Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2022

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

JAEA-Review-2023-046.pdf:4.2MB

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.

Isotopic composition of enriched Mo for production of medical Tc by Mo()Tc

Hashimoto, Shintaro; Nagai, Yasuki*

Journal of the Physical Society of Japan, 92(12), p.124202_1 - 124202_11, 2023/12

https://doi.org/10.7566/JPSJ.92.124202

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.

Reaction of Np, Am, and Cm ions with CO and O in a reaction cell in triple quadrupole inductively coupled plasma mass spectrometry

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

https://doi.org/10.1039/D3JA00136A

Sparse modeling approach for quasiclassical theory of superconductivity

Nagai, Yuki; Shinaoka, Hiroshi*

Journal of the Physical Society of Japan, 92(3), p.034703_1 - 034703_8, 2023/03

https://doi.org/10.7566/JPSJ.92.034703

no abstracts in English

Fast phase differentiation between liquid-water and ice by pulsed neutron imaging with gated image intensifier

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

https://doi.org/10.1016/j.nima.2022.167260

Large scale production of Cu and Cu via the Zn(n, p)Cu and Zn(n, np/d)Cu reactions using accelerator neutrons

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

https://doi.org/10.1007/s10967-021-07987-3

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.

Pulsed neutron imaging for differentiation of ice and liquid water towards fuel cell vehicle applications

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

https://doi.org/10.1039/D0CP03887C

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.

Anomalous radioisotope production for ZnO using polyethylene by accelerator neutrons

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

https://doi.org/10.7566/JPSJ.89.034201

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.

Smooth self-energy in the exact-diagonalization-based dynamical mean-field theory; Intermediate-representation filtering approach

Nagai, Yuki; Shinaoka, Hiroshi*

Journal of the Physical Society of Japan, 88(6), p.064004_1 - 064004_5, 2019/06

https://doi.org/10.7566/JPSJ.88.064004

no abstracts in English

Local structure analysis of light elements included in simulated radioactive waste glasses by soft X-ray absorption fine structure

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.