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Journal Articles

"Live-autoradiography" technique reveals genetic variation in the rate of Fe uptake by barley cultivars

Higuchi, Kyoko*; Kurita, Keisuke; Sakai, Takuro; Suzui, Nobuo*; Sasaki, Minori*; Katori, Maya*; Wakabayashi, Yuna*; Majima, Yuta*; Saito, Akihiro*; Oyama, Takuji*; et al.

Plants (Internet), 11(6), p.817_1 - 817_11, 2022/03

 Times Cited Count:2 Percentile:43.33(Plant Sciences)

Genetic diversity in the rate of Fe uptake by plants has not been broadly surveyed among plant species or genotypes, although plants have developed various Fe acquisition mechanisms. We adopted the "Live-autoradiography" technique with radioactive $$^{59}$$Fe to directly evaluate the uptake rate of Fe by barley cultivars from a nutrient solution containing a very low concentration of Fe. Our observations revealed that the ability to acquire Fe from the low Fe solution was not always the sole determinant of tolerance to Fe deficiency among the barley genotypes.

Journal Articles

Summary results of subsidy program for the "Project of Decommissioning and Contaminated Water Management (Development of Analysis and Estimation Technology for Characterization of Fuel Debris (Development of Technologies for Enhanced Analysis Accuracy and Thermal Behavior Estimation of Fuel Debris))"

Koyama, Shinichi; Nakagiri, Toshio; Osaka, Masahiko; Yoshida, Hiroyuki; Kurata, Masaki; Ikeuchi, Hirotomo; Maeda, Koji; Sasaki, Shinji; Onishi, Takashi; Takano, Masahide; et al.

Hairo, Osensui Taisaku jigyo jimukyoku Homu Peji (Internet), 144 Pages, 2021/08

JAEA performed the subsidy program for the "Project of Decommissioning and Contaminated Water Management (Development of Analysis and Estimation Technology for Characterization of Fuel Debris (Development of Technologies for Enhanced Analysis Accuracy and Thermal Behavior Estimation of Fuel Debris))" in 2020JFY. This presentation summarized briefly the results of the project, which will be available shortly on the website of Management Office for the Project of Decommissioning and Contaminated Water Management.

Journal Articles

Rabi-oscillation spectroscopy of the hyperfine structure of muonium atoms

Nishimura, Shoichiro*; Torii, Hiroyuki*; Fukao, Yoshinori*; Ito, Takashi; Iwasaki, Masahiko*; Kanda, Sotaro*; Kawagoe, Kiyotomo*; Kawall, D.*; Kawamura, Naritoshi*; Kurosawa, Noriyuki*; et al.

Physical Review A, 104(2), p.L020801_1 - L020801_6, 2021/08

 Times Cited Count:12 Percentile:85.05(Optics)

Journal Articles

Comprehensive exposure assessments from the viewpoint of health in a unique high natural background radiation area, Mamuju, Indonesia

Nugraha, E. D.*; Hosoda, Masahiro*; Kusdiana*; Untara*; Mellawati, J.*; Nurokhim*; Tamakuma, Yuki*; Ikram, A.*; Syaifudin, M.*; Yamada, Ryohei; et al.

Scientific Reports (Internet), 11(1), p.14578_1 - 14578_16, 2021/07

 Times Cited Count:17 Percentile:85.85(Multidisciplinary Sciences)

Mamuju is one of the regions in Indonesia which retains natural conditions but has relatively high exposure to natural radiation. The goals of the present study were to characterize exposure of the entire Mamuju region as a high natural background radiation area (HNBRA) and to assess the existing exposure as a means for radiation protection of the public and the environment. A cross-sectional study method was used with cluster sampling areas by measuring all parameters that contribute to external and internal radiation exposures. It was determined that Mamuju was a unique HNBRA with the annual effective dose between 17 and 115 mSv, with an average of 32 mSv. The lifetime cumulative dose calculation suggested that Mamuju residents could receive as much as 2.2 Sv on average which is much higher than the average dose of atomic bomb survivors for which risks of cancer and non-cancer diseases are demonstrated. The study results are new scientific data allowing better understanding of health effects related to chronic low-dose-rate radiation exposure and they can be used as the main input in a future epidemiology study.

Journal Articles

High temperature gas-cooled reactors

Takeda, Tetsuaki*; Inagaki, Yoshiyuki; Aihara, Jun; Aoki, Takeshi; Fujiwara, Yusuke; Fukaya, Yuji; Goto, Minoru; Ho, H. Q.; Iigaki, Kazuhiko; Imai, Yoshiyuki; et al.

High Temperature Gas-Cooled Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.5, 464 Pages, 2021/02

As a general overview of the research and development of a High Temperature Gas-cooled Reactor (HTGR) in JAEA, this book describes the achievements by the High Temperature Engineering Test Reactor (HTTR) on the designs, key component technologies such as fuel, reactor internals, high temperature components, etc., and operational experience such as rise-to-power tests, high temperature operation at 950$$^{circ}$$C, safety demonstration tests, etc. In addition, based on the knowledge of the HTTR, the development of designs and component technologies such as high performance fuel, helium gas turbine and hydrogen production by IS process for commercial HTGRs are described. These results are very useful for the future development of HTGRs. This book is published as one of a series of technical books on fossil fuel and nuclear energy systems by the Power Energy Systems Division of the Japan Society of Mechanical Engineers.

Journal Articles

A Unique high natural background radiation area; Dose assessment and perspectives

Hosoda, Masahiro*; Nugraha, E. D.*; Akata, Naofumi*; Yamada, Ryohei; Tamakuma, Yuki*; Sasaki, Michiya*; Kelleher, K.*; Yoshinaga, Shinji*; Suzuki, Takahito*; Rattanapongs, C. P.*; et al.

Science of the Total Environment, 750, p.142346_1 - 142346_11, 2021/01

 Times Cited Count:20 Percentile:87.08(Environmental Sciences)

The biological effects of low dose-rate radiation exposures on humans remains unknown. In fact, the Japanese nation still struggles with this issue after the Fukushima Dai-ichi Nuclear Power Plant accident. Recently, we have found a unique area in Indonesia where naturally high radiation levels are present, resulting in chronic low dose-rate radiation exposures. We aimed to estimate the comprehensive dose due to internal and external exposures at the particularly high natural radiation area, and to discuss the enhancement mechanism of radon. A car-borne survey was conducted to estimate the external doses from terrestrial radiation. Indoor radon measurements were made in 47 dwellings over three to five months, covering the two typical seasons, to estimate the internal doses. Atmospheric radon gases were simultaneously collected at several heights to evaluate the vertical distribution. The absorbed dose rates in air in the study area vary widely between 50 nGy h$$^{-1}$$ and 1109 nGy h$$^{-1}$$. Indoor radon concentrations ranged from 124 Bq m$$^{-3}$$ to 1015 Bq m$$^{-3}$$. That is, the indoor radon concentrations measured exceed the reference levels of 100 Bq m$$^{-3}$$ recommended by the World Health Organization. Furthermore, the outdoor radon concentrations measured were comparable to the high indoor radon concentrations. The annual effective dose due to external and internal exposures in the study area was estimated to be 27 mSv using the median values. It was found that many residents are receiving radiation exposure from natural radionuclides over the dose limit for occupational exposure to radiation workers. This enhanced outdoor radon concentration might be as a result of the stable atmospheric conditions generated at an exceptionally low altitude. Our findings suggest that this area provides a unique opportunity to conduct an epidemiological study related to health effects due to chronic low dose-rate radiation exposure.

Journal Articles

Research and development on high burnup HTGR fuels in JAEA

Ueta, Shohei; Mizuta, Naoki; Sasaki, Koei; Sakaba, Nariaki; Ohashi, Hirofumi; Yan, X.

Mechanical Engineering Journal (Internet), 7(3), p.19-00571_1 - 19-00571_12, 2020/06

JAEA has been progressing to design HTGR fuels for not only small-type practical HTGRs but also VHTR proposed in GIF which can be utilized for various purposes with high-temperature heat at 750 to 950 $$^{circ}$$C. To increase economy of these HTGRs, JAEA has been upgrading the design method for the HTGR fuel, which can maintain their integrities at the burnup of three to four times higher than that of the conventional HTTR fuel. Design principles and specifications of various concepts of the high burnup HTGR fuels designed by JAEA are reported. As the latest results on post-irradiation examinations of the high burnup HTGR fuel progressing in a framework of international collaboration with Kazakhstan, irradiation shrinkage rate of the fuel compact as a function of fast neutron fluence was obtained at around 100 GWd/t. Furthermore, the future R&Ds needed for the high burnup HTGR fuel are described based on these experimental results.

Journal Articles

Influence of dead weight and internal pressure to seismic buckling probability of fast reactor vessels

Takaya, Shigeru; Sasaki, Naoto*

Mechanical Engineering Journal (Internet), 7(3), p.19-00549_1 - 19-00549_9, 2020/06

Seismic buckling of vessels is one of main concerns for the design of fast reactor plants in Japan. In previous studies, we discussed evaluation methods of seismic buckling probability of vessels by taking account of seismic hazards in order to rationalize seismic buckling evaluation, and proposed a rule for seismic buckling of vessels based on the load and resistant factor design method. The proposed method deals with only seismic load, but in actuality, dead weight and internal pressure also exist. In this study, the rule was expanded so that dead weight and internal pressure can be taken into account. Furthermore, the influences of dead weight and internal pressure to seismic buckling evaluation were discussed. As result, it was shown that approximately 10 to 20% of further rationalization of allowable seismic load could be achieved by considering dead weight and internal pressure in the evaluation.

Journal Articles

Spectroscopic and first-principles investigations of iodine species incorporation into ettringite; Implications for iodine migration in cement waste forms

Guo, B.*; Xiong, Y.*; Chen, W.*; Saslow, S. A.*; Kozai, Naofumi; Onuki, Toshihiko*; Dabo, I.*; Sasaki, Keiko*

Journal of Hazardous Materials, 389, p.121880_1 - 121880_11, 2020/05

 Times Cited Count:40 Percentile:91.14(Engineering, Environmental)

Journal Articles

${it In-situ}$ investigation of radioactive Cs mobility around litter zone in contaminated forest using spent mushroom substrata

Onuki, Toshihiko*; Sakamoto, Fuminori; Kozai, Naofumi; Yamasaki, Shinya*; Sasaki, Yoshito; Niizato, Tadafumi

Journal of Nuclear Science and Technology, 56(9-10), p.814 - 821, 2019/09

 Times Cited Count:2 Percentile:22.31(Nuclear Science & Technology)

We used the spent mushroom substrata (SMSs) which are a kind of by-product after growing edible mushrooms for the ${it in-situ}$ investigation of radioactive Cs mobility in litter zone in a forest of Fukushima prefecture, Japan. The powder SMS was filled in a plastic net bag of 0.35$$times$$0.55 m, then was placed in a forest for $$sim$$6 months under three kinds of different conditions without treatment (No treatment), covered with wooden box (With box), and with zeolite placed on upper position of ground surface (With zeolite). We determined the ratio of radioactivity (TF) in the SMS to that of the soil and litter beneath the SMS bags. TFs of "No treatment" and of "With zeolite" were determined between $$sim$$0.01 and $$sim$$0.05 for 6 months. On the other hand, TFs of "With box" were lower by one order at 2 and 4 months than those of "No treatment" and of "With zeolite", and nearly the same values as TFs of "No treatment" and "With zeolite" at 6 months. These results clearly indicate that radioactive Cs accumulates in SMS mainly by throughfall. In addition, for a period of several months, fungi contribute to the accumulation of radioactive Cs in the litter zone, even though radioactive Cs was tightly associated with the soil.

Journal Articles

Role of filamentous fungi in migration of radioactive cesium in the Fukushima forest soil environment

Onuki, Toshihiko; Sakamoto, Fuminori; Kozai, Naofumi; Namba, Kenji*; Neda, Hitoshi*; Sasaki, Yoshito; Niizato, Tadafumi; Watanabe, Naoko*; Kozaki, Tamotsu*

Environmental Science; Processes & Impacts, 21(7), p.1164 - 1173, 2019/07

 Times Cited Count:10 Percentile:45.95(Chemistry, Analytical)

The fate of radioactive Cs deposited after the Fukushima nuclear power plant accident and its associated radiological impacts are largely dependent on its mobility from surface soils to forest ecosystems. We measured the accumulation of radioactive Cs in the fruit bodies of wild fungi in the forest at Iidate, Fukushima, Japan. The transfer factors (TFs) of radioactive Cs from soil to the fruit bodies of wild fungi were between 10 $$^{-2}$$to 10$$^{2}$$, a range similar to those reported for the fruit bodies collected in Europe after the Chernobyl accident and in parts of Japan contaminated by nuclear bomb test fallout. Comparison of the TFs of the wild mushroom and that of the fungal hyphae of 704 stock strains grown on agar medium containing nutrients and radioactive Cs showed that the TFs of wild mushroom were lower. TF was less than 0.1 after addition of the minerals zeolite, vermiculite, phlogopite, smectite, or illite of 1% weight to the agar medium. These results indicate that the presence of minerals decrease Cs uptake by fungi grown in the agar medium.

Journal Articles

Research and development on high burnup HTGR fuels in JAEA

Ueta, Shohei; Mizuta, Naoki; Sasaki, Koei; Sakaba, Nariaki; Ohashi, Hirofumi; Yan, X.

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05

JAEA has been progressing to design HTGR fuels for not only small-type practical HTGRs but also VHTR proposed in GIF which can be utilized for various purposes with high-temperature heat at 750 to 950 $$^{circ}$$C. To increase economy of these HTGRs, JAEA has been upgrading the design method for the HTGR fuel, which can maintain their integrities at the burnup of three to four times higher than that of the conventional HTTR fuel. Design principles and specifications of various concepts of the high burnup HTGR fuels designed by JAEA are reported. As the latest results on post-irradiation examinations of the high burnup HTGR fuel progressing in a framework of international collaboration with Kazakhstan, irradiation shrinkage rate of the fuel compact as a function of fast neutron fluence was obtained at around 100 GWd/thm. Furthermore, the future R&Ds needed for the high burnup HTGR fuel are described based on these experimental results.

Journal Articles

Advanced analysis technology for new material and product development

Sasaki, Hirokazu*; Nishikubo, Hideo*; Nishida, Shinsuke*; Yamazaki, Satoshi*; Nakasaki, Ryusuke*; Isomatsu, Takemi*; Minato, Ryuichiro*; Kinugawa, Kohei*; Imamura, Akihiro*; Otomo, Shinya*; et al.

Furukawa Denko Jiho, (138), p.2 - 10, 2019/02

no abstracts in English

Journal Articles

New precise measurements of muonium hyperfine structure at J-PARC MUSE

Strasser, P.*; Abe, Mitsushi*; Aoki, Masaharu*; Choi, S.*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; et al.

EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01

 Times Cited Count:13 Percentile:99.33

Journal Articles

Conceptual plant system design study of an experimental HTGR upgraded from HTTR

Ohashi, Hirofumi; Goto, Minoru; Ueta, Shohei; Sato, Hiroyuki; Fukaya, Yuji; Kasahara, Seiji; Sasaki, Koei; Mizuta, Naoki; Yan, X.; Aoki, Takeshi*

Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 6 Pages, 2018/10

Conceptual design study of an experimental HTGR is performed to upgrade the plant system from Japanese High Temperature engineering Test Reactor (HTTR) to a commercial HTGR. Safety systems of HTTR are upgraded to demonstrate the commercial HTGR concept, such as a passive reactor cavity cooling system, a confinement, etc. An intermediate heat exchanger (IHX) is replaced by a steam generator (SG) for a process heat supply to demonstrate the technology for a commercial use. This paper describes the conceptual design study results of the plant system of the experimental HTGR.

Journal Articles

Electronic structure of Li$$^{+}$$@C$$_{60}$$; Photoelectron spectroscopy of the Li$$^{+}$$@C$$_{60}$$[PF$$_{6}$$$$^{-}$$] salt and STM of the single Li$$^{+}$$@C$$_{60}$$ molecules on Cu(111)

Yamada, Yoichi*; Kuklin, A. V.*; Sato, Sho*; Esaka, Fumitaka; Sumi, Naoya*; Zhang, C.*; Sasaki, Masahiro*; Kwon, E.*; Kasama, Yasuhiko*; Avramov, P. V.*; et al.

Carbon, 133, p.23 - 30, 2018/07

 Times Cited Count:13 Percentile:54.07(Chemistry, Physical)

We report first STM observation of the Li$$^{+}$$ ion endohedral C$$_{60}$$, which is of a new class of endohedral fullerenes, prepared by means of evaporation of high-purity Li$$^{+}$$@C$$_{60}$$[PF$$_{6}$$$$^{-}$$] salt in ultra-high vacuum. Prior to the STM measurements, the electronic structure of Li$$^{+}$$@C$$_{60}$$ in the Li$$^{+}$$@C$$_{60}$$[PF$$_{6}$$$$^{-}$$] salt was also precisely determined. In the salt, it is shown that Li and PF$$_{6}$$ have nearly single positive and negative charge, respectively, and the C$$_{60}$$ cage is nearly neutral, suggesting that Li$$^{+}$$@C$$_{60}$$ in the salt retains its original electronic state.

Journal Articles

New precise measurement of muonium hyperfine structure interval at J-PARC

Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 Times Cited Count:3 Percentile:86.59

Journal Articles

Quantitative analysis of radiocesium retention onto birnessite and todorokite

Yu, Q.*; Onuki, Toshihiko*; Kozai, Naofumi; Sakamoto, Fuminori; Tanaka, Kazuya; Sasaki, Keiko*

Chemical Geology, 470, p.141 - 151, 2017/10

 Times Cited Count:15 Percentile:56.69(Geochemistry & Geophysics)

In this work, the Cs retention onto two types of Mn oxide was investigated. We found that Todorokite has sorption sites with a higher selectivity for Cs than birnessite. When the initial Cs concentration was 10$$^{-9}$$ mol/L for the sorption experiments, approximately 34% of the sorbed Cs was residual in the todorokite after the extraction using 1 M NaCl and NH$$_{4}$$Cl; this value was much higher than the results for the Cs-sorbed birnessite. These results strongly suggest that todorokite contributes to the fixation of radioactive Cs in soils.

Journal Articles

Load and resistance factor design approach for seismic buckling of fast reactor vessels

Takaya, Shigeru; Sasaki, Naoto*; Asayama, Tai; Kamishima, Yoshio*

Mechanical Engineering Journal (Internet), 4(3), p.16-00558_1 - 16-00558_12, 2017/06

In this study, we developed a new design rule for the prevention of seismic buckling of vessels using the load and resistance factor design method to enable more rational vessel designs. The effectiveness of the new design rule was illustrated in comparison with the current provision.

Journal Articles

2016 Professional Engineer (PE) test preparation course; Nuclear and radiation technical disciplines

Takahashi, Naoki; Suzuki, Soju; Saito, Hiroto; Ueno, Takashi; Abe, Sadayoshi; Yamanaka, Atsushi; Tanigawa, Masafumi; Nakamura, Daishi; Sasaki, Shunichi; Mine, Tadaharu

Nihon Genshiryoku Gakkai Homu Peji (Internet), 20 Pages, 2017/05

no abstracts in English

148 (Records 1-20 displayed on this page)