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d2o release experiments prof n momoshima kyushu university japan
D2O release experimentsProf N. Momoshima, Kyushu University, Japan
  • From a view point of health physics, studies on tritium behavior in the environment are necessary for an accurate dose assessment ; such as actual HT oxidation in the local environment, transfer of HTO to soil, plants and animals, and OBT formation and tritium elimination in them.
  • However, field experiments on environmental behavior of tritium are quite difficult to do because of the public acceptance problem in Japan.
  • Thus heavy water (D2O) vapor release experiments was planed and carried out.
grants in aid for scientific research from the ministry of education science and culture japan
Grants-in-Aid for Scientific Research from the Ministry of Education, Science and Culture, Japan
  • Environmental Behavior and Biological Conversion of Tritium -Preliminary Release Experiment of Heavy water in a Greenhouse-

1995~1996

  • Transfer of tritium to crops, animals and fishes during an accidental release of tritium and its retention

1997-1999

Prof. M. Ichimasa, Ibaraki Univ. Japan

slide3

Members of the program and joined to the D2O experiments (red)

  • M. Ichimasa (Ibaraki Univ.)
  • Y. Ichimasa (Ibaraki Univ.)
  • H. Takeda (NIRS)
  • S. Hisamatsu (Akita Univ.)
  • H. Amano (JAERI), M. Atarashi
  • H. Noguchi (JAERI), S. Yokoyama
  • N. Momoshima (Kyushu Univ.), H. Kakiuchi
  • T. Okai (Kyushu Univ.)
  • Y. Sakuma (NIFS)
  • M. Saito (Kyoto Univ.)
  • A. Ito (Hiroshima Univ.)
  • K. Komatsu (Hiroshima Univ.)
  • K. Okuno (Shizuoka Univ.)

Transfer of D2O to soil, plants and animals, and OBD formation and tritium elimination

slide4

A greenhouse was constructed in the field of the Ibaraki University. Closed type and top open type.

Closed type

(1995-97 and 1999)

D2O

Top open type

(1998)

slide8

Different points

End

D2O

Time (h)

Atmospheric D2O concentrations in the close type greenhouse (1997).

48h release

slide9

Atmospheric D2O concentrations in the top open type greenhouse(1998).

The D2O concentrations changed with time due to wind and did not reach to a steady state.

A large difference in concentration with height near the D2O humidifies but not so much apart points.

topic of research
Topic of research
  • Uptake and release of D2O by plants
    • rice, radish, tomato, komatsuna, cabbage, orange, soybean, (maze, potato・・)
  • Uptake and reemission by soil
    • Sandy soil
  • OBD formation
    • rice
list of publications related to d 2 o experiments
List of publications related to D2O experiments
  • Deposition of D2O from air to plant and soil during an experiment of D2O vapor release into a vinyl house, Mariko Atarashi, Hikaru Amano, Michiko Ichimasa, Yusuke Ichimasa, Fusion Engineering and Design 42 (1998) 133–140
  • Formation and retention of organically bound deuterium in rice in deuterium water release experiment, M. Atarashi-Andoh, H. Amano, H. Kakiuchi, M. Ichimasa and Y. Ichimasa, Heaoth Physics, 82, 863-868 (2002).
  • Uptake of heavy water vapor from atmosphere by plant leaves as a function of stomatal resistance, M. Atarashi, H. Amano, M. Ichimasa, M. Kaneko and Y. Ichimasa, Proceedings of International Meeting on Influence of Climatic Characteristics upon Behavior of Radioactive Elements, Rokkasho, Aomori, Japan, October 14-16, 1997, Edited by Y. Ohmomo and N. Sakurai, IES, 236-242 (1997).
  • Conversion rate of HTO to OBT in plants, M. Atarashi-Andoh, H. Amano, M. Ichimasa and Y. Ichimasa, Fusion Science and Technology, 41, 427-431 (2002).
  • Uptake kinetics of deuteriated water vapor by plants: Experiments of D20 release in a greenhouse as a substitute for tritiated water, N. Momoshima, H. Kakiuchi, T. Okai, S. Yokoyama, H. Noguchi, M. Atarashi, H. Amano, S. Hisamatsu, M. Ichimasa, Y. Ichimasa, Y. Maeda, Journal of Radioanalytical and Nuclear Chemistry, Vol. 239, No. 3 (1999) 459-464
  • Uptake of deuterium by dead leaves exposed to deuteriated water vapor in a greenhouse at daytime and nighttime, N. Momoshima, R. Matsushita, Y. Nagao and T. Okai, J. Environ. Radioactivity,88, 90-100 (2006).
  • Organically bound deuterium in soybean exposed to atmospheric D2O vapor as a substitute for HTO under different growth phase, M. Ichimasa, T. Maejima, N. Seino, T. Ara, A. Masukura, S. Nishihiro, H. Tauchi and Y. Ichimasa, Proceedings of the International Symposium: Transfer of Radionuclides in Biosphere –Prediction and Assessment-, Mito, December 18-19, 2002, JAERI-Conf 2003-010, 226-232 (2003).
  • Heavy water vapor release experiment in a green house –Transfer of Heavy water to tomato and dishcloth gourd—, M. Ichimasa, T. Hakamada, A. Li, Y. Ichimasa, H. Noguchi, S. Yokoyama, H. Amano and M. Atarashi, Proceedings of International Meeting on Influence of Climatic Characteristics upon Behavior of Radioactive Elements, Rokkasho, Aomori, Japan, October 14-16, 1997, Edited by Y. Ohmomo and N. Sakurai, IES, 243-248 (1997).
  • Organically bound deuterium in rice and soybean after exposure to heavy water vapor as a substitute for tritiated water, M. Ichimasa, C. Weng, T. Ara and Y. Ichimasa , Fusion Science and Technology, 41, 393-398 (2002).
  • Deposition of heavy water on soil and reemission to the atmosphere, Sumi Yokoyama, Hiroshi Noguchi, Michiko Ichimasa, Yusuke Ichimasa, Satoshi Fukutani, Fusion Engineering and Design 42 (1998) 141–148
  • Re-emission of heavy water vapor from soil to the atmosphere, S. Yokoyama, H. Noguchi, Y. Ichimasa and M. Ichimasa, Journal of Environmental Radioactivity, 71, 201-213 (2004).
slide12

Rate constants and mostly cases Cmax/Cair were obtained for various kind of plants

Uptake

Cp=Cmax (1-e-kt)

Release

Cp=Co e-k’t

slide13

Deposition of D2O from air to plant and soil during an experiment of D2O vapor release into a vinyl house, Mariko Atarashi, Hikaru Amano, Michiko Ichimasa, Yusuke Ichimasa, Fusion Engineering and Design 42 (1998) 133–140

slide14

OBD formation at daytime and nighttime

Formation and retention of organically bound deuterium in rice in deuterium water release experiment, M. Atarashi-Andoh, H. Amano, H. Kakiuchi, M. Ichimasa and Y. Ichimasa, Health Physics, 82, 863-868 (2002).

slide16

The dead cedar needles taken up more D2O than fresh ones both in daytime and nighttime exposures.

The release rate was faster in dead cedar needles.

slide17

Four kinds of leaves were exposed to D2O at daytime and nighttime in 1999.

Fresh leaves dried at 80 °C were rewetted for 3 days and the biaxial leaf surface was exposed.

slide18

茨城大学測定

Run Exp. Temp RH D2O conc.

             (℃) (%)     (ppm)

Daytime-1 1h 32.3〜33.3 58〜61 13700

Daytime-2 1h 34.2〜36.0 57〜59 12200

Nighttime 2h 23.2 9916300

slide19

Uptake of deuterium by dead leaves exposed to deuteriated water vapor in a greenhouse at daytime and nighttime, N. Momoshima, R. Matsushita, Y. Nagao and T. Okai, J. Environ. Radioactivity,88, 90-100 (2006).

slide20

F = Vex ・ (Ca - r ・ h・Cs)

Vex:exchange rate (m/s)

Ca:HTO conc. in air (Bq/m3)

r:HTO & H2Ovapor saturation ratio (0.92)

h:Water content at leaf surface

(kg-H2O/m3-air)

Cs:HTO conc. in leaf (Bq/kg)

Cinnamomum camphora

10kV(top)と30kV(below)、magnification 3500

Stoma size 20-30μm

Re-wetted

Dry

Air

H2O

D2O