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Kokubun, Yuji; Nakada, Akira; Seya, Natsumi; Koike, Yuko; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; Nagai, Shinji; et al.
JAEA-Review 2023-046, 164 Pages, 2024/03
The Nuclear Fuel Cycle Engineering Laboratories conducts environmental radiation monitoring around the reprocessing plant in accordance with the "Safety Regulations for Reprocessing Plant of JAEA, Part IV: Environmental Monitoring". This report summarizes the results of environmental radiation monitoring conducted during the period from April 2022 to March 2023 and the results of dose calculations for the surrounding public due to the release of radioactive materials into the atmosphere and ocean. In the results of the above environmental radiation monitoring, many items were affected by radioactive materials emitted from the accident at the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company, Incorporated (changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016), which occurred in March 2011. Also included as appendices are an overview of the environmental monitoring plan, an overview of measurement methods, measurement results and their changes over time, meteorological statistics results, radioactive waste release status, and an evaluation of the data which deviated of the normal range.
Higuchi, Yuki*; Yoshimune, Wataru*; Kato, Satoru*; Hibi, Shogo*; Setoyama, Daigo*; Isegawa, Kazuhisa*; Matsumoto, Yoshihiro*; Hayashida, Hirotoshi*; Nozaki, Hiroshi*; Harada, Masashi*; et al.
Communications Engineering (Internet), 3, p.33_1 - 33_7, 2024/02
Hashimoto, Shintaro; Nagai, Yasuki*
Journal of the Physical Society of Japan, 92(12), p.124202_1 - 124202_11, 2023/12
Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)Tc, which is a daughter nuclide of Mo, is used worldwide for medical imaging. However, there is a problem with the supply of Tc (Mo) due to the replacement of aging reactors. A method to produce Tc by irradiating Mo with protons using medical cyclotrons has been proposed. In this study, we presented a method to determine individual excitation functions for Mo()Tc using measured excitation functions for Mo()Tc. The method was validated by comparing estimated radionuclide purities of Tc in enriched Mo samples using the determined excitation functions with measured ones. In this study, we found that the content of Mo, Mo, and Mo should be low in order to produce Tc with high radionuclide purity. The results of this study play an important role in discussion of the required Mo compositions in enriched Mo, taking into account the constraints of each facility.
Yasuda, Yosuke*; Matsumoto, Yoshihiro*; Shinohara, Takenao; Nabeshima, Fumika*; Horiuchi, Keisuke*; Nagai, Hiroki*
International Journal of Heat and Mass Transfer, 213, p.124291_1 - 124291_2, 2023/10
Times Cited Count:0 Percentile:0.99(Thermodynamics)Kazama, Hiroyuki; Konashi, Kenji*; Suzuki, Tatsuya*; Koyama, Shinichi; Maeda, Koji; Sekio, Yoshihiro; Onishi, Takashi; Abe, Chikage*; Shikamori, Yasuyuki*; Nagai, Yasuyoshi*
Journal of Analytical Atomic Spectrometry, 38(8), p.1676 - 1681, 2023/07
Times Cited Count:1 Percentile:0.02(Chemistry, Analytical)Oba, Yojiro; Motokawa, Ryuhei; Kaneko, Koji; Nagai, Takayuki; Tsuchikawa, Yusuke; Shinohara, Takenao; Parker, J. D.*; Okamoto, Yoshihiro
Scientific Reports (Internet), 13, p.10071_1 - 10071_8, 2023/06
Times Cited Count:1 Percentile:68.31(Multidisciplinary Sciences)Nagai, Yuki; Shinaoka, Hiroshi*
Journal of the Physical Society of Japan, 92(3), p.034703_1 - 034703_8, 2023/03
Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)no abstracts in English
Wallerberger, M.*; Badr, S.*; Hoshino, Shintaro*; Huber, S.*; Kakizawa, Fumiya*; Koretsune, Takashi*; Nagai, Yuki; Nogaki, Kosuke*; Nomoto, Takuya*; Mori, Hitoshi*; et al.
Software X (Internet), 21, p.101266_1 - 101266_7, 2023/02
Times Cited Count:10 Percentile:87.16(Computer Science, Software Engineering)no abstracts in English
Isegawa, Kazuhisa; Setoyama, Daigo*; Higuchi, Yuki*; Matsumoto, Yoshihiro*; Nagai, Yasutaka*; Shinohara, Takenao
Nuclear Instruments and Methods in Physics Research A, 1040, p.167260_1 - 167260_10, 2022/10
Times Cited Count:1 Percentile:30.99(Instruments & Instrumentation)Nagai, Yasuki*; Kawabata, Masako*; Hashimoto, Shintaro; Tsukada, Kazuaki; Hashimoto, Kazuyuki*; Motoishi, Shoji*; Saeki, Hideya*; Motomura, Arata*; Minato, Futoshi; Ito, Masatoshi*
Journal of the Physical Society of Japan, 91(4), p.044201_1 - 044201_10, 2022/04
Times Cited Count:2 Percentile:44.06(Physics, Multidisciplinary)Recently, Lu is considered as one of the most important medical RIs for treating neuroendocrine tumors. A plan to produce Lu with high purity by using enriched Yb samples with irradiation of deuteron beams in accelerators has been discussed. However, since the other Yb isotopes contained in the Yb sample interacts with deuterons, Lu isotopes other than Lu are produced as impurities. Since the purity of Lu is important for medical use, a method to evaluate the impurity of Lu has been required. In this study, we proposed a new method to estimate production yields of each Lu isotopes in Yb samples with arbitrary isotopic compositions by using excitation functions of Yb()Lu reactions and the particle transport calculation code PHITS. The method plays an important role in discussing the isotopic composition of enriched samples to produce high-purity Lu using accelerators.
Kawabata, Masako*; Motoishi, Shoji*; Ota, Akio*; Motomura, Arata*; Saeki, Hideya*; Tsukada, Kazuaki; Hashimoto, Shintaro; Iwamoto, Nobuyuki; Nagai, Yasuki*; Hashimoto, Kazuyuki*
Journal of Radioanalytical and Nuclear Chemistry, 330(3), p.913 - 922, 2021/12
Times Cited Count:7 Percentile:75.99(Chemistry, Analytical)Both Cu and Cu are promising radionuclides in nuclear medicine. Production yields of these radionuclides were quantified by irradiating 55.4 g of natural zinc with accelerator neutrons. Clinically suitable Cu and Cu yields were estimated by experimental based numerical simulations using 100 g of enriched Zn and Zn, respectively, and elevated neutron fluxes from 40 MeV, 2 mA deuterons. A combined thermal- and resin-separation method was developed to isolate Cu and Cu from zinc, resulting in 73% separation efficiency and 97% zinc recovery. Such methods can provide large scale production of Cu and Cu for clinical applications.
Yin, Y.-G.*; Mori, Yoshinao*; Suzui, Nobuo*; Kurita, Keisuke; Yamaguchi, Mitsutaka*; Miyoshi, Yuta*; Nagao, Yuto*; Ashikari, Motoyuki*; Nagai, Keisuke*; Kawachi, Naoki*
New Phytologist, 232(5), p.1974 - 1984, 2021/12
Times Cited Count:9 Percentile:68.09(Plant Sciences)Rice () plants have porous or hollow organs consisting of aerenchyma, which is presumed to function as a low-resistance diffusion pathway for air to travel from the foliage above the water to submerged organs. However, gas movement in rice plants has yet to be visualized in real time. In this study involving partially submerged rice plants, the leaves emerging from the water were fed nitrogen-13-labeled nitrogen ([N]N) tracer gas, and the gas movement downward along the leaf blade, leaf sheath, and internode over time was monitored.
Higuchi, Yuki*; Setoyama, Daigo*; Isegawa, Kazuhisa; Tsuchikawa, Yusuke; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao; Nagai, Yasutaka*
Physical Chemistry Chemical Physics, 23(2), p.1062 - 1071, 2021/01
Times Cited Count:6 Percentile:50.99(Chemistry, Physical)This study is the first report on liquid water and ice imaging conducted at a pulsed spallation neutron source facility. Neutron imaging can be utilised to visualise the water distribution inside polymer electrolyte fuel cells (PEFCs). Particularly, energy-resolved neutron imaging is a methodology capable of distinguishing between liquid water and ice, and is effective for investigating ice formation in PEFCs operating in a subfreezing environment. The distinction principle is based on the fact that the cross sections of liquid water and ice differ from each other at low neutron energies. In order to quantitatively observe transient freezing and thawing phenomena in a multiphase mixture (gas/liquid/solid) within real PEFCs with high spatial resolution, a pulsed neutron beam with both high intensity and wide energy range is most appropriate. In the validation study of the present work, we used water sealed in narrow capillary tubes to simulate the flow channels of a PEFC, and a pulsed neutron beam was applied to distinguish ice, liquid water and super-cooled water, and to clarify freezing and thawing phenomena of the water within the capillary tubes. Moreover, we have enabled the observation of liquid water/ice distributions in a large field of view (300 mm 300 mm) by manufacturing a sub-zero environment chamber that can be cooled down to -30C, as a step towards visualisation of full-size fuel cells.
Shinaoka, Hiroshi*; Nagai, Yuki
Physical Review B, 103(4), p.045120_1 - 045120_8, 2021/01
Times Cited Count:3 Percentile:26.56(Materials Science, Multidisciplinary)no abstracts in English
Tsukada, Kazuaki; Nagai, Yasuki*; Hashimoto, Shintaro; Minato, Futoshi; Kawabata, Masako*; Hatsukawa, Yuichi*; Hashimoto, Kazuyuki*; Watanabe, Satoshi*; Saeki, Hideya*; Motoishi, Shoji*
Journal of the Physical Society of Japan, 89(3), p.034201_1 - 034201_7, 2020/03
Times Cited Count:2 Percentile:21.72(Physics, Multidisciplinary)We found anomalously large yields of Ga, Ga, Zn and Cu by neutron irradiation on a ZnO sample in a polyethylene shield. Neutron beams are generated from the Be() reaction for 50 MeV deuterons. The yields obtained were more than 20 times larger than those in the unshielded sample. On the other hand, the yields of Ga, Ga, Zn and Cu from a metallic Zn sample and the yields of Cu, Ni and Zn from the ZnO and Zn samples were almost insensitive to the shield conditions. This finding would provide us a unique capability of accelerator neutrons to simultaneously produce a large amount of several radioisotopes, including proton induced reaction products, by using a single sample. The experimental data were compared with the yields estimated by using the Particle and Heavy Ion Transport code System and the result was discussed.
Oba, Takashi*; Ishikawa, Tetsuo*; Nagai, Haruyasu; Tokonami, Shinji*; Hasegawa, Arifumi*; Suzuki, Gen*
Scientific Reports (Internet), 10(1), p.3639_1 - 3639_11, 2020/02
Times Cited Count:18 Percentile:84.26(Multidisciplinary Sciences)Internal doses of residents after the Fukushima Daiichi Nuclear Power Station accident have been reconstructed. In total 896 behaviour records in the Fukushima Health Management Survey were analysed to estimate thyroid doses via inhalation, using a spatiotemporal radionuclides concentration database constructed by atmospheric dispersion simulations. After a decontamination factor for sheltering and a modifying factor for the dose coefficient were applied, estimated thyroid doses were close to those estimated on the basis of direct thyroid measurement. The median and 95th percentile of thyroid doses of 1-year-old children ranged from 1.2 to 15 mSv and from 7.5 to 30 mSv, respectively.
Nagai, Yuki; Shinaoka, Hiroshi*
Journal of the Physical Society of Japan, 88(6), p.064004_1 - 064004_5, 2019/06
Times Cited Count:11 Percentile:64.45(Physics, Multidisciplinary)no abstracts in English
Kobayashi, Hideki*; Nagai, Shin*; Kim, Y.*; Yan, W.*; Ikeda, Kyoko*; Ikawa, Hiroki*; Nagano, Hirohiko; Suzuki, Rikie*
Remote Sensing, 10(7), p.1071_1 - 1071_19, 2018/07
Times Cited Count:13 Percentile:50.87(Environmental Sciences)Plant phenology timings, such as spring green-up and autumn senescence, are essential state information characterizing biological responses and terrestrial carbon cycles. Current efforts for the in situ reflectance measurements are not enough to obtain the exact interpretation of how seasonal spectral signature responds to phenological stages in boreal evergreen needleleaf forests. This study shows the first in situ continuous measurements of canopy scale (overstory + understory) and understory spectral reflectance and vegetation index in an open boreal forest in interior Alaska. Two visible and near infrared spectroradiometer systems were installed at the top of the observation tower and the forest understory, and spectral reflectance measurements were performed in 10 min intervals from early spring to late autumn. We found that canopy scale normalized difference vegetation index (NDVI) varied with the solar zenith angle. On the other hand, NDVI of understory plants was less sensitive to the solar zenith angle. Due to the influence of the solar geometry, the annual maximum canopy NDVI observed in the morning satellite overpass time (10-11 am) shifted to the spring direction compared with the standardized NDVI by the fixed solar zenith angle range (60-70 degree). We also found that the in situ NDVI time-series had a month-long high NDVI plateau in autumn, which was completely out of photosynthetically active periods when compared with eddy covariance net ecosystem exchange measurements. The result suggests that the onset of an autumn high NDVI plateau is likely to be the end of the growing season. In this way, our spectral measurements can serve as baseline information for the development and validation of satellite-based phenology algorithms in the northern high latitudes.
Okamoto, Yoshihiro; Nagai, Takayuki; Kaneko, Koji; Motokawa, Ryuhei; Haga, Yoshinori; Yamanaka, Keisuke*; Ota, Toshiaki*
2017-Nendo Seika Kokaigata Riyo Seika Hokokusho (Ritsumeikan Daigaku SR Senta), p.33 - 36, 2018/00
The high-level radioactive waste solution which generated from a spent nuclear fuel reprocessing process are mixed with a borosilicate glass frit in a vitrification process, and a chemical stable glass solidified body is produced. To understand local structure of light elements included in a glass solidified body, we carried out a B K-edge XANES measurement of raw glass frits and simulated radioactive waste glasses. As a result of this estimation of boron local structure in glass samples, it was found that the sp type boron (BO) percentage increases and the sp type (BO) percentage by increasing the sodium content in glass frits.
Minato, Futoshi; Tsukada, Kazuaki; Sato, Nozomi*; Watanabe, Satoshi*; Saeki, Hideya*; Kawabata, Masako*; Hashimoto, Shintaro; Nagai, Yasuki*
Journal of the Physical Society of Japan, 86(11), p.114803_1 - 114803_6, 2017/11
Times Cited Count:10 Percentile:56.7(Physics, Multidisciplinary)We have measured the yield of Mo, the mother nuclide of Tc used in nuclear diagnostic procedure. Mo was produced by Mo(,)Mo using neutrons with thermal energy up to about 40 MeV, provided by C(,). The Mo yield agrees with an estimated yield with the use of the latest data of C(,) and the evaluated cross section given in the JENDL. Based on this, a new calculation was carried out to produce Mo to seek for a good economical condition. Various conditions such as the MoO sample mass, the distance between the carbon target and the sample, the radius of the deuteron beam, and the neutron irradiation time were considered. The calculated Mo yield indicates that about 30% of the Mo demand in Japan can be fulfilled with a single accelerator. The elusion of Tc from the Mo twice per day would meet about 50% of the Mo demand.