Technical information
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Tritium (T) is a radioactive isotope in the hydrogen group, and the almost all of the T in water (H2O) exists as an isotopic water form: HTO. Currently, over 400 facilities of atomic plants in the world are draining radioactive effluents containing T to the ocean. Because, the extraction of trace amounts of T from large quantities of water is fundamentally difficult with respect to technology and economy when using any conventional method, due to the similarities between in the physicochemical features of the isotopes in water.
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Recently, we found a suitable oxide-absorbent for extracting T from a parts-per-trillion-level aqueous solution at room temperature. This novel function that employs an abundant oxide based absorbent will promote useful developments in the fields of water purification technologies for the lightest radioactive isotope on the periodic table.
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Decreasing radioactive concentration of T is displayed as shown in Fig. 1. The absorbent 0.5 g was added to a test water 100mL in the experiment. In Fig. 1, the radioactive concentration of T was decreased from the initial value to 3000000 Bq/L at 30 min on the reaction time. Hence, the radioactive concentration of T can be estimated as 2.68 million Bq/L. Accordingly, it is possible to separate the treated water, which was decreased about 50 % of T at 30 min by in-situ monitoring T radioactive concentration using a flow type scintillation counter.
Fig. 1 Effect of absorbent (0.5g) for decreasing radioactive concentration of T in a test water (100 mL) containing T.
Fig. 2 Continual decreasing of T concentration in a test water (120 mL) at room temperature, by using a membrane containing T-absorbent (0.25g).
A novel extraction method using a membrane can prevent re-increasing of T concentration in the test water compared to the previous method using the powdered absorbent as the result shown in Fig. 1. Moreover, the dissolution of Mn from the absorbent is not detected in the test water.
Currently, we are having many progress significantly by using this method for extracting T from water at room temperature !
The latest progress in this project is explained on the Linkedin.
REFERENCES
H. Koyanaka and H. Miyatake, Extracting tritium from water using a protonic manganese oxide spinel, Separation Science and Technology, 50, 14, 2142-2146, (2015)
PCT/JP2014/074334, Adsorbent of tritium, Separation method of tritium from water, and the method for refreshment of the adsorbent, H. Koyanaka･H. Koyanaka, 2014/09/12
JP 2013-191174, JP 2013-218747, JP 2014-069967, Adsorbent of tritium, Separation method of tritium from water, and the method for refreshment of the adsorbent, H. Koyanaka･H. Koyanaka, 2013/09/13, 2013/10/21, 2014/03/28
