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Journal Articles

Factors controlling dissolved $$^{137}$$Cs concentrations in east Japanese rivers

Tsuji, Hideki*; Ishii, Yumiko*; Shin, M.*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Kurihara, Momo*; Yasutaka, Tetsuo*; Kuramoto, Takayuki*; Nakanishi, Takahiro; Lee, S*; et al.

Science of the Total Environment, 697, p.134093_1 - 134093_11, 2019/12

 Times Cited Count:4 Percentile:35.25(Environmental Sciences)

To investigate the main factors that control the dissolved radiocesium concentration in river water in the area affected by the Fukushima Daiichi nuclear power plant accident, the correlations between the dissolved $$^{137}$$Cs concentrations at 66 sites normalized to the average $$^{137}$$Cs inventories for the watersheds with the land use, soil components, topography, and water quality factors were assessed. We found that the topographic wetness index is significantly and positively correlated with the normalized dissolved $$^{137}$$Cs concentration. Similar positive correlations have been found for European rivers because wetland areas with boggy organic soils that weakly retain $$^{137}$$Cs are mainly found on plains. However, for small Japanese river watersheds, the building area ratio in the watershed strongly affected the dissolved $$^{137}$$Cs concentration.

Journal Articles

Repeatability and reproducibility of measurements of low dissolved radiocesium concentrations in freshwater using different pre-concentration methods

Kurihara, Momo*; Yasutaka, Tetsuo*; Aono, Tatsuo*; Ashikawa, Nobuo*; Ebina, Hiroyuki*; Iijima, Takeshi*; Ishimaru, Kei*; Kanai, Ramon*; Karube, Jinichi*; Konnai, Yae*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 322(2), p.477 - 485, 2019/11

 Times Cited Count:0 Percentile:100(Chemistry, Analytical)

We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the $$^{137}$$Cs results were within $$pm$$2, indicating that the methods were accurate. The relative standard deviations (RSDs) indicating the variability in the results from different laboratories were larger than the RSDs indicating the variability in the results from each separate laboratory.

Journal Articles

Applicability of $$K_{d}$$ for modelling dissolved $$^{137}$$Cs concentrations in Fukushima river water; Case study of the upstream Ota River

Sakuma, Kazuyuki; Tsuji, Hideki*; Hayashi, Seiji*; Funaki, Hironori; Malins, A.; Yoshimura, Kazuya; Kurikami, Hiroshi; Kitamura, Akihiro; Iijima, Kazuki; Hosomi, Masaaki*

Journal of Environmental Radioactivity, 184-185, p.53 - 62, 2018/04

 Times Cited Count:5 Percentile:52.92(Environmental Sciences)

A study is presented on the applicability of the distribution coefficient ($$K_{d}$$) absorption/desorption model to simulate dissolved $$^{137}$$Cs concentrations in Fukushima river water. The simulation results were in good agreement with the observations on water and suspended sediment fluxes, and on particulate bound $$^{137}$$Cs concentrations under both ambient and high flow conditions. By contrast the measured concentrations of dissolved $$^{137}$$Cs in the river water were much harder to reproduce with the simulations. By tuning the $$K_{d}$$ values for large particles, it was possible to reproduce the mean dissolved $$^{137}$$Cs concentrations during base flow periods (observation: 0.32 Bq/L, simulation: 0.36 Bq/L). However neither the seasonal variability in the base flow dissolved $$^{137}$$Cs concentrations (0.14-0.53 Bq/L), nor the peaks in concentration that occurred during storms (0.18-0.88 Bq/L, mean: 0.55 Bq/L), could be reproduced with realistic simulation parameters.

JAEA Reports

Description of "Design guideline for gas entrainment prevention using CFD method" (Cooperative research)

Ohshima, Hiroyuki; Sakai, Takaaki; Kamide, Hideki; Kimura, Nobuyuki; Ezure, Toshiki; Uchibori, Akihiro; Ito, Kei; Kunugi, Tomoaki*; Okamoto, Koji*; Tanaka, Nobuatsu*; et al.

JAEA-Research 2008-049, 44 Pages, 2008/06

JAEA-Research-2008-049.pdf:42.3MB

Japan Atomic Energy Agency has conducted a conceptional design study of a sodium-cooled fast reactor in a frame work of the FBR feasibility study. The plant system concept for a commercial step is intended to minimize a vessel diameter to achieve an economical competitiveness. Therefore, the coolant in the vessel has relatively higher velocity and gas entrainment (GE) prevention from a liquid surface in the reactor vessel becomes one of important issues for the thermal-hydraulic design. In order to establish a design criteria for the GE prevention, the GE from vortex dimples at the liquid surface was investigated by a working group. The 1st proposal of "Design Guideline for Gas Entrainment Prevention Using CFD Method" was established based on the knowledge gained from the working group activities. This report introduces each study in the working group to clarify the basis of the design guideline.

JAEA Reports

Experimental Study on Gas Entrainment from Free-surface Generation Mechanism of Dimple-Eddy

Tsuji, Yoshiyuki*; Kamide, Hideki

JNC-TY9400 2005-017, 54 Pages, 2005/03

JNC-TY9400-2005-017.pdf:4.22MB

Compact reactor vessel is designed to reduce construction cost of a fast reactor. In a compact reactor vessel flow velocity will increase and it causes gas entrainment at free surface. Thus, gas entrainment is one of significant issue of the reactor design. In this study we carried out a water experiment on the gas entrainment, especially the onset condition of a dimple vortex, which causes the gas entrainment in order to establish a guide line in a deisgn.This study is planned to carry in three years from 2003 to 2005. The year of 2004 corresponds to the second term. In this year, water experiment was carried out using a flow channel, vertical suction pipe, and an obstacle in order to see influences of obstacles on the gas entrainment and dimple vortex. Onset conditions of the gas entrainment due to the dimple vortex were obtained with experimental parameters of flow velocity in the channel, water level, and free surface wave or disturbance. It was shown that the onset of gas entrainment needed vertical vortex, e.g. in a wake of an obstacle, and disturbance of free surface block the onset of the dimple vortex and the gas entrainment.

Journal Articles

Electron acceleration by a nonlinear wakefield generated by ultrashort (23-fs) high-peak-power laser pulses in plasma

Kando, Masaki; Masuda, Shinichi; Zhidkov, A.*; Yamazaki, Atsushi; Kotaki, Hideyuki; Kondo, Shuji; Homma, Takayuki*; Kanazawa, Shuhei; Nakajima, Kazuhisa; Hayashi, Yukio; et al.

Physical Review E, 71(1), p.015403_1 - 015403_4, 2005/01

 Times Cited Count:32 Percentile:20.29(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Relativistic laser plasma from micron-sized argon clusters as a debris-free X-ray source for pulse X-ray diffraction

Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Inoue, Norihiro*; Ueda, Hideki; Nakai, Yoshiki*; Tsuji, Koichi*; Yamakawa, Koichi; Hironaka, Yoichiro*; Kishimura, Hiroaki*; et al.

Applied Physics Letters, 85(21), p.5099 - 5101, 2004/11

 Times Cited Count:10 Percentile:57.8(Physics, Applied)

We have demonstrated diffraction from Si(111) crystal using X-rays from highly ionized Ar ions produced by laser irradiation with an intensity of 6$$times$$10$$^{18}$$ W/cm$$^{2}$$ and a pulse duration of 30 fs acting upon micron-sized Ar clusters. The measured total photon flux and line width in the He$$_{alpha1}$$ line (3.14 keV) were 4$$times$$10$$^{7}$$ photons/shot/4$$pi$$sr and 3.7 eV (FWHM), respectively, which is sufficient to utilize as a debris-free light source for time-resolved X-ray diffraction studies.

JAEA Reports

Experimental Study on Gas-Entrainment from Free-surface; Generation Mechanism of Dimple-Eddy

Obata, Takanori*; Tsuji, Yoshiyuki*; Kimura, Nobuyuki; Kamide, Hideki

JNC-TY9400 2004-017, 36 Pages, 2004/03

JNC-TY9400-2004-017.pdf:3.03MB

Gas entrainment at free surface is of importance due to higher flow velocity in a compact reactor vessel. Dimple-eddy is one of major reasons for gas entrainment in case of low flow velocity condition at free surface. Water experiment was carried out to see generation of dimple-eddy in this study. A round shape obstacle was set in an open channel. Eddies are generated in wake region behind the obstacle.Laser beam and photo acceptance unit of PSD were used to measure inclined angle of free surface and shape of dimple-eddy. The dimple depth is one of the key parameter of eddy development. Following findings were obtained from the experiment; 1) This laser-PSD system can measure the inclined angle of free surface and find the dimple-eddy, 2) Shape of the dimple-eddy can be estimated by statistics of the free surface angle-data.

Journal Articles

Program of in-pile IASCC testing under the simulated actual plant condition; Thermohydraulic design study of saturated temperature capsule for IASCC irradiation test

Ide, Hiroshi; Matsui, Yoshinori; Nagao, Yoshiharu; Komori, Yoshihiro; Itabashi, Yukio; Tsuji, Hirokazu; Tsukada, Takashi; Nagata, Nobuaki*; Dozaki, Koji*; Takiguchi, Hideki*

Proceedings of 11th International Conference on Nuclear Engineering (ICONE-11) (CD-ROM), 7 Pages, 2003/04

The advanced water chemistry controlled irradiation research device has been developed in JAERI to perform irradiation tests for research on IASCC. The irradiation device consists of the SATCAP (Saturated Temperature Capsule) inserted into the JMTR core and the water control unit installed out-of-core. Regarding the SATCAP, thermohydraulic design of the SATCAP was performed aiming at controlling the specimen temperature with high accuracy and increasing water flow velocity on the specimen surface to improve the controllability of water chemistry. As a result of irradiation test using the new type SATCAP, each specimen temperature and water chemistry were able to be controlled as designed.

Journal Articles

Research and development on materials as base technology in nuclear applications

Kondo, Tatsuo; Hishinuma, Akimichi; Noda, Kenji; Eto, Motokuni; Tsuji, Hirokazu; Nakajima, Hajime; Kiuchi, Kiyoshi; Ono, Hideo; Ogawa, Toru; Omichi, Hideki; et al.

Genshiryoku Kogyo, 39(8), p.1 - 80, 1993/08

no abstracts in English

Oral presentation

Radiocesium behavior of water and plankton in Dam Lake in Fukushima Prefecture

Tsuji, Hideki*; Hayashi, Seiji*; Funaki, Hironori; Iijima, Kazuki

no journal, , 

no abstracts in English

Oral presentation

Characteristics of radiocesium elution from sediment in Yokokawa Dam Lake

Tsuji, Hideki*; Koshikawa, Masami*; Ito, Shoko*; Funaki, Hironori; Iijima, Kazuki; Yasutaka, Tetsuo*

no journal, , 

no abstracts in English

Oral presentation

Simulation of behavior of dissolved and particulate radiological material in forested stream water

Sakuma, Kazuyuki; Funaki, Hironori; Kitamura, Akihiro; Iijima, Kazuki; Tsuji, Hideki*; Hayashi, Seiji*

no journal, , 

no abstracts in English

Oral presentation

Behaviour of dissolved radiocesium within a Yokokawa dam reservoir basin (Research collaboration with JAEA and NIES)

Sakuma, Kazuyuki; Tsuji, Hideki*

no journal, , 

We focus on a behavior of dissolved radiocesium within Yokokawa dam reservoir in Fukushima prefecture. (1) Horizontal distribution of dissolved $$^{137}$$Cs concentration in reservoir water, (2) $$^{137}$$Cs concentration of a plankton, (3) Investigation for sources of dissolved $$^{137}$$Cs from an upstream catchment of the dam reservoir, (4) Simulation for dissolved $$^{137}$$Cs discharge from the upstream catchment of the dam reservoir were studied. These indicated that dissolved $$^{137}$$Cs concentration in water at dam inlet and outlet were decreasing and an organic matter is one of the dissolved $$^{137}$$Cs source in forested catchment. Additionally we developed a numerical model to simulate dissolved $$^{137}$$Cs concentration at the catchment outlet, which reasonably reproduced a observation data under base flow periods.

Oral presentation

Investigation of factors controlling dissolved $$^{137}$$Cs concentrations in Japanese rivers

Tsuji, Hideki*; Shin, M.*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Kurihara, Momo*; Yasutaka, Tetsuo*; Kuramoto, Takayuki*; Nakanishi, Takahiro; Lee, S*; Shinano, Takuro*; et al.

no journal, , 

To predict the behavior of particulate and dissolved radiocesium ($$^{137}$$Cs) in river water, some soil and land use categories in the watershed should be considered because these may affect the dissolved $$^{137}$$Cs concentration. In this study, to investigate the factors that affect dissolved $$^{137}$$Cs concentrations in Japanese rivers, we measured dissolved $$^{137}$$Cs concentrations in 67 rivers under baseflow conditions 13-280 km from the Fukushima Daiichi Nuclear Power Plant in August and September 2017.

Oral presentation

Factors controlling dissolved $$^{137}$$Cs concentrations in east Japanese rivers

Tsuji, Hideki*; Ishii, Yumiko*; Hayashi, Seiji*; Shin, M.*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Kurihara, Momo*; Yasutaka, Tetsuo*; Kuramoto, Takayuki*; Nakanishi, Takahiro; et al.

no journal, , 

Controlling factor of dissolved $$^{137}$$Cs concentrations in 66 in East Japan rivers was investigated. Dissolved $$^{137}$$Cs concentrations decreased by one order of magnitude between 2012 and 2017. Normalized dissolved $$^{137}$$Cs concentrations correlated well with building area ratios. Topographic wetness index generally predicted dissolved $$^{137}$$Cs concentrations. The high concentration of dissolved $$^{137}$$Cs in urban area cannot be explained by water quality condition.

Oral presentation

Development of a model to reproduce $$^{137}$$Cs dissolution from dam lake sediment considering temperature and dissolved oxygen condition

Tsuji, Hideki*; Hayashi, Seiji*; Higashi, Hironori*; Sakuma, Kazuyuki; Yoshimura, Kazuya; Funaki, Hironori; Nakanishi, Takahiro; Tsuruta, Tadahiko

no journal, , 

no abstracts in English

Oral presentation

Evaluation of dissolved $$^{137}$$Cs discharge characteristics from a forested catchment of the Ohta River

Sakuma, Kazuyuki; Yoshimura, Kazuya; Nakanishi, Takahiro; Funaki, Hironori; Tsuruta, Tadahiko; Ochi, Kotaro; Hayashi, Seiji*; Tsuji, Hideki*; Ozaki, Hirokazu*

no journal, , 

Cesium-137 leaching from decomposing forest litter is thought to be one pathway by which dissolved $$^{137}$$Cs enters rivers from forests. To clarify whether this process contributes or not, we studied the correlation between humin-like matter from microorganism-induced plants decomposition and dissolved $$^{137}$$Cs concentrations. River water samples were collected approximately once a month from April 2017 to August 2019 at 10 locations (7 locations from April 2019) from the upstream of the Ohta River in the Namie and Minamisoma districts. These samples were filtered through 0.45-$$mu$$m-pore size membrane filters. The dissolved $$^{137}$$Cs concentrations and fluorescence intensities of humin-like matter were measured. A positive correlation was found between the fluorescence intensities of humin-like matter and normalized dissolved $$^{137}$$Cs concentration (R$$^{2}$$ = 0.17, p $$<$$ 0.001). The results indicate that $$^{137}$$Cs leaching from forest litter because of litter decomposition can contribute to increasing the dissolved $$^{137}$$Cs concentration in river water in forested catchments.

18 (Records 1-18 displayed on this page)
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