Patent Number: 047643366
Section: summary

BACKGROUND OF THE INVENTION The present invention relates to beams for supporting planar elements such as plates or panels and capable, in particular, of supporting the sheets of the fluidtight inner covering of a de-activation pool of a nuclear station. Nuclear station pools or de-activation pools, are adapted to store substances irradiated after a stay in the reactor and thus permit tne de-activation over a period of time of the substances within a large volume of water which serves to absorb the radiations emitted by said substances so that these radiations are not freely propagated in the atmosphere. Bearing in mind safety requirements, these pools must be perfectly fluidtight so as to avoid any escape of contaminated water. For this purpose, the de-activation pools comprise a fluidtight inner covering formed by sheets, for example of stainless steel, which are joined to each other by their edges by weld beads. In the region of the latter, the sheets are fixed to a structure formed by beams incorporated in the inner part of the corresponding wall of the pool, which is usually made from concrete, this structure thus supporting said sheets of the inner covering. The distinction between an outer part and an inner part in respect of each wall results from the manner of constructing the latter which is carried out in two stages, the first stage consisting in making said outer part of the walls. In this respect, such beams each comprise a flat bearing surface adapted to support the sheets and are connected to the outer part of the corresponding wall of the pool by a plurality of lugs which ensure their fastening to this outer part prior to their embedding in the concrete of the corresponding inner part. These lugs not only ensure the fastening of the beam but also serve to adjust its spacing from the surface of the outer part of the respective wall so as to compensate for unevennesses thereof. A first type of beam is thus known which comprises a corner iron whose cross-section is substantially L-shaped, one bearing surface for the sheets, whereas the other flange cooperates with the fixing lugs. However, after the filling of the inner part of the walls by concrete, there is no longer any space capable of receiving a device for radiographing the weld beads so as to check their state. Further, in the event of leakage in the region of said weld beads, the leakage is caused to infiltrate in an uncontrollable manner in the concrete if such a structure does not provide means for draining possible leakages. In a second type of known beams, the latter each comprise a cross-section in the shape of a U on the edge of the wings of which is welded a flat strip of sheet which forms with said U-section a channel having a closed cross-section and defines a flat bearing surface for the sheets of the inner covering of a pool. This type of beam provides an improvement in that a channel is formed for the radiography of the welds which is not liable to be obturated when pouring the concrete. However, no solution is provided for the problem relating to the draining of possible leakages. Thus, in a third type of beam, the latter has a structure similar to those of the second type described before and is provided on its bearing surface with localized openings adapted to receive the liquid coming from leakages in the region of the weld beads. However, it has been found that the localized openings provided in the strip of sheet metal do not provide a very effective draining of the leakage liquid. SUMMARY OF THE INVENTION An object of the present invention is to provide a reservoir in which the beams supporting the sheets each define a flat bearing surface for the sheets of the inner covering of a pool while providing a channel which permits the introduction of a radiography apparatus after the beam has been incorporated in the concrete and which is capable of permitting an effective draining of the leakage liquids coming from the weld bead which interconnects the sheets that this beam is adapted to support. The invention therefore provides a reservoir, in particular a de-activation pool of a nuclear station, whose walls are provided with a fluidtight covering of sheets welded together by their edges by weld beads and supported, under each weld bead, by a beam in the region of a support surface of the beam, each beam being fixed in a corresponding wall of the pool and comprising a section element having a roughly U-shaped cross-section, a planar bearing surface extending longitudinally in facing relation to at least a part of the bottom of the section element and a channel having an open cross-section, characterized in that each beam comprises a member disposed inside the section element, said member defining said bearing surface and at least two longitudinal channels in the inner volume of the beam. According to other features of the invention: said bearing surface and the edges of the branches of the section element are contained in a common plane; the edge of the branches of the section element each have a flange extending in a direction parallel to the bearing surface outwardly of the beam, said flanges completing the bearing surface by their surface facing outwardly of the beam; the bearing surface is spaced from each of the branches of the section element; according to a first embodiment, the beam comprises a inspection channel having a closed cross-section and two longitudinal draining channels having an open cross-section; the branches of the second section element each define a flange so that this second section element has roughly the shape of an omega in cross-section; according to a second embodiment, the beam comprises two longitudinal channels having an open cross-section and respectively forming a visiting and draining channel, and a draining channel; the member disposed inside the section element is a second section element which has, in cross-section, roughly the shape of an L one flange of which is fixed in a position perpendicular to the bottom of the first section element whereas the surface of the other flange which is oriented in a direction away from said bottom, forms said bearing surface.