Abstract: Apparatus for monitoring the neutron flux of a nuclear reactor in biological protection concrete (6) surrounding the vessel (4) containing the reactor core (2) and having, in vertical shafts (8 to 22) located in the concrete in the vicinity of said vessel (4), a certain number of neutron detecting devices, characterized in that each shaft is provided with a central, aluminium housing tube (24) and several peripheral, aluminium tubes (28), the central tube (24) being reserved for the housing of the boron deposit proportional counter and the peripheral tubes for the housing of the fission chambers, each maintained at a different height by support means connected to the tubes.

Abstract: Fission chamber with a wide measuring range and apparatus for measuring the neutron flux density using said fission chamber. The chamber comprises an enclosure (2) filled with a gaseous medium and, in the latter, electrodes (8,10) adjacent the periphery of the enclosure, whereof at least one is covered with a fissile material having a large surface density or mass, as well as other electrodes (10,12) adjacent the center of the enclosure, whereof, at least one is covered with a fissile material having a smaller surface density, chosen so as to optimize (a) the ratio of the electric currents respectively due to the neutrons and to spurious gamma radiation detected by the other electrodes and (b) the linearity of the signal supplied by the latter for a given flux density range.

Abstract: In a collector for solar boiler with linear concentration, comprising a pick-up tube through which a heat-transfer fluid passes and disposed in a supporting structure, said supporting structure is constituted by a section in omega form, with a wide opening at its base, this section being provided with an inner reinforcement, and the pick-up tube is held by rigid crosspieces made of insulating material, distributed along the section and fixed to the base of the omega.

Abstract: A process for producing a composite element comprising a plurality of sheet members 64 rigidly secured to a support 65 with their rear main faces in contact therewith, characterized in that the sheet members, which have a perceptible reflectance, are placed on a jig 61 in one or more predetermined orientations relatively to one another, and a fluid, settable substance is applied to the thus arranged sheet members 64 e.g. by pouring from a ladle 66 and is caused or allowed to set at least partially while the sheet members 64 remain on the jig 61 to form at least part of a substantially rigid support structure 65 for the sheet members 64.

Abstract: A method of producing a composite element by securing a plurality of sheet members to a support with their rear main faces in contact with the support. The method includes placing the sheets on a jig in a desired relationship and one or more fluid, settable substances are applied to the rear main faces thereof and allowed to set to form a support structure for the sheets.