Framatome Gmbh

Framatome & Cie.

Michel Babin

Guy Desfontaines

Jean-Paul Millot

Chevereau Gerard

Lower internals for a reactor--typically a PWR--having a pressure vessel containing a core cooled by an upward flow of coolant and a core support include a shell defining a coolant volume between the support plate and the lower part of the vessel. The shell has a wall and ducts opening into passages of the support plate. Guide tubes passing through the volume receive glove fingers for in-core instrumentation probes. The internals further include a separation plate fixed to the wall means, situated below the core support plate. The separation plate is formed with holes connected to the coolant conveying ducts and is fixed to the lower support plate of the core by mechanical connection means spaced apart at the periphery of the separation plate and defining passages for radial access of the coolant to the distribution chamber.

Nuclear reactor lower 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

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

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

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). This second rod (3), fitted coaxially within the rod (2), forms a piston (3b) in this rod (2) driven for its upward movement by the opening of a pressure relief valve (65) of the fluid-tight enclosure (1) in which the actuating rods (2 and 3) move. The rod (3) in the top position can be connected to the rod (2) by the fingers (41) engaging in a groove (53) of the rod (3). The invention is applicable particularly to nuclear reactors with improved efficiency employing neutron spectrum variation clusters.

Growing community of inventors

Pantin, France

Michel Babin