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Journal Articles

Development of field estimation technique and improvement of environmental tritium behavior model

Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; Atarashi-Andoh, Mariko; et al.

Plasma and Fusion Research (Internet), 14(Sp.2), p.3405099_1 - 3405099_4, 2019/06

The Large Helical Device of the National Institute for Fusion Science started D-D experiments in 2017. To ensure the safety of the facility, it is important to develop evaluation methods for environmental tritium transfer. Tritiated water (HTO) in atmosphere and soil is transferred to plants, and organically bound tritium (OBT) is formed by photosynthesis. Prediction of OBT formation is important, because OBT accumulates in plants and causes dose through ingestion. The objective of this study is to estimate environmental tritium transfer using a simple compartment model and practical parameters. We proposed a simple compartment model consisting of air-soil-plant components, and tried to validate the model by comparison with a sophisticated model, SOLVEG. In this study, we plan to add wet deposition to the model and obtain parameters from measurements of soil permeability and tritium concentrations in air, soil and plants. We also establish rapid pretreatment methods for OBT analysis.

Journal Articles

Impacts of anthropogenic source from the nuclear fuel reprocessing plants on global atmospheric iodine-129 cycle; A Model analysis

Kadowaki, Masanao; Katata, Genki*; Terada, Hiroaki; Suzuki, Takashi; Hasegawa, Hidenao*; Akata, Naofumi*; Kakiuchi, Hideki*

Atmospheric Environment, 184, p.278 - 291, 2018/07

 Times Cited Count:1 Percentile:59.32(Environmental Sciences)

The long-lived radioactive iodine ($$^{129}$$I) is a useful geochemical tracer in the atmospheric environment. We recently observed clear seasonal trends in air concentration and deposition of $$^{129}$$I in Japan. Using these data, we developed a global atmospheric $$^{129}$$I transport model to reveal key processes for the global atmospheric $$^{129}$$I cycle. The model generally reproduced the observed seasonal change in air concentration and deposition of $$^{129}$$I in Japan, and the global distribution of $$^{129}$$I concentration in rain as presented in past literature. Numerical experiments changing the intensity of anthropogenic and natural sources were conducted to quantify the impact of anthropogenic sources on the global $$^{129}$$I cycle. The results indicated that the atmospheric $$^{129}$$I from the anthropogenic sources was deposited in winter and can be accumulated mainly in the northern part of Eurasia. In contrast, the atmospheric $$^{129}$$I from the natural sources dominated the deposition in summer. These results suggested that the re-emission process of $$^{129}$$I from the Earth's surface may be important as a secondary impact of $$^{129}$$I in the global-scaled environment. Furthermore, although wet deposition dominated the total deposition in the Northern hemisphere, dry deposition regionally and seasonally contributed to the total deposition over arctic and northern part of Eurasia in winter, suggesting that the dry deposition may play a key role in the seasonal change of $$^{129}$$I deposition in the Northern hemisphere high latitudes.

Journal Articles

Formation and retention of organically bound deuterium in rice in deuterium water release experiment

Atarashi-Andoh, Mariko; Amano, Hikaru; Kakiuchi, Hideki; Ichimasa, Michiko*; Ichimasa, Yusuke*

Health Physics, 82(6), p.863 - 868, 2002/06

 Times Cited Count:6 Percentile:55.82(Environmental Sciences)

As a substitute of tritium, deuterium water (D2O) vapor release experiments were performed to estimate the difference of formation and subsequent retention of organically bound deuterium (OBD) in rice plants between daytime and nighttime exposure. Potted plants were exposed to deuterium water vapor in a greenhouse for 8 hours, under day and night conditions. Deuterium concentrations in free water and organic matter in rice leaves and ears were investigated until the harvest time. Data analysis was carried out using a model in which different generating processes of organic matter were considered. The calculated results agreed with the measured value.

Journal Articles

Chemical speciation of radionuclides through the microbial process in soils

Kakiuchi, Hideki; Amano, Hikaru; Ichimasa, Michiko*

Journal of Radioanalytical and Nuclear Chemistry, 252(2), p.437 - 439, 2002/05

 Times Cited Count:6 Percentile:55.82(Chemistry, Analytical)

no abstracts in English

Journal Articles

Results of D$$_{2}$$O release experiement; Transfer of deutrium and Carbon-13 from air to plant

Atarashi-Andoh, Mariko; Amano, Hikaru; Porntepkasemsan, B.; Kakiuchi, Hideki; Ichimasa, Michiko*; Ichimasa, Yusuke*

KURRI-KR-53, p.18 - 21, 2000/10

no abstracts in English

Oral presentation

Development of a global transport model for airborne iodine-129 including atmospheric photolysis and gas-particle conversion processes

Kadowaki, Masanao; Katata, Genki*; Terada, Hiroaki; Suzuki, Takashi; Hasegawa, Hidenao*; Akata, Naofumi*; Kakiuchi, Hideki*

no journal, , 

Iodine-129 ($$^{129}$$I) has been shown as a useful isotope for dating of water, tracing of marine sediments and investigating the geochemical cycle of iodine. Main sources of atmospheric $$^{129}$$I are volatilization from ocean and discharge from nuclear fuel reprocessing facilities. Although released $$^{129}$$I is globally transported in the atmosphere and deposited to the Earth's surface, spatial and temporal distributions of atmospheric $$^{129}$$I are still not well understood. In this study, we developed an atmospheric global transport model of $$^{129}$$I which includes the processes such as advection and turbulent diffusion, dry and wet deposition, discharge from nuclear fuel reprocessing facility, volatilization from ocean and atmospheric chemical reactions (atmospheric photolysis and gas-particle conversion). Input meteorological fields of three-dimensional components of wind, air temperature, atmospheric pressure, and turbulent diffusion coefficient were calculated using WRF (Weather Research and Forecasting) with ERA-Interim dataset. The simulation period was set to be from 1 Jan 2006 to 31 Dec 2010. For model validation, we used air concentration and deposition of gaseous and particulate forms of $$^{129}$$I measured at Rokkasho in Japan from 2006 to 2010 and past measurements of $$^{129}$$I concentration in rain water in Europe, Asia, and North America. The model successfully reproduced the seasonal variations of measured air concentration and deposition of $$^{129}$$I at Rokkasho as maximum and minimum values during the wintertime and summertime, respectively. Furthermore, spatial patterns of simulated $$^{129}$$I concentration in globe were similar to those of measurements. In the presentation, key factors in controlling the spatiotemporal distribution of airborne $$^{129}$$I and its cycle in the atmosphere suggested by model results will be discussed.

Oral presentation

R&D for introducing silicon carbide materials to safety improvement of BWR's core, 3; Plant transient analysis with SiC cladding fuel for RIA accident

Horie, Hideki*; Takeuchi, Yutaka*; Kakiuchi, Kazuo*; Sato, Hisaki*; Shirasu, Noriko; Saito, Hiroaki; Yamashita, Shinichiro; Fukahori, Tokio

no journal, , 

The problem in the accident tolerance fuel development was considered in comparison the fuel behavior of SiC/SiC composite cladding tube with current Zry cladding tube. In this study, Reactivity Initiated Accident (RIA) was evaluated using the plant excess security analysis code TRACTTM and the fuel performance code FEMAXI.

Oral presentation

Technical discussion on tritiated water treatment for Fukushima Daiichi Nuclear Power Station

Yamanishi, Toshihiko*; Kakiuchi, Hideki*; Tauchi, Hiroshi*; Yamamoto, Tokuhiro; Yamamoto, Ichiro*

no journal, , 

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