Development and validation of a dynamical atmosphere–vegetation–soil HTO transport and OBT formation model

Radiological impact models are important tools that support nuclear safety. For tritium, a special radionuclide that readily enters the life cycle, the processes involved in its transport into the environment are complex and inadequately understood. For example, tritiated water (HTO) enters plants by leaf and root uptake and is converted to organically bound tritium (OBT) in exchangeable and non-exchangeable forms; however, the observed OBT/HTO ratios in crops exhibit large variability and contradict the current models for routine releases.Non-routine or spike releases of tritium further complicate the prediction of OBT formation.The experimental data for a short and intense atmospheric contamination of wheat are presented together with various models' predictions. The experimental data on wheat demonstrate that the OBT formation is a long process, it is dependent on receptor location and stack dynamics, there are differences between night and day releases, and the HTO dynamics in leaf and ear is a very important contributor to OBT formation.

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“…-JAEA (Japan Atomic Energy Agency, Japan) (with SOLVEG model ), a complex research grade model (Ota and Nagai, 2011);…”

Section: Uncertainty Of Tritium Dynamics For Short Term Atmospheric Ementioning

confidence: 99%

Uncertainty of current understanding regarding OBT formation in plants

Melintescu

Galeriu

2017

Journal of Environmental Radioactivity

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“…Tritium can enter the body by ingestion of foods containing tritium and can also be drunk, inhaled, and absorbed through the skin if tritiated water (HTO) is present [1][2][3]. It pre-dominantly exists under the form of water and is widely dispersed in the environment [4][5][6][7][8][9]. In order to estimate the risks for humans due to environmental tritium, it is necessary to understand the behavior of tritium in different ecological compartments.…”

Section: Introductionmentioning

confidence: 99%

Tritium concentration in soybean plants exposed to atmospheric HTO during nighttime and daytime

Shen

Liu

2016

NUCL SCI TECH

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Potted soybean plants were exposed to evaporate HTO for 1 h inside an exposure box at two different growth stage (flowering and podding stage, filling stage) during nighttime and daytime. The concentration of tissuefree water tritium (TFWT) and organically bound tritium (OBT) in leaves and beans was measured at the end of the exposure. The results indicated that the quasi-equilibrium between the TFWT concentrations in the soybean leaves and the HTO concentration of the ambient air moisture required more than 1 h to be reached. The relative TFWT concentrations in the nighttime represent about 1/2 to 2/3 of the concentrations obtained in the day in the leaves compared to about 1/2 to 4/3 in the beans. The relative OBT concentrations under night conditions were about 2/5 to 1/2 of those under day conditions in the leaves, contrary to 1/2-7/10 for the beans. By developing tritium concentration assessment model with a short-term release of atmospheric HTO, we comprehensively considered the plant growth stage and the environmental conditions.

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“…And the tritium amounts are large for fusion power and about 56 kg tritium is required per GW year of fusion power [13]. Because of the special chemical properties and permeation, tritium is easily released into the environment and transferred to the food chain, thus causing biological effects [14][15][16][17]. Therefore, it is of high importance to study on fusion tritium environmental assessment.…”

Section: Introductionmentioning

confidence: 99%