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Ota M, Kwamena NOA, Mihok S, Korolevych V. Role of soil-to-leaf tritium transfer in controlling leaf tritium dynamics: Comparison of experimental garden and tritium-transfer model results. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2017; 178-179:212-231. [PMID: 28910625 DOI: 10.1016/j.jenvrad.2017.09.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 08/24/2017] [Accepted: 09/01/2017] [Indexed: 06/07/2023]
Abstract
Environmental transfer models assume that organically-bound tritium (OBT) is formed directly from tissue-free water tritium (TFWT) in environmental compartments. Nevertheless, studies in the literature have shown that measured OBT/HTO ratios in environmental samples are variable and generally higher than expected. The importance of soil-to-leaf HTO transfer pathway in controlling the leaf tritium dynamics is not well understood. A model inter-comparison of two tritium transfer models (CTEM-CLASS-TT and SOLVEG-II) was carried out with measured environmental samples from an experimental garden plot set up next to a tritium-processing facility. The garden plot received one of three different irrigation treatments - no external irrigation, irrigation with low tritium water and irrigation with high tritium water. The contrast between the results obtained with the different irrigation treatments provided insights into the impact of soil-to-leaf HTO transfer on the leaf tritium dynamics. Concentrations of TFWT and OBT in the garden plots that were not irrigated or irrigated with low tritium water were variable, responding to the arrival of the HTO-plume from the tritium-processing facility. In contrast, for the plants irrigated with high tritium water, the TFWT concentration remained elevated during the entire experimental period due to a continuous source of high HTO in the soil. Calculated concentrations of OBT in the leaves showed an initial increase followed by quasi-equilibration with the TFWT concentration. In this quasi-equilibrium state, concentrations of OBT remained elevated and unchanged despite the arrivals of the plume. These results from the model inter-comparison demonstrate that soil-to-leaf HTO transfer significantly affects tritium dynamics in leaves and thereby OBT/HTO ratio in the leaf regardless of the atmospheric HTO concentration, only if there is elevated HTO concentrations in the soil. The results of this work indicate that assessment models should be refined to consider the importance of soil-to-leaf HTO transfer to ensure that dose estimates are accurate and conservative.
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Affiliation(s)
- Masakazu Ota
- Research Group for Environmental Science, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 Japan.
| | - Nana-Owusua A Kwamena
- Canadian Nuclear Safety Commission, 280 Slater Street, PO Box 1046, Station B, Ottawa, Ontario K1P5S9, Canada
| | - Steve Mihok
- Canadian Nuclear Safety Commission, 280 Slater Street, PO Box 1046, Station B, Ottawa, Ontario K1P5S9, Canada
| | - Volodymyr Korolevych
- Environmental, Radiological and Chemical Sciences Division, STN51A, Canadian Nuclear Laboratories, Chalk River, Ontario, Canada
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Tanaka S, Nishikawa M, Ichimasa Y, Nishi M. Activities of Tritium Studies in Japan. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst02-a22602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- S. Tanaka
- The University of Tokyo Hongou, Bunkyo, Tokyo 113-8656, JAPAN
| | - M. Nishikawa
- Kyushu University Hakozaki, Higashi, Fukuoka 812-8581, JAPAN
| | - Y. Ichimasa
- Ibaraki University HBunkyo, Mito, Ibaraki 310-8512, JAPAN
| | - M. Nishi
- Japan Atomic Energy Research Institute Tokai, Ibaraki, 319-1195, JAPAN
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Atarashi-Andoh M, Kumakura Y, Amano H, Fukui M. Formation of Organically Bound Deuterium at Each Growing Stage of Rice. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst05-a1034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Mariko Atarashi-Andoh
- Japan Atomic Energy Research Institute: Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Yasuharu Kumakura
- TAKII&CO.,Ltd.: Umekoji, Inokuma, Shimogyo-ku, Kyoto 600-8686, Japan
| | - Hikaru Amano
- Japan Atomic Energy Research Institute: Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Masami Fukui
- Research Reactor Institute, Kyoto University: Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
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Ichmasa Y, Sasajima E, Makihara H, Tauchi H, Uda T, Ichimasa M. Uptake of Heavy Water and Loss by Tangerine in the Heavy Water Vapor Release Experiment in a Greenhouse as a Substitute for Tritiated Water. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst05-a1035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Y. Ichmasa
- Department of Environmental Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan
| | - E. Sasajima
- Department of Environmental Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan
| | - H. Makihara
- Department of Environmental Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan
| | - H. Tauchi
- Department of Environmental Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan
| | - T. Uda
- Department of Environmental Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan
| | - M. Ichimasa
- Department of Environmental Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan
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Galeriu D, Melintescu A, Strack S, Atarashi-Andoh M, Kim SB. An overview of organically bound tritium experiments in plants following a short atmospheric HTO exposure. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2013; 118:40-56. [PMID: 23246588 DOI: 10.1016/j.jenvrad.2012.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 11/05/2012] [Accepted: 11/06/2012] [Indexed: 06/01/2023]
Abstract
The need for a less conservative, but reliable risk assessment of accidental tritium releases is emphasized in the present debate on the nuclear energy future. The development of a standard conceptual model for accidental tritium releases must be based on the process level analysis and the appropriate experimental database. Tritium transfer from atmosphere to plants and the subsequent conversion into organically bound tritium (OBT) strongly depends on the plant characteristics, seasons, and meteorological conditions, which have a large variability. The present study presents an overview of the relevant experimental data for the short term exposure, including the unpublished information, also. Plenty of experimental data is provided for wheat, rice, and soybean and some for potato, bean, cherry tomato, radish, cabbage, and tangerine as well. Tritiated water (HTO) uptake by plants during the daytime and nighttime has an important role in further OBT synthesis. OBT formation in crops depends on the development stage, length, and condition of exposure. OBT translocation to the edible plant parts differs between the crops analyzed. OBT formation during the nighttime is comparable with that during the daytime. The present study is a preliminary step for the development of a robust model of crop contamination after an HTO accidental release.
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Affiliation(s)
- D Galeriu
- Horia Hulubei National Institute of Physics and Nuclear Engineering, Department of Life and Environmental Physics, 30 Reactorului St., PO Box MG-6, RO-077125 Bucharest-Magurele, Romania
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Baglan N, Alanic G, Le Meignen R, Pointurier F. A follow up of the decrease of non exchangeable organically bound tritium levels in the surroundings of a nuclear research center. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2011; 102:695-702. [PMID: 21530023 DOI: 10.1016/j.jenvrad.2011.03.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 03/01/2011] [Accepted: 03/22/2011] [Indexed: 05/30/2023]
Abstract
In the past decades limited amounts of tritium were handled on the CEA site of Bruyères le Châtel with authorised atmospheric releases. A small fraction of the tritium released entered into environmental samples under three forms: (i) as part of free water (TFWT - Tissue Free Water Tritium), or associated with organic matter in two ways; either (ii) bound to the oxygen and nitrogen atoms of the material as exchangeable organically bound tritium (E-OBT), or (iii) bound to carbon atoms as non exchangeable organically bound tritium (NE-OBT). The first two components provide only a picture of atmospheric tritium concentrations at the sampling time as they are in equilibrium with atmospheric moisture and soil humidity. Unlike these exchangeable forms, however, NE-OBT is tightly bound to the organic matter and provides an integrated record of atmospheric tritium during the growing phase of the vegetation. We mapped NE-OBT in tree leaf samples in an area of about 25×30km(2) around the centre of the CEA site and compared the results with those obtained during a previous sampling exercise in 1989. At this time, the activity levels were almost ten times higher than those observed presently in a similar area almost 20 years later which is consistent with the decrease of atmospheric releases issued from the centre. As the activity levels are now close to environmental background specific attention was also paid to the analytical procedure to ensure reliable low level NE-OBT detection.
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Affiliation(s)
- N Baglan
- CEA/DAM/DIF, F-91297 Arpajon, France.
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Momoshima N, Matsushita R, Nagao Y, Okai T. Uptake of deuterium by dead leaves exposed to deuterated water vapor in a greenhouse at daytime and nighttime. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2006; 88:90-100. [PMID: 16513228 DOI: 10.1016/j.jenvrad.2006.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Revised: 07/13/2005] [Accepted: 01/11/2006] [Indexed: 05/06/2023]
Abstract
Dead leaves were exposed to deuterated water vapor (D(2)O) as a substitute of tritiated water (HTO) in a greenhouse at daytime and nighttime to examine uptake and release of tritium by dead leaves because they cover a wide area of the forest floor and are therefore a major target material to be exposed when HTO is atmospherically derived to the forest. The dead cedar needles showed faster uptake and faster release rates during and after the exposure than the fresh ones, and the equilibrium concentration of the dead cedar needles was about two times higher than the fresh ones, indicating a quick response and a high buffering potential of dead leaves. The relation between uptake of D(2)O and number of stoma was examined for dead deciduous leaves; the species with larger number of stoma accumulated more D(2)O at the daytime and nighttime exposures. However, drying of the dead leaves suppressed D(2)O uptake greatly at daytime, suggesting stomata's opening and closing controls the D(2)O uptake of dead leaves.
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Affiliation(s)
- N Momoshima
- Faculty of Science, Kumamoto University, 2-39 Kurokami, Kumamoto 860-8555, Japan.
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Tanaka S, O'hira S, Ichimasa Y. Overview of tritium safety studies in Japan. FUSION ENGINEERING AND DESIGN 2002. [DOI: 10.1016/s0920-3796(02)00240-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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