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Nagai, Haruyasu
Insights Concerning the Fukushima Daiichi Nuclear Accident, Vo.2; Environmental Effects and Remediation for Restoration, p.37 - 46, 2021/07
Radioactive materials were released into the environment due to the accident that occurred at the Fukushima Daiichi Nuclear Power Plant, which is operated by the Tokyo Electric Power Company. This release immediately led to the performance of an internal exposure dose assessment of iodine and other nuclides with a short halflife. To determine the necessary dose estimation, the spatial-temporal distribution of the atmospheric concentration of radioactive materials was reassessed by performing dispersion simulations with 
I, 
I, 
Te, and 
Cs with due consideration given to their contribution to the internal exposure doses. A database of the spatial-temporal distribution of the concentration was developed based on the results obtained from the calculations performed for each defined time at a horizontal interval of 3 km near the ground surface.
locus in normal human fibroblasts induced by C-, Ne- and Ar-ion microbeamsSuzuki, Masao*; Funayama, Tomoo; Yokota, Yuichiro; Muto, Yasuko*; Suzuki, Michiyo; Ikeda, Hiroko; Hattori, Yuya; Kobayashi, Yasuhiko
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 78, 2015/03
We have been studying the radiation-quality dependent bystander cellular effects, such as cell killing, mutation induction and chromosomal damage, using heavy-ion microbeams with different ion species. This year we focused on the ion-species dependent bystander mutagenic effect on locus in normal human fibroblasts. The confluent culture were irradiated using a 256 (16
16)-cross-stripe method using C, Ne and Ar microbeam. Gene mutation on locus was detected with 6-thioguanine resistant clones. The mutation frequency in cells irradiated with C-ion microbeams was 6 times higher than that of non-irradiated control cells and of the sample treated with specific inhibitor of gap-junction cell-to-cell communication. On the other hand, no enhanced mutation frequencies were observed in cells irradiated with either Ne- or Ar-ion microbeams. There is clear evidence that the bystander mutagenic effect via gap-junction communication depends on radiation quality.
Autsavapromporn, N.*; Plante, I.*; Liu, C.*; Konishi, Teruaki*; Usami, Noriko*; Funayama, Tomoo; Azzam, E.*; Murakami, Takeshi*; Suzuki, Masao*
International Journal of Radiation Biology, 91(1), p.62 - 70, 2015/01
Times Cited Count：31 Percentile：93.49(Biology)Radiation-induced bystander effects have important implications in radiotherapy. Their persistence in normal cells may contribute to risk of health hazards, including cancer. This study investigates the role of radiation quality and gap junction intercellular communication (GJIC) in the propagation of harmful effects in progeny of bystander cells. Confluent human skin fibroblasts were exposed to microbeam radiations with different linear energy transfer (LET) by which 0.036
0.4% of the cells were directly targeted by radiation. Following 20 population doublings, the cells were harvested and assayed for micronucleus formation, gene mutation and protein oxidation. The results showed that expression of stressful effects in the progeny of bystander cells is dependent on LET.
Sato, Tatsuhiko; Kataoka, Ryuho*; Yasuda, Hiroshi*; Yashiro, Seiji*; Kuwabara, Takao*; Shiota, Daiko*; Kubo, Yuki*
Radiation Protection Dosimetry, 161(1-4), p.274 - 278, 2014/10
Times Cited Count：22 Percentile：85.25(Environmental Sciences)We applied our simulation technique to the analysis of air shower induced by mono-energetic protons and alpha particles, which are the dominant component of SEP. The results of the simulations were summarized in a database containing particle fluxes for each condition as a function of the atmospheric depth. This database was then incorporated into our developing Warning System of AVIation Exposure to SEP called WASAVIES. In this system, the aircrew doses due to SEP exposure are estimated within 6 hours after the flare onset, using the established database multiplied with the SEP fluxes incident to the earth. The MHD Cube model is employed in the determination of the incident SEP fluxes. The procedures for the air shower simulation together with some initial results of the aircrew dose calculations for past ground-level enhancement (GLE) events will be presented at the meeting.
Suzuki, Masao*; Autsavapromporn, N.*; Usami, Noriko*; Funayama, Tomoo; Plante, I.*; Yokota, Yuichiro; Muto, Yasuko*; Suzuki, Michiyo; Ikeda, Hiroko; Hattori, Yuya; et al.
Journal of Radiation Research, 55(Suppl.1), P. i54, 2014/03
Nagai, Haruyasu
Nihon Genshiryoku Gakkai-Shi ATOMO
, 55(12), p.712 - 717, 2013/12
no abstracts in English
Autsavapromporn, N.*; Suzuki, Masao*; Funayama, Tomoo; Usami, Noriko*; Plante, I.*; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Katsumi*; Kobayashi, Yasuhiko; et al.
Radiation Research, 180(4), p.367 - 375, 2013/10
Times Cited Count：58 Percentile：89.88(Biology)We investigated the role of gapjunction intercellular communication (GJIC) in the propagation of stressful effects in confluent normal human fibroblast cultures wherein only 0.036-0.144% of cells in the population were traversed by primary radiation tracks. Confluent cells were exposed to graded doses from X ray, carbon ion, neon ion or argon ion microbeams in the presence or absence of an inhibitor of GJIC. After 4 h incubation, the cells were assayed for micronucleus (MN) formation. Micronuclei were induced in a greater fraction of cells than expected based on the fraction of cells targeted by primary radiation, and the effect occurred in a dose-dependent manner with any of the radiation sources. Interestingly, the inhibition of GJIC depressed the enhancement of MN formation in bystander cells from cultures exposed to high-LET radiation but not low-LET radiation. The results highlight the important role of radiation quality and dose in the observed effects.
H2AX foci caused by heavy ion particle traversal; Distribution between core track versus non-track damageNakajima, Nakako*; Brunton, H.*; Watanabe, Ritsuko; Shrikhande, A.*; Hirayama, Ryoichi*; Matsufuji, Naruhiro*; Fujimori, Akira*; Murakami, Takeshi*; Okayasu, Ryuichi*; Jeggo, P.*; et al.
PLOS ONE (Internet), 8(8), p.e70107_1 - e70107_14, 2013/08
Times Cited Count：63 Percentile：91.05(Multidisciplinary Sciences)Heavy particle irradiation can produce complex DNA double strand breaks (DSBs) within the particle trajectory. Additionally, secondary electrons, termed delta-electrons, can create low linear energy transfer (LET) damage distant from the track. Using imaging with deconvolution, we show that at 8 hours after exposure to Fe ions, H2AX foci forming at DSBs within the particle track are large and encompass multiple smaller and closely localised foci, which we designate as clustered H2AX foci. We also identified simple H2AX foci distant from the track. They are rapidly repaired. Clustered H2AX foci induced by heavy particle radiation cause prolonged checkpoint arrest compared to simple H2AX foci. However, mitotic entry was observed when 10 clustered foci remain. Thus, cells can progress into mitosis with multiple clusters of DSBs following the traversal of a heavy particle.
Kataoka, Ryuho*; Sato, Tatsuhiko; Yasuda, Hiroshi*
Space Weather, 9(8), p.S08004_1 - S08004_2, 2011/08
Times Cited Count：12 Percentile：36.02(Astronomy & Astrophysics)We held a half day session entitled "Predicting radiation dose from solar energetic particles" in the Japan Geoscience Union 2011 Meeting on 24 May 2011, in response to increasing public interest for space radiation dose during the ascending phase of the solar cycle 24. This is the first session in Japan to discuss the fundamental problems to predict the aviation radiation dose from SEP, provides a unique start point of an interdisciplinary approach.
Yasuda, Hiroshi*; Sato, Tatsuhiko; Yonehara, Hidenori*; Kosako, Toshiso*; Fujitaka, Kazunobu*; Sasaki, Yasuhito*
Radiation Protection Dosimetry, 146(1-3), p.123 - 125, 2011/07
Times Cited Count：14 Percentile：71.96(Environmental Sciences)The National Institute of Radiological Sciences (NIRS) has helped the airlines companies to follow the guideline, particularly for the calculation of aviation route doses. The presentation will show the annual individual doses of aircraft crew calculated for the 2007 fiscal year.
Sato, Tatsuhiko; Endo, Akira; Zankl, M.*; Petoussi-Henss, N.*; Yasuda, Hiroshi*; Niita, Koji*
Progress in Nuclear Science and Technology (Internet), 1, p.134 - 137, 2011/02
We calculated the dose conversion coefficients for the 2 irradiation geometries; one is for the semi-isotropic irradiation from the upper hemisphere, and the other is for exactly representing the geometrical condition of aircrew exposure, whose angular distribution was estimated from the atmospheric propagation simulation of cosmic-rays performed by PHITS.
Yasuda, Hiroshi*; Yajima, Kazuaki*; Takada, Masashi*; Sato, Tatsuhiko; Nakamura, Takashi*
Progress in Nuclear Science and Technology (Internet), 1, p.356 - 359, 2011/02
It was verified that CREPAS can successfully measure cosmic-ray energetic neutrons (
10 MeV) separately from other components.
Takada, Masashi*; Yajima, Kazuaki*; Yasuda, Hiroshi*; Sato, Tatsuhiko; Nakamura, Takashi*
Radiation Measurements, 45(10), p.1297 - 1300, 2010/12
Times Cited Count：3 Percentile：24.08(Nuclear Science & Technology)In this study, we carried the phoswich-typed neutron detector on the business jet, and measured neutron energy spectrum above Japan.
Takada, Masashi*; Yajima, Kazuaki*; Yasuda, Hiroshi*; Sato, Tatsuhiko; Nakamura, Takashi*
Journal of Nuclear Science and Technology, 47(10), p.932 - 944, 2010/10
Times Cited Count：7 Percentile：45.04(Nuclear Science & Technology)Neutron energy spectrum from 7 to 180 MeV and photon energy spectrum from 3.5 to 42 MeV were measured on board an aircraft using a newly-developed phoswich-type neutron detector at 10.8 km altitude over Japan. The measured neutron energy spectrum using the phoswich neutron detector was compared with other on-board measurements using a multi-sphere moderator neutron detector, so called Bonner ball and the measurement on the ground using an organic liquid scintillator, and with the calculations using the LUIN2000, EXPACS and RMC codes.
Takada, Masashi*; Yajima, Kazuaki*; Yasuda, Hiroshi*; Nakamura, Takashi*; Baba, Mamoru*; Homma, Toshihiro*; Endo, Akira; Tanimura, Yoshihiko
Journal of Nuclear Science and Technology, 47(10), p.917 - 931, 2010/10
Times Cited Count：6 Percentile：40.28(Nuclear Science & Technology)A phoswich-type neutron detector was developed in order to measure high-energy cosmic-ray neutron spectrum in aircrafts. The neutron detector consists of a 121.7 mm diameter and a 121.7 mm long EJ309 organic liquid scintillator covered with a 15 mm thick EJ299-13 outer plastic scintillator. Neutron response functions of the detector are required for an unfolding method to get the energy spectrum. The neutron response functions were evaluated from measurements using quasi-monoenergetic neutron sources of various peak energies from 35 to 78 MeV and from the MCNPX simulation. Light output and scintillation attenuation in the scintillator were measured for proton, deuteron and helium-ion beams. The measured neutron response functions well agreed with the MCNPX simulation. Neutron response matrix was created up to 300 MeV neutron energy based on the MCNPX simulation in order to cover the wide neutron energy range in the fight experiment. Photon response matrix also was created up to 50 MeV.
Yamashita, Shinichi
Hoshasen Kagaku (Internet), (90), p.11 - 16, 2010/09
Water radiolysis with heavy-ion beams of energies up to 28 GeV provided from HIMAC (Heavy Ion Medical Accelerator in Chiba), NIRS (National Institute of Radiological Sciences) has been investigated from the viewpoint of correlation of products yields with track structure and its dynamics. For wide variety of heavy-ion beams in terms of LET, velocity, charge, etc., primary yields of major products in water radiolysis, 
, 
OH and H
O, have been measured by employing scavenging method to convert transient water radicals into stable and easily detectable species. Temporal behavior of approximate sum of water radicals has also been experimentally measured by a scavenging method with methyl viologen cation and formate anion. A Monte-Carlo simulation code of water radiolysis developed by a group of Universit
de Sherbrooke, Canada was complementally used in discussion of microscopic track structure and its dynamics. In addition, a fluorescent probe, 7-hydroxyl-coumarin-3-carboxylic acid, was utilized in sensitive OH detection with HPLC connected fluorometry.
Nishiuchi, Mamiko; Sakaki, Hironao; Hori, Toshihiko; Bolton, P.; Ogura, Koichi; Sagisaka, Akito; Yogo, Akifumi; Mori, Michiaki; Orimo, Satoshi; Pirozhkov, A. S.; et al.
Physical Review Special Topics; Accelerators and Beams, 13(7), p.071304_1 - 071304_7, 2010/07
Times Cited Count：25 Percentile：79.43(Physics, Nuclear)A laser-driven repetition-rated 1.9 MeV proton beam line composed of permanent quadrupole magnets (PMQs), a radio frequency (rf) phase rotation cavity, and a tunable monochromator is developed to evaluate and to test the simulation of laser-accelerated proton beam transport through an integrated system for the first time. In addition, the proton spectral modulation and focusing behavior of the rf phase rotationcavity device is monitored with input from a PMQ triplet. In the 1.9 MeV region we observe very weakproton defocusing by the phase rotation cavity. The final transmitted bunch duration and transverse profile are well predicted by the PARMILA particle transport code. The transmitted proton beam duration of 6 ns corresponds to an energy spread near 5% for which the transport efficiency is simulated to be 10%. The predictive capability of PARMILA suggests that it can be useful in the design of future higher energy transport beam lines as part of an integrated laser-driven ion accelerator system.
Nishiuchi, Mamiko; Sakaki, Hironao; Hori, Toshihiko; Bolton, P.; Ogura, Koichi; Sagisaka, Akito; Yogo, Akifumi; Mori, Michiaki; Orimo, Satoshi; Pirozhkov, A. S.; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.88 - 90, 2010/05
The concept of a compact ion particle accelerator has become attractive in view of recent progress in laser-driven ion acceleration. We report here the recent progress in the laser-driven proton beam transport at the Photo Medical Research Center (PMRC) at JAEA, which is established to address the challenge of laser-driven ion accelerator development for ion beam cancer therapy.
Yajima, Kazuaki*; Yasuda, Hiroshi*; Takada, Masashi*; Sato, Tatsuhiko; Goka, Tateo*; Matsumoto, Haruhisa*; Nakamura, Takashi*
Journal of Nuclear Science and Technology, 47(1), p.31 - 39, 2010/01
Times Cited Count：11 Percentile：59.22(Nuclear Science & Technology)Cosmic-ray neutron energy spectra from thermal to 15 MeV were measured with the multi-moderator spectrometer named the Bonner Ball Neutron Detector (BBND) at aviation altitude (9-11 km). Four flights were carried out around the Nagoya Airport in Japan. The measured data were unfolded using the maximum entropy deconvolution code MAXED, and the derived spectra agreed with calculated results using PHITS-based Analytical Radiation Model in the Atmosphere (PARMA) based on the Monte Carlo calculations by Particle and Heavy Ion Transport code System (PHITS). The results of the aircraft measurement verified the accuracy of model calculation.
Yasuda, Hiroshi*; Yajima, Kazuaki*; Sato, Tatsuhiko; Takada, Masashi*; Nakamura, Takashi*
Health Physics, 96(6), p.655 - 660, 2009/06
Times Cited Count：11 Percentile：59.85(Environmental Sciences)Cosmic radiation exposure of aircraft crew is generally evaluated by numerical simulations and those are desirably verified by measurements. We examined the applicability of selected transportable neutron monitors that are commercially available for measurements of neutron ambient dose equivalent.
