Nagai, Takayuki; Sasage, Kenichi; Okamoto, Yoshihiro; Shiwaku, Hideaki; Yamagishi, Hirona*; Ota, Toshiaki*; Inose, Takehiko*; Sato, Seiichi*; Hatakeyama, Kiyoshi*; Takahashi, Tomoe*; et al.
JAEA-Research 2019-003, 94 Pages, 2019/09
The local structures of glass-forming elements and waste elements would change by the chemical composition of waste glass including those elements. In this study, simulated waste glass samples were prepared from borosilicate glass frit including phosphorus (P) or vanadium (V), and we investigated local structures of boron, sodium, and waste elements in these P glass and V glass samples by using synchrotron XAFS measurements in soft and hard X ray region.
Matsuya, Yusuke; Kai, Takeshi; Yoshii, Yuji*; Yachi, Yoshie*; Naijo, Shingo*; Date, Hiroyuki*; Sato, Tatsuhiko
Journal of Applied Physics, 126(12), p.124701_1 - 124701_8, 2019/09
Biological effects after ionizing radiation exposure arise from initial DNA strand breaks. DNA damage can be estimated from the simulation with both track structure analysis and diffusion of free radicals; however, the simulation is a time-consuming process. In this study, we present a simple model for estimating yields of strand breaks based only on spatial patterns of inelastic interactions (i.e., ionization and electronic excitation) generated by electrons, which are evaluated by PHITS code without considering the production and diffusion of free radicals. In this model, the number of events per track and that of the two events pair within 3.4 nm (corresponding to 10 base pair) were stochastically sampled for calculating SSB and DSB yields, respectively. The calculated results agreed well with other simulations and experimental data on DSB yield and yield ratio of DSB/SSB for the exposure to mono-energetic electrons. The present model also can demonstrate the relative biological effectiveness at the DSB endpoint for various photon exposures. This study indicated that the spatial pattern of inelastic events composed of ionization and electronic excitation is sufficient to obtain the impact of electrons on initial induction to DNA strand break.
Sato, Yuki; Terasaka, Yuta; Utsugi, Wataru*; Kikuchi, Hiroyuki*; Kiyooka, Hideo*; Torii, Tatsuo
Journal of Nuclear Science and Technology, 56(9-10), p.801 - 808, 2019/09
Yamashiki, Yosuke*; Maehara, Hiroyuki*; Airapetian, V.*; Notsu, Yuta*; Sato, Tatsuhiko; Notsu, Shota*; Kuroki, Ryusuke*; Murashima, Keiya*; Sato, Hiroaki*; Namekata, Kosuke*; et al.
Astrophysical Journal, 881(2), p.114_1 - 114_24, 2019/08
The impact of Stellar flares on extrasolar planetary systems has been discussed and argued, especially whether there is a potential impact on their life systems. Here, we propose a comprehensive evaluation system for stellar flares, focusing on Stellar Proton Events (SPE) on selected extrasolar planets with hypothetical atmospheres and oceans. This is done by cross-linking KIC flare-observed and flare-estimated stars by their start pots that are directly linked with the Monte Carlo simulation system PHITS through the exoplanetary database system ExoKyoto. The estimated dose at ground level for each planetary surface did not exceed the critical dose for complex animals.
Nagai, Takayuki; Kobayashi, Hidekazu; Okamoto, Yoshihiro; Akiyama, Daisuke*; Sato, Nobuaki*; Uehara, Akihiro*; Fujii, Toshiyuki*; Sekimoto, Shun*
KURNS Progress Report 2018, P. 105, 2019/08
To understand this structural change of a borosilicate glass by a neutron irradiation in detail, the irradiation test was carried out in KUR in 2017FY. The glass structure was estimated by using Raman spectrometry in 2018FY. Comparing with the Raman spectra of glass samples before and after irradiation, it could be observed the change of peak height of Si-O bridging structure by the irradiation.
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.
Machida, Akihiko*; Saito, Hiroyuki*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Sato, Toyoto*; Orimo, Shinichi*; Aoki, Katsutoshi*
Scientific Reports (Internet), 9(1), p.12290_1 - 12290_9, 2019/08
Hexagonal close-packed iron hydride, hcp FeHx, is absent from the conventional phase diagram of the Fe-H system, although hcp metallic Fe exists stably over extensive temperature () and pressure () conditions, including those corresponding to the Earth's inner core. X-ray and neutron diffraction measurements at temperatures ranging from 298 to 1073 K and H pressures ranging from 4 to 7 GPa revealed that the hcp hydride was formed for FeH compositions when . Hydrogen atoms occupied the octahedral interstitial sites of the host metal lattice both partially and randomly. The hcp hydride exhibited a H-induced volume expansion of 2.48(5) /H-atom, which was larger than that of the face-centered cubic (fcc) hydride. The hcp hydride showed an increase in with , whereas the fcc hydride showed a corresponding decrease. The present study provides guidance for further investigations of the Fe-H system over an extensive -- region.
Kwon, Saerom*; Konno, Chikara; Ota, Masayuki*; Ochiai, Kentaro*; Sato, Satoshi*; Kasugai, Atsushi*
Fusion Engineering and Design, 144, p.209 - 214, 2019/07
We performed a TENDL-2017 benchmark test with iron shielding experiments by using 40 and 65 MeV neutrons, in order to verify a nuclear data library above 20 MeV for neutronics analyses of A-FNS. We found out that the calculated neutron spectra with TENDL-2017 unnaturally increased near 30 MeV. We figured out that incorrect secondary neutron spectrum data in Fe, Fe and Fe at 30 MeV caused the increase of the neutron flux. Similar problems occurred in a lot of nuclei of TENDL-2017, TENDL-2015 and FENDL-3.1d from TENDL-2010 and TENDL-2011.
Matsuya, Yusuke; McMahon, S. J.*; Ghita, M.*; Yoshii, Yuji*; Sato, Tatsuhiko; Date, Hiroyuki*; Prise, K. M.*
Scientific Reports (Internet), 9(1), p.9483_1 - 9483_12, 2019/07
In radiotherapy, intensity modulated radiation fields and complex dose-delivery are used to prescribe doses to tumors. Here, we analyzed the impact of modulated field on radio-sensitivity and cell recovery during irradiation time. The dose was delivered to either 50% of the area of the flask containing cells (half-field) or 100% of the flask (uniform-field). We also modelled cell-killing considering dose-rate effects and intercellular signals. It is found that (i) in-field cell survival under half-field exposure is higher than uniform-field exposure even with the same dose; (ii) the importance of sub-lethal damage repair in normal human skin fibroblast cells under the half-field is reduced; (iii) the increase of cell survival under half-field is predominantly attributed to not rescue effects (increased repair) but protective effects (reduced initial DNA lesion yield). These findings provide new understanding of radio-sensitivity for hit and non-hit cells under non-uniform exposure.
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.
Otani, Kyohei; Sato, Tomonori; Kaji, Yoshiyuki; Yamamoto, Masahiro
JAEA-Review 2019-007, 15 Pages, 2019/06
Metallic pipes under solid-liquid two phase flow is damaged by collision of solid particle to the pipe walls, and this phenomenon is named "erosion". In the case of the liquid is corrosive solution, further damage is occurred on the pipe walls chemically, and this named "erosion-corrosion". In the Fukushima Daiichi decommissioning project, the fuel debris will be crushed during removal operation of the debris and micro debris particles would be generated. It is estimated that the pipes of the circulating cooling system would be damaged under the solid-liquid two phase flow containing fuel debris particles. For the reason, the previous study about erosion and erosion-corrosion of metallic materials under solid-liquid two phase flow was surveyed. The survey showed that the damage rate by erosion and erosion-corrosion is influence by a lot of parameter in comparison to the corrosion rate which occurred in no-flow solution. Therefore, it is necessary to pay attention to selecting the experimental method and condition before the investigation about erosion-corrosion of metallic materials under solid-liquid two phase flow is carried out.
Marufuji, Takato; Sato, Takumi; Ito, Hideaki; Suzuki, Hisashi; Fujishima, Tadatsune; Nakano, Tomoyuki
JAEA-Technology 2019-006, 22 Pages, 2019/05
Radioactive contamination incident occurred at Plutonium Fuel Research Facility (PFRF) in Oarai Research and Development Institute, Japan Atomic Energy Agency on June 6, 2017. During inspection work of storage container containing nuclear fuel materials, the PVC bag packaging in the storage container ruptured when a worker opened the lid in the hood, and a part of contents was spattered over the room. The cause of the increase of internal pressure of the storage container was gas generation by alpha radiolysis of the epoxy resin mixed with nuclear fuel materials. Opening inspection of about 70 similar containers stored in PFRF has been planned to confirm the condition of the contents and to stabilize the stored materials containing organic compounds. For safe and reliable open inspection of the storage containers with high internal pressure in the glove box, it is necessary to develop a pressure-resistant chamber in which the storage containers are opened and the contents are inspected under gastight condition. This report summarizes the concerns and countermeasures of the chamber design and the design results of the chamber.
Nawa, Kazuhiro*; Tanaka, Kimihito*; Kurita, Nubuyuki*; Sato, Taku*; Sugiyama, Haruki*; Uekusa, Hidehiro*; Kawamura, Seiko; Nakajima, Kenji; Tanaka, Hidekazu*
Nature Communications (Internet), 10, p.2096_1 - 2096_8, 2019/05
Search for topological materials has been actively promoted in the field of condensed matter physics for their potential application in energy-efficient information transmission and processing. Recent studies have revealed that topologically invariant states, such as edge states in topological insulators, can emerge not only in a fermionic electron system but also in a bosonic system, enabling nondissipative propagation of quasiparticles. Here we report the topologically nontrivial triplon bands measured by inelastic neutron scattering on the spin-1/2 two-dimensional dimerized antiferromagnet BaCuSiOCl. The excitation spectrum exhibits two triplon bands that are clearly separated by a band gap due to a small alternation in interdimer exchange interaction, consistent with a refined crystal structure. By analytically modeling the triplon dispersion, we show that BaCuSiOCl is the first bosonic realization of the coupled Su-Schrieffer-Heeger model, where the presence of topologically protected edge states is prompted by a bipartite nature of the lattice.
Sato, Hiroyuki; Ohashi, Hirofumi
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05
To establish a probabilistic approach for assessment of toxic gas leakage accidents in a H plant, the present study focusses on development of an uncertainty analysis method for toxic gas concentration in a control room. The method consists of 6 steps; (1) Identification of uncertainty factors, (2) derivation of variable parameters, (3) identification of uncertainties in variable parameters, (4) identification of important factors considering the sensitivity analysis results and expert opinions, (5) uncertainty propagation analysis, (6) assessment of uncertainty analysis results. The method is then applied to representative toxic gas leakage accidents in a H plant by IS process coupled to the HTTR. The results obtained in the study leads us to the conclusion that the suggested method can successfully characterize and quantify uncertainties in the toxic gas concentration in control room.
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.
Takeda, Yusuke; Iida, Kiyoshi*; Sato, Shinji*; Matsuo, Tadatoshi*; Nagashima, Yasuyuki*; Okubo, Nariaki; Kondo, Keietsu; Hirade, Tetsuya
JPS Conference Proceedings (Internet), 25, p.011023_1 - 011023_3, 2019/03
In this study, we prepared samples under two different conditions, (1) 810C, for 600 min, and (2) 850C, for 720 min. A depth-profile analysis of the surfaces of the samples is conducted through Doppler broadening (DB) measurements of positron annihilation rays using a slow positron beam. It was indicated that many of positrons annihilated in defects near the surface. According to the TEM image, there are nano-crystal grains near the surface and then positrons can diffuse in the grains and annihilate in defects at the grain boundaries. Furthermore, DB measurements indicated that there is a depth dependence on the chemical composition where positrons annihilate. EDS spectroscopy measurements also indicated that there is a depth dependence of impurities such as Vanadium. These results indicated change of the chemical composition at the grain boundaries.
Sato, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Miyoshi, Yoshizumi*; Ueno, Haruka*; Nagamatsu, Aiko*
Journal of Space Weather and Space Climate (Internet), 9, p.A9_1 - A9_11, 2019/03
Real-time estimation of astronaut doses during solar particle events (SPE) is one of the most challenging tasks in cosmic-ray dosimetry. We therefore develop a new computational method that can nowcast the solar energetic particle (SEP) as well as galactic cosmic-ray (GCR) fluxes on any Earth orbit during a large SPE associating with ground level enhancement. It is an extended version of WArning System for AVIation Exposure to Solar Energetic Particle, WASAVIES. The extended version, called WASAVIES-EO, can calculate the GCR and SEP fluxes outside a satellite based on its two-line element data. Moreover, organ dose and dose-equivalent rates of astronauts in the International Space Station (ISS) can be estimated using the system, considering its shielding effect. The accuracy of WASAVIES-EO was validated based on the dose rates measured in ISS, as well as based on high-energy proton fluxes observed by POES satellites.
Sato, Hiroyuki; Yan, X.
Nuclear Engineering and Design, 343, p.178 - 186, 2019/03
A hybrid system combining HTGR and renewable energy is investigated to compensate intermittent renewable energy power generation. A new proposal of using the inventory and bypass control devices already built in the gas turbine, is found to be effective to compensate hourly to daily variation of renewable energy. The reactor thermal power remains at constant full power while the heat output is increased or decreased subject to the need of reactor power generation. On the other hand, the massive heat capacity in the graphite core is shown to be sufficient to compensate renewable energy on a time scale of seconds to minutes and up to about 20% of the rated power output of the nuclear plant. Similarly, no additional control devices are required to perform this control operation. These findings demonstrate the technical and economic potential of the HTGR system to maintain the stability of a grid being incorporated with significant portfolios of renewable energy power generation.
Sato, Fuminori; Matsushima, Ryotatsu; Ito, Yoshiyuki
QST-M-16; QST Takasaki Annual Report 2017, P. 60, 2019/03
Hydrogen gas generation by -radiation from cement solidified products loading low-level radioactive liquid waste generated at LWTF in Tokai Reprocessing Facility was studied.
Futemma, Akira; Sanada, Yukihisa; Iwai, Takeyuki*; Seguchi, Eisaku; Matsunaga, Yuki*; Kawabata, Tomoki; Toyoda, Masayuki*; Tobita, Shinichiro*; Hiraga, Shogo*; Sato, Kazuhiko*; et al.
JAEA-Technology 2018-016, 98 Pages, 2019/02
By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We have carried out the background monitoring around the nuclear power stations of the whole country to apply the airborne radiation monitoring technique that has been cultivated in Fukushima against nuclear emergency response. The results of monitoring around Tomari, Kashiwazaki-Kariwa and Genkai Nuclear Power Station in the fiscal 2017 were summarized in this report. In addition, technical issues were described.