Installation and method for converting uranium hexafluoride to uranium dioxide

Patent metadata

Field	Value
Publication number	US-2026008689-A1
Application number	US-202519259814-A
Country	US
Kind code	A1
Filing date	Jul 3, 2025
Priority date	Oct 9, 2018
Publication date	Jan 8, 2026
Grant date	—

Abstract

An installation for the conversion of uranium hexafluoride (UF6) to uranium dioxide (UO2) comprises a hydrolysis reactor (4) for the conversion of UF6 into uranium oxyfluoride powder (UO2F2), a pyrohydrolysis furnace (6) for converting the UO2F2 powder supplied by the reactor (4) into UO2 powder, a supply device (8) comprising reagent injection ducts (10) for the injection of UF6, water vapor or H2, 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.

First claim

What is claimed is:

1 . A method for converting uranium hexafluoride (UF 6 ) into uranium dioxide (UO 2 ) in a conversion installation comprising a hydrolysis reactor configured for converting UF 6 into powder of uranium oxyfluoride (UO 2 F 2 ) by reaction between gaseous UF 6 and dry water vapor injected into the hydrolysis reactor, and a pyrohydrolysis furnace configured for converting UO 2 F 2 powder supplied by the hydrolysis reactor into UO 2 powder by reaction between UO 2 F 2 and dry water vapor and hydrogen gas (H 2 ) injected into the pyrohydrolysis furnace, the method comprising the steps of:
converting UF 6 into UO 2 by supplying the hydrolysis reactor and the pyrohydrolysis furnace with reactive gases via reagent injection ducts during a conversion phase, each reagent injection duct opening into the hydrolysis reactor or into the pyrohydrolysis furnace; and supplying at least one of the reagent injection ducts with a neutral gas during a shut-down or start-up phase of the conversion installation.

2 . The conversion method according to claim 1 , wherein during the shut-down or start-up phase of the conversion installation, each reagent injection duct is supplied with neutral gas.

3 . The conversion method according to claim 1 , wherein during a production phase, the neutral gas is injected into the hydrolysis reactor via at least one neutral gas injection duct to achieve conversion under a neutral gas atmosphere.

4 . The conversion method according to claim 1 , wherein the shut-down phase of the conversion installation comprises a purging step during which the reagent injection ducts are supplied with neutral gas sequentially from upstream to downstream of the conversion installation, taking into account a direction of uranium movement.

5 . The conversion method according to claim 1 , further comprising, in the shut-down phase of the conversion installation, the successive steps of:
stopping the supply of UF 6 to the hydrolysis reactor and replace the supply of UF 6 with a supply of neutral gas; then stopping the supply of dry water vapor to the hydrolysis reactor and replace the supply of dry water vapor with a supply of neutral gas; then optionally, after removing all the UO 2 F 2 powder from the hydrolysis reactor, stopping a transfer device configured to transfer the UO 2 F 2 powder from the hydrolysis reactor to the pyrohydrolysis furnace; then stopping the supply of H 2 to the pyrohydrolysis furnace and replacing the supply of H 2 with a supply of neutral gas; then stopping the supply of dry water vapor to the pyrohydrolysis furnace and replace the supply of dry water vapor with a supply of neutral gas; then optionally, after removing all the UO 2 powder from the pyrohydrolysis furnace and cooling a drum of the pyrohydrolysis furnace, stopping the drum from rotating.

6 . The conversion method according to claim 1 , comprising, in a start-up phase of the conversion installation, the successive steps of:
injecting neutral gas into the hydrolysis reactor and the pyrohydrolysis furnace via the reagent injection ducts and neutral gas injection ducts during a heating step of the conversion installation; then replacing the neutral gas supply via the reagent injection ducts of the pyrohydrolysis furnace and the hydrolysis reactor with a reactive gas supply, by supplying the reagent injection ducts with reactive gases sequentially from downstream to upstream of the conversion installation taking into account a direction of uranium movement.

Assignees

• Framatome Sa

Inventors

• Mesona Bruno
• Hebrard Stéphane

Classifications

• G21C19/46

  Aqueous processes {, e.g. by using organic extraction means, including the regeneration of these means} · CPC title

• G21C3/623

  Oxide fuels · CPC title

• B01J2219/00245

  Avoiding undesirable reactions or side-effects · CPC title

• B01J19/26

  Nozzle-type reactors, i.e. the distribution of the initial reactants within the reactor is effected by their introduction or injection through nozzles · CPC title

• B01J19/14

  Production of inert gas mixtures; Use of inert gases in general · CPC title