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 Chemical, Molecular, Nuclear, Materials and Metallurgical 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.

Partitioning of plutonium by acid split method with dissolver solution derived from irradiated fast reactor fuel with high concentration of plutonium

中原 将海; 佐野 雄一; 野村 和則; 竹内 正行

Journal of Chemical Engineering of Japan, 51(3), p.237 - 242, 2018/03

https://doi.org/10.1252/jcej.17we264

酸分配法における高Pu濃度フィード溶液条件におけるPuの分配挙動を調べるため、向流多段試験を行った。フィード溶液に比べてU/PuプロダクトのPu富荷度を1.51倍に高めることができた。Pu分配工程において、Pu重合体や第三相の生成はみられず、安定して遠心抽出器の運転が行われた。

Micro-PIXE analysis on adsorbent of extraction chromatography for MA(III) recovery

高畠 容子; 渡部 創; 小藤 博英; 竹内 正行; 野村 和則; 佐藤 隆博*

International Journal of PIXE, 26(3&4), p.73 - 83, 2017/09

BB2016-1248.pdf:0.36MB

https://doi.org/10.1142/S0129083517500012

次世代再処理ガラス固化技術基盤研究で技術開発を行っている吸着ガラスについて、開発の対象とする抽出クロマトグラフィ技術に用いる吸着材の吸着元素分布情報をマイクロPIXE分析により明らかにすることを検討している。本研究では高レベル放射性廃液の模擬液をカラム法にて吸着並びに吸着/溶離した吸着材を用いて、実使用に即した条件下での吸着材の元素分布情報取得に対するマイクロPIXE技術の適用性評価を行った。検討に供した吸着材はCMPO/SiO-P吸着材及びHDEHP/SiO-P吸着材であり、分析には高崎量子応用研究所のシングルエンド加速器を用いた。分析結果より、カラム内での吸着バンドの形成や溶離後に吸着材に残留する元素の存在を確認できた。これより、マイクロPIXE分析を吸着材性能の定性的な評価に適用することが期待できた。

Control of fine particles accumulation in the extraction chromatography column system for minor actinide recovery

渡部 創; 後藤 一郎; 佐野 雄一; 野村 和則; 駒 義和

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 7 Pages, 2017/04

Clogging of the extraction chromatography column caused by inflow of insoluble residue into the bed possible to lead accumulation of decay heat and explosive gas inside the bed. Behavior of small particle is necessary to be investigated to prevent hazardous events. In this study, influence of fine particles contained in the feed solution on the clogging and on separation performance of the bed were evaluated by laboratory scale experiments. Discharging operation of the simulated particles from the bed was experimentally demonstrated using an engineering scale system. The particles were accumulated on top of the bed and hardly come inside the bed. Backwashing operation was effective to discharge a part of the accumulated powder. Supplying water into the column with normal flow rate condition was possible after the short time backwashing operation. Backwashing with cold water as a normal operation must be one of the most appropriate countermeasures for preventing from the clogging.

Characterization of the insoluble sludge from the dissolution of irradiated fast breeder reactor fuel

粟飯原 はるか; 荒井 陽一; 柴田 淳広; 野村 和則; 竹内 正行

Procedia Chemistry, 21, p.279 - 284, 2016/12

BB2015-3214.pdf:0.31MB

https://doi.org/10.1016/j.proche.2016.10.039

Insoluble sludge is generated in reprocessing process. Actual sludge data, which had been obtained from the dissolution experiments of irradiated fuel of fast reactor "Joyo" were reevaluated especially from the view point of the characterization of sludge. The yields of sludge were calculated from the weight and there were less than 1%. Element concentrations of sludge were analyzed after decomposing by alkaline fusion. As the results, molybdenum, technetium, ruthenium, rhodium and palladium accounted for mostly of the sludge. From their chemical compositions and structure analyzed by XRD show good agree that main component of sludge is MoRuRhPdTc regardless of the experimental condition. At the condition of reprocessing fast breeder fuel, it is indicated that molybdenum and zirconium in dissolved solution is low, therefore zirconium molybdate hydrate may not produce abundant amount in the process.

Safety operation of chromatography column system with discharging hydrogen radiolytically generated

渡部 創; 佐野 雄一; 野村 和則; 駒 義和; 岡本 芳浩

European Physical Journal; Nuclear Sciences & Technologies (Internet), 1, p.9_1 - 9_8, 2015/12

https://doi.org/10.1051/epjn/e2015-50006-1

In the extraction chromatography system, accumulation of hydrogen gas in the chromatography column is suspected to lead to fire or explosion. In order to prevent the hazardous accidents, it is necessary to evaluate behaviors of gas radiolytically generated inside the column. In this study, behaviors of gas inside the extraction chromatography column were investigated through experiments and Computation Fluid Dynamics (CFD) simulation. N gas once accumulated as bubbles in the packed bed was hardly discharged by the flow of mobile phase. However, the CFD simulation and X-ray imaging on -ray irradiated column revealed that during operation the hydrogen gas generated in the column was dissolved into the mobile phase without accumulation and discharged.

Comparative study of Sr adsorbents for radioactive contaminated water on severe accident

高畠 容子; 柴田 淳広; 野村 和則

Proceedings of 21st International Conference & Exhibition; Nuclear Fuel Cycle for a Low-Carbon Future (GLOBAL 2015) (USB Flash Drive), p.2099 - 2104, 2015/09

The radioactive contaminated water has accumulated at Fukushima Dai-ichi Nuclear Power Station after the severe damage by the events accompanying the earthquake and tsunami. The concentration of Ca in the accumulated water is higher than that of Sr. Because of their chemical similarity, the secondary radioactive waste from Sr decontamination process will contains Ca more than Sr. Therefore, the volume of the secondary waste will increase more unnecessarily. Three kinds of Sr adsorbents; SW-KAZLS, the Hydrous titanic acid and SrTreat,were characterized and assessed from the viewpoint of Sr decontamination for radioactive contaminated water. The amount of Sr in SW-KAZLS showed the highest Sr selectivity. Since the Hydrous titanic acid was the hardest adsorbent of three, it is applied well to adsorption tower. The amount of Sr in SrTreat was favorable, and it could be applied to decontamination for the radioactive contaminated water of low Sr concentration.

Effect of crystal size on purity of uranyl nitrate hexahydrate crystalline particles grown in nitric acid medium

中原 将海; 野村 和則

Radiochimica Acta, 100(11), p.821 - 826, 2012/11

https://doi.org/10.1524/ract.2012.1978

照射済燃料溶解液から回収した硝酸ウラニル六水和物の結晶粒径と除染係数の関係を調べた。表面に付着している液体不純物は、粒径が大きくなると結晶の表面積が小さくなるため、除染係数が高い傾向を示した。しかしながら、固体不純物はそれほど効果がみられなかった。

Decontamination of radioactive liquid waste with hexacyanoferrate(II)

高畠 容子; 渡部 創; 柴田 淳広; 野村 和則; 駒 義和

Procedia Chemistry, 7, p.610 - 615, 2012/00

https://doi.org/10.1016/j.proche.2012.10.093

Concerning decontamination of a radioactive liquid waste which comprise seawater and nuclides from irradiated fuels and activated materials, the in-situ generation of metal hexacyanoferrates(II) by adding potassium hexacyanoferrate(II) and co-decontamination of Cs and some activation products were investigated. Transition metals arising from seawater in the waste solution precipitates in the preference order of Zn Ni Co Mn according to their solubility. The precipitate adsorbs Cs, and decontamination will be attained by the following sedimentation with a polymer and filtration, as an example. Decontamination factor of activated products, Co and Mn, is dependent on concentration of hexacyanoferrate(II) in the solution.

Americium and curium separation from simulated acidic raffinate from the reprocessing process by extraction chromatography

松村 達郎; 森田 泰治; 松村 和美; 佐野 雄一; 駒 義和; 野村 和則

Proceedings of 11th OECD/NEA Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation (Internet), 8 Pages, 2012/00

http://www.oecd-nea.org/pt/iempt11/poster/IV-7.pdf

FaCTの一環として、抽出クロマトグラフ法によるMA回収技術を確立するため、担体であるSiO-P粒子に抽出剤を担持させた吸着材を用いるフローシートを検討している。抽出クロマトグラフ法においても、抽出剤は溶媒抽出法と同様な特性を発揮すると考えられるため、MA・Ln回収工程とMA/Ln分離工程の2サイクルから構成されるフローシートとして進めている。本研究では、MA・Ln回収工程にTODGA吸着材及びCMPO吸着剤、MA/Ln分離工程にHDEHP吸着材,R-BTP吸着剤及びTOPEN吸着剤を使用した。フローシート全体を通じた各元素の分離挙動を観察した結果、TODGA吸着剤とR-BTP吸着剤あるいはTOPEN吸着剤を組合せたフローシートによってMA(III)を模擬再処理抽残液から分離することが可能であることを確認した。