Japan Nuclear Cycle Development Institute

Ippei Amamoto

Koji Sato

Miyuki Igarashi

Fluorine or a fluorine compound is subjected to a reaction with a spent oxide fuel to produce fluorides of uranium and plutonium, and recovering the fluorides using a difference in volatility behavior. The method includes steps of: subjecting a mixture of UOand PuOwith hydrogen fluoride mixed with hydrogen to HF-fluorinate uranium and plutonium into UFand PuF; subjecting UFand PuFwith a fluorine gas to F-fluorinate uranium and plutonium into UFand PuF; and fractionating UFand PuFusing a difference in phase change of obtained UFand PuF, removing a part of UF, and volatilizing the remaining UFand PuFat the same time. By such a reprocessing method, PuFhard to undergo a reaction is prevented from being formed as an intermediate fluoride, the material of a reactor is hard to be corroded, and a consumption of expensive fluorine gas is reduced.

Reprocessing method by fluoride volatility process using fractional distillation

Fluorine or a fluorine compound is subjected to a reaction with a spent oxide fuel to produce fluorides of uranium and plutonium, and the fluorides are recovered using a difference in volatility behavior. The spent oxide fuel is subjected to a reaction with an HF gas, whereby uranium, plutonium and most impurities are converted into solid fluorides having low valences or remained as oxides to inhibit volatilization thereof, and then in an Ffluorination step, the HF fluorination product is subjected to a reaction with a fluorine gas in two stages: one at a low temperature and the other at a high temperature, whereby a certain amount of gaseous uranium and volatile impurities are separated with plutonium kept in a solid form in the first stage, and mixed fluorides of remaining uranium and plutonium are fluorinated into hexafluorides at the same time in the second stage. By such a reprocessing method, plutonium enrichment can be adjusted, uranium and plutonium can be purified, and steps are simplified as well. In addition, reactors are hard to be corroded or deteriorated.

Reprocessing method by fluoride volatility process using solid-gas separation

In a dry chemical reprocessing method, uranium type elements are electrolytically refined continuously. Molten cadmium in which these uranium type elements are dissolved is transferred to a rotating cathode electrolysis tank 30 for performing electrolytic refining. The rotating cathode electrolysis tank 30 is filled with molten cadmium, and a mixture of potassium chloride and lithium chloride. In the salt phase are placed a rotating cathode 32 and a receiving dish 36 for uranium type elements which deposit at the cathode, while in the molten cadmium phase a fixed anode 42 is installed. When uranium type elements deposited at the rotating cathode 32 have grown to at least a predetermined size, they are scraped off by a scraper 34 and collect in a receiving dish 36. These uranium type elements are sent to a U/salt separating tank 50 where uranium is separated from salts. The separated uranium and molten cadmium are aspirated by a pump 59, and sent to a Cd distiller 60 via a pipe 58a where the uranium type elements are recovered as their oxides and the cadmium is distilled off and recovered.

Growing community of inventors

Higashiibaraki-gun, Japan

Ippei Amamoto