Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 395

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Zeolite-assisted radiolysis of aromatic chlorides mitigating influence of coexisting ions in water matrix

Kumagai, Yuta; Kimura, Atsushi*; Taguchi, Mitsumasa*; Watanabe, Masayuki

Radiation Physics and Chemistry, 191, p.109831_1 - 109831_8, 2022/02

 Times Cited Count:0 Percentile:0.01(Chemistry, Physical)

In this study, we investigated and compared the effects of a high-silica zeolite (HMOR) on the radiation-induced degradation of three aromatic chlorides, 2-chlorophenol (2-ClPh), 2-chloroaniline (2-ClAn), and 2-chlorobenzoic acid (2-ClBA), in order to examine its potential to reduce the influence of ions in water matrix in the irradiation treatment of water-soluble organic compounds. In the presence of ions reactive to radicals, the degradation of 2-ClPh in water was inhibited, but the combined use of HMOR much improved the degradation yield. This improvement was attributed to high performance of HMOR in adsorption of 2-ClPh. Similarly, HMOR was effective for adsorption of 2-ClAn and facilitated the 2-ClAn degradation by irradiation. In contrast, HMOR was poor at adsorption of 2-ClBA and consistently the degradation of 2-ClBA in the water-HMOR mixture was inhibited by the radical scavenger. These results demonstrate that HMOR can mitigate the influence of radical scavengers in water.

Journal Articles

Measurement and evaluation of hydrogen production from mixtures of seawater and zeolite in decontamination of radioactive water

Kumagai, Yuta; Nagaishi, Ryuji; Kimura, Atsushi*; Taguchi, Mitsumasa*; Nishihara, Kenji; Yamagishi, Isao; Ogawa, Toru

Insights Concerning the Fukushima Daiichi Nuclear Accident, Vol.4; Endeavors by Scientists, p.37 - 45, 2021/10

Zeolite adsorbents are to be used for decontamination of radioactive water in Fukushima Dai-ichi Nuclear Power Station. Evaluation of hydrogen production by water radiolysis during decontamination is important for safe operation. Thus hydrogen production from the mixture of zeolite adsorbents and seawater was studied because seawater was urgently used as a coolant for the fuels. The hydrogen yield from the mixture decreased at a high weight fraction of zeolites. However, the measured yield was higher than the yield expected from the direct radiolysis of seawater in the mixture, which would decrease proportional to the weight fraction of seawater. The result suggests that the radiation energy deposited to zeolites was involved in the hydrogen formation. From the results, the hydrogen production rate was evaluated to be 3.6 mL/h per ton of radioactive water before decontamination. After the process, it was evaluated to be 1.5 L/h per ton of waste adsorbents due to the high dose rate.

JAEA Reports

Database for corrosion under irradiation conditions (Contract research)

Sato, Tomonori; Hata, Kuniki; Kaji, Yoshiyuki; Ueno, Fumiyoshi; Inoue, Hiroyuki*; Taguchi, Mitsumasa*; Seito, Hajime*; Tada, Eiji*; Abe, Hiroshi*; Akiyama, Eiji*; et al.

JAEA-Review 2021-001, 123 Pages, 2021/06

JAEA-Review-2021-001.pdf:10.33MB

In the implement of the decommissioning of Fukushima Daiichi Nuclear Power Station (1F), there are many problems to be solved. Specially, the mitigation of the aging degradation by the corrosion of the structural materials is important to implement the decommissioning safely and continuously. However, there are limited data for the environmental factors of corrosion in 1F, and the condition of 1F is continuously changing. So, the literature data for the water radiolysis and the corrosion under irradiation are listed as the database of corrosion under irradiation in this report. And the new obtained radiolysis and corrosion data, which have not been reported in the literature and will be required in the decommissioning of 1F, are reported.

Journal Articles

Corrosion monitoring in humidity-controlled environment simulating gamma ray irradiation

Omori, Atsushi*; Akiyama, Eiji*; Abe, Hiroshi*; Hata, Kuniki; Sato, Tomonori; Kaji, Yoshiyuki; Inoue, Hiroyuki*; Taguchi, Mitsumasa*; Seito, Hajime*; Tada, Eiji*; et al.

Zairyo To Kankyo, 69(4), p.107 - 111, 2020/04

To evaluate the effect of oxidants, which are formed by radiolysis of water under gamma ray irradiation, on the corrosion of a carbon steel in humid environment, ozone was introduced as a model oxidant in to humidity-controlled air at 50$$^{circ}$$C in a thermo-hygrostat chamber. Corrosion monitoring was performed by using an Atmospheric Corrosion Monitor-type (ACM) sensor consisting of a carbon steel anode and an Ag cathode. The output current of the ACM sensor was increased with the increase in relative humidity and it was obviously increased with the increase in the introduced ozone concentration at each relative humidity. The results indicate that ozone accelerates the corrosion of the carbon steel. The effect of ozone on the corrosion acceleration is attributed to the fast reduction reaction and fast dissolution reaction in to water compared to that of oxygen.

Journal Articles

On-line rapid purification of [$$^{13}$$N]N$$_2$$ gas for visualization of nitrogen fixation and translocation in nodulated soybean

Yin, Y.-G.*; Ishii, Satomi*; Suzui, Nobuo*; Igura, Masato*; Kurita, Keisuke; Miyoshi, Yuta*; Nagasawa, Naotsugu*; Taguchi, Mitsumasa*; Kawachi, Naoki*

Applied Radiation and Isotopes, 151, p.7 - 12, 2019/09

 Times Cited Count:6 Percentile:66.72(Chemistry, Inorganic & Nuclear)

Accurate analysis of N fixation in leguminous crops requires determination of N utilization within an intact plant$$;$$ however, most approaches require tissue disassembly. We developed a simple and rapid technique to generate high-purity and high-yield [$$^{13}$$N]N$$_2$$ gas and obtained real-time images of N fixation in an intact soybean plant. The purification efficiency was $$sim$$ 81.6% after decay correction.

Journal Articles

Radiation-induced degradation of aqueous 2-chlorophenol assisted by zeolites

Kumagai, Yuta; Kimura, Atsushi*; Taguchi, Mitsumasa*; Watanabe, Masayuki

Journal of Radioanalytical and Nuclear Chemistry, 316(1), p.341 - 348, 2018/04

 Times Cited Count:2 Percentile:25.4(Chemistry, Analytical)

We studied effect of adsorption and condensation by zeolites on radiation-induced degradation of aqueous 2-chlorophenol (2-ClPh). This study aims to demonstrate that the solid-phase extraction using zeolites has potential advantage in treatments of aqueous organic pollutants. Among three zeolites examined in this study, a mordenite type zeolite (HMOR) that has a high Si to Al ratio (127 $$pm$$ 3) exhibited preferable performance as the matrix for the 2-ClPh degradation. HMOR adsorbed far more 2-ClPh than the other zeolites, which have lower Si/Al ratios. The irradiation of HMOR induced degradation of adsorbed 2-ClPh into Cl$$^{-}$$ and organic by-products. We found a significant increase in Cl$$^{-}$$ production by HMOR. The yield of Cl$$^{-}$$ production in the presence of HMOR was as high as the yield in aqueous solution of 2-ClPh at a concentration 10 times higher. The increased Cl$$^{-}$$ production indicates that the high concentration of adsorbed 2-ClPh led to effective use of the adsorbed energy of HMOR.

Journal Articles

Treatment of pharmaceuticals/antibiotics in wastewater by combination of zeolite adsorbent with ionizing radiation

Taguchi, Mitsumasa*; Kumagai, Yuta; Kimura, Atsushi*

IAEA-TECDOC-1855, p.106 - 116, 2018/00

The technology for the decomposition of trace amounts of halogenated pharmaceuticals/antibiotics was developed in wastewater by use of the combination method of zeolite adsorbent and ionizing radiation. HMOR, a hydrophobic high-silica mordenite-type zeolite, was employed to concentrate 2-chlorophenol (2-ClPh) as a simple model of halogenated pharmaceuticals/antibiotics. HMOR adsorbed above 99% of 2-ClPh from dilute aqueous solutions. The yield of Cl$$^{-}$$ production in HMOR mixture corresponded to the aqueous solution containing 10 fold higher concentration of dissolved 2-ClPh. Clofibrate and triclosan, one of chlorinated pharmaceuticals/antibiotics, in real wastewater were treated by use of the combination method of HMOR and ionizing radiation. Production yield of Cl$$^{-}$$ by use of the adsorbent was about twice higher than that in aqueous solution, and HMOR was contributed for effective reduction of chlorinated pharmaceuticals/antibiotics in real wastewater.

Journal Articles

Hydrogen production by $$gamma$$-ray irradiation from different types of zeolites in aqueous solution

Kumagai, Yuta; Kimura, Atsushi*; Taguchi, Mitsumasa*; Watanabe, Masayuki

Journal of Physical Chemistry C, 121(34), p.18525 - 18533, 2017/08

 Times Cited Count:3 Percentile:13.61(Chemistry, Physical)

H$$_{2}$$ production by irradiation of zeolite-water mixtures was studied, to investigate effect of zeolites in the reaction process for H$$_{2}$$. Four different types of zeolites were examined comparatively under anoxic and under aerated conditions. High production yields of H$$_{2}$$ were observed for the zeolites of high Al contents at low water fraction and under anoxic condition, compared to zeolites having lower Al contents. A comparison of the H$$_{2}$$ yields in connection with chemical analysis of the zeolites suggests that extraframework Al species in the zeolites are involved in a reaction pathway for H$$_{2}$$. Meanwhile, under aerated condition and at high mixing ratio of water, the difference in H$$_{2}$$ yield among the zeolites was suppressed and the yields of H$$_{2}$$ were lower than those under anoxic condition probably due to H$$_{2}$$O$$_{2}$$ produced by water radiolysis. The comparable H$$_{2}$$ yields suggest another reaction pathway for H$$_{2}$$ which is less dependent on the structure and composition of the zeolites.

Journal Articles

Radiolysis of boiling water

Yang, S.*; Katsumura, Yosuke*; Yamashita, Shinichi*; Matsuura, Chihiro*; Hiroishi, Daisuke*; Lertnaisat, P.*; Taguchi, Mitsumasa

Radiation Physics and Chemistry, 123, p.14 - 19, 2016/06

 Times Cited Count:2 Percentile:22.12(Chemistry, Physical)

$$gamma$$-radiolysis of boiling water has been investigated. The G-value of H$$_{2}$$ evolution was found to be very sensitive to the purity of water. In high-purity water, both H$$_{2}$$ and O$$_{2}$$ gases were formed in the stoichiometric ratio of 2:1; a negligible amount of H$$_{2}$$O$$_{2}$$ remained in the liquid phase. The G-values of H$$_{2}$$ and O$$_{2}$$ gas evolution depend on the dose rate: lower dose rates produce larger yields. To clarify the importance of the interface between liquid and gas phase for gas evolution, the gas evolution under Ar gas bubbling was measured. A large amount of H$$_{2}$$ was detected, similar to the radiolysis of boiling water. The evolution of gas was enhanced in a 0.5 M NaCl aqueous solution. Deterministic chemical kinetics simulations elucidated the mechanism of radiolysis in boiling water.

Journal Articles

Quick measurement of continuous absorption spectrum in ion beam pulse radiolysis; Application of optical multi-channel detector into transient species observation

Iwamatsu, Kazuhiro*; Muroya, Yusa*; Yamashita, Shinichi*; Kimura, Atsushi; Taguchi, Mitsumasa; Katsumura, Yosuke*

Radiation Physics and Chemistry, 119, p.213 - 217, 2016/02

 Times Cited Count:1 Percentile:12.11(Chemistry, Physical)

A quick measurement system of a continuous absorption spectrum covering a wide range from 200 to 950 nm was constructed by employing an optical multi-channel detector. Ion beam pulse radiolysis with 12.5 MeV/u He, 18.3 MeV/u C and 17.5 MeV/u Ne ions were performed with the measurement system. Transient absorption spectrum of (SCN)$$_{2}$$$$^{-}$$ was clearly observed in KSCN aqueous solutions within a few minutes in spite of their very small absorbance, demonstrating high sensitivity of 0.001-0.003 in absorbance in the range from 260 to 660 nm as well as short measurement time of a few minutes. Two different absorption peaks attributed to Br$$_{2}$$$$^{-}$$ and Br$$_{3}$$$$^{-}$$ were observed simultaneously in NaBr aqueous solutions, showing powerfulness of the measurement system in overviewing chemical kinetics under ion beam irradiation especially in not well investigated chemical systems.

Journal Articles

Influence of linear energy transfer on the scintillation decay behavior in a lithium glass scintillator

Koshimizu, Masanori*; Iwamatsu, Kazuhiro*; Taguchi, Mitsumasa; Kurashima, Satoshi; Kimura, Atsushi; Yanagida, Takayuki*; Fujimoto, Yutaka*; Watanabe, Kenichi*; Asai, Keisuke*

Journal of Luminescence, 169(Part B), p.678 - 681, 2016/01

We analyzed the effects of linear energy transfer (LET) on the scintillation properties of a Li glass scintillator, GS20. The scintillation time profiles were measured by using pulsed ion beams having different LETs. The rise in the scintillation time profiles was faster for higher LET, whereas the decay part was not significantly different for largely different LETs. The LET effects in the rise was ascribed to the effects of excited states interaction during the energy transfer process from the host glass to the luminescent centers, Ce$$^{3+}$$ ions. Supposing that the light yield decreases with LET, the fast rise at high LET was explained in terms of the competition between the energy transfer and the quenching due to the excited states interaction.

Journal Articles

Effect of heavy ion irradiation on optical property of radiation-crosslinked hydroxypropyl cellulose gel containing methacrylate monomers

Hiroki, Akihiro; Yamashita, Shinichi*; Kimura, Atsushi; Nagasawa, Naotsugu; Taguchi, Mitsumasa

Nuclear Instruments and Methods in Physics Research B, 365(Part B), p.583 - 586, 2015/12

Effects of liner energy transfer (LET) and dose rate on the optical property of polymer gel dosimeters were investigated. The dosimeter prepared by using a radiation-crosslinked hydroxypropyl cellulose gel and methacrylate monomers such as 2-hydroxyethyl methacrylate and nonaethylene glycol dimethacrylate showed the color change from colorless to white with the He, C, Fe ions irradiation. Absorbance of the irradiated dosimeters increased with the dose up to 10 Gy. The absorbance of the dosimeters at the same total dose decreased with increasing dose rate in the range of 0.1 to 6.8 Gy/min. The absorbance decreased in order of He, C, Fe ions, which was in agreement with a change of LET. The increase in LET affected the decrease in the number of polymerization initiator such as OH radical and hydrated electron, resulting in the reduction of the absorbance of the dosimeters.

Journal Articles

Linear energy transfer effects on time profiles of scintillation of Ce-doped LiCaAlF$$_{6}$$ crystals

Yanagida, Takayuki*; Koshimizu, Masanori*; Kurashima, Satoshi; Iwamatsu, Kazuhiro*; Kimura, Atsushi; Taguchi, Mitsumasa; Fujimoto, Yutaka*; Asai, Keisuke*

Nuclear Instruments and Methods in Physics Research B, 365(Part B), p.529 - 532, 2015/12

 Times Cited Count:10 Percentile:68.27(Instruments & Instrumentation)

We measured temporal profiles of scintillation of Ce-doped LiCaAlF$$_{6}$$ scintillator crystals at different linear energy transfers (LETs). Based on the comparison of the high-LET temporal profiles with those at low LET, we found that a fast component was observed only at low LET. The disappearance of the fast component at high LET is tentatively ascribed to quenching of excited states at defects owing to the interaction between excited states via Auger process. In addition, the rise and the initial decay behavior was dependent on the LET. This LET-dependent behavior is explained by a seeming acceleration process and a slowing down process in energy transfer at high LET. The LET-dependent temporal profiles provide a basis of discrimination technique of $$gamma$$-ray and neutron detection events using these scintillators based on the nuclear reaction, $$^{6}$$Li(n,$$alpha$$)t.

Journal Articles

Educational material kit to learn radiation effect on plastic

Nagasawa, Naotsugu; Taguchi, Mitsumasa

Isotope News, (736), p.47 - 50, 2015/08

no abstracts in English

Journal Articles

Enhancement of beam pulse controllability for a single-pulse formation system of a cyclotron

Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Okumura, Susumu; Taguchi, Mitsumasa; Fukuda, Mitsuhiro*

Review of Scientific Instruments, 86(7), p.073311_1 - 073311_8, 2015/07

 Times Cited Count:11 Percentile:49.25(Instruments & Instrumentation)

The single-pulse formation technique using a beam chopping system consisting of two types of high-voltage beam kickers was modified to improve the quality and intensity of the single-pulse beam with pulse intervals over 1 $$mu$$s at TIARA cyclotron facility of Japan Atomic Energy Agency. Reduction of the multi-turn extraction number for suppressing the neighboring beam bunch contamination was achieved by restriction of a beam phase width and precise optimization of a particle acceleration phase. In addition, the single-pulse beam intensity was increased by a factor of two or more by a combination of two types of beam bunchers using sinusoidal and saw-tooth voltage waveforms. As a result, a contamination rate of neighboring beam bunches in the single-pulse beam was reduced to less than 0.1 %. Long-term purification of the single pulse beam was guaranteed by the well-controlled magnetic field stabilization system for the TIARA cyclotron magnet. Provision of the high quality intense single-pulse beam contributes to improve the accuracy of experiments for investigation of scintillation light time-profile and for neutron energy measurement by a time-of-flight method.

Journal Articles

$$alpha$$-radiation effect on solvent extraction of minor actinide

Sugo, Yumi; Sasaki, Yuji; Taguchi, Mitsumasa; Ishioka, Noriko

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1381 - 1384, 2015/02

 Times Cited Count:2 Percentile:19.47(Chemistry, Analytical)

Journal Articles

Sequential radiation chemical reactions in aqueous bromide solutions; Pulse radiolysis experiment and spur model simulation

Yamashita, Shinichi*; Iwamatsu, Kazuhiro; Maehashi, Yuki*; Taguchi, Mitsumasa; Hata, Kuniki; Muroya, Yusa*; Katsumura, Yosuke*

RSC Advances (Internet), 5(33), p.25877 - 25886, 2015/02

 Times Cited Count:11 Percentile:38.33(Chemistry, Multidisciplinary)

Pulse radiolysis experiments were carried out to observe transient absorptions of reaction intermediates produced in N$$_{2}$$O$$^{-}$$ and Ar-saturated aqueous solutions containing 0.9-900 mM NaBr. The most important species among the reaction intermediates are BrOH $$^{cdot -}$$ and Br$$_{2}$$ $$^{cdot -}$$, which commonly have absorption peaks around 360 nm. The experimental results were compared with the results of simulation based on a spur diffusion model. Each of several complicated sequential radiation-induced chemical reactions was carefully considered, optimizing its rate constant within a range of reported values. All the experimental results were able to be universally reproduced by the simulation, assuming a reaction not yet reported, 2BrOH$$^{cdot -}$$ $$rightarrow$$ Br$$_{2}$$ + 2OH$$^{-}$$, with a rate constant of 3.8 $$times$$ 10$$^{9}$$ M$$^{-1}$$ s$$^{-1}$$, which is significant only within 10 micro-s for rather high bromide concentrations ($$>$$ 10 mM). Primary $$G$$ values, which are yields after sufficient diffusion from the spur to the perimeter region during 100 ns, of major water decomposition products, as well as of the reaction intermediates, were calculated for N$$_{2}$$O$$^{-}$$ and Ar-saturated conditions as a function of NaBr concentration.

Journal Articles

Enhancement in dose sensitivity of polymer gel dosimeters composed of radiation-crosslinked gel matrix and less toxic monomers

Hiroki, Akihiro; Yamashita, Shinichi*; Taguchi, Mitsumasa

Journal of Physics; Conference Series, 573(1), p.012028_1 - 012028_4, 2015/01

BB2014-0610.pdf:0.75MB

 Times Cited Count:4 Percentile:80.59

Polymer gel dosimeters based on radiation-crosslinked hydroxypropyl cellulose gel were prepared, which comprised 2-hydroxyethyl methacrylate (HEMA) and polyethylene glycol dimethacrylate (9G) as less toxic monomers and tetrakis (hydroxymethyl) phosphoniumu chloride (THPC) as an antioxidant. The dosimeters exposed to $$^{60}$$Co $$gamma$$-rays became cloudy at only 1 Gy. The irradiated dosimeters were optically analyzed by using a UV-vis spectrophotometer to evaluate dose response. Absorbance of the dosimeters linearly increased in the dose range from 0 to 10 Gy. The dose sensitivity increased with increasing 9G concentration. The dosimeter with 2 wt% HEMA, 3 wt% 9G, and 0.16 wt% THPC exhibited about 0.04 Abs Gy$$^{-1}$$ of the dose sensitivity. The dose sensitivity of the dosimeters was also enhanced by increment in THPC, reached about 0.06 Abs Gy$$^{-1}$$ at 0.40 wt% THPC.

Journal Articles

System for measuring temporal profiles of scintillation at high and different linear energy transfers by using pulsed ion beams

Koshimizu, Masanori*; Kurashima, Satoshi; Taguchi, Mitsumasa; Iwamatsu, Kazuhiro; Kimura, Atsushi; Asai, Keisuke*

Review of Scientific Instruments, 86(1), p.013101_1 - 013101_5, 2015/01

 Times Cited Count:10 Percentile:45.99(Instruments & Instrumentation)

We have developed a system for measuring the temporal profiles of scintillation at high linear energy transfer (LET) by using pulsed ion beams from a cyclotron. The half width at half maximum time resolution was estimated to be 1.5-2.2 ns, which we attributed mainly to the duration of the pulsed ion beam and timing jitter between the trigger signal and the arrival of the ion pulse. The temporal profiles of scintillation of BaF$$_{2}$$ at different LETs were successfully observed. These results indicate that the proposed system is a powerful tool for analyzing the LET effects in temporal profiles of scintillation.

Journal Articles

Effect of oxygen on radiolytic hydrogen production from X-type zeolite-water mixtures

Kumagai, Yuta; Kimura, Atsushi; Taguchi, Mitsumasa

Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10

395 (Records 1-20 displayed on this page)