K. Munakata

K. Wada

M. Bessho

M. Tanaka

S. Imagawa

T. Wajima

National Institute for Fusion Science (NIFS-Repository)

    The deuterium-tritium (D-T) fusion reactor is expected to be a system to provide the main electricity in the future without any serous release of hazardous products such as a radioisotope of tritium, and it is the easiest fusion reaction to achieve. Lithium will be required in amounts dependent on the reactor design concept. When liquid lithium is used as a tritium breeder and a coolant, lithium inventories are large 1). Lithium is now recovered from the mines and from salt lakes which contains about 33 million tons of lithium globally 2). Although the amount of lithium in those resources is quite insufficient at this point, alternative resources should be found to satisfy lithium inventories for nuclear fusion plants and the increasing demand for battery and so on in the near future.  Naturally occurring lithium (chemical symbol Li) (standard atomic mass: 6.941(2) atomic mass units, a.m.u.) is composed of two stable isotopes, lithium-6 and lithium-7, with the latter being by far the more abundant one: about 92.5 percent of the atoms. Lithium-6 is an important isotope in the deuterium-tritium (D-T) fusion reactor because tritium is produced from the reaction: 6Li + 1n ? 4He + 3H(tritium) + 4.78 MeV. Therefore, it is important point to secure the amount of 6Li to operate nuclear fusion reactor.Japan is oceanic and volcanic country, and development of these resources is important issue in 21stcentury. Seawater, which contains 2300 hundred million tons of lithium in total 3) and geothermal water (hot spring water) containing Li content, has thus recently become an attractive source of this element. The separation and recovery of lithium from these natural water resources byco-precipitation, solvent extraction, adsorption, etc. have been investigated 4-7).In this research, we will estimate 6Li contents in various natural waters, so firstly total Li content and other typical elements in natural water were investigated. Five different types of samples, seawater, geothermal water, hot spring water, ground water and tap water, were used in this study. Seawater was collected from the surface layer of Imari Bay, Saga prefecture. Two geothermal waters were collected from injection well of Geothermal power plants in Sumikawa and Ohnuma, Akita prefecture. Three hot spring waters were collected from hot springs in Gero, Shitajima, and Nigorigo, Gifu prefecture. Ground water was collected from Tounou mine, Gifu prefecture. Tap water was collected from National institute of fusion science, Toki, Gifu prefecture.   The concentrations of Li+, Mg2+ and Ca2+ in the samples was measured by ICP emission spectroscopy (SPS5510, SII Nanotechnology Inc.), and those of Na+, K+,Cl-, and SO42- were measured by ion chromatography (ICS-3000, Dionex Japan).     Table 1 shows Chemical compositions of various natural waters. While there are little Li+ content in ground water and tap water, three typical types of natural water, seawater, geothermal water and hot spring water, contains Li+ ion. Seawater has 0.18 mg/L of Li+, and high other elements, especially Na+ and Cl-. It is indicated that minor content of Li+ has to be separated from high contents of coexisting ions while total amount of Li+ is far large due to the large amount of seawater on earth. Geothermal waters and hot spring waters are 6-54 times higher Li+ contents than seawater, while other typical ions are lower contents.     1) Hartley, J. N. et al.: Energy 3 (1978) 337. 2) United States Geological Survey: Mineral Commodity Summaries (2011) 94. 3) Wajima, T. et al.: Proc. Renew. Energy (2006) 1489. 4) Kunugita, E. et al.: Kagaku Kogaku Ronbunshu 16 (1990) 1045. 5) Chitrakar, R. et al.: Ind. Eng. Chem. Res. 40 (2001) 2054. 6) Abe, M. et al.: Water Treat. 5 (1990) 425.7) Tang, W. et al.: J. Solid State Chem. 142 (1991) 142. Table 1 Chemical compositions of various natural waters.Li+ Na+ K+ Mg2+ Ca2+ Cl- SO42-Seawater Imari, Saga 0.17 11433 449 1422 330 18309 2073Geothermal water Sumikawa, Akita 1.69 416 82 3 15 733 156Onuma, Akita 1.02 313 51 3 12 537 206Hot spring water Gero, Gifu 1.13 106 2 0 1 228 34Shitajima, Gifu 9.7 1657 68 19 9 713 15Nigorigo, Gifu 1.62 356 61 62 100 137 604Ground water Tounou mine, Gifu 0.07 46 0 0 4 3 0Tap water Toki, Gifu 0 0 0 1 5 6 6Sample Sample pointChemical composition of various natural waters (mg/L)285§23. Investigation of Lithium Isotope Ratios in Natural Water for Resource Supply to Nuclear Fusion ReactorWajima, T., Munakata, K., Wada, K., Bessho, M. (Akita Univ.),  Tanaka, M., Imagawa, S.

Investigation of Lithium Isotope Ratios in Natural Water for Resource Supply to Nuclear Fusion Reactor

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