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Journal Articles

Observation of morphological abnormalities in silkworm pupae after feeding $$^{137}$$CsCl-supplemented diet to evaluate the effects of low dose-rate exposure

Tanaka, Sota; Kinouchi, Tadatoshi*; Fujii, Tsuguru*; Imanaka, Tetsuji*; Takahashi, Tomoyuki*; Fukutani, Satoshi*; Maki, Daisuke*; Notomi, Akihiro*; Takahashi, Sentaro*

Scientific Reports (Internet), 10, p.16055_1 - 16055_7, 2020/09

Since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, morphological abnormalities of the lepidopteran insects have been reported. However, it is unclear whether the abnormalities were caused directly by radiation because they did not study on absorbed dose and dose-effect relationship. In this study, we conducted an internal exposure experiment on silkworm using $$^{137}$$CsCl-supplemented artificial diet and estimated the absorbed dose to evaluate the morphological abnormalities in silkworm. The ratio of wing to whole body of pupae was compared between the $$^{137}$$CsCl-exposured and control groups and no significant differences were observed between the groups. This result suggest that morphological abnormalities in lepidopterans are unlikely due to direct radiation effects from $$^{137}$$Cs contamination after the FDNPP accident.

Journal Articles

Preliminary investigation of pretreatment methods for liquid scintillation measurements of environmental water samples using ion exchange resins

Nakasone, Shunya*; Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; et al.

Plasma and Fusion Research (Internet), 15, p.2405027_1 - 2405027_3, 2020/05

A quick preprocessing system for tritium analysis of environmental samples is important to judge environmental influence of tritium releases due to accident or tritium-handling facilities. Analysis of tritium in water samples with liquid scintillation counting method requires removal of impurities such as organic matter and ion species from water samples. Generally, a distillation method is adopted as a pretreatment of analysis for tritium; however, the distillation method is a time-consuming process. The aim of this study is to evaluate a rapid pretreatment method for tritium analysis with ion exchange resin. From batch and column experiments that used inland water and ion exchange resin, we confirmed removals of impurities of the water sample and that the removal of impurities was possible for a short time (by 5 minutes).

Journal Articles

Radioactive cesium contamination of arthropods and earthworms after the Fukushima Daiichi Nuclear Power Plant Accident

Tanaka, Sota; Adachi, Taro*; Takahashi, Tomoyuki*; Takahashi, Sentaro*

Low-Dose Radiation Effects on Animals and Ecosystems; Long-Term Study on the Fukushima Nuclear Accident, p.43 - 52, 2020/00

To understand the behavior of radiocesium in terrestrial invertebrates, chronological changes in the concentration of radiocesium in arthropods and earthworms from different trophic levels were investigated after the Fukushima Daiichi Nuclear Power Plant accident. The median radiocesium concentrations in the rice grasshopper, Oxya yezoensis, and the Emma field cricket, Teleogryllus emma, were 0.46 and 0.15 Bq/g fw in 2012, respectively, which dropped continuously to 0.05 and 0.01 Bq/g fw in 2016. In contrast, no significant reduction in radiocesium concentration was observed in the Joro Spider, Nephila clavata, in which the concentration was 0.31 Bq/g fw in 2012 and remained at 0.14 Bq/g fw in 2016. The comparison of radiocesium concentrations at each trophic level showed that the amount in detritivorous earthworms was 85 times higher than in herbivorous grasshoppers. This suggests that detritus food web could be a primary pathway of radiocesium through food webs.

Journal Articles

Radiocesium concentration in flying insects collected from a radioactive contaminated area after the Fukushima Dai-ichi Nuclear Power Plant accident

Tanaka, Sota; Kakinuma, Hotaru*; Adachi, Taro*; Takahashi, Tomoyuki*; Takahashi, Sentaro*

KEK Proceedings 2019-2, p.179 - 182, 2019/11

The concentration of $$^{137}$$Cs in flying insects was investigated after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. The insects were collected at about 11 km north west of the FDNPP at two different sites in the forest and riverside. The median concentration of $$^{137}$$Cs in flying insects in the forest was significantly higher than riverside. However, high concentration of $$^{137}$$Cs in detritus fly (Diptera: Calliphoridae) was observed at both sites. The concentration of fly at the forest and riverside were 16$$times$$10$$^{2}$$ Bq/kg fw and 18$$times$$10$$^{2}$$ Bq/kg fw, respectively. The result shows that the concentration of radiocesium in detritus fly were still high 8 years after the accident. This suggests that detritus food chain is a dominant transfer pathway of radiocesium to higher trophic level species such as spiders.

Journal Articles

Development of field estimation technique and improvement of environmental tritium behavior model

Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; Atarashi-Andoh, Mariko; et al.

Plasma and Fusion Research (Internet), 14(Sp.2), p.3405099_1 - 3405099_4, 2019/06

The Large Helical Device of the National Institute for Fusion Science started D-D experiments in 2017. To ensure the safety of the facility, it is important to develop evaluation methods for environmental tritium transfer. Tritiated water (HTO) in atmosphere and soil is transferred to plants, and organically bound tritium (OBT) is formed by photosynthesis. Prediction of OBT formation is important, because OBT accumulates in plants and causes dose through ingestion. The objective of this study is to estimate environmental tritium transfer using a simple compartment model and practical parameters. We proposed a simple compartment model consisting of air-soil-plant components, and tried to validate the model by comparison with a sophisticated model, SOLVEG. In this study, we plan to add wet deposition to the model and obtain parameters from measurements of soil permeability and tritium concentrations in air, soil and plants. We also establish rapid pretreatment methods for OBT analysis.

Journal Articles

Estimation of the release time of radio-tellurium during the Fukushima Daiichi Nuclear Power Plant accident and its relationship to individual plant events

Takahashi, Sentaro*; Kawashima, Shigeto*; Hidaka, Akihide; Tanaka, Sota*; Takahashi, Tomoyuki*

Nuclear Technology, 205(5), p.646 - 654, 2019/05

 Times Cited Count:2 Percentile:28.85(Nuclear Science & Technology)

Journal Articles

Long-term predictions of ambient dose equivalent rates after the Fukushima Daiichi Nuclear Power Plant accident

Kinase, Sakae; Takahashi, Tomoyuki*; Saito, Kimiaki

Journal of Nuclear Science and Technology, 54(12), p.1345 - 1354, 2017/12

 Times Cited Count:15 Percentile:3.74(Nuclear Science & Technology)

Journal Articles

Uncertainty in predictions of the ambient dose equivalent rates for 30 years following the Fukushima Daiichi Nuclear Power Plant accident

Kinase, Sakae; Takahashi, Tomoyuki*; Sato, Satoshi; Yamamoto, Hideaki; Saito, Kimiaki

Proceedings of 17th NSFS Conference (Internet), p.27 - 33, 2016/02

Journal Articles

Prediction of ambient dose equivalent rates for the next 30 years after the accident

Kinase, Sakae; Takahashi, Tomoyuki*; Sato, Satoshi*; Yamamoto, Hideaki; Saito, Kimiaki

Proceedings of International Symposium on Radiological Issues for Fukushima's Revitalized Future, p.40 - 43, 2015/00

To support recovery and rehabilitation in Fukushima, prediction models have been developed for ambient dose equivalent rate distribution within the 80 km-radius around the Fukushima Daiichi Nuclear Power Plant. The prediction models that are based on bi-exponential functions characterized by ecological half-lives of radioactive caesium for land-use, enable Fukushima residents to obtain distribution maps of ambient dose equivalent rates for the next 30 years after the accident. Model parameters were evaluated using ambient dose equivalent rates through car-borne surveys. The model parameters in deciduous and evergreen forest areas were found to be different from those in other areas. In addition, it was found that distribution maps of ambient dose equivalent rates for the next 30 years after the accident, created by the prediction models would be useful for follow-up of the radiological situation.

Journal Articles

Development of prediction models for radioactive caesium distribution within the 80-km radius of the Fukushima Daiichi Nuclear Power Plant

Kinase, Sakae; Takahashi, Tomoyuki*; Sato, Satoshi; Sakamoto, Ryuichi*; Saito, Kimiaki

Radiation Protection Dosimetry, 160(4), p.318 - 321, 2014/00

 Times Cited Count:25 Percentile:5.83(Environmental Sciences)

JAEA Reports

Study on the evaluation method to determine the radioactivity concentration in low-level radioactive wastes generated at JPDR facilities, 1

Tsuji, Tomoyuki; Kameo, Yutaka; Sakai, Akihiro; Hoshi, Akiko; Takahashi, Kuniaki

JAEA-Technology 2012-045, 37 Pages, 2013/02

JAEA-Technology-2012-045.pdf:2.43MB

It is necessary to establish practical evaluation methods to determine radioactivity concentrations of the important nuclides for safety assessment on disposal of radioactive wastes in order to dispose of low-level radioactive wastes generated from various nuclear facilities in JAEA. In this report, the practical evaluation methods such as the scaling factor method for JPDR facilities have been studied for disposal of the low-level radioactive wastes generated from nuclear reactor facilities in JAEA.

JAEA Reports

Study on the evaluation method to determine the radioactivity concentration in the bituminized products generated from research facilities

Tsuji, Tomoyuki; Kameo, Yutaka; Sakai, Akihiro; Amazawa, Hiroya; Takahashi, Kuniaki

JAEA-Technology 2011-028, 66 Pages, 2011/11

JAEA-Technology-2011-028.pdf:3.16MB

In order to dispose of low-level radioactive wastes generated from various nuclear facilities in JAEA, we need to establish practical evaluation methods to determine radioactivity concentrations of the important nuclides for safety assessment on disposal of radioactive wastes. In this report, we have studied on establishing the practical evaluation methods such as the scaling factor method for bituminized products generated at Nuclear Science Research Institute and also summarized subjects for establishment of the practical evaluation methods for the bituminized products.

Journal Articles

Behavior of environmental tritium at NIFS Toki Site of Japan

Sugihara, Shinji*; Tanaka, Masahiro*; Tamari, Toshiya*; Shimada, Jun*; Takahashi, Tomoyuki*; Momoshima, Noriyuki*; Fukutani, Satoshi*; Atarashi-Andoh, Mariko; Sakuma, Yoichi*; Yokoyama, Sumi*; et al.

Fusion Science and Technology, 60(4), p.1300 - 1303, 2011/11

 Times Cited Count:1 Percentile:87.5(Nuclear Science & Technology)

The purpose of this study is to develop the technique to evaluate the environmental tritium behavior of the nuclear facility origin. Tritium concentrations of river water, precipitation and ground water around the NIFS site were determined by low background liquid scintillation measurement system combined with the electrolysis using solid polymer electrolyte. The electric conductivity and flow rate of the river and isotopic ratio of oxygen and hydrogen of water samples were also measured. The tritium concentrations in precipitation showed the seasonal variation and the range were 0.09-0.78 Bq/L. The tritium concentrations of river water and ground water were almost constant, 0.34 and 0.24 Bq/L respectively. The simple dynamic model for the site around the NIFS facilities was developed using measured data, and the behavior of tritium was simulated.

JAEA Reports

Analysis of the radioactivity concentrations in low-level radioactive waste generated from JPDR facilities

Hoshi, Akiko; Tsuji, Tomoyuki; Tanaka, Kiwamu; Yasuda, Mari; Watanabe, Koichi; Sakai, Akihiro; Kameo, Yutaka; Kogure, Hiroto; Higuchi, Hidekazu; Takahashi, Kuniaki

JAEA-Data/Code 2011-011, 31 Pages, 2011/10

JAEA-Data-Code-2011-011.pdf:1.7MB

Simple and rapid methods to evaluate the radioactivity concentrations are required to be established for the near surface disposal of radioactive wastes generated from research facilities at Japan Atomic Energy Agency. In order to establish the methods to evaluate the radioactivity concentrations of miscellaneous solid wastes generated from research and testing reactors, we collected and analyzed samples from miscellaneous solid wastes generated by the decommissioning of JPDR (Japan Power Demonstration Reactor). In the present paper, we summarized data (262 data) about the radioactivity concentrations of the 7 important nuclides ($$^{3}$$H, $$^{14}$$C, $$^{60}$$Co, $$^{59}$$Ni, $$^{63}$$Ni, $$^{90}$$Sr, $$^{137}$$Cs) which accumulated by the analysis.

Journal Articles

Spin transfer torque in MTJs with synthetic ferrimagnetic layers by the Keldysh approach

Ichimura, Masahiko*; Hamada, Tomoyuki*; Imamura, Hiroshi*; Takahashi, Saburo*; Maekawa, Sadamichi

Journal of Applied Physics, 109(7), p.07C906_1 - 07C906_3, 2011/03

 Times Cited Count:4 Percentile:77.69(Physics, Applied)

JAEA Reports

Analysis of the radioactivity concentrations in asphalt- or cement-solidified products generated from research facilities

Hoshi, Akiko; Kameo, Yutaka; Katayama, Atsushi; Sakai, Akihiro; Tsuji, Tomoyuki; Nakashima, Mikio; Kihara, Shinji; Takahashi, Kuniaki

JAEA-Data/Code 2009-023, 84 Pages, 2010/03

JAEA-Data-Code-2009-023.pdf:12.81MB

In order to establish the practical evaluation methods such as scaling factor method to determine the radioactivity concentrations of the important nuclides for safety assessment of disposal of radioactive wastes, we analyzed low-level radioactive liquid waste (56 samples), which is generated from various research facilities at Nuclear Science Research Institute from FY1998 to FY2007 and accumulated the radioactivity concentrations data (563 data) of the 17 important nuclides. We investigated the correlation of the radioactivity concentrations of the important nuclides with the "Key nuclides ($$^{60}$$Co or $$^{137}$$Cs)". In present paper, the radioactivity concentrations data of the 17 important nuclides and the results of the correlation of the radioactivity concentrations are summarized for the data to establish the practical evaluation methods to determine the radioactivity concentrations in asphalt-solidified or cement-solidified products.

JAEA Reports

The Outline of investigation on integrity of JMTR concrete structures, cooling system and utility facilities

Ebisawa, Hiroyuki; Hanakawa, Hiroki; Asano, Norikazu; Kusunoki, Hidehiko; Yanai, Tomohiro; Sato, Shinichi; Miyauchi, Masaru; Oto, Tsutomu; Kimura, Tadashi; Kawamata, Takanori; et al.

JAEA-Technology 2009-030, 165 Pages, 2009/07

JAEA-Technology-2009-030.pdf:69.18MB

The condition of facilities and machinery used continuously were investigated before the renewal work of JMTR on FY 2007. The subjects of investigation were reactor building, primary cooling system tanks, secondary cooling system piping and tower, emergency generator and so on. As the result, it was confirmed that some facilities and machinery were necessary to repair and others were used continuously for long term by maintaining on the long-term maintenance plan. JMTR is planed to renew by the result of this investigation.

Journal Articles

Demonstration of remote fabrication for FBR MOX fuel at the PFPF

Takahashi, Saburo; Kikuno, Hiroshi; Shiromo, Hideo; Kuba, Meiji; Abe, Tomoyuki; Takeda, Seiichiro

Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10

Japan Atomic Energy Agency (JAEA) has been accumulating various experience and knowledge on development of MOX fuel technologies for more than 40 years since 1966. Plutonium Fuel Production Facility (PFPF) has introduced a fully automated and remote operation in 1988 as a pioneer in the world, based on the operational and technical experience obtained in the existing facilities. The PFPF has fabricated MOX fuel assemblies for a fast reactor "JOYO" and a fast breeder reactor "MONJU" so far. Through MOX fuel fabrication for JOYO and MONJU, many operational experiences such as a hold-up material problem have been gained. Based on the experiences, process equipments have been newly developed and a process technology has been improved. As the results, fully automated and remote fabrication technologies including easy contact maintenance of process equipments for FBR MOX fuel have been demonstrated in the PFPF on a large scale.

JAEA Reports

Construction, management and operation on advanced volume reduction facilities

Higuchi, Hidekazu; Osugi, Takeshi; Nakashio, Nobuyuki; Momma, Toshiyuki; Tohei, Toshio; Ishikawa, Joji; Iseda, Hirokatsu; Mitsuda, Motoyuki; Ishihara, Keisuke; Sudo, Tomoyuki; et al.

JAEA-Technology 2007-038, 189 Pages, 2007/07

JAEA-Technology-2007-038-01.pdf:15.13MB
JAEA-Technology-2007-038-02.pdf:38.95MB
JAEA-Technology-2007-038-03.pdf:48.42MB
JAEA-Technology-2007-038-04.pdf:20.53MB
JAEA-Technology-2007-038-05.pdf:10.44MB

The Advanced Volume Reduction Facilities (AVRF) is constructed to manufacture the waste packages of radioactive waste for disposal in the Nuclear Science Research Institute of the Japan Atomic Energy Agency. The AVRF is constituted from two facilities. The one is the Waste Size Reduction and Storage Facility (WSRSF) which is for reducing waste size, sorting into each material and storing the waste package. The other is the Waste Volume Reduction Facility (WVRF) which is for manufacturing the waste package by volume reducing treatment and stabilizing treatment. WVRF has an induction melting furnace, a plasma melting furnace, an incinerator, and a super compactor for treatment. In this report, we summarized about the basic concept of constructing AVRF, the constitution of facilities, the specifications of machineries and the state of trial operation until March of 2006.

Journal Articles

Diffuse X-ray and neutron scattering from powder PbS

Xianglian*; Basar, K.*; Honda, Hiroyuki*; Hojo, Tomoyuki*; Sakuma, Takashi*; Takahashi, Haruyuki*; Igawa, Naoki; Ishii, Yoshinobu

Proceedings of 10th Asian Conference on Solid State Ionics, p.185 - 192, 2006/00

no abstracts in English

83 (Records 1-20 displayed on this page)