高レベル放射性物質研究施設における放射性廃液の安定化処理

小木 浩通*; 荒井 陽一; 粟飯原 はるか; 渡部 創; 柴田 淳広; 野村 和則

JAEA-Technology 2021-007, 27 Pages, 2021/06

JAEA-Technology-2021-007.pdf:2.43MB

放射性物質取扱施設である高レベル放射性物質研究施設(CPF: Chemical Processing Facility)では、過去の試験や分析で発生した多種の廃液をホットセル及びグローブボックス内で保管してきた。2015年7月より、保管されている放射性廃液について、管理方法の適正化を図るべく、実廃液の安定化処理を進めている。また、分析廃液等の多種多様な試薬が混在する廃液については安定化処理が非常に困難であるため、大学等と共同でSTRAD(Systematic Treatments of Radioactive liquid wastes for Decommissioning)プロジェクトを発足させ、処理技術の研究開発を進めている。これらの実績は、他の放射性物質取り扱い施設においても保管する廃液の処理をより効率的かつ安全に進められることが期待できる。本書は、CPFで安定化処理を実施した実廃液の処理方法及び処理状況に関して報告するものである。

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.

Stabilization processing of hazardous and radioactive liquid wastes derived from advanced aqueous separation experiments for safety handling and management of waste

中原 将海; 渡部 創; 小木 浩通*; 荒井 陽一; 粟飯原 はるか; 本山 李沙; 柴田 淳広; 野村 和則; 梶並 昭彦*

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.66 - 70, 2019/09

高レベル放射性物質研究施設では、先進湿式分離試験に由来する多種多様な有害性及び放射性液体廃棄物が発生する。そのため、これらを安全に取り扱い及び管理するために安定化処理を行う必要がある。今回は、これらの溶液に含まれる有害物質の沈殿処理若しくは酸化処理、核物質回収のための溶媒抽出による分離、フリーズドライ法を用いた濃縮処理について報告する。

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.

Study of treatment scenarios for fuel debris removed from Fukushima Daiichi NPS

鷲谷 忠博; 矢野 公彦; 鍛治 直也; 山田 誠也*; 紙谷 正仁

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05

福島第一原子力発電所の燃料デブリ取出し後の処置については、燃料デブリ取出し開始時までにデブリの処置の選択決定に係る一定の議論が必要になるものと想定し、それまでに各シナリオの比較評価に用いる情報や比較評価の進め方を決める必要がある。そのため、本検討では燃料デブリの取出し後の処置シナリオの検討に向けた技術的要件の整理として、各処置シナリオ案の得失評価を行った。評価の結果、総合すると技術課題は有するものの経済性、廃棄物発生量の面で有利なシナリオは長期保管及び直接処分と推定された。一方、安定化処理、湿式処理、乾式処理は経済性、廃棄物発生量の面で不利と推定された。