鈴井 伸郎*; 柴田 卓弥; 尹 永根*; 船木 善仁*; 栗田 圭輔; 保科 宏行*; 山口 充孝*; 藤巻 秀*; 瀬古 典明*; 渡部 浩司*; et al.
Scientific Reports (Internet), 10, p.16155_1 - 16155_9, 2020/10
Visualizing the dynamics of cesium (Cs) is desirable to understand the impact of radiocesium when accidentally ingested or inhaled by humans. The positron-emitting nuclide Cs was produced using the I (, 4n) Cs reaction, which was induced by irradiation of sodium iodide with a He beam from a cyclotron. We excluded sodium ions by using a material that specifically adsorbs Cs as a purification column and successfully eluted Cs by flowing a solution of ammonium sulfate into the column. We injected the purified Cs tracer solution into living rats and the dynamics of Cs were visualized using positron emission tomography; the distributional images showed the same tendency as the results of previous studies using disruptive methods. Thus, this method is useful for the non-invasive investigation of radiocesium in a living animal.
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
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.
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*; 久保田 俊夫*
QST-M-23; QST Takasaki Annual Report 2018, P. 59, 2020/03
Radioactive spent solvent waste contains U and Pu is generated from reprocessing process of spent nuclear fuel. The nuclear materials should be removed from the solvent for safety storage or disposal. We are focusing on the nuclear materials recovery from spent solvent using imino diacetic acid (IDA) type chelating resin as a promising method. In order to reveal adsorbed amount of Zr, which is simulated of Pu, Micro-Particle Induced X-ray Emission (PIXE) was carried out. Micro-PIXE analysis succeeded in quantitative analysis on trace amount of adsorbed Zr from simulated spent solvent.
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
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.
瀬古 典明*; 保科 宏行*; 笠井 昇*; 柴田 卓弥; 佐伯 誠一*; 植木 悠二*
Radiation Physics and Chemistry, 143, p.33 - 37, 2018/02
Six years after the Fukushima-nuclear accident, the dissolved radioactive cesium (Cs) is now hardly detected inenvironmental natural waters. These natural waters are directly used as source of drinking and domestic waters in disaster-stricken areas in Fukushima. However, the possibility that some radioactive Cs adsorbed on soil or leaves will contaminate these natural waters during heavy rains or typhoon is always present. In order for the returning residents to live with peace of mind, it is important to demonstrate the safety of the domestic waters that they will use for their daily life. For this purpose, we have synthesized a material for selective removal of radioactive Cs by introducing ammonium 12-molybdophosphate (AMP) onto polyethylene nonwoven fabric through radiation-induced emulsion graft polymerization technique. Water purifiers filled with the grafted Csadsorbent were installed in selected houses in Fukushima. The capability of the grafted adsorbent to remove Cs from domestic waters was evaluated for a whole year. The results showed that the tap water filtered through the developed water purifier contained no radioactive Cs, signifying the very effective adsorption performance of thedeveloped grafted adsorbent. From several demonstrations, we have commercialized the water purifier named "KranCsair".
柴田 卓弥; 瀬古 典明; 天田 春代; 笠井 昇; 佐伯 誠一; 保科 宏行; 植木 悠二
Radiation Physics and Chemistry, 119, p.247 - 252, 2016/02
A fibrous adsorbent for radioactive cesium (Cs) removal has been developed by radiation induced graft polymerization. To apply the developed adsorbent to drinking water, the stability of adsorbent having high affinity for Cs ligand, ammonium 12-molybdophosphate (AMP), was evaluated. As a result, since a crosslinking structure was introduced onto the grafted AMP, it could be successfully satisfied the regulation of Food Sanitation Act. Finally, the Cs adsorbent was commercialized as water purifier named by "KranCsairtextregistered".
電気評論, 100(12), p.47 - 51, 2015/12
瀬古 典明; 柴田 卓弥; 笠井 昇; 植木 悠二; 佐伯 誠一; 保科 宏行
放射線と産業, (138), p.9 - 12, 2015/06
柴田 卓弥; 瀬古 典明; 笠井 昇; 保科 宏行; 植木 悠二
International Journal of Organic Chemistry, 5(2), p.100 - 107, 2015/06
To obtain the safety of drinking water, an antibacterial material was prepared by loading Ag onto fibrous iminodiacetate (IDA) adsorbent, which was synthesized by radiation induced graft polymerization of a glycidyl methacrylate and subsequent chemical modification of the produced epoxy group to an IDA group(IDA-Ag). A total amount of loaded Ag on the IDA-Ag fabric was 0.4 mmol-Ag/g-fabric. As a result of evaluating antibacterial effects by the column mode water flow test with a stream water, the effective Ag concentration was monitored 0.05 ppm at irrespective of flow rate which was functioned to the antibacterial performance. The antibacterial effects for general bacteria were indicated until BV (BV: steam water volume/IDA-Ag fabric volume) 6,000, and for colitis germ legions were completely disinfected until BV 6,000.
柴田 卓弥; 瀬古 典明; 天田 春代; 笠井 昇; 佐伯 誠一; 保科 宏行; 植木 悠二
日本イオン交換学会誌, 26(1), p.9 - 14, 2015/01
It is important task for recovering of Cs from the contaminated area caused by the accident at the Fukushima Daiichi Nuclear Power Station. We developed a highly efficient Cs adsorbent by radiation grafting of ammonium 12-molybdophosphate (AMP) and crosslinking of grafted chains with a suitable crosslinker at the same time. As a result of the optimizaion, the Cs adsorbent with 1 mol% of polyethylene glycol dimethacrylate satisfied the specification as a water purifier. The resultant grafted Cs adsorbent could work to maintain the highly performance of Cs removal in the standard pH range for drinking water (from pH 5.8 to 8.6) and even in the presence of coexisting ions such as K, Ca, Mg, and Na.
佐伯 誠一; 柴田 卓弥; 保科 宏行; 植木 悠二; 笠井 昇; 瀬古 典明
日本イオン交換学会誌, 25(4), p.170 - 175, 2014/11
After Fukushima Daiichi Nuclear Power Plant accidents, a lot of contaminated wastes have been produced by decontamination works at contaminated areas around Fukushima prefecture, Japan. At some temporary storage sites, it was found that contaminated leaching water was accumulated under stacks of contaminated "plant" wastes. To handle the wastes and the solution properly, decontamination tests of the leaching water were examined with molybdophosphate type cesium adsorbents synthesized by radiation-induced grafting method. At batch adsorption tests, 75% of radioactive cesium was successfully removed with cesium adsorbents. At column adsorption tests, radioactivity concentration of the leaching water could be reduced under provisional limit value up to around 500 times volume as large as an adsorbent volume. For development of volume reduction method of contaminated plant wastes, radioactive cesium extraction tests from the wastes and removal tests from the extracts were executed using contaminated oil cakes of sunflower seeds as a model of contaminated plant wastes. As a result, 65% of radioactive cesium was successfully extracted from the oil cakes to liquid phase, and more than 65% of radioactive cesium could be collected from the extract by grafted cesium adsorbents. These results showed a possibility of an application of these processes to volume reduction method for contaminated plant wastes.
林 菜月*; 保科 宏行; 天田 春代; 山延 健*; 瀬古 典明
日本イオン交換学会誌, 25(4), p.105 - 108, 2014/11
A fibrous phosphoric acid adsorbents for scandium were synthesized by radiation graft polymerization of glycidyl methacrylate (GMA), subsequent chemical modification, and direct grafting with a phosphoric monomer having both vinyl and phosphoric groups onto a polypropylene coated by polyethylene nonwoven fabric. The resultant grafted fibrous phosphoric acid adsorbent (HMP-g) having long side grafted chains has high affinity for scandium (Sc) ions even under the coexistence with Fe ion. The breakthrough capacity for Sc of 0.5 ppm with Fe coexistence was 10.9 mol-Sc per kg-adsorbent for the GMA derivative phosphoric adsorbent, and 17.8 mol-Sc per kg-adsorbent for HMP-g, respectively.
保科 宏行; 笠井 昇; 天田 春代; 高橋 牧克*; 田中 和也*; 瀬古 典明
日本イオン交換学会誌, 25(4), p.248 - 251, 2014/11
An adsorbent for Scandium (Sc) recovery was developed with radiation-induced graft polymerization of phosphoric acids that have a high affinity for Sc onto polyethylene fabrics. The adsorption performance of Sc was evaluated with the Sc adsorption equipment, consisting of 155 mm internal diameter columns and a pump that were set up near Yukawa River in Kusatsu town. To achieve a practical use of Sc recovery, the adsorbent requires repeated use with maintaining its efficiency in terms of cost reduction. So, the reusability of the adsorbent was investigated by repeating adsorption and elution. The breakthrough curves of Sc adsorption showed similar behavior in all tests. The adsorbed Sc from the 19th adsorption test was 56 mg, which was comparable capacity to the average amount of the adsorbed Sc during the 19 tests. These results indicated that the adsorbent was used more than 19 times with maintaining high adsorption performance of Sc.
天田 春代; 高橋 牧克*; 保科 宏行; 瀬古 典明
日本イオン交換学会誌, 25(4), p.109 - 113, 2014/11
A large amount of arsenic waste solution which was dissolved in neutral aqueous media, was generated from the manufacturing process of gallium arsenide component in semiconductor industry. As for arsenic removal, an adsorbent was developed by radiation graft polymerization and subsequent chemical modification with N-methyl-D-glucamine (NMDG) as a functional group. Furthermore, the grafting and the modification were carried out using water based solvent instead of organic solvent in view of an environmental emission and a working environment. The solvents were comprised of water and surfactant, and the adsorption performances compared with a conventional method synthesized in 1,4-dioxane of organic solvent. Total amount of arsenic for arsenic(III) and arsenic(V) at pH 6.5 were 3.2 times and 2.1 times higher than our previous fibrous adsorbent. From the pH dependency studies, the developed grafted adsorbent gave high removal ratio in a neutral media area for both arsenic species. Breakthrough capacities in the column mode tests for arsenic(III) and arsenic(V) were 0.3 and 18 mg/g at pH 6.5, respectively.
植木 悠二; 佐伯 誠一; 瀬古 典明
日本イオン交換学会誌, 25(4), p.99 - 104, 2014/11
The dynamic adsorption/elution properties of an ethyl p-styrenesulfonate (EtSS)-based fibrous graft adsorbent having sulfonic acid (SOH) groups were evaluated by column-mode adsorption/elution tests for various cations. The EtSS-based fibrous graft adsorbent could work to capture various cations rapidly even under high flow rate conditions, compared with a commercial granular resin. The reason for this difference of adsorption rates was thought to be that the target ions were easily and rapidly transported near the SOH groups of graft chains by fluid convection. The affinity order of the fibrous graft adsorbent for cations depended on the cationic size and valence. It was found that the EtSS-based fibrous graft adsorbent preferentially adsorbed more multiply-charged cations having a larger cationic radius. The adsorbed cations could be easily eluted and concentrated by 1 M HNO aqueous solution, and the recovery of each cation was reached over 90%. Based on the above results, it was found that the EtSS-based fibrous graft adsorbent could be available as a sophisticated metal adsorbent in the industrial processes.
保科 宏行; 植木 悠二; 佐伯 誠一; 瀬古 典明
International Journal of Organic Chemistry, 4(3), p.195 - 200, 2014/09
2-Ethylhexyl hydrogen-2-ethylhexylphosphonate (EHEP) is commonly used as a metal extractant because it has a particular affinity for rare-earth metals like Scandium (Sc). To develop a highly-selective polymeric adsorbent of Sc(III), EHEP was introduced as a functional group onto a polyethylene fabric with radiation-induced graft polymerization (RIGP). The adsorption performances for Sc(III) were evaluated in aqueous solutions containing Sc(III) and Fe(III) by a column test. The adsorption capacities of Sc(III) and Fe(III) until the bed volume reached 5000 were 5.22 and 0.12 mg/g, respectively. The adsorbents showed 44 times higher Sc(III) adsorption capacity than that of Fe(III). These results indicated that the grafted adsorbent containing EHEP had an extremely high selectivity for Sc(III) adsorption.
植木 悠二; 佐伯 誠一; 柴田 卓弥; 保科 宏行; 笠井 昇; 瀬古 典明
International Journal of Organic Chemistry, 4(2), p.91 - 105, 2014/06
佐伯 誠一; 岡屋 慶子*; 瀬古 典明
JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 54, 2014/03
植木 悠二; 瀬古 典明
JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 53, 2014/03
齋藤 広明*; 溝手 範人*; 植木 悠二; 瀬古 典明
JAEA-Review 2013-059, JAEA Takasaki Annual Report 2012, P. 57, 2014/03