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Journal Articles

R&D for tritium removal system using bacteria for safety enhancement of tritium handling in fusion reactor

Hayashi, Takumi; Kobayashi, Kazuhiro; Yamanishi, Toshihiko; Ichimasa, Yusuke*; Ichimasa, Michiko*

Karyoku Genshiryoku Hatsuden, 59(4), p.316 - 321, 2008/04

In order to enhance safety of fusion reactor, JAEA investigates effective tritium removal system in case of incidental tritium release in the building. Recently, we paid attention to the bacteria, which had an ability of hydrogen oxidation at room temperature, and a new effective detritiation system using the bacteria has been studied under the collaboration with Ibaraki University, instead of catalytic oxidation reactor of rare metal.

Journal Articles

Tritium elimination system using tritium gas oxidizing bacteria

Ichimasa, Michiko*; Awagakubo, Sayuri*; Takahashi, Miho*; Tauchi, Hiroshi*; Hayashi, Takumi; Kobayashi, Kazuhiro; Nishi, Masataka; Ichimasa, Yusuke*

Fusion Science and Technology, 48(1), p.759 - 762, 2005/07

 Times Cited Count:7 Percentile:46.25(Nuclear Science & Technology)

There exists various kinds of HT oxidizing soil bacteria in the world, and we have conducted the investigation of HT oxidation activity of such bacteria. In the fusion facility where deuterium and tritium will be used as its fuel, the system is necessary to eliminate tritium from atmospheric air. General tritium elimination method is oxidation and dehumidification, and high temperature catalyst is used in the present system for oxidation. Application of the HT oxidation bioreactor, which can oxidize in room temperature, to this oxidation process has possibility to get higher tritium elimination efficiency, so we started to study the bioreactor. In the recent study, we can get high oxidation ratio of 85% in the processing conditions of 200 Bq/cm$$^{3}$$ as tritium concentration in air, 100 cm$$^{3}$$/min as flow rate and once-through processing using the Caisson Assembly for Tritium Safety Study (CATS) in JAERI. This result encourages this development study.

Journal Articles

Re-emission of heavy water vapour from soil to the atmosphere

Yokoyama, Sumi; Noguchi, Hiroshi; Ichimasa, Yusuke*; Ichimasa, Michiko*

Journal of Environmental Radioactivity, 71(3), p.201 - 213, 2004/01

 Times Cited Count:10 Percentile:23.75(Environmental Sciences)

The reemission process of tritiated water (HTO) deposited on a soil surface is an important process to assess tritium doses to the general public around nuclear fusion facilities. A field experiment using heavy water (HDO) as a substitute for HTO was curried out in the summertime to investigate the reemission process of HTO from soil to the atmosphere. In the experiment, the time variations of the depth profiles of HDO concentrations in soil exposed to HDO vapour and soil mixed with HDO were measured during the reemission process on the field. The decrease of HDO concentration insoil water of exposed soil was much greater than that of mixed soil. The reemission process was analysed using a model including the evaporation of HDO from soil, the exchange between the soil HDO and air H$$_{2}$$O, and the diffusion of HDO in soil. It was found that the model is applicable to calculating the time variations of detailed depth profiles of HDO concentration in soil water in surface soil layers.

Journal Articles

Overview of tritium safety studies in Japan

Tanaka, Satoru*; Ohira, Shigeru; Ichimasa, Yusuke*

Fusion Engineering and Design, 63-64, p.139 - 152, 2002/12

 Times Cited Count:2 Percentile:17.6(Nuclear Science & Technology)

no abstracts in English

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:40.67(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

Conversion rate of HTO to OBT in plants

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

Fusion Science and Technology, 41(3), p.427 - 431, 2002/05

In processes of tritium transfer in the environment, conversion of HTO to OBT in plant by photosynthesis is important for both aspects of monitoring and dose estimation. Because once OBT is formed in plant, it stays in the plant for longer time than HTO, and OBT is more harmful than HTO for human body. Conversion rate of HTO in plant leaf to OBT in plant edible parts in the open air were obtained for some plants (komatsuna, radish and cherry tomato) during the chronic HT release experiment at Chalk River in 1994. At the experiment, HT gas was released to the atmosphere at the cultivated site for 12 days continuously [1]. HTO and OBT concentration in cultivated plants were measured during the experiment. For plant leaves conversion rate of HTO to OBT was about 0.2 (% h$$^{-1}$$) but it varied with their growth stage. A chamber experiment in laboratory was also carried out for comparison.

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

Journal Articles

Deposition of D$$_{2}$$O from air to plant and soil during an experiment of D$$_{2}$$O vapor release into a vinyl house

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

Fusion Engineering and Design, 42, p.133 - 140, 1998/00

 Times Cited Count:11 Percentile:67.36(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Deposition of heavy water on soil and reemission to the atmosphere

Yokoyama, Sumi; Noguchi, Hiroshi; Fukatani, S.; Ichimasa, Michiko*; Ichimasa, Yusuke*

Fusion Engineering and Design, 42, p.141 - 148, 1998/00

 Times Cited Count:3 Percentile:32.54(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Uptake of heavy water vapor from atmosphere by plant leaves as a function of stomatal resistance

Atarashi, Mariko; Amano, Hikaru; Ichimasa, Michiko*; Ichimasa, Yusuke*; *

Proc. of Int. Meeting on Influence of Climatic Characteristics upon Behavior of Radioactive Elements, p.236 - 242, 1997/00

no abstracts in English

Journal Articles

Overview of the 1994 chronic HT release experiment at Chalk River

P.A.Davis*; W.J.G.Workman*; B.D.Amiro*; F.S.Spencer*; Noguchi, Hiroshi; Amano, Hikaru; Ichimasa, Yusuke*; Ichimasa, Michiko*

Fusion Technology, 28, p.840 - 845, 1995/10

no abstracts in English

Journal Articles

Tritium behavior on a cultivated plot in the 1994 chronic HT release experiment at Chalk River

Noguchi, Hiroshi; Yokoyama, Sumi; Kinouchi, Nobuyuki; Murata, Mikio; Amano, Hikaru; Atarashi, Mariko; Ichimasa, Yusuke*; Ichimasa, Michiko*

Fusion Technology, 28, p.924 - 929, 1995/10

no abstracts in English

Journal Articles

Formation of organically bound tritium in plants during the 1994 chronic HT release experiment at Chalk Rever

Amano, Hikaru; Atarashi, Mariko; Noguchi, Hiroshi; Yokoyama, Sumi; Ichimasa, Yusuke*; Ichimasa, Michiko*

Fusion Technology, 28, p.803 - 808, 1995/10

no abstracts in English

Journal Articles

In vitro determination of HT oxidation activity and tritium concentration in soil and vegetation during the chronic HT release experiment at Chalk River

Ichimasa, Yusuke*; Ichimasa, Michiko*; H.Jiang*; *; Noguchi, Hiroshi; Yokoyama, Sumi; Amano, Hikaru; Atarashi, Mariko

Fusion Technology, 28, p.877 - 882, 1995/10

no abstracts in English

14 (Records 1-14 displayed on this page)
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