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JAEA Reports

Annual report on the effluent control of low level liquid waste in Nuclear Fuel Cycle Engineering Laboratories FY2022

Kokubun, Yuji; Nakada, Akira; Seya, Natsumi; Nagaoka, Mika; Koike, Yuko; Kubota, Tomohiro; Hirao, Moe; Yoshii, Hideki*; Otani, Kazunori*; Hiyama, Yoshinori*; et al.

JAEA-Review 2023-052, 118 Pages, 2024/03

JAEA-Review-2023-052.pdf:3.67MB

Based on the regulations (the safety regulation of Tokai Reprocessing Plant, the safety regulation of nuclear fuel material usage facilities, the radiation safety rule, the regulation about prevention from radiation hazards due to radioisotopes, which are related with the nuclear regulatory acts, the local agreement concerning with safety and environment conservation around nuclear facilities, the water pollution control law, and by law of Ibaraki Prefecture), the effluent control of liquid waste discharged from the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency has been performed. This report describes the effluent control results of the liquid waste in the fiscal year 2022. In this period, the concentrations and the quantities of the radioactivity in liquid waste discharged from the reprocessing plant, the plutonium fuel fabrication facilities, and the other nuclear fuel material usage facilities were much lower than the limits authorized by the above regulations.

Journal Articles

Radiocesium-bearing microparticles cause a large variation in $$^{137}$$Cs activity concentration in the aquatic insect ${it Stenopsyche marmorata}$ (Tricoptera: Stenopsychidae) in the Ota River, Fukushima, Japan

Ishii, Yumiko*; Miura, Hikaru*; Jo, J.*; Tsuji, Hideki*; Saito, Rie; Koarai, Kazuma; Hagiwara, Hiroki; Urushidate, Tadayuki*; Nishikiori, Tatsuhiro*; Wada, Toshihiro*; et al.

PLOS ONE (Internet), 17(5), p.e0268629_1 - e0268629_17, 2022/05

 Times Cited Count:3 Percentile:45.99

We investigated the variability in $$^{137}$$Cs activity concentration in individual aquatic insects in detritivorous caddisfly (${it Stenopsyche marmorata}$) and carnivorous dobsonfly (${it Protohermes grandis}$) larvae from the Ota River, Fukushima. Caddisfly larvae showed sporadically higher radioactivity, whereas no such outliers were observed in dobsonfly larvae. Autoradiography and scanning electron microscopy analyses confirmed that these caddisfly larvae samples contained radiocesium-bearing microparticles (CsMPs), which are insoluble Cs-bearing silicate glass particles. CsMPs were also found in potential food sources of caddisfly larvae, such as periphyton and drifting particulate organic matter, indicating that larvae may ingest CsMPs along with food particles of similar size. Although CsMPs distribution and uptake by organisms in freshwater ecosystems is relatively unknown, our study demonstrates that CsMPs can be taken up by aquatic insects.

Journal Articles

Dynamics of radiocaesium within forests in Fukushima; Results and analysis of a model inter-comparison

Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.

Journal of Environmental Radioactivity, 238-239, p.106721_1 - 106721_10, 2021/11

 Times Cited Count:8 Percentile:58.13(Environmental Sciences)

This study was aimed at analysing performance of models for radiocesium migration mainly in evergreen coniferous forest in Fukushima, by inter-comparison between models of several research teams. The exercise included two scenarios of countermeasures against the contamination, namely removal of soil surface litter and forest renewal, and a specific konara oak forest scenario in addition to the evergreen forest scenario. All the models reproduced trend of time evolution of radiocesium inventories and concentrations in each of the components in forest such as leaf and organic soil layer. However, the variations between models enlarged in long-term predictions over 50 years after the fallout, meaning continuous field monitoring and model verification/validation is necessary.

Journal Articles

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

 Times Cited Count:30 Percentile:96.87(Astronomy & Astrophysics)

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 $$^{circ}$$C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 $$^{circ}$$C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Journal Articles

Effect of crystal orientation on incipient plasticity during nanoindentation of magnesium

Somekawa, Hidetoshi*; Tsuru, Tomohito; Singh, A.*; Miura, Seiji*; Schuh, C. A.*

Acta Materialia, 139, p.21 - 29, 2017/10

 Times Cited Count:26 Percentile:80.02(Materials Science, Multidisciplinary)

The effect of crystal orientation on incipient plasticity during nanoindentation was investigated by experiments and molecular statics simulation. Pop-in behavior is a result of dislocation activity, and is therefore influenced by crystal orientation. Experimental results using single crystals indicated that indentations on the basal plane had higher pop-in loads and larger pop-in displacements than those on the prismatic plane, an effect also captured by molecular statics simulation. The difference can be traced to the types of activated dislocations, with not only basal but also pyramidal dislocations active for indentations on the basal plane, but only basal dislocations triggered at the first pop-in on the prismatic plane.

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

Journal Articles

The Beam diagnostics system for J-PARC synchrotrons

Hayashi, Naoki; Hiroki, Seiji; Sato, Kenichiro; Toyokawa, Ryoji; Arakawa, Dai*; Lee, S.*; Hashimoto, Yoshinori*; Miura, Takako*; Toyama, Takeshi*

KEK Proceedings 2006-15 (CD-ROM), p.128 - 130, 2007/03

The beam diagnostics system for J-PARC synchrotrons (RCS and MR) will be presented. The design of the system will be described for high current machines. Some test results will be reported.

Journal Articles

Development of the beam diagnostics system for the J-PARC rapid-cycling synchrotron

Hayashi, Naoki; Hiroki, Seiji; Kishiro, Junichi*; Teruyama, Yuzo*; Toyokawa, Ryoji; Arakawa, Dai*; Lee, S.*; Miura, Takako*; Toyama, Takeshi*

Proceedings of 2005 Particle Accelerator Conference (PAC '05) (CD-ROM), p.299 - 301, 2005/00

Development of the beam diagnostics system for the J-PARC (Japan Proton Accelerator Research Complex) Rapid-Cycling Synchrotron is described. The system consists of Beam Position Monitor (BPM), Beam Loss Monitor (BLM), Current monitors (DCCT, SCT, MCT, FCT, WCM), Tune meter system, 324MHz-BPM, Profile monitor, and Halo monitor. BPM electrode is electro-static type and its electronics is designed for both COD and turn-by-turn measurements. Five current monitors have different time constants in order to cover wide frequency range. The tune meter is consisted of RFKO and the beam pick-up electrode. For the continuous injected beam monitoring, 324MHz-BPM detects Linac frequency. Two types of profile monitor are multi-wire for low intensity tuning and the residual gas monitor for non-destructive measurement.

Journal Articles

Prototype tokamak fusion power reactor based on SiC/SiC composite material, focussing on easy maintenance

Nishio, Satoshi; Ueda, Shuzo; Kurihara, Ryoichi; Kuroda, Toshimasa*; Miura, H.*; Sako, Kiyoshi*; Takase, Kazuyuki; Seki, Yasushi; Adachi, Junichi*; Yamazaki, Seiichiro*; et al.

Fusion Engineering and Design, 48(3-4), p.271 - 279, 2000/09

 Times Cited Count:16 Percentile:72.09(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Japanese contributions to blanket design for ITER

Kuroda, Toshimasa*; Yoshida, Hiroshi; Takatsu, Hideyuki; Seki, Yasushi; Noda, Kenji; Watanabe, H.; Koizumi, Koichi; Nishio, Satoshi; *; *; et al.

JAERI-M 91-133, 191 Pages, 1991/08

JAERI-M-91-133.pdf:5.79MB

no abstracts in English

JAEA Reports

Japanese contributions to ITER testing program of solid breeder blankets for DEMO

Kuroda, Toshimasa*; Yoshida, Hiroshi; Takatsu, Hideyuki; *; Mori, Seiji*; *; *; Hirata, Shingo*; Miura, H.*

JAERI-M 91-063, 72 Pages, 1991/04

JAERI-M-91-063.pdf:1.55MB

no abstracts in English

Oral presentation

The Precipitation behavior of $$gamma$$ double-prime (Ni$$_{3}$$Nb) in the high Ni steel

Sano, Keisuke*; Ono, Naoko*; Ukai, Shigeharu*; Hayashi, Shigenari*; Miura, Seiji*; Yamashita, Shinichiro; Inoue, Toshihiko

no journal, , 

no abstracts in English

Oral presentation

The Precipitation behavior of $$gamma$$ double-prime (Ni$$_{3}$$Nb) in the high Ni steel

Sano, Keisuke*; Ono, Naoko*; Ukai, Shigeharu*; Hayashi, Shigenari*; Miura, Seiji*; Yamashita, Shinichiro; Inoue, Toshihiko

no journal, , 

JAEA is study in the high Ni-alloy behavior as ODS substitute materials for the use in fast reactor. The precipitation behavior of $$gamma$$ double-prime (Ni$$_{3}$$Nb) in the high Ni steel was tested in prescription examinations. The results was the $$gamma$$ double-prime (Ni$$_{3}$$Nb) became a fault size and the hardness was decreased in the high prescription temperature and the long prescription time.

Oral presentation

Dynamics of radiocaesium in forests deposited by the Fukushima Daiichi Nuclear Power Plant accident; Long-term monitoring and modelling approaches

Hashimoto, Shoji*; Tanaka, Taku*; Komatsu, Masabumi*; Gonze, M.-A.*; Sakashita, Wataru*; Kurikami, Hiroshi; Nishina, Kazuya*; Ota, Masakazu; Ohashi, Shinta*; Calmon, P.*; et al.

no journal, , 

We applied modelling approaches to evaluate the past and future dynamics of $$^{137}$$Cs in forests. In the model inter-comparison exercise using Fukushima data, six models with diverse model structures, processes, parameters and numerical approaches joined this exercise and the performance and uncertainties of the state-of-the-art models were explored. The inter-comparison revealed that, after appropriate calibration, the models reproduced the observed data reliably and the ranges of calculated trajectories were narrow in the early phase after the fallout. However, the envelope of the calculated model end points enlarged in long-term simulations over 50 years after the fallout. The model-inter comparison exercise emphasizes the importance of decadal data for various forest types and repetitive verification/validation processes using holistic, long-term data to improve the models and to update the forecasting capacity of the models.

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