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Journal Articles

Optimization in granulation conditions for adsorbent of extraction chromatography

Hasegawa, Kenta; Goto, Ichiro*; Miyazaki, Yasunori; Ambai, Hiromu; Watanabe, So; Watanabe, Masayuki; Sano, Yuichi; Takeuchi, Masayuki

Mechanical Engineering Journal (Internet), 11(2), p.23-00407_1 - 23-00407_8, 2024/04

Journal Articles

Development of engineering scale extraction chromatography separation system, 2; Spray drying granulation of silica support for adsorbent

Hasegawa, Kenta; Goto, Ichiro*; Miyazaki, Yasunori; Ambai, Hiromu; Watanabe, So; Watanabe, Masayuki; Sano, Yuichi; Takeuchi, Masayuki

Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 5 Pages, 2023/05

Journal Articles

Effect of seawater components on corrosion behavior of SUS316L in nitric acid solution containing metal ions

Ambai, Hiromu; Nishizuka, Yusuke*; Sano, Yuichi; Uchida, Naoki; Iijima, Shizuka; Shiwaku, Hideaki; Yaita, Tsuyoshi

Journal of Nuclear Science and Technology, 56(2), p.193 - 200, 2019/02

 Times Cited Count:2 Percentile:18.62(Nuclear Science & Technology)

During the accident that occurred at the Fukushima Daiichi Nuclear Power Plant, a large volume of seawater was introduced as coolant into the storage pools for spent nuclear fuel. If this fuel is reprocessed, some components of seawater will be mixed with the nitric acid solution containing metal ions in the reprocessing process where stainless steels are used as structural material. In this study, we investigated the effect of seawater components in high active liquid waste (HAW) containing nitric acid and metal ions as fission products on the corrosion behavior of SUS316L stainless steel. Corrosion tests were conducted in surrogate HAW containing artificial seawater (ASW). Intergranular corrosion was observed in the HAW with ASW, where Ru increased the corrosion potential to the transpassive region. An increase in the amount of ASW led to a decrease in the corrosion rate and suppression of intergranular corrosion. Interactions between Ru ions and seawater components, such as chloride ions, were indicated by the results of extended Xray absorption fine structure spectroscopy and cyclic voltammetry analyses of the solution containing ASW and HAW.

Journal Articles

Corrosion behaviour of FeCrAl-ODS steels in nitric acid solutions with several temperatures

Takahatake, Yoko; Ambai, Hiromu; Sano, Yuichi; Takeuchi, Masayuki; Koizumi, Kenji; Sakamoto, Kan*; Yamashita, Shinichiro

Proceedings of Annual Topical Meeting on Reactor Fuel Performance (TopFuel 2018) (Internet), 9 Pages, 2018/10

The corrosion behaviour of FeCrAl-ODS steels for the accident tolerant fuel cladding of LWRs were investigated in nitric acid solutions for the reprocessing process of spent fuels. The corrosion tests were carried out at 60$$^{circ}$$C, 80$$^{circ}$$C and the boiling point of the solutions, and the specimens were then analysed by XPS. The corrosion remarkably progressed at the boiling point, and the highest corrosion rate was 0.22 mm/y. In the oxide film, the atomic concentration of Fe was lower, than that in the base material, and those of Cr and Al were higher. The results show that the corrosion of FeCrAl-ODS steels in hot nitric acid solution is not severe because of the high corrosion resistance of the oxide film formed on the material; hence, the corrosion resistance of the new cladding materials in the dissolution process of spent fuel is acceptable for reprocessing operations.

Journal Articles

Effect of Ru chemical form on corrosion behavior of structural materials in spent fuel reprocessing process

Sano, Yuichi; Ambai, Hiromu; Takahatake, Yoko

Aichi Shinkurotoron Hikari Senta 2017-Nendo Kokyoto Riyo Seika Hokokusho (Internet), 1 Pages, 2018/00

In order to elucidate the mechanism of corrosion in the reprocessing process and propose a method for suppressing corrosion, the effect of coexisting substances on the chemical form of Ru in nitric acid solution containing seawater components was evaluated. The result of XAFS measurement for Ru showed the structural change around a Ru atom due to the interaction with chloride ion, which will suppress the corrosion promoting action of Ru in nitric acid solution.

Journal Articles

Effect of chloride ion on corrosion behavior of SUS316L-grade stainless steel in nitric acid solutions containing seawater components under $$gamma$$-ray irradiation

Sano, Yuichi; Ambai, Hiromu; Takeuchi, Masayuki; Iijima, Shizuka; Uchida, Naoki

Journal of Nuclear Materials, 493, p.200 - 206, 2017/09

 Times Cited Count:9 Percentile:61.86(Materials Science, Multidisciplinary)

Concerning the Fukushima Daiichi Nuclear Power Plant accident, we investigated the effect of chloride ion on the corrosion behavior of SUS316L stainless steel, which is a typical material for the equipment used in reprocessing, in HNO$$_{3}$$ solution containing seawater components, including under the $$gamma$$-ray irradiation condition. Electrochemical and immersion tests were carried out using a mixture of HNO$$_{3}$$ and artificial seawater (ASW). In the HNO$$_{3}$$ solution containing high amounts of ASW, the cathodic current densities increased and uniform corrosion progressed. This might be caused by strong oxidants, such as Cl$$_{2}$$ and NOCl, generated in the reaction between HNO$$_{3}$$ and Cl$$^{-}$$ ions. The corrosion rate decreased with the immersion time at low concentrations of HNO$$_{3}$$, while it increased at high concentrations. Under the $$gamma$$-ray irradiation condition, the corrosion rate decreased due to the suppression of the cathodic reactions by the reaction between the above oxidants and HNO$$_{2}$$ generated by radiolysis.

Journal Articles

Effect of sulfate ion on corrosion behavior of SUS316L in high active liquid waste

Ambai, Hiromu; Sano, Yuichi; Nishizuka, Yusuke*; Iijima, Shizuka; Uchida, Naoki

Zairyo To Kankyo, 66(5), p.169 - 172, 2017/05

We study the effect of sulfate ion which is one component of seawater or concrete on the corrosion behavior in high active liquid waste tank environment. The corrosion tests were conducted using SUS316L and surrogate high active liquid waste containing some metal ions and nitric acid. The results showed that sulfate ion inhibited the corrosion rates. The XPS results indicated the attachment of sulfate ion to material surfaces suppressed the anode reaction.

Journal Articles

Effect of seawater on corrosion of SUS316L in HAW under $$gamma$$-ray irradiation

Ambai, Hiromu; Nishizuka, Yusuke*; Sano, Yuichi; Uchida, Naoki; Iijima, Shizuka

QST-M-2; QST Takasaki Annual Report 2015, P. 90, 2017/03

The spent fuel stored in the storage pools at the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company Holdings, Inc. is exposed with the environment containing seawater components, owing to the injection of seawater into the storage pools. Therefore, during reprocessing, it is expected that the spent fuel will be contaminated with seawater components, and the influence of seawater on reprocessing needs to be investigated. We conducted the corrosion tests of the HAW storage tanks under $$gamma$$-ray irradiation, and revealed that no significant effect of seawater components was emerged.

Journal Articles

Corrosion behavior of SUS316L in nitric acid solution containing seawater components

Sano, Yuichi; Ambai, Hiromu; Takeuchi, Masayuki; Iijima, Shizuka; Uchida, Naoki

Proceedings of European Corrosion Congress 2016 (EUROCORR 2016) (USB Flash Drive), 10 Pages, 2016/09

During the Fukushima Daiichi Nuclear Power Plant accident, significant volume of seawater was injected into the storage pool for spent nuclear fuel as the coolant. In this study, we investigated the effect of seawater components on the corrosion behavior of SUS316L stainless steel in HNO$$_{3}$$ solution. Electrochemical and immersion tests were carried out using a mixture of HNO$$_{3}$$ and artificial seawater (ASW). In the HNO$$_{3}$$ solution containing high amounts of ASW, the cathodic current densities increased and uniform corrosion progressed. This might be caused by strong oxidants, such as Cl$$_{2}$$ and NOCl, generated in the reaction between HNO$$_{3}$$ and Cl$$^{-}$$ ions. In addition, pitting corrosion occurred simultaneously at low HNO$$_{3}$$ concentrations. The corrosion rate decreased with the immersion time at low concentrations of HNO$$_{3}$$, while it increased at high concentrations. It is assumed that the cathodic reactions proceed slowly and the anodic reactions are gradually prevented by the growth of an oxide film on the surface of the coupon in low-concentration HNO$$_{3}$$. On the other hand, high-concentration HNO$$_{3}$$ triggers a vigorous cathodic reaction, which disturbs the growth of the oxide film and activates the anodic reactions. This competition between the cathodic and anodic reactions causes a change in the corrosion rates with the immersion time in a mixture of HNO$$_{3}$$ and ASW.

JAEA Reports

Countercurrent extraction/stripping experiments using TDdDGA solvent extractant in a centrifugal contactors system

Kibe, Satoshi; Fujisaku, Kazuhiko*; Ambai, Hiromu; Sakamoto, Atsushi; Sano, Yuichi; Takeuchi, Masayuki; Suzuki, Hideya; Tsubata, Yasuhiro; Matsumura, Tatsuro

JAEA-Research 2015-021, 40 Pages, 2016/02

JAEA-Research-2015-021.pdf:2.3MB

The flowsheet with TDdDGA extractant has been being developed for recovering MA from PUREX raffinate. In the previous study, the yields of MA and other elements in countercurrent extraction/stripping experiments using mixer-settlers were not enough for the target and it would be due to the insufficient phase (aqueous/organic) separation. In this study, we carried out countercurrent experiments with surrogate PUREX raffinate using centrifugal contactors which had superior phase separation ability, and evaluated the extraction/stripping behavior of each element. During the operation, abnormal fluid behavior, such as overflow and entrainment, was not observed, and sufficient phase separation was achieved by centrifugal contactors. Extraction behavior of lanthanides was similar to that in mixer-settlers, but their stripping efficiencies decreased. This would be due to shorter residence time in mixing zone.

Patent

粒子製造方法及び粒子製造装置

佐野 雄一; 渡部 創; 宮崎 康典; 安倍 弘; 長谷川 健太

後藤 一郎*

JP, 2022-032647  Patent licensing information

【課題】粒子径が従来よりも大きく、粒子径の均一性が比較的高い粒子を製造することができる粒子製造方法を提供する。 【解決手段】本発明に係る粒子製造方法は、組成物を、振動するノズルから、撹拌機により撹拌された溶媒中に滴下し、組成物が含まれる粒子を造粒する造粒工程(ステップS1)と、前記造粒工程(ステップS1)で得られた溶媒を含む粒子から、溶媒を除去し、粒子を得る溶媒除去工程(ステップS2)と、を含むことを特徴とする。

Oral presentation

Corrosion resistance of tank material used for flock storage

Ambai, Hiromu; Sano, Yuichi; Takeuchi, Masayuki; Sakauchi, Nobuyuki; Hoshi, Masayuki; Ogino, Hideki; Aose, Shinichi

no journal, , 

As a part of studies on corrosion resistance of storage tanks for flock generated in the coagulation process for radioactive contaminated water from the Fukushima Daiichi Nuclear Power Plant, several corrosion tests considering the radiation and the contact with flock were carried out with SS400 in the settling condition. Average corrosion rates of SS400 were around 0.1mm/y and severe corrosion including local corrosion was not observed.

Oral presentation

Corrosion resistance of tank material for flock storage, 2; Corrosion behavior in fluid flow condition by air agitation

Ambai, Hiromu; Sano, Yuichi; Takeuchi, Masayuki; Sakauchi, Nobuyuki; Hoshi, Masayuki; Ogino, Hideki; Koizumi, Kenji

no journal, , 

We studied the corrosion behavior of the tank material SS400 for flock storage in fluid flow condition by air agitation. Fluid flow increased the corrosion rate and this effect was reduced by the presence of the flock. Decreasing of flow rate and change of air to inactive gas are effective in corrosion prevention measures.

Oral presentation

Corrosion behavior of SUS316L in nitric acid solution containing seawater components; Effect of metal ions in high active liquid waste

Ambai, Hiromu; Nishizuka, Yusuke*; Sano, Yuichi; Uchida, Naoki; Iijima, Shizuka

no journal, , 

During the Fukushima Daiichi Nuclear Power Plant accident, a large volume of seawater was injected as coolant into the storage pool for spent nuclear fuel. If this fuel is reprocessed, some components of seawater will be mixed with the nitric acid used during spent fuel reprocessing. In this study, we investigated the effect of seawater components in high activity liquid waste (HAW) on the corrosion behavior of SUS316L stainless steel. The immersion and electrochemical tests were conducted using a solution containing artificial seawater (ASW) and surrogate HAW. In the nitric acid solution containing only ASW (without any metal ions in the HAW), pitting and / or uniform corrosion were observed. Intergranular corrosion was observed in the solution containing ASW and HAW with added metal ions, wherein Ru increased the corrosion potential to the transpassive region. An increase in amount of ASW led to decreased corrosion rates and the suppression of intergranular corrosion.

Oral presentation

Evaluation of elution reaction on fuel debri having two-phase by scanning electrochemical microscopy

Ambai, Hiromu

no journal, , 

The fuel debris which generated in the severe accident of Fukushima Daiichi Nuclear Power Plant (1F) of the Tokyo Electric Power Company Holdings, Inc. are under the water. Thus, it is important to understand the elution behavior of nuclear species in water. It has been reported that fuel debris consist of a number of phase by studies for TMI-2 and 1F accident. We can get only averaged information about all phases using normal methods. It is expected to have a better understanding about the elution mechanism of debris. In this study, we tried the evaluation of the elution reaction on fuel debris by getting the electrochemical properties of each phase, using scanning electrochemical microscopy which can measure local electrochemical property.

Oral presentation

Granulation of silica support for minor actinide recovery by spray drying method

Ambai, Hiromu; Goto, Ichiro*; Miyazaki, Yasunori; Sano, Yuichi; Takeuchi, Masayuki; Watanabe, Masayuki; Nemoto, Gentaro*

no journal, , 

no abstracts in English

Oral presentation

Hybrid process combining solvent extraction and low pressure loss extraction chromatography for a reasonable MA recovery, 8; Evaluation of adsorption and elution rates using adsorbent for MA/Ln separation by microspectroscopy

Kuzure, Yoshiaki*; Miyagawa, Akihisa*; Nagatomo, Shigenori*; Nakatani, Kiyoharu*; Yoshida, Masaaki*; Nemoto, Shuhei*; Arai, Tsuyoshi*; Ambai, Hiromu; Hasegawa, Kenta; Sano, Yuichi

no journal, , 

Concentration dependencies of nitric acid, nitrate ion, and so on for the adsorption and elution rates (mass transfer coefficients) of FP (Ln) in silica adsorbent, carrying various NTAamide extractants, were measured in the single silica particle/solution system by fluorescence microspectroscopy. The adsorption and elution rates were improved by changing polymercoating conditions for the silica adsorbent granulated by the freeze-drying method. We will discuss the mass transfer coefficients influenced by the nitric acid and nitrate ionconcentrations.

Oral presentation

Oral presentation

Basic research programs of vitrification technology for waste volume reduction, 99; Radiation impact assessment on mechanical property of rubber materials for improving devices durability of MA separation system by extraction chromatography

Hasegawa, Kenta; Ambai, Hiromu; Watanabe, So; Okamura, Nobuo; Watanabe, Masayuki; Sano, Yuichi; Takeuchi, Masayuki

no journal, , 

Separation of minor actinides (MA; Am, Cm) is one of the important issues to reduce the volume of radioactive waste. Previous researches have promoted development of separation flows, safety assessment and engineering scale equipment, while long-term equipment durability for radiation and nitric acid is required for putting MA separation system into practical use. We focused on diaphragm composed of rubber materials on feed pump in contact with high-level radioactive liquid waste (HLLW). In this study, we report radiation impact assessment on mechanical property of diaphragm candidate materials which were degraded by gamma-ray irradiation in acidic or stress loading condition.

Oral presentation

Analysis of lanthanide partitioning process on extractant-impregnated silica gel in a model radioactive liquid waste system containing several elements

Hayashi, Naoki*; Miyagawa, Akihisa*; Nagatomo, Shigenori*; Nakatani, Kiyoharu*; Sato, Kiyomori*; Arai, Tsuyoshi*; Ambai, Hiromu; Hasegawa, Kenta; Watanabe, So; Sano, Yuichi

no journal, , 

The fluorescence of lanthanide ions within a single extractant-impregnated silica particle was obtained using a microspectrometer to evaluate their distribution behavior within the particle.

31 (Records 1-20 displayed on this page)