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Nakasone, Shunya*; Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; et al.
Plasma and Fusion Research (Internet), 16, p.2405035_1 - 2405035_5, 2021/02
Removal of impurities such as organic and other types of dissolved matters from environmental water samples is required for precise analysis of tritium with a liquid scintillation counting method. In general, a distillation method is a conventional one for tritium analysis in environmental water samples, but is a time-consuming process that takes 24 hours for removal of impurities. We have proposed a rapid pretreatment method for tritium analysis, that uses ion exchange resins. In this study, we performed batch experiments, to evaluate the effectiveness of the ion exchange resins on the tritium measurement. The results obtained demonstrated that removal of impurities in the sample water by ion exchange resins can be achieved during a short period of time (i.e., in 5 min).
Hirouchi, Jun; Tani, Kotaro*; Tamakuma, Yuki*; Nakasone, Shunya*; Koike, Hiromi*
Hoken Butsuri (Internet), 55(4), p.185 - 190, 2020/12
no abstracts in English
Nakasone, Shunya*; Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; et al.
Plasma and Fusion Research (Internet), 15, p.2405027_1 - 2405027_3, 2020/05
A quick preprocessing system for tritium analysis of environmental samples is important to judge environmental influence of tritium releases due to accident or tritium-handling facilities. Analysis of tritium in water samples with liquid scintillation counting method requires removal of impurities such as organic matter and ion species from water samples. Generally, a distillation method is adopted as a pretreatment of analysis for tritium; however, the distillation method is a time-consuming process. The aim of this study is to evaluate a rapid pretreatment method for tritium analysis with ion exchange resin. From batch and column experiments that used inland water and ion exchange resin, we confirmed removals of impurities of the water sample and that the removal of impurities was possible for a short time (by 5 minutes).
Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; Atarashi-Andoh, Mariko; et al.
Plasma and Fusion Research (Internet), 14(Sp.2), p.3405099_1 - 3405099_4, 2019/06
The Large Helical Device of the National Institute for Fusion Science started D-D experiments in 2017. To ensure the safety of the facility, it is important to develop evaluation methods for environmental tritium transfer. Tritiated water (HTO) in atmosphere and soil is transferred to plants, and organically bound tritium (OBT) is formed by photosynthesis. Prediction of OBT formation is important, because OBT accumulates in plants and causes dose through ingestion. The objective of this study is to estimate environmental tritium transfer using a simple compartment model and practical parameters. We proposed a simple compartment model consisting of air-soil-plant components, and tried to validate the model by comparison with a sophisticated model, SOLVEG. In this study, we plan to add wet deposition to the model and obtain parameters from measurements of soil permeability and tritium concentrations in air, soil and plants. We also establish rapid pretreatment methods for OBT analysis.
Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; Atarashi-Andoh, Mariko; et al.
no journal, ,
To ensure safety of fusion facilities, it is important to develop evaluation methods for tritium transfer in the environment. For estimation of tritium transfer in the terrestrial environment, we had developed a simple compartment model using the Migration Of GRound Additions (MOGRA) code. The model was composed by an air-soil-plant system. The target source terms were HT and HTO in the air. In addition, wet deposition was modeled by input of HTO to the system by rainfall. Tritium in the plant was divided into free water tritium (FWT) and organically bound tritium (OBT). The tritium concentration in the environmental medium was trial calculated for chronic and accidental HTO releases to the atmosphere, as preliminary calculation run of the model.
Kakiuchi, Hideki*; Tanaka, Masahiro*; Fukutani, Satoshi*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; Atarashi-Andoh, Mariko; Furukawa, Masahide*; et al.
no journal, ,
no abstracts in English
Nakasone, Shunya*; Yoshii, Taiki*; Shibuya, Kengo*; Yunoki, Akira*; Sakai, Hirotaka*; Shimada, Taro; Manabe, Seiya*; Matsumoto, Tetsuro*
no journal, ,
Cable has become subject to clearance since the revision of the clearance regulations. Ni-63, a nuclide that is difficult to measure, is produced by the activation of copper in cables. When calculating the amount of Ni-63 produced, the activation cross section in the thermal neutron region differs by a factor of about 6 between nuclear data libraries, so that accurate activation calculations have not been possible. Therefore, the purpose of this study is to improve the accuracy of the calculation of Cu activation and to estimate the reaction cross section of Cu-63(n,p)Ni-63 in the thermal neutron region with good accuracy based on actual measurements. In this presentation, the uncertainty of the thermal neutron fluence contributing to the Cu activation was evaluated using Au-198 after neutron irradiation at JRR-3 in JAEA. High-purity gold and copper samples were placed alternately, and the entire sample was packaged in aluminum foil and sealed in an irradiation capsule, which was placed at the bottom of JRR-3 HR-2 with the capsule lid facing upward. Three irradiation capsules were prepared and irradiated with neutrons for 10, 20, and 30 minutes, respectively. About 50 days after irradiation, the radioactivity was measured using a Ge semiconductor detector. The results showed that the radioactivity per unit mass of gold samples irradiated in each irradiation was the highest in the sample placed at the top of the capsule and decreased by 6
8% toward the bottom of the capsule. This trend is reasonable. The average value of the thermal neutron fluence rate for all samples was 7 
10
cm
s
. These results confirm that the thermal neutron fluence can be determined with an accuracy on the order of percent.
