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Manabe, Sachi; Matsubara, Natsumi; Saegusa, Jun; Takeishi, Minoru
KEK Proceedings 2016-8, p.281 - 285, 2016/10
no abstracts in English
Amano, Hikaru
Fusion Science and Technology, 41(3), p.488 - 492, 2002/05
no abstracts in English
Amano, Hikaru; Atarashi, Mariko
Int. Workshop Proc., Improvement of Environmental Transfer Models and Parameters, 0, p.136 - 145, 1996/00
no abstracts in English
Amano, Hikaru; Atarashi, Mariko; Noguchi, Hiroshi; Yokoyama, Sumi; Ichimasa, Yusuke*; Ichimasa, Michiko*
Fusion Technology, 28, p.803 - 808, 1995/10
no abstracts in English
Fujiwara, Kenso; Kuwata, Haruka*
no journal, ,
Tritium is included in liquid waste from Tokyo Electric Fukushima Daiichi Nuclear Power Station. Since different concentrations of tritium in marine products and seawater was reported, concentrations of Organically Bound Tritium (OBT) and Tissue Free Water Tritium (TFWT) in marine products also have differences. Therefore, it is important to distinguish the concentration of OBT and TFWT in marine products. However, a chemical procedure of OBT analysis needs very long time because a pretreatment process is complicated. Thus, for environmental monitoring, a rapid analytical method for OBT in marine products by using oxygen combustion vessel was developed. In the case of pretreatment process combined freeze-drying with heating-drying, the total analysis time was shorter than a conventional method from 14 to 7 days.
Fujiwara, Kenso; Kuwata, Haruka*; Misono, Toshiharu; Kitamura, Akihiro
no journal, ,
Since various radionuclides including tritium was released into the ocean by the Fukushima Dai-ichi Nuclear Power Station accident, transfer of those to marine products has been concerned. In case of tritium, Organically Bound Tritium (OBT) was considered to be relatively important for the transfer due to its longer biological half-life. However, analysis of organically bound tritium (OBT), which is one of beta-emitting radionuclides, requires complicated pretreatment and takes a long time conventionally. Therefore, in this method, the time per combustion could be shortened compared to the conventional method by reviewing the combustion process in the analysis of OBT. As a result of comparing the amount and composition of water recovered after combustion, almost no difference between the two methods was observed. The analysis results of tritium in tissue free water (TFWT) and OBT in the conventional method are all below the lower limit of detection, Both TFWT and OBT were at the nSv level even if internal exposure was evaluated using these values.
Fujiwara, Kenso; Kuwata, Haruka*; Misono, Toshiharu; Kitamura, Akihiro
no journal, ,
Generally, when tritium is produced or released in the environment, it is required to confirm the behavior of organically bound tritium (OBT) due to its longer biological half-life. However, sequential treatment processes are needed to measure the concentration of each type of tritium and it takes a month for measurement of Tissue Free Water Tritium (TFWT) and a few weeks for measurement of OBT. Therefore, simplification of the processes and reduction of the duration were required for the purpose of rapid analysis and obtaining more data on environmental monitoring, especially in case of accident that requires emergency response. We are applying the analytical system composed of the TFWT separation process by means of freeze-drying and the OBT separation process by means of oxygen combustion vessel. In the TFWT separation process, a heater was attached to the outside of the freeze-dried cell, and freeze-drying and heating-drying were continuously performed quickly. The system has been improved that 90% TFWT was removed by freeze-drying and 10% TFWT was removed by heating drying. Then, the freeze-dried samples were divided for reducing the sample volume of one batch. Since the time of freeze-drying depends on the size of the sample, it could be shortened to about 3 days by dividing the sample into four. It successfully leads to reduction of measurement duration, from 14 days to 3 days. And in order to prevent isotope exchange, freeze- drying and heating-drying were performed inside the evacuated cell. In the OBT separation process, the pretreatment time was shortened by reducing the amount of combustion, and the value of detection limit was evaluated. When measured by the above-mentioned method, the tritium concentration of fish samples in Fukushima was below detection limit (several Bq/kg) and committed effective dose was very small (under 10
mSv).
Kuwata, Haruka*; Misono, Toshiharu; Terashima, Motoki; Fujiwara, Kenso; Kitamura, Akihiro
no journal, ,
Simplification of the processes and reduction of the duration were required for the purpose of rapid analysis and obtaining more data on environmental monitoring at the accident for emergency response. We are applying the analytical system composed of the TFWT separation process by means of freeze-drying and the OBT separation process by means of oxygen combustion vessel.
Fujiwara, Kenso; Kuwata, Haruka*; Terashima, Motoki; Akata, Naofumi*
no journal, ,
The analysis method for organically bound tritium is summarized in the radioactivity measurement method series managed by the regulatory agency, but the pretreatment takes time. So far, joint research has investigated shortening the pretreatment, but the pretreatment still takes about a week, and speeding up is expected. This time, we investigated the relationship between the shape and weight of the sample and the time to reach a constant weight during freeze-drying. In the freeze-drying process, by increasing the surface area of the sample, the process that used to take about two days was shortened to about one day. In addition, with the aim of promoting efficient combustion, we attempted to accumulate data that would contribute to the control of combustion temperature by suggestive thermal analysis of organic matter samples.