Abstract: The use of carbamides as extractants for fully or partially separating uranium(VI) from plutonium(IV) in an aqueous solution obtained by dissolving a spent nuclear fuel in nitric acid, by method of liquid-liquid extraction, without carrying out any reduction of the plutonium(IV) to plutonium(III). The invention also relates to new carbamides. Uses are the processing of spent nuclear fuels based on uranium (especially uranium oxides—UOX) or uranium and plutonium (especially mixed uranium and plutonium oxides—MOX).

Abstract: Solid nanocomposite material comprising nanoparticles of a hexacyanometallate or octacyanometallate of an alkali metal and of a transition metal, of formula [Alk+x]Mn+[M?(CN)m]z? in which Alk is an alkali metal, x is 1 or 2, M is a transition metal, n is 2 or 3, M? is a transition metal, m is 6 or 8, z is 3 or 4, attached to at least one surface of a porous inorganic solid support, in which the nanoparticles are attached by adsorption to the at least one surface of the solid support, and in which the surface is a basic surface. Method for preparing this material. Method for extracting at least one metal cation from a liquid medium containing it, wherein the liquid medium is brought into contact with the material.

Abstract: A containment airlock, in particular an airlock for intervention on a site likely to be contaminated with radiation, asbestos and biological and/or chemical agents. The containment airlock includes a self-supporting frame and a flexible containment shell. The shell is configured to be assembled with the frame. The frame is articulated so as to be extensible between a folded storage position and an extended intervention position. The frame includes articulated reinforcement rods. The articulated reinforcement rods include rigid segments and at least one intermediate articulation connecting the segments.

Abstract: A method of determining a quantity of a first radioisotope in a source term, disintegrating into a second radioisotope, the radioisotopes respectively emitting first and second gamma rays screened by the source term, the method comprising the steps: a) determining the theoretical ratio of counts between the first and second rays emitted in the absence of screening; b) measuring the net counts associated with the first and second rays emitted by the first and second radioisotopes; c) determining the screening rates of the first and second rays by the source term based on the ratio obtained in step a) and the counts obtained in step b); d) determining the quantity of the first radioisotope based on the screening rate of either the first or the second ray determined in step c).

Abstract: A process for dissolving nuclear fuel, in particular irradiated nuclear fuel, comprising immersion of the nuclear fuel in a nitric acid solution. This dissolution process further comprises mechanical milling of the nuclear fuel, this mechanical milling being performed in the nitric acid solution during the immersion. The disclosure also relates to the use of a mill equipped with mechanical milling structure to implement the dissolution process.

Abstract: The invention relates to a thermocouple (17) suspended from a part (26, 27) that can be locked onto a connecting section of the measuring stick, which comprises an opening in the form of a guiding cone (30) for inserting the thermocouple. The thermocouple is contained in a flexible cable (24) that can slide in a sheath (35) of the central compartment (16) which houses the thermocouple (17). A spring (34) can be added to lightly press the end of the thermocouple to the end of the housing thereof.

Abstract: The use of hydroxyiminoalkanoic acids including at least four carbon atoms as anti-nitrous agents in operations of reductive stripping of plutonium. The invention may be useful in any method for processing spent nuclear fuels that includes one or more operations of reductive stripping of plutonium and, more particularly, in the PUREX method as implemented in modern nuclear fuel processing plants, as well as in processes derived therefrom.

Abstract: A process is provided for preparing a powder of an oxide of at least one metal, each metal having an oxidation number between (III) and (VI). This process comprises successively and in this order: (a) reacting, with a compound comprising a hydroxide, an aqueous solution comprising, for each metal, at least one salt of the cation of said metal, (b) separating the precipitate obtained, (c) contacting the separated precipitate with an organic protic polar solvent, (d) removing the organic protic polar solvent by vacuum drying the precipitate. A process is further provided for manufacturing a pellet of an oxide of at least one metal as well as to a powder and to a pellet obtained according to these processes and to uses thereof.

Abstract: The method according to the invention enables a facility having a rather reduced dimension, for incinerating to be used, melting and vitrifying mixed waste (30) introduced into a reactor (10), by means of a basket (18) in turn passing through an air lock (12). Plasma torches (14) burn all waste (30) contained in the basket (18). The waste is then lowered in a melting bath of a furnace (20) with an inductor (24) including a crucible-forming container (23). A combustion gas treatment train completes the facility. The furnace (20) can be dismantled, after a series of treatments of several baskets (18) of waste (30) for disassembling the crucible-forming container (23) from the furnace (20). Application in treating different radiologically contaminated and/or toxic mixed waste.

Abstract: Novel dissymmetric N,N-dialkylamides which meet the following formula (I): where R represents a linear or branched alkyl group at C8 to C15. A method for synthesizing these N,N-dialkylamides, and to the uses of same as extractants, alone or in admixture, in order to extract uranium and/or plutonium from an aqueous acid solution, or to totally or separate uranium from plutonium from an aqueous acid solution and, in particular, an aqueous solution resulting from dissolving spent nuclear fuel in nitric acid. Further, a method for processing an aqueous solution resulting from the dissolution of a spent nuclear fuel in nitric acid, allowing the uranium and plutonium contained in the solution to be extracted, separated and decontaminated in a single cycle, without requiring any plutonium reduction operation, and in which one of the aforementioned N,N-dialkylamides or a mixture of same is used as extractant.

Abstract: A method for the treatment of an aqueous solution resulting from the dissolution of a spent nuclear fuel in nitric acid, allowing the uranium and plutonium contained in the solution to be extracted, separated and decontaminated in a single cycle, without requiring any operation involving a reductive stripping of plutonium. Applications for the method include the processing of uranium-based and/or plutonium-based spent nuclear fuels.

Abstract: A method for processing a spent nuclear fuel is disclosed which includes a step for decontaminating uranium(VI) from one or more actinides(IV) and more specially from neptunium and/or plutonium, by complexing this (these) actinide(s)(IV). This method includes a step for decontaminating uranium (VI) from at least one actinide(IV), which decontaminating step comprises at least one operation for stripping the actinide(IV) from an organic phase, not miscible with water, and wherein uranium(VI) and the actinide(IV) are present, by putting the organic phase into contact with an aqueous phase comprising nitric acid and at least one complexing agent which more strongly complexes actinides(IV) than uranium(VI), and then separating the organic phase from the nitric aqueous phase, wherein the at least one complexing agent is a diglycolamide.

Abstract: A device for the cyclonic separation of solid particles contained in a fluid, comprising a primary cyclone chamber, a secondary cyclone chamber, an inlet channel for fluid loaded with solid particles opening into the primary cyclone chamber, an outlet channel for fluid cleaned of the solid particles connected to the secondary cyclone chamber, and a ducting unit connecting the primary cyclone chamber to the secondary cyclone chamber and surrounded by the primary cyclone chamber. The ducting unit comprises a core delimiting the secondary cyclone chamber and having at least one helical groove having a bottom which diverges away from an axis of the secondary cyclone chamber in a direction towards the latter, and a cap covering a part of the core in such a way as to delimit, with the groove, a channel connecting the primary cyclone chamber to the secondary cyclone chamber.

Abstract: A method for measuring dosage by means of a radiation detector, especially an X-radiation or gamma-radiation detector, used in the spectroscopic mode, and a dosage measurement system using said method. A range of energies and a dose type H is chosen, a radiation detector of a given type is used, spectra measured by the detector are established for various radiations of the given type, the energies of which are within the chosen range and the respective doses of which are known, and from the spectra, a weighting function is established, that is a correspondence between a mean dose increment and a mean energy, deposited into the detector. This enables a person provided with a dosimeter identical to the detector to know at any time the mean absorbed dose rate, expressed in the amount H.

Abstract: A process is described for synthesizing a mixed peroxide or hydroxo-peroxide of an actinyl and at least one cation X1, wherein the actinyl is a uranyl or neptunyl and the at least one cation X1 is a di-, tri- or tetra-charged metal cation. This process includes the reaction in a solvent of a salt of the at least one cation X1 with a compound C2 selected from mixed peroxides and hydroxo-peroxides of the actinyl and of at least one singly charged cation X2, whereby compound C2 is converted to the peroxide or hydroxo-peroxide by replacement of the at least one cation X2 by said at least one cation X1. Also disclosed is a process for synthesizing a mixed oxide of an actinide selected from uranium and neptunium, and of at least one metal able to form a di-, tri- or tetra-charged cation, which implements the preceding synthesis process.

Abstract: A method for preparing a powder of a solid solution of dioxide of uranium and of at least one other actinide and/or lanthanide element comprising combusting a solution that comprises uranyl nitrate and at least one nitrate of the other actinide and/or lanthanide element and glycine, with the glycine being used in a predetermined amount so as to form, at the end of the combustion, the solid solution.

Abstract: The present invention relates to a process for sintering a compacted powder of at least one oxide of a metal selected from an actinide and a lanthanide, this process comprising the following successive steps, carried out in a furnace and under an atmosphere comprising an inert gas, dihydrogen and water: (a) a temperature increase from an initial temperature TI up to a hold temperature TP, (b) maintaining the temperature at the hold temperature TP, and (c) a temperature decrease from the hold temperature TP down to a final temperature TF, in which the P(H2)/P(H2O) ratio is such that: 500<P(H2)/P(H2O)?50 000, during step (a), from TI until a first intermediate temperature Ti1 between 1000° C. and TP is reached, and P(H2)/P(H2O)?500, at least during step (c), from a second intermediate temperature Ti2 between TP and 1000° C., until TF is reached.