Microscopic analyses on Zr adsorbed IDA chelating resin by PIXE and EXAFS

荒井 陽一; 渡部 創; 大野 真平; 野村 和則; 中村 文也*; 新井 剛*; 瀬古 典明*; 保科 宏行*; 羽倉 尚人*; 久保田 俊夫*

Nuclear Instruments and Methods in Physics Research B, 477, p.54 - 59, 2020/08

https://doi.org/10.1016/j.nimb.2019.10.028

Used PUREX process solvent generated from reprocessing process of spent nuclear fuel contains a small amount of U and Pu complexed with tributyl phosphate (TBP) or dibutyl phosphate (DBP). The radioactive nuclides should be removed from the solvent for safety storage or disposal. The iminodiacetic acid (IDA) type chelating resin was proposed as promising procedures for efficient recovery of the trapped cations in the solvent. In order to reveal the distribution and amount of Zr in the particle and local structure of Zr complex formed in the adsorbent, PIXE and EXAFS analyses on the Zr adsorbed chelating resin were carried out. Micro-PIXE analysis proved that it is an effectual method for quantitative analysis of trace adsorbed elements. Moreover, some of the adsorption sites were possibly occupied by the molecules. On the other hand, Zr-K edge EXAFS analysis suggested that extraction mechanism of Zr from the aqueous solution and the solvent was different.

Improvement in flow-sheet of extraction chromatography for trivalent minor actinides recovery

渡部 創; 先崎 達也; 柴田 淳広; 野村 和則; 竹内 正行; 中谷 清治*; 松浦 治明*; 堀内 勇輔*; 新井 剛*

Journal of Radioanalytical and Nuclear Chemistry, 322(3), p.1273 - 1277, 2019/12

https://doi.org/10.1007/s10967-019-06808-y

Extraction chromatography flow-sheet employing octyl(phenyl)--diisobutylcarbonoylmethylphosphine oxide (CMPO) and (2-ethylhexyl) hydrogen phosphate (HDEHP) extractants for trivalent minor actinide recovery was modified to improve column separation performance. Excellent trivalent minor actinides recovery performance was obtained by column separation experiments on nitric acid solution containing the trivalent minor actinides and representative fission product elements, i.e. recovery yields 93% with sufficient decontamination factors against the fission products. Those are the best performance which we have ever obtained by experiments inside hot cell.

Waste management in a hot laboratory of Japan Atomic Energy Agency, 1; Overview and activities in chemical processing facility

野村 和則; 小木 浩通*; 中原 将海; 渡部 創; 柴田 淳広

International Journal of Nuclear and Quantum Engineering (Internet), 13(5), p.209 - 212, 2019/00

Chemical Processing Facility of Japan Atomic Energy Agency is a basic research field for advanced back-end technology developments with using actual high-level radioactive materials. Most of them were treated properly and stored in the liquid waste vessel, but some were not treated and remained at the experimental space as a kind of legacy nuclear waste, which we must treat in safety and dispose if we continue research activities in the facility. Under this circumstance, we launched a collaborative research project called the STRAD project, which stands for Systematic Treatment of Radioactive liquid waste for Decommissioning, in order to develop the treatment processes for wastes of the nuclear research facility. In this project, decomposition methods of certain chemicals, which have been directly solidified without safety pretreatment but may cause a troublesome phenomenon, is developing and a prospect that it will be able to decompose in the facility by simple method. And solidification of aqueous or organic liquid wastes after the decomposition has been studied by adding cement or coagulants. Furthermore, we treated experimental tools of various materials with making an effort to stabilize and to compact them before the package into the waste container. It is expected to decrease the number of transportation of the solid waste and widen the operation space. The project is expected to contribute beneficial waste management outcome that can be shared world widely.

Actinides recovery from irradiated fuel for SmART cycle

佐野 雄一; 渡部 創; 中原 将海; 粟飯原 はるか; 竹内 正行

Proceedings of International Nuclear Fuel Cycle Conference (GLOBAL 2017) (USB Flash Drive), 4 Pages, 2017/09

CPFにおいて照射済燃料から数gのMAを回収し、AGFにおいてMA含有MOX燃料を製造した後、常陽において照射試験を行うSmARTサイクル構想を進めている。本報告では、CPFで実施したMAを含むアクチニド回収に係る研究開発について、過去実施した溶媒抽出法及び抽出クロマトグラフィによるアクチニド回収技術をレビューするとともに、SmARTサイクルの一環として実施した各方法によるアクチニド回収試験の概要をまとめた。

日本原子力学会2016秋の大会バックエンド部会企画セッション「ガラス固化体の実力は?; 地層処分におけるガラス固化体性能評価の現状」参加報告

亀井 玄人

原子力バックエンド研究(CD-ROM), 23(2), p.201 - 202, 2016/12

https://nuce.aesj.or.jp/jnuce/vol23/Jnuce-Vol23-2-p201-202.pdf

国内外のガラス固化体地層処分に関する研究開発の現状と課題について、日本原子力学会バックエンド部会の企画セッションが開催されたので、座長として参加し、その要点をまとめた。国内外の現状と今後の課題のほか、ガラス固化体の性能評価、基礎科学、計算科学の観点からの研究例等が報告された。

Flow-sheet study of MA recovery by extraction chromatography for SmART cycle project

渡部 創; 野村 和則; 北脇 慎一; 柴田 淳広; 小藤 博英; 佐野 雄一; 竹内 正行

Procedia Chemistry, 21, p.101 - 108, 2016/12

BB2015-3215.pdf:0.34MB

https://doi.org/10.1016/j.proche.2016.10.015

Optimization in a flow-sheet of the extraction chromatography process for minor actinides (MA(III); Am and Cm) recovery from high level liquid waste (HLLW) were carried out through batch-wise adsorption/elution experiments on diluted HLLW and column separation experiments on genuine HLLW. Separation experiments using CMPO/SiO-P and HDEHP/SiO-P adsorbent columns with an improved flow-sheet successfully achieved more than 70 % recovery yields of MA(III) with decontamination factors of Ln(III) 10, and a modified flow-sheet for less contamination with fission products was proposed consequently. These results will contribute to MA(III) recovery operations for SmART Cycle project in Japan Atomic Energy Agency which is planned to demonstrates FR fuel cycle with more than 1g of Am.

Influence of contaminants from spent fuel pools at the Fukushima Daiichi Nuclear Power Station on the reprocessing process

粟飯原 はるか; 北脇 慎一; 野村 和則; 田口 克也

Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.1076 - 1083, 2015/09

The water in the spent fuel pools at TEPCO Fukushima Daiichi Nuclear Power Station contains sea water and rubbles. When the spent fuels stored in the pools will be reprocessed, it has possibility that these contaminants enter the reprocessing process with the spent fuels. Therefore it is meaningful to estimate the influence of contaminants on reprocessing process in advance. The purpose of this study is to evaluate the behavior and influence of contaminants on the extraction process of spent fuel reprocessing by using simulated contaminants. Contaminants were dissolved into the heated nitric acid and solvent extraction using TBP was performed to obtain distribution ratios. The estimated amount of contaminants accompanied with the spent fuel is low values and solvent extraction tests showed that the distribution ratios of every major element were very low in any case. Also to evaluate the influence of sulfate and chloride ions on uranium and plutonium extraction, Ce(IV) was used for simulated Pu to predict extraction behavior. And then U and Pu test was conducted in order to confirm the simulated test result. Obtained distribution ratio suggests that contaminants will not affect the extraction process.

Co-processing of uranium and plutonium for sodium-cooled fast reactor fuel reprocessing by acid split method for plutonium partitioning without reductant

中原 将海; 駒 義和; 中島 靖雄

Journal of Nuclear Science and Technology, 50(11), p.1062 - 1070, 2013/11

https://doi.org/10.1080/00223131.2013.831330

核拡散抵抗性,安全性及びコストに優れたPu還元剤を用いない酸分配法の研究を実施した。抽出計算コードを用いてフローシートの設定を行い、その結果をもとに向流多段抽出試験を行った。Pu逆抽出液は、0.15mol/dm HNOを21Cにて供給した。フィード溶液に対してU/Pu製品のPu富化度を2.28倍に高めることができた。また、U製品中におけるPu移行率は、0.47%に抑えられた。本研究により、酸分配法の高速炉燃料再処理への適用性を確認することができた。

Plutonium partitioning in uranium and plutonium co-recovery system for fast reactor fuel recycling with enhanced nuclear proliferation resistance

中原 将海; 駒 義和; 中島 靖雄

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.539 - 542, 2013/09

高速炉燃料再処理法として、還元剤として硝酸ヒドロキシルアミンを用いたPu還元分配法とUとPuの分離係数を利用したPu無還元分配法の向流多段抽出試験を行った。Pu還元分配法においてもU再抽出部を省略することにより、U及びPuを共回収できた。一方、Pu無還元分配法においてもPu分配工程において低濃度のHNO溶液を供給することにより、ほとんどのPuをUとともに回収することができた。Pu還元分配法のみならずPu無還元分配法についても高速炉燃料再処理への適用性を確認できた。

Washing of uranyl nitrate hexahydrate crystals with nitric acid aqueous solution to improve crystal quality

中原 将海; 中島 靖雄; 小泉 務

Industrial & Engineering Chemistry Research, 51(46), p.15170 - 15175, 2012/11

https://doi.org/10.1021/ie3013067

Ceを含んだ硝酸ウラニル溶液を用いた洗浄試験では、母液に留まるCeは硝酸ウラニル六水和物結晶の表面に付着し、低HNO濃度の洗浄液による洗浄操作により除去できる傾向を示した。照射済高速炉燃料溶解液を用いた晶析試験では、液体不純物の除染係数は結晶洗浄操作により向上した。一方、固体不純物の除染係数は、数回の洗浄操作に伴い減少した。これは、硝酸ウラニル六水和物結晶が固体不純物よりもHNO溶液に溶けやすいことに起因するものと思われる。