Method of recovering nuclear fuel material

Patent metadata

Field	Value
Publication number	US-2016225473-A1
Application number	US-201313899978-A
Country	US
Kind code	A1
Filing date	May 22, 2013
Priority date	Jun 15, 2012
Publication date	Aug 4, 2016
Grant date	—

Abstract

According to an embodiment, a nuclear fuel material recovery method of recovering a nuclear fuel material containing thorium metal by reprocessing an oxide of a nuclear fuel material containing thorium oxide in a spent fuel is provided. The method has: a first electrolytic reduction step of electrolytically reducing thorium oxide in a first molten salt of alkaline-earth metal halide; a first reduction product washing step of washing a reduction product; and a main electrolytic separation step of separating the reduction product. The first molten salt further contains alkali metal halide, and contains at least one out of a group consisting of calcium chloride, magnesium chloride, calcium fluoride and magnesium fluoride. The method may further has a second electrolytic reduction step of electrolytically reducing uranium oxide, plutonium oxide, and minor actinoid oxide in a second molten salt of alkali metal halide.

First claim

What is claimed is:

1 . A nuclear fuel material recovery method of recovering a nuclear fuel material containing thorium metal by reprocessing an oxide of a nuclear fuel material containing thorium oxide in a spent fuel, the method comprising:
a first electrolytic reduction step of electrolytically reducing thorium oxide in a first molten salt of alkaline-earth metal halide; a first reduction product washing step of washing, after the first electrolytic reduction step, a reduction product obtained by the first electrolytic reduction step; and a main separation step of separating the reduction product, after the first reduction product washing step.

2 . The nuclear fuel material recovery method according to claim 1 , wherein
the first molten salt further contains alkali metal halide.

3 . The nuclear fuel material recovery method according to claim 1 , wherein
the first molten salt contains at least one out of a group consisting of calcium chloride, magnesium chloride, calcium fluoride and magnesium fluoride.

4 . The nuclear fuel material recovery method according to claim 1 , wherein
in the first molten salt, at least one out of a group consisting of calcium oxide and magnesium oxide is mixed.

5 . The nuclear fuel material recovery method according to claim 1 , before the first electrolytic reduction step, further comprising:
a second electrolytic reduction step of electrolytically reducing uranium oxide, plutonium oxide, and minor actinoid oxide in a second molten salt of alkali metal halide that does not contain any of calcium chloride, magnesium chloride, calcium fluoride, and magnesium fluoride; and a second reduction product washing step of washing, after the second electrolytic reduction step and before the first electrolytic reduction step, a reduction product obtained by the second electrolytic reduction step.

6 . The nuclear fuel material recovery method according to claim 5 , wherein
the second molten salt contains at least one out of a group containing of lithium chloride and lithium oxide.

7 . The nuclear fuel material recovery method according to claim 5 , wherein
the second molten salt further contains any alkaline-earth metal halide other than calcium chloride, magnesium chloride, calcium fluoride and magnesium fluoride.

8 . The nuclear fuel material recovery method according to claim 1 , wherein
the main separation step includes:
a first electrolytic separation step of carrying out electrolytic separation of a reduction product obtained by the first electrolytic reduction step, in a molten salt of at least one out of a group consisting of alkali metal halide, alkaline-earth metal halide and mixture of alkali metal halide and alkaline-earth metal halide, by using a solid electrode to refine and retrieve uranium metal or thorium metal; and
a second electrolytic separation step of carrying out, after the first electrolytic separation step, electrolytic separation in a molten salt of at least one out of a group consisting of alkali metal halide, alkaline-earth metal halide and mixture of alkali metal halide and alkaline-earth metal halide, by using a cadmium electrode to refine plutonium metal or minor actinoid metal.

9 . The nuclear fuel material recovery method according to claim 8 , wherein
the molten salt that is used at the first electrolytic separation step contains at least one out of a group consisting of calcium chloride, magnesium chloride, calcium fluoride and magnesium fluoride.

10 . The nuclear fuel material recovery method according to claim 5 , further comprising:
a first intermediate electrolytic separation step of carrying out, after the second reduction product washing step and before the first electrolytic reduction step, electrolytic separation in a molten salt of at least one out of a group consisting of alkali metal halide, alkaline-earth metal halide and mixture of alkali metal halide and alkaline-earth metal halide, by using a solid electrode to refine and retrieve uranium metal; and a second intermediate electrolytic separation step of carrying out, after the first intermediate electrolytic separation step and before the first electrolytic reduction step, electrolytic separation in a molten salt of at least one out of a group consisting of alkali metal halide, alkaline-earth metal halide and mixture of alkali metal halide and alkaline-earth metal halide, by using a cadmium electrode to refine plutonium metal or minor actinoid metal, wherein
the main separation step includes a step of carrying out electrolytic separation in a molten salt of at least one out of a group consisting of alkali metal halide, alkaline-earth metal halide and mixture of alkali metal halide and alkaline-earth metal halide, and separating thorium metal.

11 . The nuclear fuel material recovery method according to claim 10 , wherein
the molten salt that is used at the main electrolytic separation step contains at least one out of a group consisting of lithium chloride, potassium chloride and eutectic salt of lithium chloride and potassium chloride.

12 . A nuclear fuel material recovery method of recovering a nuclear fuel material containing thorium metal by reprocessing an oxide of a nuclear fuel material containing thorium oxide in a spent fuel, the method comprising:
a first chemical reduction step of carrying out chemical reduction by letting the thorium oxide react with a first chemical reducing agent to produce thorium metal; and a separation step of carrying out separation and refining of the thorium metal after the first chemical reduction step.

13 . The nuclear fuel material recovery method according to claim 12 , wherein
the first chemical reducing agent contains at least one out of a group consisting of calcium metal and magnesium metal.

14 . The nuclear fuel material recovery method according to claim 12 , before the first chemical reduction step, further comprising
a second chemical reduction step of carrying out chemical reduction by letting a uranium oxide, plutonium oxide, and minor actinoid oxide react with a second chemical reducing agent to produce uranium metal and plutonium metal.

15 . The nuclear fuel material recovery method according to claim 14 , wherein
the second chemical reducing agent contains at least one out of a group consisting of metallic lithium and metallic potassium.

16 . The nuclear fuel material recovery method according to claim 12 , wherein
at the chemical reduction step, the chemical reducing agent is used in the form of a molten salt or a molten metal.

Assignees

• Toshiba Kk

Inventors

• Takahashi Yuya
• Mizuguchi Koji
• Fujita Reiko
• Nakamura Hitoshi
• Kanamura Shohei
• Kishimoto Naoki
• Matsubayashi Yoshikazu
• Oomori Takashi

Classifications

• C25C3/34

  of metals not provided for in groups C25C3/02 - C25C3/32 · CPC title

• G21C19/48 Primary

  Non-aqueous processes · CPC title

• C25C7/005 Primary

  of cells for the electrolysis of melts (C25C7/02 - C25C7/06 take precedence) · CPC title

• Y02E30/30

  Nuclear fission reactors · CPC title

• G21C19/46

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