Accidental Release of Elemental Tritium Gas and Tritium Oxide: Models and In Situ Experiments on Various Plant Species

• Published in: Radiation protection dosimetry 1986-09, Vol.16 (1-2), p.107-110
• Main Authors: Kirchmann, R., Gerber, G.B., Fagniart, E., Vandecasteele, C.M., van Hees, M.
• Format: Article
• Language: English
• ISSN: 0144-8420; 1742-3406
• DOI: 10.1093/oxfordjournals.rpd.a079723

Accidents involving release of tritium either in elementary form (HT) or as water vapour (HTO) can result in contamination of plants in the form of tritium water and organically bound tritium (OBT). Actual contamination levels will depend on climatic and soil conditions, photosynthetic activity, as well as on ground deposition. These factors are difficult to predict, but information on the possible range of contamination can be obtained from experiments under controlled conditions. Accordingly, experiments were carried out on the transfer of elemental tritium or tritium water vapour to different tissues of maize, potatoes or rye grass under closed circuit conditions after a 4 hour exposure. Immediate OBT incorporation in leaves was about 200 Bq.g-1 per GBq released for tritium water vapour and about 50 Bq.g-1 per GBq released for tritium gas. Loss of OBT in leaves occurred with a half-life of about 10 days after the first day after exposure to HTO; the loss was greater after exposure to HT. Stems initially contained less activity than leaves but also lost it more slowly, particularly after HT exposure. Tritium gas entered the deeper soil layers more rapidly than HTO and was converted to HTO available to plants. Considerable conversion of HT to HTO and OBT also occurred in plants.