Development of a membrane reactor with a closed-end silica membrane for nuclear-heated hydrogen production

Myagmarjav, O.; 田中 伸幸; 野村 幹弘*; 野口 弘喜; 今井 良行; 上地 優; 久保 真治; 竹上 弘彰

Progress in Nuclear Energy, 137, p.103772_1 - 103772_7, 2021/07

https://doi.org/10.1016/j.pnucene.2021.103772

Hydrogen production from nuclear energy has attracted considerable interest as a clean energy solution to address the challenges of climate change and environmental sustainability. With respect to the large-scale and economical production of hydrogen using nuclear energy, the thermochemical water-splitting iodine-sulfur (IS) process is a promising method. The IS process uses sulfur and iodine compounds to decompose water into its elemental constituents, hydrogen and oxygen, by using three coupled chemical reactions: the Bunsen reaction; sulfuric acid decomposition; and hydrogen iodide (HI) decomposition. The decomposition of HI is the efficiency-determining step of the process. In this work, a membrane reactor with a silica membrane closed on one end was designed, and its potential for hydrogen production from HI decomposition was explored. In the reactor-module design, only one end of the membrane tube was fixed, while the closed-end of the tube was freely suspended to avoid thermal expansion effects. The closed-end silica membranes were prepared for the first time by a counter-diffusion chemical vapor deposition of hexyltrimethoxysilane. In application, HI conversion of greater than 0.60 was achieved at a decomposition temperature of 400C. Thus, the membrane reactor with closed-end silica membrane was shown to produce a successful equilibrium shift in the production of hydrogen via HI decomposition in the thermochemical IS process.

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.

放射性核種の長期安定化を指向した使用済みゼオライト焼結固化技術の開発(委託研究); 平成30年度英知を結集した原子力科学技術・人材育成推進事業

廃炉国際共同研究センター; 芝浦工業大学*

JAEA-Review 2019-028, 71 Pages, 2020/03

JAEA-Review-2019-028.pdf:6.46MB

日本原子力研究開発機構(JAEA)廃炉国際共同研究センター(CLADS)では、平成30年度英知を結集した原子力科学技術・人材育成推進事業(以下、「本事業」という)を実施している。本事業は、東京電力ホールディングス福島第一原子力発電所の廃炉等をはじめとした原子力分野の課題解決に貢献するため、国内外の英知を結集し、様々な分野の知見や経験を、従前の機関や分野の壁を越えて緊密に融合・連携させた基礎的・基盤的研究及び人材育成を推進することを目的としている。平成30年度の新規採択課題から実施主体を文部科学省からJAEAに移行することで、JAEAとアカデミアとの連携を強化し、廃炉に資する中長期的な研究開発・人材育成をより安定的かつ継続的に実施する体制を構築した。本研究は、研究課題のうち、平成30年度「放射性核種の長期安定化を指向した使用済みゼオライト焼結固化技術の開発」について取りまとめたものである。本研究は、継続して発生するCs等の放射性核種を吸着したゼオライト(使用済みゼオライト)の焼結固化法の開発を目的とする。焼結固化法は、使用済みゼオライトにガラスをバインダーとして添加し、それらを焼結することで核種を固定化する新たな固化法である。本法は、ガラス固化と比較して固化体の大幅な減容や焼成固化と同程度の安定な固化体の形成が期待できる。本事業では、コールド試験により焼結固化に適したガラスの選定、焼結温度等の最適化を図りホット試験で実証する。平成30年度においてバインダーの候補ガラスの熱特性、及び加熱雰囲気が焼結固化に及ぼす影響について調査した。また、放射性核種を含む模擬汚染水を作成するための照射済燃料を選定し、試料の状態を確認した。さらに、ゼオライトの固化、焼成固化等に関する既存の研究成果及び最新の研究動向を調査した。

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.

STRAD project for systematic treatments of radioactive liquid wastes generated in nuclear facilities

渡部 創; 小木 浩通*; 荒井 陽一; 粟飯原 はるか; 高畠 容子; 柴田 淳広; 野村 和則; 神谷 裕一*; 浅沼 徳子*; 松浦 治明*; et al.

Progress in Nuclear Energy, 117, p.103090_1 - 103090_8, 2019/11

https://doi.org/10.1016/j.pnucene.2019.103090

A new collaborative research project for systematic treatments of radioactive liquid wastes containing various reagents generating in nuclear facilities was started from 2018 initiated by Japan Atomic Energy Agency. The project was named as STRAD (Systematic Treatments of RAdioactive liquid wastes for Decommissioning) project. Tentative targets to be studied under the project are aqueous and organic liquid wastes which have been generated by experiments and analyses in a reprocessing experimental laboratory of JAEA. Currently fundamental studies for treatments of the liquid wastes with complicated compositions are underway. In the STRAD project, process flow for treatment of ammonium ion involved in aqueous waste was designed though the inactive experiments, and decomposition of ammonium ion using catalysis will be carried out soon. Adsorbents for recovery of U and Pu from spent solvent were also developed. Demonstration experiments on genuine spent solvent is under planning.

Ion beam induced luminescence of complexes formed in adsorbent for MA recovery process

渡部 創; 片井 雄也*; 松浦 治明*; 加田 渉*; 江夏 昌志*; 佐藤 隆博*; 新井 剛*

Nuclear Instruments and Methods in Physics Research B, 450, p.61 - 65, 2019/07

https://doi.org/10.1016/j.nimb.2018.08.029

Ion-beam induced luminescence (IBIL) analysis on MA recovery adsorbent was performed to give chemical states of complexes formed in the adsorbent as fundamental information for process design, and EXAFS analysis was also carried out to support discussions. The IBIL spectra of the binary extractants system seemed to be superposition of individual ones, however it has also original peaks. As intensities of those peaks rapidly decreased with iteration time of measurements and the original peaks were not observed for the adsorbent without charging Eu(III), they were attributed to complexes of Eu(III) with organic compounds. Contributions of CMPO and HDEHP extractants for Eu(III) extraction must be not only individual ones but also cooperative.

Influences of pore and particle sizes of CMPO/SiO-P adsorbent on extraction chromatography process

渡部 創; 佐野 雄一; 三田 修平*; 桜井 翔太*; 新井 剛*

日本イオン交換学会誌, 30(1), p.8 - 16, 2019/01

https://doi.org/10.5182/jaie.30.8

In order to optimize operability of the adsorbents in the extraction chromatography system and to enhance the performance of the adsorbent, CMPO/SiO-P adsorbents with various pore and particle sizes were prepared, and characteristics of the adsorbents were evaluated through distribution coefficient, adsorption isotherm, adsorption rate, and breakthrough/elution behavior. Adsorption capacity was dominated not by the structure of the adsorbent but by amount of the extractant impregnated. The adsorbent with the largest pore size were revealed to show quick elution with short tail. Enlargement in the pore size must be one of the most effective improvements of the adsorbents to enhance the adsorption/elution performance. Adsorbent with particle size of more than 200 m formed channeling or voids inside the bed. They are suspected to lead slow adsorption/elution behavior, and smaller adsorbents must be desirable in the respect of performance of the column.

Microanalysis of silica-based adsorbent for effective recovery of radioactive elements

佐野 雄一; 渡部 創; 松浦 治明*; 名越 航平*; 新井 剛*

Journal of Nuclear Science and Technology, 54(10), p.1058 - 1064, 2017/10

https://doi.org/10.1080/00223131.2017.1344574

ポリマー架橋度が吸着材の吸着・溶離性能に与える影響についてポリマー架橋度をパラメータとした吸着材を用いた試験により評価するとともに、その要因をSTXM分析及びEXAFS分析により考察した。吸着材中に形成された金属錯体構造については、ポリマー架橋度により大きな違いは生じないことを確認した。一方、ポリマー架橋度の増加に伴いポリマーは細孔中に均一に広がる様子が認められるとともに、架橋度が高い条件では細孔が狭小化し、水分子が捕捉されやすくなるため、溶離率が低下するものと考えられた。

Microscopic analyses of complexes formed in adsorbent for Mo and Zr separation chromatography

安倍 諒治*; 名越 航平*; 新井 剛*; 渡部 創; 佐野 雄一; 松浦 治明*; 高木 秀彰*; 清水 伸隆*; 江夏 昌志*; 佐藤 隆博*

Nuclear Instruments and Methods in Physics Research B, 404, p.173 - 178, 2017/08

https://doi.org/10.1016/j.nimb.2017.02.082

Molybdenum and zirconium obstruct the efficient recovery of minor actinides (MA(III): Am(III) and Cm(III)) by extraction chromatography; hence, the removal of these elements prior to MA(III) recovery is desirable. The use of an adsorbent impregnated with bis(2-ethylhexyl) hydrogen phosphate (HDEHP) for Mo and Zr decontamination was evaluated in this report. The adsorption/elution and column separation experiments showed that Mo and Zr in the simulated HLLW were selectively adsorbed on the particles, and that Mo was eluted by HO. EXAFS analysis and SAXS patterns of the adsorbent containing Zr revealed that the Zr-HDEHP complex had a crystal-like periodic structure similar to the structure of the precipitate produced in the solvent extraction system. Micro-PIXE analysis revealed that distribution of the residual Zr on the adsorbent was uniform.

Electroplating of Ni microstructures on the cross section of Cu wire using PMMA mother fabricated by proton beam writing

田邊 祐介*; 岩本 隆志*; 高橋 潤一*; 西川 宏之*; 佐藤 隆博; 石井 保行; 神谷 富裕

JAEA-Review 2012-046, JAEA Takasaki Annual Report 2011, P. 129, 2013/01

https://doi.org/10.11484/jaea-review-2012-046

In this study, the Ni microstructures were attempted to be fabricated on a distal surface of Cu wires with a diameter of 1.0 mm aiming at the use for imprint lithography. Firstly a PMMA master block was fabricated on the distal surface by exposing PB with beam size of 1.1 m at 3.0 MeV and developing it by IPA-water for electroplating. The master block was composed of the 4-m wide lines with pitches of 25 m and depths of 20 m. Secondly the electroplating was performed on the PMMA master block using a nickel sulfamate bath. Thirdly the electroplated Ni surface was mechanically polished easily to remove PMMA by smoothing its surface. Finally, the Ni microstructures with 20.5 m were fabricated by removing the PMMA after polishing. We additionally performed UV imprint lithography of the photosensitive polymer using the Ni microstructures as a mold. The observation result of SEM images of Ni microstructures and UV imprinted grooves showed that their imprinted grooves were successfully transferred by way of the Ni microstructures from the PMMA master block using the combination of the electroplating and imprinting.