Abstract: Process for the preparation of pulverulent metallic oxides with predetermined reactivity which is adjusted by the specific surface area, which are intended to be subjected to subsequent conversions, by thermal treatment of corresponding nitrates in the form of an aqueous solution or of a solids material, consisting of hydrated uranyl nitrate, on its own or in admixture with at least one of thorium nitrate, cerium nitrate and plutonium nitrate, which process is characterized in that it consists of two treatment stages:(a) the first stage essentially consisting of incompletely dehydrating the hydrated uranyl nitrate.(b) the second stage essentially consisting of decomposing the product resulting from the first stage by calcination under controlled steam pressure.The process is used for obtaining uranium oxide on its own or in admixture with thorium oxide, cerium oxide and plutonium oxide, with a view to subsequent chemical conversions and/or sintering.

Abstract: Process for the selective separation of uranium in carbonated aqueous solution from soluble impurities including in particular at least one of the elements zirconium and/or hafnium and/or molybdenum, thereby making it possible to produce a uraniferous liquor in a greatly improved state of purity, comprising precipitation of the zirconium and/or hafnium by introducing an alkali metal hydroxide, then separation of the zirconiferous precipitate which possibly contains hafnium and/or molybdenum from the resulting uraniferous solution with its reduced impurities content, which still possibly contains molybdenum, which is characterized in that in order to increase the removal of zirconium and/or hafnium and/or molybdenum, the uraniferous carbonated aqueous solution is treated by means of a dilute alkaline aqueous solution containing at most 17 g/l of at least one alkali metal hydroxide expressed in respect of OH.sup.

Abstract: A process for the purification by selective separation of uranium and/or molybdenum from zirconium and/or hafnium among other impurities contained in an amino organic phase by bringing them together with an aqueous sulphuric re-extraction solution, characterized in that, with a view to increasing the separation factor of the zirconium and/or hafnium on the one hand and the uranium and/or molbydenum on the other hand, the aqueous sulphuric re-extraction solution contains at least one alkali or equivalent sulphate.

Abstract: A method of purifying uraniferous aqueous solutions containing impurities, particularly at least one of the elements zirconium and/or hafnium, and also containing at least one of the anions SO.sub.4.sup.=, NO.sub.3.sup.-, Cl.sup.- or F.sup.- acting as complexing agents for the uranium and impurities, by precipitation of said impurities by means of an alkaline agent, characterized in that the following stages are carried out for the purpose of selectively and quantitatively separating the impurities from the uranium:(a) said uraniferous solution is brought to a temperature of at least 40.degree. C.,(b) the content of complexing agent is adjusted to bring the molar ratio: [complexing agent]/[soluble U+Zr and/or Hf] to at least 3,(c) the pH of said solution is adjusted between 2.2 and 4.3 by introducing an alkaline agent.

Abstract: The equipment is connected through a line to an auxiliary buoyant element to form an assembly of positive buoyancy, the equipment to be submerged and the auxiliary element being at first held in spaced relationship. The equipment is thereafter dropped into water, the length of the connecting line being so limited that the equipment then becomes suspended in water under the auxiliary element without reaching the water bottom. The location of the assembly is then optionally adjusted, and its buoyancy is reduced to a negative value.

Abstract: This device comprises a pipe formed of separate flexible pipe sections which in use are supported by buoyant elements maintained immersed by anchoring means. The flexible pipe sections are interconnected by couplings with at least some of these couplings being connected to a buoyant element and comprising stress limiters applied to the pipe sections adjacent said couplings.

Abstract: This device comprises in combination means for passive compensation of the alternating movements of the installation, comprising at least one articulated jack connected to a source of pressurized fluid, and complementary means for fine compensation, these complementary means activating the passive compensating means in response to the variation of a parameter which characterizes the movements of the installation.

Abstract: This apparatus comprises a main jack for supporting elements from the installation and a regulating device which includes at least one pivoting jack and makes use of a source of pressurized fluid in communication with a chamber of variable volume in which the pressure of the fluid varies in inverse proportion with respect to the volume of the chamber. The main jack and the regulating device are connected in parallel to the source of pressurized fluid and the regulating device supplies a pressurized auxiliary fluid to means for adjusting the force exerted by the main jack.