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-edge for Ce in bauxites using transition-edge sensors; Implications for Ti-rich geological samplesLi, W.*; Yamada, Shinya*; Hashimoto, Tadashi; Okumura, Takuma*; Hayakawa, Ryota*; Nitta, Kiyofumi*; Sekizawa, Oki*; Suga, Hiroki*; Uruga, Tomoya*; Ichinohe, Yuto*; et al.
Analytica Chimica Acta, 1240, p.340755_1 - 340755_9, 2023/02
Times Cited Count：2 Percentile：31.9(Chemistry, Analytical)no abstracts in English
Hayakawa, Sho*; Okita, Taira*; Itakura, Mitsuhiro; Kawabata, Tomoya*; Suzuki, Katsuyuki*
Journal of Materials Science, 54(16), p.11096 - 11110, 2019/08
Times Cited Count：11 Percentile：42.21(Materials Science, Multidisciplinary)Ishimori, Yuu; Yokoyama, Kaoru*; Hayakawa, Tomoya; Hata, Haruhi; Sakoda, Akihiro; Naganuma, Masaki
Dekomisshoningu Giho, (55), p.36 - 44, 2017/03
This paper gives an outline of the current status of uranium measurements and their related techniques at the Ningyo-toge Environmental Engineering Center of Japan Atomic Energy Agency. The JAWAS-N and the Q
system have been adopted to evaluate uranium contents in the wastes. About 10 g or more of uranium in a 200 
drum can be evaluated by these systems. The equivalent model developed to correct the evaluation results with Q system is not available to less than dozens of grams of uranium in a 200 L drum. The paper illustrates the advantage of use of the improved equivalent model which evaluates uranium content from full energy peak of 1001 keV and its Compton spectrum in order to correct the inhomogeneous distribution of uranium in measuring objects. The use of model achieved the limit of uranium quantitative determination under one tenth of those of previous evaluation methods. To determine 
U, it was demonstrated that the shielding factor, 
for evaluation of 1001 keV 
-ray is also possible to use for evaluation of 186 keV -ray. The measurement systems adopting the model have been introduced to other nuclear operators in Japan. In addition, it is also examined to use for clearance. As a related technique, feasibility studies on machine learning algorithms have been performed to classify the waste drums depending on their -ray spectrum.
Yomogida, Takumi; Yamada, Shinya*; Ichinohe, Yuto*; Sato, Toshiki*; Hayakawa, Ryota*; Okada, Shinji*; Toyama, Yuichi*; Hashimoto, Tadashi; Noda, Hirofumi*; Isobe, Tadaaki*; et al.
no journal, ,
Biotite is known as a host phase that retains uranium (U) in uranium deposits at Ningyo-Toge and Tono, and it is expected that the distribution of U in biotite will provide insight into the concentration and long-term immobilization of U. However, biotite contains rubidium (Rb), which interferes with X-ray fluorescence analysis, making it difficult to accurately determine the distribution of U-Rb in biotite by measurement using a conventional solid state detector (SSD). In this study, we developed a method to use a transition edge sensor (TES) as a detector in microbeam X-ray fluorescence analysis, which enables us to detect X-ray fluorescence with an energy resolution of about 20 eV and to obtain a Rb K
line at 13.373 keV and a U L line at 13.612 keV can be completely separated. Therefore,the developed method enables us to accurately determine the distribution of U-Rb in biotite.
Yomogida, Takumi; Yamada, Shinya*; Ichinohe, Yuto*; Sato, Toshiki*; Hayakawa, Ryota*; Okada, Shinji*; Toyama, Yuichi*; Hashimoto, Tadashi; Noda, Hirofumi*; Isobe, Tadaaki*; et al.
no journal, ,
The reduction of uranium on biotite was studied to obtain insight into the immobilization of uranium in the environment. The chemical species of uranium in biotite were studied using a superconducting transition edge sensor and an X-ray emission spectrometer to remove interference from rubidium in biotite. As a result, the speciation of uranium in biotite collected from former uranium deposits was possible. The XANES spectra of the biotite indicated that the uranium in the biotite was partially reduced.
