A method of manufacturing particles of UO.sub.2 for a porous matrix of a target for use in the manufacture of .sup.99Mo, comprising: infiltrating a solution of uranyl nitrate into a polymer template (62); either (i) introducing an alkali chemical to the uranyl nitrate infiltrated polymer template (64), causing precipitation of uranium oxide/hydroxide, and converting the uranium oxide/hydroxide to U.sub.3O.sub.8 (68) and concurrently removing the polymer template (70), by heating the infiltrated polymer template; or (ii) converting the uranyl nitrate to U.sub.3O.sub.8 (66) and concurrently removing the polymer template (74), by heating the infiltrated polymer template; and reducing the U.sub.3O.sub.8 to UO.sub.2 via heating in a reducing atmosphere (72).

A method of manufacturing particles of UO.sub.2 for a porous matrix of a target for use in the manufacture of .sup.99Mo, comprising: infiltrating a solution of uranyl nitrate into a polymer template (62); either (i) introducing an alkali chemical to the uranyl nitrate infiltrated polymer template (64), causing precipitation of uranium oxide/hydroxide, and converting the uranium oxide/hydroxide to U.sub.3O.sub.8 (68) and concurrently removing the polymer template (70), by heating the infiltrated polymer template; or (ii) converting the uranyl nitrate to U.sub.3O.sub.8 (66) and concurrently removing the polymer template (74), by heating the infiltrated polymer template; and reducing the U.sub.3O.sub.8 to UO.sub.2 via heating in a reducing atmosphere (72).

An installation for the conversion of uranium hexafluoride (UF.sub.6) to uranium dioxide (UO.sub.2) comprises a hydrolysis reactor (4) for the conversion of UF.sub.6 into uranium oxyfluoride powder (UO.sub.2F.sub.2), a pyrohydrolysis furnace (6) for converting the UO.sub.2F.sub.2 powder supplied by the reactor (4) into UO.sub.2 powder, a supply device (8) comprising reagent injection ducts (10) for the injection of UF.sub.6, water vapor or H.sub.2, and a control system (16) designed to control the supply device (8) so as to supply at least one of the reagent injection ducts (10) with a neutral gas during a shutdown or start-up phase of the conversion installation.

An installation for the conversion of uranium hexafluoride (UF.sub.6) to uranium dioxide (UO.sub.2) comprises a hydrolysis reactor (4) for the conversion of UF.sub.6 into uranium oxyfluoride powder (UO.sub.2F.sub.2), a pyrohydrolysis furnace (6) for converting the UO.sub.2F.sub.2 powder supplied by the reactor (4) into UO.sub.2 powder, a supply device (8) comprising reagent injection ducts (10) for the injection of UF.sub.6, water vapor or H.sub.2, and a control system (16) designed to control the supply device (8) so as to supply at least one of the reagent injection ducts (10) with a neutral gas during a shutdown or start-up phase of the conversion installation.

A conversion process for converting uranium hexafluoride into uranium dioxide includes the steps of hydrolysis of UF.sub.6 to uranium oxyfluoride (UO.sub.2F.sub.2) in a hydrolysis reactor (4) by reaction between gaseous UF6 and dry water vapour injected into the reactor (4), pyrohydrolysis of UO.sub.2F.sub.2 to UO.sub.2 in a pyrohydrolysis furnace (6) by reacting UO.sub.2F.sub.2 with dry steam and gaseous hydrogen (H.sub.2) injected into the furnace (6), extracting excess gas in the reactor (4) via a collecting device (50) comprising several filters (52), periodically cleaning the filters (52) by injecting a neutral gas into the filters (52) from the outside to the inside of the reactor (4) to remove powder stuck on the filters (52), and measuring the relative pressure in the reactor (4). The conversion method further includes carrying out point cleaning of the filters (52) when the relative pressure in the reactor (4) exceeds a predetermined point cleaning threshold.

A conversion process for converting uranium hexafluoride into uranium dioxide includes the steps of hydrolysis of UF.sub.6 to uranium oxyfluoride (UO.sub.2F.sub.2) in a hydrolysis reactor (4) by reaction between gaseous UF6 and dry water vapour injected into the reactor (4), pyrohydrolysis of UO.sub.2F.sub.2 to UO.sub.2 in a pyrohydrolysis furnace (6) by reacting UO.sub.2F.sub.2 with dry steam and gaseous hydrogen (H.sub.2) injected into the furnace (6), extracting excess gas in the reactor (4) via a collecting device (50) comprising several filters (52), periodically cleaning the filters (52) by injecting a neutral gas into the filters (52) from the outside to the inside of the reactor (4) to remove powder stuck on the filters (52), and measuring the relative pressure in the reactor (4). The conversion method further includes carrying out point cleaning of the filters (52) when the relative pressure in the reactor (4) exceeds a predetermined point cleaning threshold.

A reactor (1) for hydrolysis of uranium hexafluoride comprises a tubular injector (9) comprising first (11), second (13) and third (15) concentric fluid circulation ducts intended to be connected respectively with a source of UF.sub.6, a source of inert gas and a source of water vapor. The tubular injector (9) is obtained by additive manufacturing.

A reactor (1) for hydrolysis of uranium hexafluoride comprises a tubular injector (9) comprising first (11), second (13) and third (15) concentric fluid circulation ducts intended to be connected respectively with a source of UF.sub.6, a source of inert gas and a source of water vapor. The tubular injector (9) is obtained by additive manufacturing.

An installation for the conversion of uranium hexafluoride (UF.sub.6) to uranium dioxide (UO.sub.2) comprises a hydrolysis reactor (4) for the conversion of UF.sub.6 into uranium oxyfluoride powder (UO.sub.2F.sub.2), a pyrohydrolysis furnace (6) for converting the UO.sub.2F.sub.2 powder supplied by the reactor (4) into UO.sub.2 powder, a supply device (8) comprising reagent injection ducts (10) for the injection of UF.sub.6, water vapor or H.sub.2, and a control system (16) designed to control the supply device (8) so as to supply at least one of the reagent injection ducts (10) with a neutral gas during a shut-down or start-up phase of the conversion installation.

An installation for the conversion of uranium hexafluoride (UF.sub.6) to uranium dioxide (UO.sub.2) comprises a hydrolysis reactor (4) for the conversion of UF.sub.6 into uranium oxyfluoride powder (UO.sub.2F.sub.2), a pyrohydrolysis furnace (6) for converting the UO.sub.2F.sub.2 powder supplied by the reactor (4) into UO.sub.2 powder, a supply device (8) comprising reagent injection ducts (10) for the injection of UF.sub.6, water vapor or H.sub.2, and a control system (16) designed to control the supply device (8) so as to supply at least one of the reagent injection ducts (10) with a neutral gas during a shut-down or start-up phase of the conversion installation.