Some embodiments include a method comprising: flowing a molten salt out of a molten salt reactor at a first temperature, heating the molten salt reactor to a second temperature above the melding point of the second salt mixture causing the second salt mixture to melt; flowing the second salt mixture out of the molten salt reactor; flowing a third salt mixture into the molten salt reactor; and cooling the molten salt reactor from the second temperature to a third temperature causing the third salt mixture to solidify on the interior surface of the housing. In some embodiments, the molten salt may include a first salt mixture comprising at least uranium. In some embodiments, the first temperature is a temperature above the melting point of the first salt mixture.

Embodiments of the disclosure relate to a treatment method and a treatment apparatus for a UF.sub.6 heel, using a gas phase reaction. A specific treatment method includes (1) vaporizing the UF.sub.6 heel, (2) manufacturing solid phase UO.sub.2F.sub.2 by using UF.sub.6 gas vaporized at step (1), (3) separating the solid phase UO.sub.2F.sub.2 and by-product gas from each other, and (4) separating hydrogen fluoride from the by-product gas. According to the disclosure, stabilization of a reconversion process and the quality of UO.sub.2 powder may be improved by manufacturing the solid phase UO.sub.2F.sub.2, which is an intermediate of the UO.sub.2 powder, through the UF.sub.6 heel treatment, and the high cost of radioactive waste disposal is reduced by minimizing the UF.sub.6 heel to be less than 0.5 kg.

The present disclosure provides systems and methods for fast molten salt reactor fuel-salt preparation. In one implementation, the method may comprise providing fuel assemblies having fuel pellets, removing the fuel pellets and spent fuel constituents from the fuel assemblies, granulating the removed fuel pellets or process feed to a chlorination process, processing the granular spent fuel salt into chloride salt by ultimate reduction and chlorination of the uranium and associated fuel constituents chloride salt solution, enriching the granular spent fuel salt, chlorinating the enriched granular spent fuel salt to yield molten chloride salt fuel, analyzing, adjusting, and certifying the molten chloride salt fuel for end use in a molten salt reactor, pumping the molten chloride salt fuel and cooling the molten chloride salt fuel, and milling the solidified molten chloride salt fuel to predetermined specifications.

The present disclosure provides systems and methods for fast molten salt reactor fuel-salt preparation. In one implementation, the method may comprise providing fuel assemblies having fuel pellets, removing the fuel pellets and spent fuel constituents from the fuel assemblies, granulating the removed fuel pellets or process feed to a chlorination process, processing the granular spent fuel salt into chloride salt by ultimate reduction and chlorination of the uranium and associated fuel constituents chloride salt solution, enriching the granular spent fuel salt, chlorinating the enriched granular spent fuel salt to yield molten chloride salt fuel, analyzing, adjusting, and certifying the molten chloride salt fuel for end use in a molten salt reactor, pumping the molten chloride salt fuel and cooling the molten chloride salt fuel, and milling the solidified molten chloride salt fuel to predetermined specifications.

A method of synthesizing rubidium uranium fluoride crystals. The method includes combining uranium-based feedstock with a mineralizer solution that includes a rubidium fluoride. The feedstock and mineralizer solution are pressurized and a thermal gradient applied thereto such that a first portion of the feedstock and the mineralizer solution is heated to a temperature that is greater than a temperature of a second portion of the feedstock and the mineralizer solution. Uranium nutrient enters the mineralizer solution from the feedstock in the first portion and uranium nutrient precipitates to spontaneously form crystals in the second portion.

A method of synthesizing rubidium uranium fluoride crystals. The method includes combining uranium-based feedstock with a mineralizer solution that includes a rubidium fluoride. The feedstock and mineralizer solution are pressurized and a thermal gradient applied thereto such that a first portion of the feedstock and the mineralizer solution is heated to a temperature that is greater than a temperature of a second portion of the feedstock and the mineralizer solution. Uranium nutrient enters the mineralizer solution from the feedstock in the first portion and uranium nutrient precipitates to spontaneously form crystals in the second portion.

A method of synthesizing uranium dioxide crystals. The method of synthesizing includes combining a uranium-based feedstock with a mineralizer solution. The uranium-based feedstock is selected from uranium dioxide, uranium tetrafluoride, uranium tetrachloride, triuranium octoxide, and uranium trioxide. The feedstock and mineralizer solution are pressurized, and then a thermal gradient is applied thereto such that a first portion of the feedstock and the mineralizer solution is heated to a temperature that is greater than a temperature of a second portion of the feedstock and the mineralizer solution. The uranium nutrient enters the mineralizer solution from the feedstock in the first portion and uranium nutrient precipitates to spontaneously form crystals in the second portion.

A method of synthesizing uranium dioxide crystals. The method of synthesizing includes combining a uranium-based feedstock with a mineralizer solution. The uranium-based feedstock is selected from uranium dioxide, uranium tetrafluoride, uranium tetrachloride, triuranium octoxide, and uranium trioxide. The feedstock and mineralizer solution are pressurized, and then a thermal gradient is applied thereto such that a first portion of the feedstock and the mineralizer solution is heated to a temperature that is greater than a temperature of a second portion of the feedstock and the mineralizer solution. The uranium nutrient enters the mineralizer solution from the feedstock in the first portion and uranium nutrient precipitates to spontaneously form crystals in the second portion.

This disclosure describes systems and methods for removing uranium hexafluoride (UF.sub.6) and/or other uranium fluoride (uranium fluorides identified herein generally as UF.sub.x) gases from a hydrogen fluoride (HF) gas stream.

This disclosure describes systems and methods for removing uranium hexafluoride (UF.sub.6) and/or other uranium fluoride (uranium fluorides identified herein generally as UF.sub.x) gases from a hydrogen fluoride (HF) gas stream.