H. Obayashi

H. Yamanishi

M. Ichimasa

N. Momoshima

T. Hisamatu

T. Okai

Y. Ichimasa

Y. Sakuma

National Institute for Fusion Science (NIFS-Repository)

§7. Environmental Tritium Studies at Toki Site of NIFS (1993) lchimasa, Y., lchimasa, M. (lbaraki Univ. Sci.) Okai, T. (Kyushu Univ. Eng.) Hisamatu, T. (Akita Univ. Med.) Momoshima, N. (Kyushu Univ. Sci.) Obayashi, H., Sakuma, Y., Yamanishi, H. Tritium monitoring method around nuclear fusion plant is under developing as a model case at Toki area where fusion research installations are constructed by NIFS. Background tritium concentrations and their variations in air, pine needles, litter and underlying humus at pine trees were therefore investigated. Three kinds of chemical form of tritium, water vapor (HTO), molecular hydrogen (HT) and hydrocarbons (primarily methane, CH3T), were also collected successively from air by specially developed sampling system and tritium concentration was determined. Further measurements should be necessary to clarify the background levels of environmental tritium and their variations at Toki area. Othetwhile, we have been studing seasonal changes in tritium gas oxidation activity in surface soil, various plant leaves, mosses and lichens in in vitro experiments, in order to obtain basic data to estimate their contribution to oxidation of tritium gas released in the environment from a nuclear fusion facility and td evaruate the absorption dose. To investigate whether tritium gas is biologically oxidized in the air, isolation of airbone bacteria with tritium gas oxidation activity was intended. The numbers of airbone bacteria in the air at Toki and Higashiyama area was small, but tritium gas oxidizing airbone bacteria were obtained. Table 1 shows tritium gas oxidation activity ( hydro-genase) of these airbone bacteria compared with those obtained from Ibaraki prefecture. Identification of these bacteria was undertaken using morphological and biochemichal analyses. The scanning electron microscopic pictures of some typical bacteria collected from NIFS were showen in Figure 1. Table 1 Isolated airbone bacteria with hydrogenase St:rain* HT Oxid:otJ"tion St:rain~ HT Oxidation ("/min/vial) ("/nti n/va i I) #W. W. -1-2-4 1.:>"2 23 #Coop-1-1-6 0. It 0 - 1-3-1 1. 20 24 0-t-4-3 0. I 0 0-1-3-3 0. 84 25 B-1-2-6 0. 067 4 0-t-3-6 0. 84 26 #T.-1-1-7 0. 061 5 F.S.-1-1-3 0. 82 27 0-1-2-7 0. 060 6 A-1-2-4 0. 71 28 #G. -1-4-7 0. 053 0-1-3-2 0. 61 29 F. S. -t-5-8 0. 050 8 0-1-1-1 0. 59 30 0.-1-1-7 0. 044 9 #Coop-1 -1 -8 0. 58 31 F. S. -1-5-1 0. 042 10 0.-1-1-6 0. 57 32 0-1-<4-8 0. 039 11 C-1-1-2 0. 53 33 B-1-5-7 0. 029 12 0-1-1-5 0. 52 34 #Coop-1-4-2 0. 026 13 0-1-3-4 0. 43 35 0. -1-1-1 0. 025 14 F. S. -1-5-5 0. 43 36 0-1-4-1 0. 023 15 SB' -3-<4 0. 38 37 0. -1-3-5 0. 020 16 A-1-2-3 0. 29 38 SF' -2-3 0. 016 17 #Forea't-1-2-4 o. 29 39 0. -1-2-6 0. 016 18 B-1 -2-4 o. 25 40 #W. W. -1-2-6 0. 016 19 &7-1-1 0 . 23 B-1-1-3 0. 015 20 0. -1-2-5 0. 22 42 0. -1-2-2 0. 0093 21 B-1-2-7 0. 21 43 &7-1-6 0. 0081 22 #T. -1-2-2 0. 19 0.-1-1-8 0. 0044 s Nagoya-shi (H l gash i yalfta)(N I FS) & Toki-shi (NIFS) Fig. 1. 269 

Environmental Tritium Studies at Toki Site of NIFS (1993)

Environmental Tritium Studies at Toki Site of NIFS (1993)

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