Patent Number: 048287881
Section: summary

FIELD OF THE INVENTION The invention relates to a support device for a discharge tank of a suspended pump for circulating the coolant fluid of a nuclear reactor, and in particular a primary pump of a fast neutron nuclear reactor of the integrated type. BACKGROUND OF THE INVENTION Primary pumps of fast neutron nuclear reactors which are generally cooled by a liquid metal such as sodium are disposed, in the case where the reactor is of the integrated type, inside the vessel of the reactor which also encloses the core immersed in the primary liquid sodium filling the vessel. These primary pumps comprise a generally cylindrical body disposed vertically and supported in its upper part by the slab of the reactor closing the vessel. The pump body communicates, in its lower part, with a discharge tank which generally has a spherical shape. This spherical tank is connected to two discharge pipes which open, at their end opposed to the end connected to the spherical tank, onto the bed supporting the core of the reactor. The liquid sodium which is drawn in by the pump in the region of ports extending through the case of its vertical body is discharged into the spherical tank and distributed in the discharge pipes and then re-injected under the assemblies of the core of the reactor. The discharge sphere is rigidly fixed to the plating which is a fixed structure of the reactor resting on the bottom of the vessel and carrying the bed which acts as a support for the assemblies of the core. Upon rapid variations in the operating conditions of the reactor, accompanied by rapid and large-amplitude variations in the temperature of the coolant fluid, and in the case of an abnormal operation of the reactor owing to an incident, which is also accompanied by large temperature variations, the discharge sphere, which is rigidly connected to the plating, is subject to considerable stresses of thermal origin. Indeed, the sphere has a tendency to move under the effect of variations in expansions accompanying the temperature variations, but it is practically immobilized by its rigid connection to the plating. High stresses result in the materials constituting the discharge sphere and the elements connected thereto. SUMMARY OF THE INVENTION An object of the invention is therefore to propose a support device for a discharge tank associated with a pump for circulating the coolant fluid of a nuclear reactor comprising a vertical body supported in its upper part and communicating in its lower part with the discharge tank carried by a fixed structure of the reactor and connected to discharge means opening out under the core of the reactor and symmetrically disposed relative to a vertical plane containing the axis Z-Z' of the pump, this support having a structure whereby it is possible to limit to a low value the stresses of thermal origin which are exerted on its discharge tank and elements connected thereto, in the event of rapid variations in the temperature of the coolant fluid of the reactor. For this purpose, the support device comprises at least one substantially planar metal strip disposed vertically on the axis Z-Z' of the pump and perpendicular to the plane of symmetry of the discharge means, the tank being fixed to the strip in a region located below the region of this strip ensuring its connection with the fixed structure so as to be suspended from the fixed structure by the strip.