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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:12 Percentile:63.95(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:2 Percentile:32.52(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.

JAEA Reports

Development of fabrication technologies for ITER in-vessel components

Kuroda, Toshimasa*; Sato, Kazuyoshi; Akiba, Masato; Ezato, Koichiro; Enoeda, Mikio; Osaki, Toshio*; Kosaku, Yasuo; Sato, Satoshi; Sato, Shinichi*; Suzuki, Satoshi*; et al.

JAERI-Tech 2002-044, 25 Pages, 2002/03

JAERI-Tech-2002-044.pdf:2.68MB

no abstracts in English

Oral presentation

Development of seismic assessment method toward the demonstration reactor of JSFR, 1; Vibration test of 1/2.5 scale test assembly in triangular arrangement

Iwasaki, Akihisa*; Monde, Masatsugu*; Sawa, Naoki*; Ikarimoto, Iwao*; Taniguchi, Yoshihiro*; Kitamura, Seiji

no journal, , 

The three-dimensional seismic analysis technology of a reactor core is developed. The vibration test of 1/2.5 scale test assembly in triangular arrangement was carried out, and the three-dimensional response behavior has been grasped.

Oral presentation

Development of seismic assessment method toward the demonstration reactor of JSFR, 2; Analysis of vibration test of 1/2.5 scale test assembly in triangular arrangement

Monde, Masatsugu*; Iwasaki, Akihisa*; Sawa, Naoki*; Ikarimoto, Iwao*; Taniguchi, Yoshihiro*; Kitamura, Seiji

no journal, , 

The three-dimensional analysis method of a reactor core is developed. The outline of the analysis method and the applicability of the method by comparison with a vibration test of 1/2.5 scale test assembly are reported.

Oral presentation

Metal nano-particle formation by femtosecond laser filamentation

Nakashima, Nobuaki*; Yamanaka, Kenichi*; Yatsuhashi, Tomoyuki*; Taniguchi, Seiji*; Saeki, Morihisa; Oba, Hironori

no journal, , 

no abstracts in English

Oral presentation

Reduction of Eu$$^{3+}$$ by multiphoton excitation in alcohol solutions

Matsuda, Shohei; Nakashima, Nobuaki*; Yokoyama, Keiichi; Yatsuhashi, Tomoyuki*; Chosrowjan, H.*; Taniguchi, Seiji*; Somekawa, Toshihiro*

no journal, , 

The photoredox reactions of lanthanides as a photochemical separative technique proposed in the 1970s are expected to be applied for recovery and recycling of rare metals and nuclear fuel reprocessing. In this study, Eu$$^{3+}$$ ions in methanol and ethanol solutions were reduced to Eu$$^{2+}$$ ions upon irradiation with nanosecond laser pulses. Eu$$^{2+}$$ was observed when the laser wavelength was tuned to f-f transition bands at 394 and 465 nm. The formation rate of Eu$$^{2+}$$ was proportional to the square of the incident laser intensity, indicating that the photoreduction is induced by a two-photon process. The efficiency of the photoreduction in ethanol was higher than that in methanol.

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

Fluence dependence of multiphoton reduction of Eu(III) via f-f transition

Matsuda, Shohei; Nakashima, Nobuaki*; Yokoyama, Keiichi; Yatsuhashi, Tomoyuki*; Chosrowjan, H.*; Taniguchi, Seiji*; Somekawa, Toshihiro*

no journal, , 

The photochemical reactions of lanthanide and actinide ions are expected to be utilized for recovery and recycling of rare earths, and nuclear fuel reprocessing. Heading towards research for implementation of photochemical purification, a unified evaluation of the efficiency of multiphoton processes is required. In this study, we have evaluated the fluence dependence of photoreduction of Eu(III) more precisely than before by measuring the beam profile of the excitation laser. The reduction rate of Eu(III)$$rightarrow$$Eu(II) is proportional to the square of the laser fluence, indicating that the photoreduction of Eu(III) is induced by a two-photon process.

Oral presentation

Radiocaesium dynamics in forested watersheds in Fukushima Prefecture

Taniguchi, Keisuke*; Takeuchi, Yukio*; Fujita, Kazuki*; Dohi, Terumi; Hayashi, Seiji*; Kuramoto, Takayuki*; Nomura, Naoki*; Aono, Tatsuo*

no journal, , 

In Fukushima Prefecture, although decontamination has been completed except for difficult-to-return areas, most of the forest has not been decontaminated yet. From the forest, radiocaesium may enter rivers and affect downstream areas. A survey was conducted in three forested watersheds of the Nanokazawa, Saruta, Nuno rivers located in Fukushima Prefecture to understand the amount and characteristics of radiocaesium flowing out. In each watershed, suspended solids (SS) were collected by a suspended sand sampler, water was collected every few months, and the water level and flow rate were measured. After freeze-drying the SS sample, the concentration of suspended Cs-137 was measured by a germanium semiconductor detector. The water sample was filtered through a membrane filter with a pore size of 0.45 $$mu$$m, then the dissolved Cs-137 was collected by the solid-phase extraction disk method or AMP coprecipitation method, and the dissolved Cs-137 concentration was measured by a germanium semiconductor detector. The ranges of dissolved Cs-137 concentration in FY2019 were 69-190 mBq/L in the Saruta River, 9.7-16 mBq/L in the Nanokazawa river, and ND-3.2 mBq/L in the Nuno River. In the poster, we will also present the results of SS measurements and flow observations.

Oral presentation

Estimation of the radiocaesium particle fraction in suspended sediment in river waters

Takeuchi, Yukio*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Yoshita, Hirofumi*; Fujita, Kazuki*; Takahashi, Yusuke*; Kuramoto, Takayuki*; Nomura, Naoki*; Hagiwara, Hiroki; Dohi, Terumi; et al.

no journal, , 

no abstracts in English

12 (Records 1-12 displayed on this page)
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