Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 50

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

Redistribution and export of contaminated sediment within eastern Fukushima Prefecture due to typhoon flooding

Kitamura, Akihiro; Kurikami, Hiroshi; Sakuma, Kazuyuki; Malins, A.; Okumura, Masahiko; Machida, Masahiko; Mori, Koji*; Tada, Kazuhiro*; Tawara, Yasuhiro*; Kobayashi, Takamaru*; et al.

Earth Surface Processes and Landforms, 41(12), p.1708 - 1726, 2016/09

 Times Cited Count:14 Percentile:62.25(Geography, Physical)

Sediment erosion and transport processes that are considered to be important in predicting the future radioactive material distribution through sediment-sorbed form in Fukushima Prefecture are simulated. Since large portion of the sediment is considered to be supplied into the rivers, it is important to trace their migration process in terms of each river basin. We choose five river basins, namely the Odaka, the Ukedo, the Maeda, the Kuma, and the Tomioka, from north to south, because of their importance in contamination aspects and prediction studies. The results are summarized as comprehensive dataset of sediment migration for particular river basins in typical typhoon events that account for the most of annual soil erosion. Detail calculations implemented for the amount of sediment supplied in to the river, deposited on river and dam beds, and exported to the ocean.

Journal Articles

Decomposition of halophenols in room-temperature ionic liquids by ionizing radiation

Kimura, Atsushi; Taguchi, Mitsumasa; Kondo, Takafumi*; Yang, J.*; Nagaishi, Ryuji; Yoshida, Yoichi*; Hirota, Koichi

Radiation Physics and Chemistry, 79(11), p.1159 - 1164, 2010/11

 Times Cited Count:3 Percentile:26.36(Chemistry, Physical)

Much of this past research has focused on finding more effective reactions between charged reactive species in room temperature ionic liquid (RTILs), which have a coulombic field. Reactions in RTILs involving the charged reactive species, particularly solvated electrons, have been studied by the techniques of radiation chemistry. The reaction behavior of halophenols in RTILs were investigated by $$gamma$$ ray and pulsed electron radiolysis. The yield of CP decomposition in the RTILs was almost the same as that of solvated electrons formation. The yield of CP decomposition and phenol formation in the RTILs was low in the presence of electron scavengers such as nitrous oxide, indicating that solvated electrons primarily contributed to the decomposition of CP. The type of halogen group with the exception of fluorine had a negligible effect on the decomposition of halophenols in the RTILs. Therefore, RTILs could be applied as an reaction media for the reduction by ionizing radiation.

Journal Articles

Pulse radiolysis study of ion-species effects on the solvated electron in alkylammonium ionic liquids

Kondo, Takafumi*; Asano, Akira*; Yang, J.*; Norizawa, Kimihiro*; Takahashi, Kenji*; Taguchi, Mitsumasa; Nagaishi, Ryuji; Kato, Ryuji*; Yoshida, Yoichi*

Radiation Physics and Chemistry, 78(12), p.1157 - 1160, 2009/12

 Times Cited Count:28 Percentile:88.32(Chemistry, Physical)

Spectrum and kinetic behavior of solvated electrons (e$$_{sol}$$$$^{-}$$) in alkyl ammonium ionic liquids (ILs), ${it i.e.}$ DEMMA-TFSI, DEMMA-BF4, TMPA-TFSI, PP13-TFSI, P13-TFSI and P14-TFSI were investigated by pulse radiolysis method. The e$$_{sol}$$$$^{-}$$ in the ILs have same absorption peak at 1100 nm with a molar absorption coefficient of 1.5-2.3$$times$$10$$^{4}$$ dm$$^{3}$$mol$$^{-1}$$cm$$^{-1}$$. The reaction rate constant of e$$_{sol}$$$$^{-}$$ with Pyrene (Py) was 1.5-3.5$$times$$10$$^{8}$$ dm$$^{3}$$mol$$^{-1}$$s$$^{-1}$$. These values were about one order of magnitude higher than that of diffusion controlled limit, which was calculated from measured viscosity. The dry electron (e$$_{dry}$$$$^{-}$$) reacts with Py, and its rate constant in DEMMA-TFSI was 7.9$$times$$10$$^{11}$$ dm$$^{3}$$mol$$^{-1}$$s$$^{-1}$$, three orders of magnitude higher than that of the e$$_{sol}$$$$^{-}$$ reactions.

Journal Articles

Study on the reaction of chlorophenols in room temperature ionic liquids with ionizing radiation

Kimura, Atsushi; Taguchi, Mitsumasa; Kondo, Takafumi*; Yang, J.*; Yoshida, Yoichi*; Hirota, Koichi

Radiation Physics and Chemistry, 77(10-12), p.1253 - 1257, 2008/10

 Times Cited Count:10 Percentile:59.39(Chemistry, Physical)

Journal Articles

Molar absorption coefficient and radiolytic yield of solvated electrons in diethylmethyl(2-methoxy)ammonium bis (trifluoromethanesulfonyl)imide ionic liquid

Asano, Akira*; Yang, J.*; Kondo, Takafumi*; Norizawa, Kimihiro*; Nagaishi, Ryuji; Takahashi, Kenji*; Yoshida, Yoichi*

Radiation Physics and Chemistry, 77(10-12), p.1244 - 1247, 2008/10

 Times Cited Count:24 Percentile:84.21(Chemistry, Physical)

The molar extinction coefficient and the radiolytic yield of solvated electrons in ionic liquid of DEMMA-TFSI were estimated respectively to be 2.3$$times$$10$$^{4}$$ L mol$$^{-1}$$ cm$$^{-1}$$ and 0.8$$times$$10$$^{-7}$$ mol J$$^{-1}$$ by observing the reaction and kinetics of solvated electron and dry electron in the ionic liquid. The solvated electron in DEMMA-TFSI has a very broad absorption spectrum peaking at 1100 nm and reacts slowly with pyrene with a rate constant of 3.5$$times$$10$$^{8}$$ L mol$$^{-1}$$ s$$^{-1}$$, while the dry electron is captured rapidly by pyrene with C$$_{37}$$ value of 0.065 mol L$$^{-1}$$.

Journal Articles

Picosecond pulse radiolysis; Dynamics of solvated electrons in ionic liquid and geminate ion recombination in liquid alkanes

Yang, J.*; Kondo, Takafumi*; Norizawa, Kimihiro*; Nagaishi, Ryuji; Taguchi, Mitsumasa; Takahashi, Kenji*; Kato, Ryuji*; Anishchik, S. V.*; Yoshida, Yoichi*; Tagawa, Seiichi*

Radiation Physics and Chemistry, 77(10-12), p.1233 - 1238, 2008/10

 Times Cited Count:23 Percentile:83.43(Chemistry, Physical)

First observation of picosecond dynamics in ionic liquid of DEMMA-TFSI in radiation chemistry was reported. It is found that the electron produced by ionization is solvated to full solvation in ionic liquid with a rate constant of 3.9$$times$$10$$^{10}$$ s$$^{-1}$$. The yield of solvated electrons in picosecond time region is 1.2$$times$$10$$^{-7}$$ mol J$$^{-1}$$. The dry electron in ionic liquid reacts rapidly with biphenyl and pyrene with a rate constant of 3.8 to 7.9$$times$$10$$^{11}$$ L mol$$^{-1}$$ s$$^{-1}$$. The geminate ion recombination in n-dodecane and n-hexane was also observed by monitoring the transient absorptions at 523 nm.

Journal Articles

Transient absorption of a cation radical of pyrene induced by heavy ion beam pulses

Kondo, Takafumi*; Yang, J.*; Kan, Koichi*; Yoshida, Yoichi*; Shibata, Hiromi*; Taguchi, Mitsumasa; Kojima, Takuji

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 160, 2008/03

no abstracts in English

Journal Articles

Development of the heavy ion beam pulse radiolysis

Kondo, Takafumi*; Yang, J.*; Kan, Koichi*; Yoshida, Yoichi*; Shibata, Hiromi*; Taguchi, Mitsumasa; Kojima, Takuji

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 141, 2007/02

no abstracts in English

Journal Articles

Core performance tests for the JOYO MK-III upgrade

Aoyama, Takafumi; Sekine, Takashi; Maeda, Shigetaka; Yoshida, Akihiro; Maeda, Yukimoto; Suzuki, Soju; Takeda, Toshikazu*

Nuclear Engineering and Design, 237(4), p.353 - 368, 2007/02

 Times Cited Count:13 Percentile:69.08(Nuclear Science & Technology)

Many changes were made in the recent upgrade of the experimental fast reactor JOYO to the MK-III design. The core changes which were made to achieve a fourfold increase in irradiation capacity include the introduction of a second enrichment zone, an increase in core radius and a decrease in core height. Performance tests done at low power, during the rise to power, and at full power, which focus on the neutronics characteristics, are presented. These tests include the nuclear instrumentation system response, the approach to criticality and excess reactivity evaluation, control rod worth calibration, isothermal temperature coefficient evaluation, the calibration of the nuclear instrumentation system with reactor thermal power, and the burn-up reactivity coefficient evaluation. The measurements and comparisons with calculated predictions are shown. The design predictions are consistent with the performance test results, and all technical safety specifications are satisfied. The JOYO MK-III core will provide enhanced irradiation testing capability, as well as serve as a test bed for improving fast reactor operation, performance and safety. Through the performance test evaluation, the core characteristics of a small size sodium cooled fast reactor with a hard neutron spectrum are clarified.

Journal Articles

Study of radiation-induced primary process by ion pulse radiolysis

Yoshida, Yoichi*; Yang, J.*; Kondo, Takafumi*; Seki, Shuhei*; Kozawa, Takahiro*; Tagawa, Seiichi*; Shibata, Hiromi*; Taguchi, Mitsumasa; Kojima, Takuji; Namba, Hideki

JAEA-Review 2005-001, TIARA Annual Report 2004, p.183 - 185, 2006/01

A heavy-ion-pulse radiolysis technology was developed using a single-photon-counting system. In the system, the ion beam was injected a thin scintillator before irradiating the sample. The light emitted from the scintillator by the ion irradiation was used as analyzing source to detect the absorption of primary species in water. Measurement of time-dependent absorption of hydrated electrons in water was achieved using the system, which demonstrates the usefulness of this technique.

JAEA Reports

Summary Report of the Experimental Fast Reactor JOYO MK-III Performance Test

Maeda, Yukimoto; Aoyama, Takafumi; Yoshida, Akihiro; Sekine, Takashi; Ariyoshi, Masahiko; Ito, Chikara; Masaaki, Nemoto; Murakami, Takanori; Isozaki, Kazunori; Hoshiba, Hideaki; et al.

JNC TN9410 2003-011, 197 Pages, 2004/03

JNC-TN9410-2003-011.pdf:10.26MB

MK-III performance tests began in June 2003 to fully characterize the upgraded core and heat transfer system. Then, the last pre-use inspection was finished in November 2003.This report summarize the result of each performance test.

Journal Articles

Joyo Upgrading Program(MK-III Program)

; Yoshida, Akihiro; Aoyama, Takafumi; Maeda, Yukimoto

Saikuru Kiko Giho, (21), p.5 - 25, 2003/00

A Joyo upgrade program named MK-III program was started to develop future FBR in 1987. The main objectives of this program are increasing the capability as an irradiation test bed core and developing innovative FBR technologies.In order to modify the irradiation capability, the core and plant modification program which consists of increasing the neutron flux density of the core, modification of the cooling system, modification of the plant availability factor and upgrading irradiation technologies were decided based on the result s of survey calculations. The licensing work completed in 1995, and all the modification work completed in 2003. JOYO will start rated power operation along with several irradiation tests in 2004. Also the installation and demonstration program of innovative technologies such as Self-actuated shut down system for demonstration FBR and double-walled steam generator for future FBR were investigated.

Journal Articles

The design works for the MK-III core from a viewpoint of improving the irradiation capability

; Yoshida, Akihiro; Aoyama, Takafumi; Maeda, Yukimoto

Saikuru Kiko Giho, (21), p.17 - 25, 2003/00

Design works on the MK-III upgrading core were carried out and detailed core specification was determined from a viewpoint of increasing a fast neutron flux and a capacity for irradiation rigs. Based on the results of nuclear, thermal hydraulic calculation and shielding calculation, it was confirmed that the MK-III core shows expected core performance along with the integrity of the whole core.

JAEA Reports

Evaluation for the nuclear characteristics of the low $$^{235}$$U enriched fueled MK-III core

Yoshida, Akihiro; Aoyama, Takafumi

PNC TN9410 98-084, 37 Pages, 1998/08

PNC-TN9410-98-084.pdf:0.9MB

The investigation is underway to reduce the $$^{235}$$U enrichment of Joyo MK-III core fuel. The difficulties of obtaining enriched Uranium and reducing fuel fabrication costs are the items being investigated. In addition, the utilization of weapon-grade Plutonium, of which $$^{239}$$Pu content exceeds 90%, instead of current reactor-grade Pu, is also under investigation. Initially, specification of the MK-III core fuel was adjusted in order to have the same reactivity worth as the current fuel. The $$^{235}$$U enrichment were reduced from 18% to 10%, and in some cases as low as 5%. The results are as follows: (1)When Pu content was improved from 30% to 35%, or when weapon-grade Pu was adopted, $$^{235}$$U enrichment can be decreased lower than 5% for the inner core fuel. (2)To decrease $$^{235}$$U enrichment lower than 5% for outer core fuel, Pu content must be improved up to 37%. Then deplated Uranium can be adopted for the inner core fuel. When weapon-grade Pu was adopted and Pu content was improved up to 33%, deplated Uranium can be utilized for both inner and outer core fuel. The nuclear characteristics of the low $$^{235}$$U enriched fueled core were calculated and compared with that of the MK-III standard core (reference corc). The results are as follows: (1)With the increase of $$^{239}$$Pu and $$^{241}$$Pu, burn-up reactivity increase. By increasing the substitution reactivity between a spent fuel and fresh fuel subassembly, burn-up reactivity could be compensated. (2)When weapon-grade Pu was adopted, the change of Pu vector per unit burn-up increased when compared with current core fuel. However, the nuclear characteristics were almost the same when compared with the standard core.

Oral presentation

Heavy-ion pulse radiolysis

Yang, J.*; Taguchi, Mitsumasa; Kondo, Takafumi*; Yoshida, Yoichi*; Shibata, Hiromi*; Namba, Hideki; Kojima, Takuji

no journal, , 

no abstracts in English

Oral presentation

Time resolved absorption spectroscopy for ion beam excitation

Kondo, Takafumi*; Yang, J.*; Kan, Koichi*; Yoshida, Yoichi*; Shibata, Hiromi*; Taguchi, Mitsumasa; Kojima, Takuji

no journal, , 

no abstracts in English

Oral presentation

Development of the ion beam pulse radiolysis

Kondo, Takafumi*; Yang, J.*; Kan, Koichi*; Yoshida, Yoichi*; Taguchi, Mitsumasa; Kojima, Takuji; Shibata, Hiromi*

no journal, , 

no abstracts in English

Oral presentation

Picosecond pulse radiolysis study of solvated electrons in ionic liquid

Asano, Akira*; Kondo, Takafumi*; Yang, J.*; Nagaishi, Ryuji; Takahashi, Kenji*; Yoshida, Yoichi*

no journal, , 

The spectrum and kinetic behavior of solvated electrons in DEMMA-TFSI and DEMMA-BF$$_{4}$$ ionic liquids (ILs) were investigated by using nanosecond pulse radiolysis technique. The reactions of the solvated electrons with pyrene and biphenylene were studied. The molar extinction coefficent and G value of the solvated electrons in ILs were estimated. The formation of the solvated electrons in IL on picosecond time scale was observed by picosecond pulse radiolysis.

Oral presentation

Solvated electrons in ionic liquids

Takahashi, Kenji*; Hiejima, Yusuke*; Kato, Ryuji*; Nagaishi, Ryuji; Taguchi, Mitsumasa; Kojima, Takuji; Kondo, Takafumi*; Yang, J.*; Yoshida, Yoichi*

no journal, , 

Solvated electrons were studied using the pulse radiolysis and photo ionization methods. The Vis-NIR spectra and reactivity of the solvated electrons in ionic liquids are discussed.

Oral presentation

Reduction of chlorophenols in ionic liquid by radiation

Taguchi, Mitsumasa; Kimura, Atsushi; Kondo, Takafumi*; Yang, J.*; Yoshida, Yoichi*; Hirota, Koichi

no journal, , 

no abstracts in English

50 (Records 1-20 displayed on this page)