Kodama, Yu*; Katabuchi, Tatsuya*; Rovira Leveroni, G.; Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Iwamoto, Nobuyuki; Iwamoto, Osamu; Hori, Junichi*; Shibahara, Yuji*; et al.
Journal of Nuclear Science and Technology, 58(11), p.1159 - 1164, 2021/11
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 950C, 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.
Sakashita, Tetsuya*; Sato, Tatsuhiko; Hamada, Nobuyuki*
PLOS ONE (Internet), 14(8), p.e0221579_1 - e0221579_20, 2019/08
Cataracts have long been known, but a biologically based mathematical model is still unavailable for cataratogenesis. We here report for the first time an in silico model for cataractogenesis. First, a simplified cell proliferation model was developed for human lens growth based on stem and progenitor cell proliferation as well as epithelial-fiber cell differentiation. Then, a model for spontaneous cataractogenesis was developed to reproduce the human data on a relationship between age and cataract incidence. Finally, a model for radiation cataractogenesis was developed that can reproduce the human data on a relationship between dose and cataract onset at various ages, which was further applied to estimate cataract incidence following chronic lifetime exposure.
Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.
Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07
Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.
Matsuya, Yusuke; Satou, Yukihiko; Hamada, Nobuyuki*; Date, Hiroyuki*; Ishikawa, Masayori*; Sato, Tatsuhiko
Scientific Reports (Internet), 9(1), p.10365_1 - 10365_9, 2019/07
Insoluble radioactive microparticles (so called Cs-bearing particles) have been assumed to adhere in the long term to trachea after aspirated into respiratory system, leading to heterogeneous dose distribution within healthy tissue around the particles. The biological effects posed by such a particle remain unclear. Here, we show cumulative DNA damage in cultured cells proximal and distal to the particle under localized chronic exposure in comparison with uniform exposure. We placed the particle-contained microcapillary onto a glass-base dish containing normal human lung cells in vitro, and observed a significant change in nuclear -H2AX foci after 24 h or 48 h exposure to the particle. The dose calculation by a Monte Carlo simulation and the comparison with nuclear foci under uniform exposure suggested that the localized exposure to a Cs-bearing particle leads to not only signal-induced DNA damage to distal cells but also the reduction of DNA damage induction yield to proximal cells (protective effects). Considering the small organ dose, the conventional radiation risk assessment is adequate. This study is the first to quantify the spatial distribution of cumulative DNA lesions under heterogeneous exposure by insoluble Cs-bearing particles.
Sato, Tatsuhiko; Masunaga, Shinichiro*; Kumada, Hiroaki*; Hamada, Nobuyuki*
Radiation Protection Dosimetry, 183(1-2), p.247 - 250, 2019/05
As an application of Particle and Heavy Ion Transport code System PHITS, We have developed the stochastic microdosimetric kinetic (SMK) model for estimating the therapeutic effects of various kinds of radiation therapy. In this study, we improved the SMK model for estimating the therapeutic effect of boron neutron capture therapy, BNCT. The improved SMK model can consider not only the intra- and intercellular heterogeneity of B-10 distribution but also the dose rate effect. The accuracy of the model was well verified by comparisons made between calculated and measured surviving fractions of tumor cells, which we previously determined in vivo in mice with B-10 compounds exposed to reactor neutron beam. Details of the improved SMK model together with the verification results will be presented at the meeting.
Sato, Yuji*; Tsukamoto, Masahiro*; Shobu, Takahisa; Yamashita, Yoshihiro*; Yamagata, Shuto*; Nishi, Takaya*; Higashino, Ritsuko*; Okubo, Tomomasa*; Nakano, Hitoshi*; Abe, Nobuyuki*
Applied Physics A, 124(4), p.288_1 - 288_6, 2018/04
The dynamics of titanium (Ti) melted by laser irradiation was investigated in a synchrotron radiation experiment. As an indicator of wettability, the contact angle between a selective laser melting (SLM) baseplate and the molten Ti was measured by synchrotron X-rays at 30 keV during laser irradiation. As the baseplate temperature increased, the contact angle decreased, down to 28 degrees at a baseplate temperature of 500C. Based on this result, the influence of wettability of a Ti plate fabricated by SLM in a vacuum was investigated. It was revealed that the improvement of wettability by preheating suppressed sputtering generation, and a surface having a small surface roughness was fabricated by SLM in a vacuum.
Sato, Tatsuhiko; Masunaga, Shinichiro*; Kumada, Hiroaki*; Hamada, Nobuyuki*
Scientific Reports (Internet), 8(1), p.988_1 - 988_14, 2018/01
We here propose a new model for estimating the biological effectiveness for boron neutron capture therapy (BNCT) considering intra- and intercellular heterogeneity in B distribution. The new model was developed from our previously established stochastic microdosimetric kinetic model that determines the surviving fraction of cells irradiated with any radiations, their synergetic effect being taken into account. The model can predict the biological effectiveness of newly developed B compounds based on their intra- and intercellular distributions, and thus, it can play important roles not only in treatment planning but also in drug discovery research for future BNCT.
Sato, Tatsuhiko; Hamada, Nobuyuki*
Hoshasen Seibutsu Kenkyu, 51(4), p.397 - 401, 2016/12
A workshop entitled "Radiation Research Based on Computer Simulation" was held at the 59th annual meeting of the Japanese Radiation Research Society. Approximately 50 participants attended the workshop, and six speakers gave a talk about their computational radiation biology studies. The title of the presentations are "Research on DNA damage and track structure simulation", "Study of cellular response based on stochastic model for simulating irradiated and non-irradiated cells", "Effectiveness of mathematical model for low-dose radiation effect", "Research on particle therapy based on cell surviving fraction model", "Development of model for natural induction of cataract", and "Mathematical model for carcinogenesis considering the differences of temporal and spatial doses". In the workshop, possible future collaborations were intensively discussed. This report briefly summarizes the outline of the workshop.
Hamada, Nobuyuki*; Sato, Tatsuhiko
Mutation Research; Reviews in Mutation Research, 770(Part B), p.262 - 291, 2016/10
From the radiation protection viewpoint, the ocular lens is among the most radiosensitive tissues in the body, and cataract is classified as tissue reactions with a threshold below which no effect would occur. After 2011, the International Commission on Radiological Protection (ICRP) has recommended an equivalent dose limit for the lens to 20 mSv/year. Although such reduction of the threshold was based on findings from low-LET radiation, the dose limit was recommended in Sv. This review is thus designed to provide an update on the current knowledge as to high-LET radiation cataractogenesis. To this end, changes in ICRP recommendations on lenticular radiation protection, epidemiological and biological findings on high-LET cataractogenesis are reviewed, and future research needs are then discussed.
Kunieda, Satoshi; Iwamoto, Osamu; Iwamoto, Nobuyuki; Minato, Futoshi; Okamoto, Tsutomu; Sato, Tatsuhiko; Nakashima, Hiroshi; Iwamoto, Yosuke; Iwamoto, Hiroki; Kitatani, Fumito; et al.
JAEA-Conf 2016-004, p.41 - 46, 2016/09
Neutron- and proton-induced cross-section data are required in a wide energy range beyond 20 MeV, for the design of accelerator applications. New evaluations are performed with recent knowledge in the optical and pre-equilibrium model calculations. We also evaluated cross-sections for p+Li and p+Be which have been highly requested from a medical field. The present high-energy nuclear data library, JENDL-4.0/HE, includes evaluated cross-sections for incident neutrons and protons up to 200 MeV (for about 130 nuclei). We overview substantial features of the library, i.e., (1) systematic evaluation with CCONE code, (2) challenges for evaluations of light nuclei and (3) inheritance of JENDL-4.0 and JENDL/HE-2007. In this talk, we also focus on the results of benchmark calculation for neutronics to show performance of the present library.
Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03
The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.
Ando, Masaki; Nakahara, Yukio; Tsuda, Shuichi; Yoshida, Tadayoshi; Matsuda, Norihiro; Takahashi, Fumiaki; Mikami, Satoshi; Kinouchi, Nobuyuki; Sato, Tetsuro*; Tanigaki, Minoru*; et al.
Journal of Environmental Radioactivity, 139, p.266 - 280, 2015/01
A series of car-borne surveys using the KURAMA and KURAMA-II systems was conducted in a wide area in eastern Japan from June 2011 to December 2012 to evaluate the distribution of air dose rates around the Fukushima Dai-ichi Nuclear Power Plant, and to determine the time-dependent trend of decrease in air dose rates. An automated data processing system was established, which enables analyses of large amounts of data obtained with the use of about 100 units of the measurement system in a short time. The initial data for studying the migration status of radioactive cesium was obtained in the first survey, followed by the other car-borne surveys having wider measurement ranges. Comparing the measured air dose rates obtained in each survey, it was found that the decreasing trend of air dose rates measured through car-borne surveys was larger than that expected from the physical decay of radioactive cesium and that measured using NaI (Tl) survey meters around the road.
Sato, Tatsuhiko; Hamada, Nobuyuki*
PLOS ONE (Internet), 9(11), p.e114056_1 - e114056_20, 2014/11
We here propose a new model assembly for estimating the surviving fraction of cells irradiated with various types of ionizing radiation, considering both targeted and nontargeted effects in the same framework. The probability densities of specific energies in cell nucleus and domain calculated by PHITS were employed as the physical index for characterizing the radiation fields. In the model assembly, our previously established double stochastic microdosimetric kinetic (DSMK) model was used to express the targeted effect, whereas a newly developed model was used to express the nontargeted effect. The radioresistance caused by overexpression of anti-apoptotic protein Bcl-2 known to frequently occur in human cancer was also considered by introducing the concept of the adaptive response in the DSMK model. The accuracy of the model assembly was examined by comparing the computationally and experimentally determined surviving fraction of Bcl-2 and Neo cells irradiated with microbeam or broadbeam of energetic heavy ions, as well as the WI-38 normal human fibroblasts irradiated with X-ray microbeam. The model assembly reproduced very well the experimentally determined surviving fraction over a wide range of dose and linear energy transfer (LET) values. Our newly established model assembly will be worth being incorporated into treatment planning systems for heavy-ion therapy, brachytherapy, and boron neutron capture therapy, given critical roles of the frequent Bcl-2 overexpression and the nontargeted effect in estimating therapeutic outcomes and harmful effects of such advanced therapeutic modalities.
Sato, Nozomi; Tsukada, Kazuaki; Watanabe, Satoshi; Ishioka, Noriko; Kawabata, Masako; Saeki, Hideya; Nagai, Yasuki; Kin, Tadahiro*; Minato, Futoshi; Iwamoto, Nobuyuki; et al.
Journal of the Physical Society of Japan, 83(7), p.073201_1 - 073201_4, 2014/07
We have for the first time demonstrated that the therapeutic nuclide of Cu produced by Zn(,)Cu has highest radionuclide purity compared to previous ones. We measured a -ray spectrum of the reaction product produced by bombarding an enriched Zn sample with neutrons with a HPGe detector. The neutrons were obtained by C(,) using 41 MeV deuterons provided from Takasaki Ion Accelerators for Advanced Radiation Application of Japan Atomic Energy Agency. Relative production yields of impurity radionuclides such as Zn to Cu are extremely low, which allow us to chemically separate Cu from an irradiated Zn sample with a few steps and to reuse high cost an enriched Zn sample. The present result strongly suggest that the Zn(,)Cu reaction is the most promising route to produce high quality Cu and could solve a longstanding problem of establishing an appropriate production method of Cu.
Sato, Tatsuhiko; Manabe, Kentaro; Hamada, Nobuyuki*
PLOS ONE (Internet), 9(6), p.e99831_1 - e99831_10, 2014/06
The RBEs of the internal exposure to Cs, Cs and were evaluated on the basis of the microdosimetric analysis.
Kobayashi, Nobuyuki*; Nakamura, Takashi*; Kondo, Yosuke*; Tostevin, J. A.*; Utsuno, Yutaka; Aoi, Nori*; Baba, Hidetada*; Barthelemy, R.*; Famiano, M. A.*; Fukuda, Naoki*; et al.
Physical Review Letters, 112(24), p.242501_1 - 242501_5, 2014/06
no abstracts in English
Nakamura, Takashi*; Kobayashi, Nobuyuki*; Kondo, Yosuke*; Sato, Yoshiteru*; Tostevin, J. A.*; Utsuno, Yutaka; Aoi, Nori*; Baba, Hidetada*; Fukuda, Naoki*; Gibelin, J.*; et al.
Physical Review Letters, 112(14), p.142501_1 - 142501_5, 2014/04
no abstracts in English
Nagai, Yasuki; Hashimoto, Kazuyuki; Hatsukawa, Yuichi; Saeki, Hideya; Motoishi, Shoji; Sonoda, Nozomi; Kawabata, Masako; Harada, Hideo; Kin, Tadahiro*; Tsukada, Kazuaki; et al.
Journal of the Physical Society of Japan, 82(6), p.064201_1 - 064201_7, 2013/06
Kamei, Gento; Honda, Akira; Oda, Chie; Hirano, Fumio; Ichige, Satoru; Kurimoto, Yoshitaka; Hoshino, Seiichi; Akagi, Yosuke; Sato, Nobuyuki; Takahashi, Kuniaki; et al.
JAEA-Research 2012-010, 80 Pages, 2012/06
Based on Japanese governmental policy and general scheme, research and development of geological disposal technology for TRU waste has been proceeding to improve reliability of the safety assessment of the co-locational disposal of TRU waste and of HLW, to expand the basement of generic safety assessment, and to develop the alternative technology to cope with the broad geologic environment of Japan. Japan Atomic Energy Agency is dealing with the assignments in the governmental generic scheme. We report here the progress of the studies at the end of H22 (2010) Japanese fiscal year and their products during the last 5 years. These include (1) evaluation of long-term mechanical stability in the near-field including development of a creep mode of rock and analyses of mechanical behavior of TRU waste repository, (2) performance assessment of the disposal system including cementitious material alteration, bentonite and hostrock alteration with alkaline solution and nitrate effect, and (3) alternative technology development including decomposition of nitrate.