circulation. The invention applies in particular to pressurized water nuclear reactors of improved efficiency and with a varying neutron spectrum.

Modular lining for adapting the containment to the core of a pressurized

The invention relates to a fuel assembly with cooled guide tubes for a nuclear reactor. It consists of a bundle of parallel fuel tubes (1) held in a structure comprising spacer grids, guide tubes (6) and end plates. At least a part of the guide tubes (10) comprises a set of guiding surfaces (16) projecting towards the interior of the tubes (10) over the whole of their length. The projections (16) are formed by embossing of the wall of the tube (10) and permit the guidance of the rod of absorbing material which is moved in the tube and the provision of circulating spaces for the cooling fluid between the tube and the rod of absorbing material. The invention applies in particular to pressurized water reactors and to reactors with neutron spectrum variation.

Fuel assembly with cooled guide tubes for a nuclear reactor

A nuclear fuel assembly has fuel rods connected to the lower end plate of the assembly. The connecting structure comprises an attachment plate which is superimposed on the lower end plate and which is formed with openings corresponding to the rods. The openings lead out into parallel grooves machined on the lower surface of the plate. Each rod comprises a lower part having three radial branches at 120.degree., each formed with an end extension projecting radially outwardly from the outline of the rod. The extensions engaged in a groove have a height substantially equal to the depth of the groove. Axial fixing and locking against rotation of the rods are thus ensured.

Fuel assembly for a nuclear reactor

Device for fixing a fuel assembly to the lower core plate of a nuclear reactor, comprising a fastening element (23) fixed to the lower core plate (18), in the central part of the opening (19) in this plate (18) corresponding to the assembly, an expandable sleeve fixed to the lower end (3) of the assembly in its central part, a guide tube (10) passing through the assembly in its central part in the axial direction, a rod (25) mounted for sliding movement in the tube (10) and fixed to an oval locking knob (38), and a socket (26) fixed to the upper end of the bar (25) and having a gripping surface for a lifting tool. The fastening element has an axial opening (31) for engagement of the expandable sleeve. The bar (25) and the socket (26) allow displacement of the oval knob (38) between service and out-of-service positions in which the latter spreads the expandable sleeve inside the opening (31) in order to fix the assembly.

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Puteaux, France

Guy Desfontaines