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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
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.
Nakada, Akira; Kanai, Katsuta; Seya, Natsumi; Nishimura, Shusaku; Futagawa, Kazuo; Nemoto, Masashi; Tobita, Keiji; Yamada, Ryohei*; Uchiyama, Rei; Yamashita, Daichi; et al.
JAEA-Review 2022-078, 164 Pages, 2023/03
JAEA-Review-2022-078.pdf:2.64MB
Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2021 to March 2022. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.
Yamashita, Takuya; Ueda, Masashi; Yamaguchi, Toshihiko; Tagawa, Akihiro; Uemoto, Yohei*; Tsujita, Yoshihiro*
no journal, ,
We are studying in service inspection of JSFR in reactor vessel and steam generator tubes. This paper describes that development of under sodium inspection in reactor vessel.
Tagawa, Akihiro; Yamashita, Takuya; Uemoto, Yohei*; Takeishi, Masayuki*
no journal, ,
For driving device of under sodium vehicle can not use motor with propeller. The main reason is that oil leaks occur most often at the shaft seals in motor. We developed electromagnetic thruster. The reason why electromagnetic thruster is that sodium have Electromagnetic-Hydro property.
Motohashi, Jun; Terauchi, Makoto; Yamashita, Takuya; Tagawa, Akihiro; Ishikawa, Satoshi*; Yamaguchi, Katsuyoshi*; Kosuge, Fumiaki*; Kinoshita, Naoki*; Homma, Ryohei*
no journal, ,
no abstracts in English
Yamashita, Takuya; Terauchi, Makoto; Motohashi, Jun; Tagawa, Akihiro; Ishikawa, Satoshi*; Yamaguchi, Katsuyoshi*; Kosuge, Fumiaki*; Kinoshita, Naoki*; Homma, Ryohei*
no journal, ,
The Restoration Support System for Environment "RESET" was developed to estimate the dose rate of post-decontamination and assist planning of the future decontamination by using a cloud computer installed on the Internet. This paper describes the outline of development of the system.
Yamashita, Takuya; Tagawa, Akihiro; Terauchi, Makoto; Motohashi, Jun; Homma, Ryohei*; Ishikawa, Satoshi*; Yamaguchi, Katsuyoshi*; Kosuge, Fumiaki*; Kinoshita, Naoki*
no journal, ,
In order to support decontamination activities, the system which evaluates the reduction effect of the environmental dose rate before and after the decontamination for a wade area was developed.
Jeon, H.; Otosaka, Shigeyoshi; Yamashita, Yohei*; Ogawa, Hiroshi*
no journal, ,
The ocean is a huge reservoir of dissolved organic carbon that contains almost the same amount of carbon in the atmosphere. Radiocarbon signatures of dissolved organic carbon (DO
C) in seawater can provide useful information on how organic carbon is produced, transported, and ultimately sequestered in the ocean's interior. In order to measure radiocarbon contents of seawater samples, they should be processed with a specific preparation system consists of the custom quartz reactor, dedicated vacuum line and UV lamp followed by radiocarbon counting with an accelerator mass spectrometer. As the first step of the study, we developed the irradiation procedure using a low-pressure Hg lamp and an oxidation catalyst. We present here not only how the system is progressing but also what radiocarbon study in the central Pacific Ocean means for better understanding of oceanic carbon cycle.
Jeon, H.; Otosaka, Shigeyoshi; Yamashita, Yohei*; Ogawa, Hiroshi*
no journal, ,
Measurements of the radiocarbon content of marine dissolved organic carbon (DOC) broadened our perspective on the role of DOC in the marine carbon cycle. However fewer measurements have been performed because of methodological difficulties associated with low concentration of DOC and an overwhelming proportion of salts. In order to collect enough DOC for radiocarbon analysis, UV oxidation is one of the most commonly used methods by irradiating seawater samples with ultraviolet light. Unlike other studies where medium pressure mercury arc UV lamp are used, this study attempts to improve the system with two grid lamps in order to reduce the demand for high electric power installation and to miniaturize the instrument for easier handling. We aim to verify the performance of improved equipment by processing C reference materials as well as seawater samples.
Oka, Toshitaka; Mitsuyasu, Yusuke*; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Sekine, Tsutomu*; Okutsu, Kenichi*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
no journal, ,
Releases of the radioactive materials from the Fukushima Daiichi Nuclear Power Plant accident result in a low dose exposure to wild animals. The external dose of wild animals is commonly estimated by the external dose rate of the captured point, but the estimated exposure dose has huge uncertainties because the size of the habitat and/or the movement of the wild animals are not included in the estimation. To estimate the external dose precisely, we utilize electron spin resonance (ESR) dosimetry. In this work, we investigated the sample preparation procedure of wild animals. The ESR spectrum of enamel of racoon captured in Namie-town, Fukushima has a broad ESR signal due to metal components. The linear relationship between the Co
intensity and the absorbed dose that we can apply ESR dosimetry for racoon teeth. Using this relationship, the external exposure dose was estimated.
Oka, Toshitaka; Takahashi, Atsushi*; Mitsuyasu, Yusuke*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Yamashita, Takuma*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
no journal, ,
Electron spin resonance (ESR) dosimetry technique is a powerful tool that has been used in the study of external exposure dose assessment of human by measuring CO radicals of teeth. In this work, we applied this technique for wild monkey and wild racoon captured in Fukushima prefecture, and estimated the external exposure dose.