JPH05203790A - Separation and refinement of uranium, plutonium and neptunium out of spent fuel - Google Patents

Separation and refinement of uranium, plutonium and neptunium out of spent fuel

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Publication number
JPH05203790A
JPH05203790A JP5105092A JP5105092A JPH05203790A JP H05203790 A JPH05203790 A JP H05203790A JP 5105092 A JP5105092 A JP 5105092A JP 5105092 A JP5105092 A JP 5105092A JP H05203790 A JPH05203790 A JP H05203790A
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JP
Japan
Prior art keywords
nitric acid
butyraldehyde
plutonium
uranium
neptunium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP5105092A
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Japanese (ja)
Other versions
JP3104181B2 (en
Inventor
Gunzou Uchiyama
軍蔵 内山
Shinobu Houtoku
忍 宝徳
Yukio Fujine
幸雄 藤根
Mitsuru Maeda
充 前田
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Japan Atomic Energy Agency
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Japan Atomic Energy Research Institute
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Priority to JP5105092A priority Critical patent/JP3104181B2/en
Publication of JPH05203790A publication Critical patent/JPH05203790A/en
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies

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  • Inorganic Compounds Of Heavy Metals (AREA)

Abstract

PURPOSE:To prevent dispersion of a butylaldehide down to a post-treatment process by decomposing the butylaldehide in flowing-out liquid into carbondioxide gas and water. CONSTITUTION:By providing a decomposition process 10 of an n-butylaldehide in nitric acid water solution after a separation process 5 of a neptunium Np in a fuel reprocessing process, and also by providing both decomposition processes 11 and 12 of the n- and iso-butylaldehide in nitric acid water solution, and of the n and iso-butylaldehide in an organic solvent, next to a distribution process 7 of a uranium U/plutonium Pu, nitric acid water solution containing the butylaldehide which is generated from an Np separation process, and, nitric acid water solution and the organic solvent both containing the n- and iso- butylaldehide which are generated from a U/Pu separation process, are air- oxidized respectively, and consequently are decomposed to stable compounds, a carbondioxide and water.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は使用済み核燃料からウラ
ン（Ｕ）、プルトニウム（ＰＵ）及びネプツニウム（Ｎ
ｐ）を分離する方法に関する。詳しくは、本発明は、使
用済み核燃料からウラン、プルトニウム及びネプツニウ
ムを分離する核燃料再処理工程において使用するプルト
ニウム及びネプツニウムの還元剤であるブチルアルデヒ
ド異性体を分解して工程全体への拡散を防止する方法に
関する。BACKGROUND OF THE INVENTION The present invention relates to spent nuclear fuels such as uranium (U), plutonium (PU) and neptunium (N).
p). More specifically, the present invention decomposes the butyraldehyde isomer, which is a reducing agent for plutonium and neptunium used in a nuclear fuel reprocessing step for separating uranium, plutonium and neptunium from spent nuclear fuel, to prevent diffusion throughout the step. Regarding the method.

【０００２】[0002]

【従来の技術】核燃料再処理工程においては、ウラン
（Ｕ）、プルトニウム（ＰＵ）及び核分裂生成物（Ｆ
Ｐ）は、有機溶媒（リン酸トリブチル（ＴＢＰ）とその
希釈剤（例えば、ドデカン）との混合物）と硝酸水溶液
とから成る二相系での溶媒抽出によって分離されてい
る。2. Description of the Related Art Uranium (U), plutonium (PU) and fission products (F) are used in the nuclear fuel reprocessing process.
P) has been separated by solvent extraction in a two-phase system consisting of an organic solvent (a mixture of tributyl phosphate (TBP) and its diluent (eg dodecane)) and an aqueous nitric acid solution.

【０００３】本願発明者は、先に、核燃料再処理工程に
おいて、有機還元剤であるブチルアルデヒド異性体を用
いて、使用済み核燃料に含まれるウラン、プルトニウム
及びネプツニウム（Ｐｕ）を相互に分離する技術を開発
した。The inventor of the present application has previously proposed a technique for separating uranium, plutonium and neptunium (Pu) contained in spent nuclear fuel from each other in the nuclear fuel reprocessing step by using butyraldehyde isomer which is an organic reducing agent. Was developed.

【０００４】この技術は、図１に示すごとく、使用済み
核燃料を硝酸水溶液に溶解する工程（１）、原子価調整
工程（２）、有機溶媒を用いてウラン、プルトニウム及
びネプツニウムを溶解液から抽出し核分裂生成物と分離
するための共除染工程（４）、ネプツニウムの分離工程
（５）、ウラン及びプルトニウムの回収工程（６）、有
機溶媒中のＩＶ価のプルトニウムのみをｉｓｏ−ブチル
アルデヒドを用いて選択的にＩＩＩ価に還元し硝酸水溶
液に逆抽出することによりＶＩ価のウランと分離するＵ
／Ｐｕ分配工程（７）、有機溶媒中のＶＩ価ウランを溶
媒抽出により精製する工程（８）及び硝酸水溶液中のＩ
ＩＩ価のプルトニウムを精製する工程から成る。As shown in FIG. 1, this technique comprises a step (1) of dissolving a spent nuclear fuel in an aqueous nitric acid solution, a valence adjustment step (2), and extraction of uranium, plutonium and neptunium from an organic solvent using an organic solvent. Co-decontamination step (4) to separate from the fission product, neptunium separation step (5), uranium and plutonium recovery step (6), and only IV-valent plutonium in the organic solvent is added with iso-butyraldehyde. U selectively separated to III-valent and back-extracted into an aqueous nitric acid solution to separate from VI-valent uranium U
/ Pu partition step (7), step (8) of purifying VI-valent uranium in an organic solvent by solvent extraction, and I in an aqueous nitric acid solution
It comprises the step of purifying II-valent plutonium.

【０００５】而して、この技術においては、ネプツニウ
ムの分離工程（５）ではＶＩ価のＮｐの還元剤にｎ−ブ
チルアルデヒドを用い、また、Ｕ／Ｐｕの分配工程
（７）ではＩＶ価のＰｕの還元剤にｉｓｏ−ブチルアル
デヒドを使用する。In this technique, therefore, n-butyraldehyde is used as the reducing agent for the Np having a VI value in the neptunium separation step (5), and the IV value is used in the U / Pu distribution step (7). Iso-butyraldehyde is used as the reducing agent for Pu.

【０００６】これらブチルアルデヒド異性体は、親水性
基であるアルデヒド基（−ＣＨＯ）を有する低分子量
（分子量：７８）の有機化合物であるため、再処理溶液
系では有機溶媒と硝酸水溶液（１〜６Ｍ）の両相にそれ
ぞれ溶解する性質を有する。そして、ブチルアルデヒド
異性体の二相間分配比は２〜４である。Since these butyraldehyde isomers are low-molecular-weight (molecular weight: 78) organic compounds having an aldehyde group (-CHO) which is a hydrophilic group, in the reprocessing solution system, the organic solvent and nitric acid aqueous solution (1- 6M) has the property of being dissolved in both phases. And, the partition ratio between the two phases of the butyraldehyde isomer is 2 to 4.

【０００７】Ｐｕ及びＮｐに対して選択的な還元力を有
するｎ−及びｉｓｏ−ブチルアルデヒドを用いてＵ、Ｐ
ｕ及びＮｐを相互に分離するには、再処理工程の限られ
た工程範囲においてブチルアルデヒド異性体を用いる必
要がある。[0007] U, P using n- and iso-butyraldehyde having a reducing power selective to Pu and Np
Separation of u and Np from each other requires the use of butyraldehyde isomers in the limited process range of the reprocessing step.

【０００８】しかしながら、これまでのところ、再処理
工程においてブチルアルデヒド異性体を工程管理する技
術は未だ開発されていない。ブチルアルデヒド異性体を
分解する技術としては、酸性水溶液（過塩素酸）中にお
いてコバルト触媒を用いて酸分解する方法がある。しか
しながら、この方法は、金属触媒を用いるため、二次廃
棄物が発生する。However, so far, no technique has been developed for controlling the butyraldehyde isomer in the reprocessing step. As a technique for decomposing the butyraldehyde isomer, there is a method of acid decomposing using a cobalt catalyst in an acidic aqueous solution (perchloric acid). However, since this method uses a metal catalyst, secondary waste is generated.

【０００９】[0009]

【発明が解決しようとする課題】有機溶媒と硝酸水溶液
（１〜６Ｍ）の両相にそれぞれ溶解する性質を有するブ
チルアルデヒド異性体を用いて、Ｕ、Ｐｕ及びＮｐを相
互に分離するには、再処理工程の限られた工程範囲にお
いてブチルアルデヒドを用いる必要がある。また、廃棄
物管理上、発生する各廃液中のブチルアルデヒドは最終
的に安定な化合物にしなければならない。本発明の目的
は、従来技術における問題点を解消し、ブチルアルデヒ
ド異性体を分解して、ブチルアルデヒド異性体が各相に
溶解して有機相流及び水相流に沿って再処理工程全体へ
拡散するのを防止した使用済み核燃料からウラン、プル
トニウム及びネプツニウムを分離精製する方法を提供す
ることにある。In order to separate U, Pu and Np from each other using a butyraldehyde isomer having a property of being dissolved in both phases of an organic solvent and an aqueous nitric acid solution (1 to 6M), Butyraldehyde must be used in a limited process range of the reprocessing process. Further, in terms of waste management, the butyraldehyde in each generated waste liquid must be finally made into a stable compound. The object of the present invention is to eliminate the problems in the prior art, decompose the butyraldehyde isomers, and dissolve the butyraldehyde isomers in each phase to the entire reprocessing step along the organic and aqueous phases. It is an object of the present invention to provide a method for separating and refining uranium, plutonium and neptunium from spent nuclear fuel that has prevented diffusion.

【００１０】[0010]

【課題を解決するための手段】本願発明者は、この目的
達成のため鋭意研究の結果、ｎ−及びｉｓｏ−ブチルア
ルデヒドを用いた各工程から流出する溶液中のｎ−及び
ｉｓｏ−ブチルアルデヒドを炭酸ガスと水とに分解する
ことによって、後工程への拡散を防止する方法を想到
し、本願発明を発明するに到った。The inventors of the present invention have conducted extensive studies to achieve this object, and as a result, have studied the use of n- and iso-butyraldehyde in the solution flowing out from each step using n- and iso-butyraldehyde. The present invention has been devised by devising a method of preventing diffusion to a subsequent step by decomposing it into carbon dioxide gas and water.

【００１１】本願発明は、図２に示すごとく、図１に示
す再処理工程におけるネプツニウムの分離工程（５）の
あとに硝酸水溶液中のｎ−ブチルアルデヒドを分解する
工程（１０）を設け、Ｕ／Ｐｕ分配工程（７）の次に硝
酸水溶液中のｎ−及びｉｓｏ−ブチルアルデヒドを分解
する工程（１１）及び有機溶媒中のｎ−及びｉｓｏ−ブ
チルアルデヒドを分解する工程（１２）を設けたことを
特徴とする。In the present invention, as shown in FIG. 2, a step (10) for decomposing n-butyraldehyde in a nitric acid aqueous solution is provided after the step (5) for separating neptunium in the reprocessing step shown in FIG. / Pu distribution step (7) was followed by a step (11) of decomposing n- and iso-butyraldehyde in an aqueous nitric acid solution and a step (12) of decomposing n- and iso-butyraldehyde in an organic solvent. It is characterized by

【００１２】具体的には、Ｎｐ分離工程から発生するブ
チルアルデヒド含有硝酸水溶液、Ｕ／Ｐｕ分配工程から
発生するｎ−及びｉｓｏ−ブチルアルデヒド含有硝酸水
溶液及び有機溶媒を、それぞれ空気酸化し、安定な化合
物の二酸化炭素及び水に分解する方法である。Specifically, the butyraldehyde-containing nitric acid aqueous solution generated in the Np separation step, the n- and iso-butyraldehyde-containing nitric acid aqueous solution and the organic solvent generated in the U / Pu partitioning step are each air-oxidized to obtain a stable solution. It is a method of decomposing a compound into carbon dioxide and water.

【００１３】[0013]

【化１】 [Chemical 1]

【００１４】図３にブチルアルデヒド異性体の空気を用
いた酸化分解装置に示す。酸化分解槽（２１）の硝酸水
溶液中のブチルアルデヒド異性体に空気供給ポンプ（２
４）から空気供給ノズル（２２）を通して空気を吹き込
み撹拌機（２３）で撹拌し、硝酸水溶液中のブチルアル
デヒド異性体を空気酸化し分解させる。ことができる。FIG. 3 shows an oxidative decomposition apparatus using air of butyraldehyde isomers. An air supply pump (2) is added to the butyraldehyde isomers in the nitric acid aqueous solution in the oxidative decomposition tank (21).
Air is blown from 4) through the air supply nozzle (22) and stirred by a stirrer (23), and the butyraldehyde isomer in the nitric acid aqueous solution is air-oxidized and decomposed. be able to.

【００１５】有機溶媒中のブチルアルデヒド異性体を酸
化分解処理する場合は、水溶液へ逆抽出し酸化分解する
ため、硝酸水溶液を一緒に添加する必要がある。二相系
で処理することで、有機相中のブチルアルデヒドを逆抽
出しながら、空気酸化することができる。なお、逆抽出
に用いる水溶液の硝酸の濃度は、高濃度ほどブチルアル
デヒド異性体の溶解度が大きく望ましい。ブチルアルデ
ヒド異性体の酸化分解は、常温でも進行するが、昇温す
ることで加速される。When the butyraldehyde isomers in the organic solvent are subjected to oxidative decomposition treatment, it is necessary to add an aqueous nitric acid solution together because the butyl aldehyde isomers are back-extracted into an aqueous solution for oxidative decomposition. By treating with a two-phase system, it is possible to perform air oxidation while back-extracting butyraldehyde in the organic phase. The higher the concentration of nitric acid in the aqueous solution used for back extraction, the higher the solubility of the butyraldehyde isomer, and therefore desirable. The oxidative decomposition of butyraldehyde isomers proceeds at room temperature, but is accelerated by increasing the temperature.

【００１６】[0016]

【作用効果】本発明に依れば、Ｎｐ分離工程から発生す
る硝酸水溶液中のｎ−ブチルアルデヒド、Ｕ／Ｐｕ分配
工程から発生する硝酸水溶液及び有機溶媒中のｎ−及び
ｉｓｏ−ブチルアルデヒドをそれぞれ空気酸化し、安定
な化合物の二酸化炭素及び水に分解することができるた
め、後工程への拡散及び二次廃棄物の発生を防ぐことが
できる。According to the present invention, the n-butyraldehyde in the nitric acid aqueous solution generated in the Np separation step, the nitric acid aqueous solution generated in the U / Pu partitioning step, and the n- and iso-butyraldehyde in the organic solvent are respectively separated. Since it can be oxidized by air and decomposed into stable compounds of carbon dioxide and water, it is possible to prevent diffusion to the subsequent steps and generation of secondary waste.

【００１７】[0017]

【実施例】実施例１ 硝酸水溶液中のｎ−ブチルアルデヒドの空気酸化分解実
験 実験には、３０ｍｌのガラス製分解槽を用いた。３Ｍ硝
酸水溶液（２０ｍｌ）中のｎ−ブチルアルデヒドの初期
濃度は１％であった。実験は、室温（２０℃）及び６０
℃で行った。マグネチックスターラーで十分攪拌した状
態の溶液中に、気送ポンプを用いて、空気を供給した。
図４より、分解温度２０℃では（実線で示す）、約３０
分で９２％以上が、また、６０℃では（点線で示す）、
約１５分で９９％が酸化分解した。図４に、３Ｍ硝酸水
溶液中のｎ−ブチルアルデヒドの空気酸化分解実験結果
を示す。図において、横軸は経過時間（分）を示し、縦
軸は酸化率（％）を示す。これらの結果は、硝酸水溶液
中のブチルアルデヒド異性体を空気を用いて酸化分解で
きることを示している。 Example 1 Air-oxidation decomposition experiment of n-butyraldehyde in nitric acid aqueous solution In the experiment, a 30 ml glass decomposition tank was used. The initial concentration of n-butyraldehyde in a 3M aqueous nitric acid solution (20 ml) was 1%. Experiments were conducted at room temperature (20 ° C) and 60
Performed at ° C. Air was supplied using a pneumatic pump into the solution that had been sufficiently stirred with a magnetic stirrer.
From FIG. 4, at a decomposition temperature of 20 ° C. (shown by the solid line), about 30
More than 92% in minutes, and at 60 ° C (shown by dotted line)
99% was oxidatively decomposed in about 15 minutes. FIG. 4 shows the results of an air oxidation decomposition experiment of n-butyraldehyde in a 3M nitric acid aqueous solution. In the figure, the horizontal axis represents the elapsed time (minutes) and the vertical axis represents the oxidation rate (%). These results indicate that the butyraldehyde isomers in aqueous nitric acid can be oxidatively decomposed using air.

【００１８】実施例２ 有機溶媒中のｎ−ブチルアルデヒドの空気酸化分解実験 実験には、３０ｍｌのガラス製分解槽を用いた。ｎ−ブ
チルアルデヒドを１％含有する有機溶媒（ＴＢＰ／ｎ−
ドデカン）８ｍｌと３Ｍ硝酸水溶液１６ｍｌを分解槽に
入れた。マグネチックスターラーで十分攪拌した状態の
溶液中に、気送ポンプを用いて、空気を供給した。実験
は、室温（２０℃）および６０℃で行った。図５より、
分解温度２０℃では（実線で示す）、約５０分で９４％
以上が、また、６０℃では（点線で示す）、約１０分で
９９％が酸化分解した。なお、実験前後の赤外分光スペ
クトル分析及び硝酸の二相間分配比測定結果から判断
し、空気酸化による有機溶媒（ＴＢＰ及びｎ−ドデカ
ン）の劣化はなかった。図５に３Ｍ硝酸水溶液中のｎ−
ブチルアルデヒドの空気酸化分解実験の結果を示す。図
において、横軸は経過時間（分）を示し、縦軸は酸化率
（％）を示す。これらの結果は、有機溶媒中のブチルア
ルデヒド異性体を、硝酸水溶液添加により水相に逆抽出
しながら、空気酸化分解できることを示している。 Example 2 Air-oxidation decomposition experiment of n-butyraldehyde in organic solvent A 30 ml glass decomposition tank was used for the experiment. Organic solvent containing 1% of n-butyraldehyde (TBP / n-
8 ml of dodecane) and 16 ml of 3M nitric acid aqueous solution were put in the decomposition tank. Air was supplied using a pneumatic pump into the solution that was sufficiently stirred with a magnetic stirrer. Experiments were performed at room temperature (20 ° C) and 60 ° C. From Figure 5,
At a decomposition temperature of 20 ° C (shown by the solid line), 94% in about 50 minutes
Further, at 60 ° C. (shown by a dotted line), 99% was oxidatively decomposed in about 10 minutes. Judging from the results of infrared spectroscopic analysis before and after the experiment and the measurement results of the distribution ratio of nitric acid between the two phases, there was no deterioration of the organic solvent (TBP and n-dodecane) due to air oxidation. Fig. 5 shows n- in 3M nitric acid aqueous solution.
The result of the air oxidation decomposition experiment of butyraldehyde is shown. In the figure, the horizontal axis represents elapsed time (minutes) and the vertical axis represents oxidation rate (%). These results indicate that the butyraldehyde isomers in the organic solvent can be oxidatively decomposed by air while back-extracting into the aqueous phase by adding a nitric acid aqueous solution.

【図面の簡単な説明】[Brief description of drawings]

図１ 使用済各燃料中のＵ、Ｐｕ及びＮｐを相互に分離する従
来の再処理工程の概要を示す図である。 図２ Ｎｐ分離工程から発生するｎ−ブチルアルデヒド含有硝
酸水溶液、Ｕ／Ｐｕ分配工程から発生するｎ−及びｉｓ
ｏ−ブチルアルデヒド含有硝酸水溶液及び有機溶媒中を
それぞれ分解する工程を考慮した本願発明の再処理工程
の概要を示す図である。 図３ ブチルアルデヒド異性体の空気酸化分解装置の概要を示
す図である。 図４ 硝酸水溶液中のｎ−ブチルアルデヒドの空気酸化実験結
果を示す図である。 図５ 有機溶媒中のｎ−ブチルアルデヒドの空気酸化実験結果
を示す図である。1 is a diagram showing an outline of a conventional reprocessing step of separating U, Pu and Np in each spent fuel from each other. Figure 2 N-butyraldehyde-containing nitric acid aqueous solution generated from Np separation step, n- and is generated from U / Pu distribution step
It is a figure which shows the outline | summary of the reprocessing process of this invention which considered the process which decomposes | disassembles each in o-butyraldehyde containing nitric acid aqueous solution and an organic solvent. 3 is a diagram showing an outline of an air oxidation decomposition apparatus of butyraldehyde isomers. 4 is a diagram showing the results of air oxidation experiment of n-butyraldehyde in a nitric acid aqueous solution. 5 is a diagram showing the results of an air oxidation experiment of n-butyraldehyde in an organic solvent.

【符号の説明】 １ 使用すみ核燃料を硝酸水溶液に溶解する工程 ２ 原子価調整工程 ３ 有機溶媒を用いてＵ、Ｐｕ及びＮｐを溶解液から抽
出しＦＰから分離するための共除染工程 ４ Ｎｐ酸化工程 ５ Ｎｐ分離工程 ６ Ｕ及びＰｕ回収工程 ７ 有機溶媒中のＩＶ価のＰｕのみをｉｓｏ−ブチルア
ルデヒドを用いて選択的にＩＩＩ価に還元する工程 ８ 有機溶媒中のＶＩ価のＵを溶媒抽出により精製ふる
工程 ９ 硝酸水溶液中のＩＩＩ価のＰｕを精製する工程 １０ 硝酸水溶液中のｎ−ブチルアルデヒドを分解する
工程 １１ 硝酸水溶液中のｎ−及びｉｓｏ−ブチルアルデヒ
ドを分解する工程 １２ 有機溶媒中のｎ−及びｉｓｏ−ブチルアルデヒド
を分解する工程 Ａ 使用済み核燃料 Ｂ 有機溶媒（ＴＢＰ希釈剤） Ｃ 核分裂生成物（高レベル廃液） Ｄ 酸化剤 Ｅ 有機溶媒 Ｆ 硝酸 Ｇ ｎ−ブチルアルデヒド Ｈ ｉｓｏ−ブチルアルデヒド Ｐ１ウラン製品 Ｐ２プルトニウム製品 Ｐ３ネプツニウム製品 ─── 水溶液の流れ ……… 有機溶媒の流れ ２１ 空気酸化分解槽 ２２ 空気供給ノズル ２３ 攪拌機 ２４ 空気供給ポンプ ２５ 炭化水素酸化塔 Ｍ モーター[Explanation of Codes] 1 step of dissolving used nuclear fuel in nitric acid aqueous solution 2 valence adjustment step 3 co-decontamination step for extracting U, Pu and Np from the solution by using an organic solvent and separating from FP 4 Np Oxidation step 5 Np separation step 6 U and Pu recovery step 7 Step in which only IV-valent Pu in the organic solvent is selectively reduced to III-valent using iso-butyraldehyde 8 VI-valent U in the organic solvent is used as a solvent Purifying and sieving step by extraction 9 Step of purifying III-valent Pu in nitric acid aqueous solution 10 Step of decomposing n-butyraldehyde in nitric acid aqueous solution 11 Step of decomposing n- and iso-butyraldehyde in nitric acid aqueous solution 12 Organic solvent Process for decomposing n- and iso-butyraldehyde in liquids A Spent nuclear fuel B Organic solvent (TBP diluent) C Fission product (high level waste liquid) D Oxidizing agent E Organic solvent F Nitric acid G n-Butyraldehyde H iso-butyraldehyde P 1 Uranium product P 2 Plutonium product P 3 Neptunium product ─── Flow of aqueous solution ………… Organic solvent flow 21 Air oxidation decomposition tank 22 Air supply Nozzle 23 Stirrer 24 Air supply pump 25 Hydrocarbon oxidation tower M Motor

───────────────────────────────────────────────────── フロントページの続き (72)発明者 前田 充 茨城県那珂郡東海村白方字白根２番地の４ 日本原子力研究所 東海研究所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Maeda 4 2-2 Shirane, Shikatakata, Tokai-mura, Naka-gun, Ibaraki Prefecture Japan Atomic Energy Research Institute Tokai Research Institute

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】使用済み核燃料を硝酸水溶液に溶解する工
程、原子価調整工程、有機溶媒を用いてウラン、プルト
ニウム及びネプツニウムを溶解液から抽出し核分裂生成
物と分離するための共除染工程、ネプツニウムの分離工
程、ウラン及びプルトニウムの回収工程、有機溶媒中の
ＩＶ価のプルトニウムのみをｉｓｏ−ブチルアルデヒド
を用いて選択的にＩＩＩ価に還元し硝酸水溶液に逆抽出
することによりＶＩ価のウランと分離するＵ／Ｐｕ分配
工程、有機溶媒中のＶＩ価ウランを溶媒抽出により精製
する工程及び硝酸水溶液中のＩＩＩ価のプルトニウムを
精製する工程から成る使用済み核燃料からウラン、プル
トニウム及びネプツニウムを分離する核燃料再処理工程
において、ネプツニウムの分離工程の次に硝酸水溶液中
のｎ−ブチルアルデヒドを分解する工程を設け、Ｕ／Ｐ
ｕ分配工程の次に硝酸水溶液中のｎ−及びｉｓｏ−ブチ
ルアルデヒドを分解する工程及び有機溶媒中のｎ−及び
ｉｓｏ−ブチルア１デヒドを分解する工程を設けて、使
用したブチルアルデヒド異性体を空気酸化して二酸化炭
素と水とに分解することを特徴とする使用済み核燃料か
らウラン、プルトニウム及びネプツニウムを分離精製す
る方法。1. A step of dissolving spent nuclear fuel in an aqueous nitric acid solution, a valence adjustment step, a co-decontamination step for extracting uranium, plutonium and neptunium from the solution using an organic solvent to separate them from fission products, Neptunium separation step, uranium and plutonium recovery step, and only IV-valent plutonium in an organic solvent is selectively reduced to III-valent with iso-butyraldehyde and back-extracted into a nitric acid aqueous solution to obtain VI-valent uranium. Nuclear fuel for separating uranium, plutonium and neptunium from spent nuclear fuel comprising a U / Pu partitioning step for separation, a step for purifying VI-valent uranium in an organic solvent by solvent extraction, and a step for purifying III-valent plutonium in an aqueous nitric acid solution In the reprocessing step, the neptunium separation step was followed by n-butylalcohol in an aqueous nitric acid solution. The provided decomposing the hydrate, U / P
After the u partitioning step, a step of decomposing n- and iso-butyraldehyde in a nitric acid aqueous solution and a step of decomposing n- and iso-butylaldehyde in an organic solvent are provided, and the used butyraldehyde isomer is separated by air. A method for separating and purifying uranium, plutonium and neptunium from spent nuclear fuel, which is characterized by oxidizing and decomposing into carbon dioxide and water.
JP5105092A 1992-01-27 1992-01-27 Method for separating and purifying uranium, plutonium and neptunium from spent nuclear fuel Expired - Fee Related JP3104181B2 (en)

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