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Iketani, Shotaro; Suzuki, Takeshi; Yokobori, Tomohiko; Sugawara, Satoshi; Yokota, Akira; Kikuchi, Genta; Muraguchi, Yoshinori; Kitahara, Masaru; Seya, Manato; Kurosawa, Tsuyoshi; et al.
JAEA-Technology 2025-001, 169 Pages, 2025/08
JAEA-Technology-2025-001.pdf:14.22MB
The radioactive waste treatment facilities at the Nuclear Science Research Institute includes the Radioactive Waste Treatment Facility No. 3, Waste Size Reduction and Storage Facility, and Waste Volume Reduction Facility. These three facilities come under the purview of the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors, and are included under Class C of the act based on the seismic requirements specified in the Act. We assessed the seismic capacity of these three radioactive waste treatment facilities based on the current Building Standards Act, to verify whether they comply with the new regulatory requirements enforced by the Nuclear Regulation Authority (NRA) in the aftermath of the 2011 nuclear accident at the Fukushima Daiichi Nuclear Power Station operated by the Tokyo Electric Power Company. We found that the allowable stress of a few structural members used in the construction of the facilities did not meet the regulatory requirements. After studying the approval granted by the NRA for the construction plans, including the design and construction methods (design and construction plans) of the three facilities on March 5, 2021, we made aseismic reinforcement at these facilities between 2021 and 2022. This report presents an overview of the seismic design of these facilities and an outline of the aseismic reinforcement conducted, management system existing, safety measures adopted, and the preoperational inspections conducted at these facilities.
Hirohata, Atsufumi*; Lloyd, D. C.*; Kubota, Takahide*; Seki, Takeshi*; Takanashi, Koki; Sukegawa, Hiroaki*; Wen, Z.*; Mitani, Seiji*; Koizumi, Hiroki*
IEEE Access, 11, p.117443 - 117459, 2023/10
Times Cited Count：6 Percentile：21.88(Computer Science, Information Systems)Porcheron, E.*; Journeau, C.*; Delacroix, J.*; Berlemont, R.*; Bouland, A.*; Lallot, Y.*; Tsubota, Yoichi; Ikeda, Atsushi; Mitsugi, Takeshi
Proceedings of International Conference on Environmental Remediation and Radioactive Waste Management (ICEM2023) (Internet), 5 Pages, 2023/10
Results of the URASOL project aimed at evaluating the generation and dispersion of radioactive aerosols during the cutting of fuel debris, a key issue in the decommissioning of the damaged reactors at the Fukushima Daiichi Nuclear Power Station (1F), are presented in this report. Characterization of aerosols generated during heating and mechanical cutting of simulated fuel debris in terms of mass concentration, real-time number density, mass-based particle size distribution, morphology, and chemical properties is reported. In the heating tests, an increase in particle size with increasing temperature was observed, and in terms of particle number density, the case using depleted uranium simulated fuel debris had a smaller number density than the test using Hf-containing simulated fuel debris. In mechanical cleavage, the aerodynamic median mass diameter of the aerosol was almost the same for the radioactive and non-radioactive samples (about 3.7
4.4 
m).
Tsubota, Yoichi; Porcheron, E.*; Journeau, C.*; Delacroix, J.*; Suteau, C.*; Lallot, Y.*; Bouland, A.*; Roulet, D.*; Mitsugi, Takeshi
Proceedings of International Conference on Environmental Remediation and Radioactive Waste Management (ICEM2023) (Internet), 6 Pages, 2023/10
In order to safely remove fuel debris from the Fukushima Daiichi Nuclear Power Station (1F), it is necessary to quantitatively evaluate radioactive airborne particulate generated by the cutting of nuclear fuel debris. We fabricated Uranium-bearing simulated fuel debris (SFD) with In/Ex-Vessel compositions and evaluated the physical and chemical properties of aerosols generated by heating the SFDs. Based on these results, we estimated the isotopic composition and radioactivity of aerosols produced when 1F-Unit2 fuel debris is laser cut, which is a typical example of a heating method. Plutonium, mainly 
Pu,
Am, and 
Cm were found to be the alpha nuclide, and Pu, 
Cs-Ba, and 
Sr-Y were found to be the beta nuclide of interest.
Yamazaki, Takumi*; Seki, Takeshi*; Kubota, Takahide*; Takanashi, Koki
Applied Physics Express, 16(8), p.083003_1 - 083003_4, 2023/08
Times Cited Count：3 Percentile：24.10(Physics, Applied)Choi, B.; Nishida, Akemi; Shiomi, Tadahiko; Kawata, Manabu; Li, Y.; Ota, Akira*; Sonobe, Hideaki*; Ino, Susumu*; Ugata, Takeshi*
Mechanical Engineering Journal (Internet), 10(4), p.23-00026_1 - 23-00026_11, 2023/08
In the seismic evaluation of nuclear facility buildings, basemat uplift-the phenomenon during which the bottom of the basemat of a building partially rises from the ground owing to overturning moments during earthquakes-is a very important aspect because it affects not only structural strength and integrity, but also the response of equipment installed in the building. However, there are not enough analytical studies on the behavior of buildings with a low ground contact ratio due to basemat uplift during earthquakes. In this study, we conducted a simulation using a three-dimensional finite element model from past experiments on basemat uplift; further, we confirmed the validity of this approach. In order to confirm the difference in the analytical results depending on the analysis code, the simulation was performed under the same analytical conditions using the three analysis codes, which are E-FrontISTR, FINAS/STAR and TDAPIII, and the obtained analysis results were compared. Accordingly, we investigated the influence of the difference in adhesion on the structural response at low ground contact ratio. In addition, we confirmed the effects of significant analysis parameters on the structural response via sensitivity analysis. In this paper, we report the analytical results and insights obtained from these investigations.
OKondo, Yosuke*; Achouri, N. L.*; Al Falou, H.*; Atar, L.*; Aumann, T.*; Baba, Hidetada*; Boretzky, K.*; Caesar, C.*; Calvet, D.*; Chae, H.*; et al.
Nature, 620(7976), p.965 - 970, 2023/08
Times Cited Count：41 Percentile：94.75(Multidisciplinary Sciences)no abstracts in English
Zhou, Z.*; Frost, W.*; Lloyd, D. C.*; Seki, Takeshi*; Kubota, Takahide*; Ramos, R.*; Saito, Eiji; Takanashi, Koki; Hirohata, Atsufumi*
Journal of Magnetism and Magnetic Materials, 571, p.170575_1 - 170575_5, 2023/04
Times Cited Count：1 Percentile：5.82(Materials Science, Multidisciplinary)
MnSiShigeta, Iduru*; Oku, Shuta*; Kubota, Takahide*; Kimura, Shojiro*; Seki, Takeshi*; Shinozaki, Bunju*; Awaji, Satoshi*; Takanashi, Koki; Hiroi, Masahiko*
AIP Advances (Internet), 13(2), p.025116_1 - 025116_5, 2023/02
Times Cited Count：1 Percentile：6.72(Nanoscience & Nanotechnology)Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Nishimura, Koji*; Hashimoto, Taishi*; Tanaka, Yoshimasa*; Kadokura, Akira*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Ogawa, Yasunobu*; et al.
Journal of Space Weather and Space Climate (Internet), 12, p.18_1 - 18_16, 2022/06
Times Cited Count：4 Percentile：28.31(Astronomy & Astrophysics)We identified two energetic electron precipitation (EEP) events during the growth phase of moderate substorms and estimated the mesospheric ionization rate for an EEP event for which the most comprehensive dataset from ground-based and space-born instruments was available. The mesospheric ionization signature reached below 70 km altitude and continued for ~15 min until the substorm onset, as observed by the PANSY radar and imaging riometer at Syowa Station in the Antarctic region. We also used energetic electron flux observed by the Arase and POES 15 satellites as the input for the air-shower simulation code PHITS to quantitatively estimate the mesospheric ionization rate. Combining the cutting-edge observations and simulations, we shed new light on the space weather impact of the EEP events during geomagnetically quiet times, which is important to understand the possible link between the space environment and climate.
Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.
Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12
Times Cited Count：7 Percentile：30.99(Geosciences, Multidisciplinary)The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.
Nogami, Satoshi*; Kadota, Kazunori*; Uchiyama, Hiromasa*; Arima-Osonoi, Hiroshi*; Iwase, Hiroki*; Tominaga, Taiki*; Yamada, Takeshi*; Takata, Shinichi; Shibayama, Mitsuhiro*; Tozuka, Yuichi*
International Journal of Biological Macromolecules, 190, p.989 - 998, 2021/11
Times Cited Count：11 Percentile：45.54(Biochemistry & Molecular Biology)Frost, W.*; Seki, Takeshi*; Kubota, Takahide*; Ramos, R.*; Saito, Eiji; Takanashi, Koki*; Hirohata, Atsufumi*
Applied Physics Letters, 118(17), p.172405_1 - 172405_5, 2021/04
Times Cited Count：3 Percentile：13.48(Physics, Applied)Shimizu, Takeshi*; Wang, H.*; Matsumura, Daiju; Mitsuhara, Kei*; Ota, Toshiaki*; Yoshikawa, Hirofumi*
ChemSusChem, 13(9), p.2256 - 2263, 2020/05
Times Cited Count：32 Percentile：73.87(Chemistry, Multidisciplinary)Kurihara, Momo*; Yasutaka, Tetsuo*; Aono, Tatsuo*; Ashikawa, Nobuo*; Ebina, Hiroyuki*; Iijima, Takeshi*; Ishimaru, Kei*; Kanai, Ramon*; Karube, Jinichi*; Konnai, Yae*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 322(2), p.477 - 485, 2019/11
Times Cited Count：8 Percentile：53.83(Chemistry, Analytical)We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the Cs results were within 
2, indicating that the methods were accurate. The relative standard deviations (RSDs) indicating the variability in the results from different laboratories were larger than the RSDs indicating the variability in the results from each separate laboratory.
Shimizu, Takeshi*; Wang, H.*; Tanifuji, Naoki*; Matsumura, Daiju; Yoshimura, Masashi*; Nakanishi, Koji*; Ota, Toshiaki*; Yoshikawa, Hirofumi*
Chemistry Letters, 47(5), p.678 - 681, 2018/05
Times Cited Count：14 Percentile：39.61(Chemistry, Multidisciplinary)Kubota, Masato; Sakurai, Takeaki*; Miyadera, Tetsuhiko*; Nakao, Hironori*; Sugita, Takeshi*; Yoshida, Yuji*
Journal of Applied Physics, 120(16), p.165501_1 - 165501_5, 2016/10
Times Cited Count：0 Percentile：0.00(Physics, Applied)We performed soft X-ray resonant scattering experiments on P3HT:PCBM blend thin films to reveal the domain structure and electronic state, where P3HT and PCBM mean regioregular poly (3-hexylthiophene) and [6,6]-phenyl-C61-buteric acid methyl ester, respectively. We measured two films, where chloroform (CF sample) and 1,2-dichlorobenzene (DCB sample) are used as solvents in the fabrication process. There is negligible X-ray incident angle dependence of the X-ray absorption spectra at the S 
-absorption edge in the CF sample, whereas the DCB sample exhibits clear incident angle dependence. We obtained the wave-number resolved spectra at 
= (1, 0, 0) for P3HT molecules in both samples. The packing growth of P3HT molecules is revealed to be much more developed in the DCB sample than the CF sample. In addition, the electronic structure at local sulfur element sites clearly changes for both of the samples.
Fujita, Hiroe*; Yuyama, Kenta*; Li, X.*; Hatano, Yuji*; Toyama, Takeshi*; Ota, Masayuki; Ochiai, Kentaro; Yoshida, Naoaki*; Chikada, Takumi*; Oya, Yasuhisa*
Physica Scripta, 2016(T167), p.014068_1 - 014068_5, 2016/02
Times Cited Count：35 Percentile：81.71(Physics, Multidisciplinary)The irradiation defects were introduced by Fe
irradiation, fission neutron irradiation and D-T neutron irradiation. After the irradiation, the deuterium ions (D
) implantation was performed and the D retention behavior was evaluated by thermal desorption spectroscopy. The experimental results indicated that dense vacancies and voids within the shallow region near the surface were introduced by Fe irradiation. The trapping state of D by vacancies and void were clearly controlled by the damage concentration and the voids would become the most stable D trapping site. For fission neutron irradiated W, most of the D was adsorbed on the surface and/or trapped by dislocation loops and no vacancies and voids for D trapping due to its lower damage concentration. D trapping by vacancies were found in the bulk of D-T neutron irradiated W, indicating that the neutron energy distribution could make a large impact on irradiation defect formation and the D retention behavior.
Shinohara, Takenao; Kai, Tetsuya; Oikawa, Kenichi; Segawa, Mariko; Harada, Masahide; Nakatani, Takeshi; Oi, Motoki; Aizawa, Kazuya; Sato, Hirotaka*; Kamiyama, Takashi*; et al.
Journal of Physics; Conference Series, 746, p.012007_1 - 012007_6, 2016/00
Times Cited Count：59 Percentile：99.77(Physics, Nuclear)no abstracts in English
Hama, Katsuhiro; Mizuno, Takashi; Sasao, Eiji; Iwatsuki, Teruki; Saegusa, Hiromitsu; Sato, Toshinori; Fujita, Tomoo; Sasamoto, Hiroshi; Matsuoka, Toshiyuki; Yokota, Hideharu; et al.
JAEA-Research 2015-007, 269 Pages, 2015/08
JAEA-Research-2015-007.pdf:68.65MBJAEA-Research-2015-007(errata).pdf:0.07MB
We have synthesised the research results from Mizunami/Horonobe URLs and geo-stability projects in the second mid-term research phase. It could be used as technical bases for NUMO/Regulator in each decision point from sitting to beginning of disposal (Principal Investigation to Detailed Investigation Phase). High quality construction techniques and field investigation methods have been developed and implemented and these will be directly applicable to the National Disposal Program (along with general assessments of hazardous natural events and processes). It will be crucial to acquire technical knowledge on decisions of partial backfilling and final closure by actual field experiments in Mizunami/Horonobe URLs as main themes for the next phases.
