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Sumita, Takehiro*; Osawa, Takahito; Chiu, I.-H.; Ikeda, Atsushi
Analytica Chimica Acta, 1329, p.343256_1 - 343256_10, 2024/11
Sumita, Takehiro; Ikeda, Atsushi
Isotope News, (783), p.28 - 32, 2022/10
no abstracts in English
Liu, J.; Dotsuta, Yuma; Sumita, Takehiro; Kitagaki, Toru; Onuki, Toshihiko; Kozai, Naofumi
Journal of Radioanalytical and Nuclear Chemistry, 331(6), p.2785 - 2794, 2022/06
Times Cited Count：4 Percentile：63.92(Chemistry, Analytical)Remnant nuclear fuel debris in the damaged nuclear reactors at the Fukushima Daiichi Nuclear Power Plant (FDNPP) has contacted the groundwater containing microorganisms for over ten years. Herein, we report the possibility of bacterial alteration of fuel debris. We investigated the physical and chemical changes of fuel debris simulants (FDS) in the powder and pellet forms via exposure to two ubiquitous bacteria, Pseudomonas fluorescens and Bacillus subtilis. In the experiments using FDS composed of the powders of Fe(0), solid solution of CeO
and ZrO, and SiO, Ce, Zr, and Si were hardly dissolved, while Fe was dissolved, a fraction of the dissolved Fe was present in the liquid phase as Fe(II) and Fe(III), and the rest was precipitated as the nano-sized particles of iron (hydr)oxides. In the experiment using P. fluorescens and FDS pellet pieces prepared by melting the Fe(0) particles and solid solution of CeO and ZrO, the bacteria selectively gathered on the Fe(0) particle surface and made corrosion pits. These results suggest that bacteria in groundwater corrode the iron in fuel debris at FDNPP, change fuel debris into porous one, releasing the nano-sized iron (hydr)oxide particles into the water.
temperature measurement for lamp-based heating deviceSumita, Takehiro; Sudo, Ayako; Takano, Masahide; Ikeda, Atsushi
Science and Technology of Advanced Materials; Methods (Internet), 2(1), p.50 - 54, 2022/02
CSumita, Takehiro; Kobata, Masaaki; Takano, Masahide; Ikeda, Atsushi
Materialia, 20, p.101197_1 - 101197_11, 2021/12
C eutectic mixtureSumita, Takehiro; Kitagaki, Toru; Takano, Masahide; Ikeda, Atsushi
Journal of Nuclear Materials, 543, p.152527_1 - 152527_15, 2021/01
Times Cited Count：13 Percentile：87.70(Materials Science, Multidisciplinary)Chiu, I.-H.; Osawa, Takahito; Sumita, Takehiro*; Ikeda, Mizuha*; Ninomiya, Kazuhiko*; Takeda, Shinichiro*; Minami, Takahiro*; Takahashi, Tadayuki*; Watanabe, Shin*
no journal, ,
no abstracts in English
Chiu, I.-H.; Osawa, Takahito; Sumita, Takehiro*; Ikeda, Mizuha*; Ninomiya, Kazuhiko*; Takeda, Shinichiro*; Takahashi, Tadayuki*; Minami, Takahiro*; Watanabe, Shin*
no journal, ,
Boron neutron capture therapy (BNCT) is a cancer treatment method that uses neutrons. After administering a boron drug that has the property of collecting in cancer cells to the human body, the affected area is irradiated with neutrons, and the generated alpha rays selectively destroy the cancer cells. To confirm the effectiveness of the treatment, it is extremely important to accurately confirm the area where boron reacts with neutrons. Therefore, we investigated the possibility of applying BNCT-SPECT using a CdTe double-sided strip-type detector. The CdTe-DSD is a comma-ray two-dimensional imaging detector that combines a high energy resolution of several keV with a FWHM of several hundred keV and a spatial resolution of 250 micro-m. By utilizing such high resolution of the detector, the prompt gamma rays originating from boron that causes a nuclear reaction can be detected, and the localization location of boron can be precisely identified. In this study, the CdTe-DSD was combined with a pinhole collimator to evaluate the boron distribution in solid samples in the research reactor JRR-3 of the Japan Atomic Energy Agency. The sample weighed 8.86 mg and contained 0.3 mg of boron. The figure shows the energy spectrum measured in this experiment and an image in the boron signal region. A circular boron projection image with a diameter of 11.5 mm was successfully obtained. The boron count rate was 0.115 cps and the signal-to-noise ratio was about 0.25. These results indicate that the CdTe-DSD has the potential to contribute to the development of BNCT-SPECT.
Chiu, I.-H.; Osawa, Takahito; Sumita, Takehiro*; Ikeda, Mizuha*; Ninomiya, Kazuhiko*; Takeda, Shinichiro*; Minami, Takahiro*; Takahashi, Tadayuki*; Watanabe, Shin*
no journal, ,
Chiu, I.-H.; Osawa, Takahito; Sumita, Takehiro*; Ikeda, Mizuha*; Ninomiya, Kazuhiko*; Takeda, Shinichiro*; Minami, Takahiro*; Takahashi, Tadayuki*; Watanabe, Shin*
no journal, ,
no abstracts in English
Sumita, Takehiro*; Yonekawa, Kazuo*; Sekio, Yoshihiro; Sato, Isamu*; Kobayashi, Yoshinao*; Osaka, Masahiko; Maeda, Koji; Akasaka, Naoaki
no journal, ,
During Fukushima Daiichi Nuclear Power Plant (1F) accident, high radionuclides such as 
Cs and 
I were mainly released as fission products (FPs) due to fuel melting in units 1 to 3, and it increased radiation dose in reactor buildings. With the aim of 1F decommissioning, it is necessary to establish methods to retrieve fuel and an adequate access route, which requires knowledge of Cs adsorption behavior on the surface of structural materials during Severe Accidents (SA). However, there are no Cs adsorption behavior evaluations under the simulated SA condition with high pressure in the previous studies. In this study, CsI adsorption behavior on SUS304L under the condition was evaluated using newly designed apparatus which can control temperature, pressure, moisture and gas atmosphere. The findings from microstructural observation and elemental analysis after the adsorption test suggested that the adsorption of CsI was influenced by especially pressure.
