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Toyoda, Shin*; Inoue, Kazuhiko*; Yamaguchi, Ichiro*; Hoshi, Masaharu*; Hirota, Seiko*; Oka, Toshitaka; Shimazaki, Tatsuya*; Mizuno, Hideyuki*; Tani, Atsushi*; Yasuda, Hiroshi*; et al.
Radiation Protection Dosimetry, 199(14), p.1557 - 1564, 2023/09
Times Cited Count：0 Percentile：0.01(Environmental Sciences)Interlaboratory comparison studies are important for radiation dosimetry in order to demonstrate how the technique is universally available. The set of standard samples are examined in each participating laboratory in the present study. After a set of standard samples together with the samples with unknown doses, which were prepared in the same laboratory as the standard samples, are measured at a participating laboratory, those samples are sent to another participating laboratory for next measurement. There is some small difference observed in the sensitivity (the slope of the dose response line) of the standard samples while the differences in the obtained doses for the samples with unknown doses are rather systematic, implying that the difference is mostly due to the samples but not to measurements.
Yasuoka, Yumi*; Fujita, Hiroki; Tsuji, Tomoya; Tsujiguchi, Takakiyo*; Sasaki, Michiya*; Miyazaki, Tomoyuki*; Hashima, Shun*; Yasuda, Hiroshi*; Shimada, Kazumasa; Hirota, Seiko*
Hoken Butsuri (Internet), 57(3), p.146 - 155, 2022/12
no abstracts in English
Yasuda, Hiroshi*; Fumoto, Hiromichi*; Saito, Tatsuo
Nihon Genshiryoku Gakkai-Shi ATOMO
, 63(8), p.610 - 614, 2021/08
Regarding the handling of uranium bearing waste, which is contaminated with uranium, which is a naturally occurring radionuclide, and its descendant nuclides, in recent years, the Japan Nuclear Regulatory Commission, etc. have been carefully and actively deliberated based on the knowledge of natural science and safety engineering. It was carried out, and as of March 2021, a certain policy has been shown. On the other hand, when disposing of uranium waste, which may cause dose exposure to future generations, the authors consider not only the science and engineering perspectives that have been conducted so far, but also the humanities and social science perspectives. We have been discussing with experts in related fields, thinking that it is necessary. In this report, we will introduce the background that brought about such an idea and the direction of future discussions.
Yasuda, Hiroshi*; Yajima, Kazuaki*; Sato, Tatsuhiko
Radiation Measurements, 134, p.106309_1 - 106309_4, 2020/06
Times Cited Count：8 Percentile：60.71(Nuclear Science & Technology)We have investigated an application of a recently developed electronic personal dosimeter (D-Shuttle) for aviation dosimetry. As results of measurements in four long-haul flights between Japan and Germany, the D-Shuttle indicated values were in the range of 25 to 30% of the total H
(10) values estimated by a route-dose calculations program JISCARD EX. Though we need more measurements and analyses under different flight conditions to conclude, according to these results obtained so far, it would be possible to perform monitoring of the annual aviation doses of frequent flyers by using D-Shuttle on an individual basis.
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
Times Cited Count：7 Percentile：38.79(Astronomy & Astrophysics)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, Tatsuhiko; Kataoka, Ryuho*; Shiota, Daiko*; Kubo, Yuki*; Ishii, Mamoru*; Yasuda, Hiroshi*; Miyake, Shoko*; Park, I.*; Miyoshi, Yoshizumi*
Space Weather, 16(7), p.924 - 936, 2018/07
Times Cited Count：19 Percentile：69.84(Astronomy & Astrophysics)A physics-based warning system of aviation exposure to solar energetic particles, WASAVIES, is improved to be capable of real-time and automatic analysis. In the improved system, the count rates of several neutron monitors (NM) at the ground level, as well as the proton fluxes measured by the GOES satellite are continuously downloaded at intervals of 5 min and used for determining the model parameters. The performance of WASAVIES is examined by analyzing the three major GLE events of the 21st century. A web-interface of WASAVIES is also developed and will be released in the near future through the public server of NICT.
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.
Kataoka, Ryuho*; Sato, Tatsuhiko; Kubo, Yuki*; Shiota, Daiko*; Kuwabara, Takao*; Yashiro, Seiji*; Yasuda, Hiroshi*
Space Weather, 12(6), p.380 - 386, 2014/06
Times Cited Count：19 Percentile：51.8(Astronomy & Astrophysics)Solar energetic particles (SEP) sometimes induce air shower that significantly increase the radiation dose at flight altitudes. In order to inform the situation of such a space radiation hazard to aircrews, a physics-based forward model is developed as WASAVIES (Warning System for Aviation Exposure to SEP) based on the focused transport equation and Monte Carlo particle transport simulation of the air shower. WASAVIES gives the fastest and simplest way to predict the time profile of dose rate during ground-level enhancements (GLEs).
Sato, Tatsuhiko; Niita, Koji*; Shurshakov, V. A.*; Yarmanova, E. N.*; Nikolaev, I. V.*; Iwase, Hiroshi*; Sihver, L.*; Mancusi, D.*; Endo, Akira; Matsuda, Norihiro; et al.
Cosmic Research, 49(4), p.319 - 324, 2011/08
Times Cited Count：11 Percentile：60.36(Engineering, Aerospace)HZE particle transport codes are the indispensable tool in the shielding design of spacecrafts. We are therefore developing a general-purpose Monte Carlo code PHITS, which can deal with the transports of all kinds of hadrons and heavy ions with energies up to 200 GeV/n in 3-dimensional phase spaces. The applicability of PHITS to space researches has been well verified by comparing the neutron spectra in spacecrafts calculated by the code with the corresponding experimental data. Recently, PHITS was employed in the estimation of radiation fields in the Russian Service Module in ISS. The results of the estimation indicate that PHITS can reproduce experimental data of the dose reduction rates due to water shielding attached on the wall of the Russian crew cabin fairly well. The details of the calculation procedures will be given in the presentation, together with the results of other applications of PHITS to the space exploration.
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.
Sato, Tatsuhiko; Endo, Akira; Yasuda, Hiroshi*; Niita, Koji*
Radiation Protection Dosimetry, 146(1-3), p.183 - 185, 2011/07
Times Cited Count：1 Percentile：10.73(Environmental Sciences)A set of the conversion coefficients from fluence to the effective dose has been calculated for neutrons and protons over wide energy ranges based on the instruction given in ICRP 103, using the PHITS code. The calculated values are generally smaller than those based on ICRP Publication 60, predominantly owing to the revision of 
for those particles. The impact of the introduction of ICRP 103 on the dosimetry for high-energy particles will be discussed by comparing between the ICRP 103- and ICRP 60-based effective doses for aircrews as well as workers in high-energy accelerator facilities.
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.
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.
Sato, Tatsuhiko; Satoh, Daiki; Endo, Akira; Shigyo, Nobuhiro*; Yasuda, Hiroshi*; Takada, Masashi*; Yajima, Kazuaki*; Nakamura, Takashi
Nuclear Technology, 168(1), p.113 - 117, 2009/10
Times Cited Count：1 Percentile：10.22(Nuclear Science & Technology)The details of the features of DARWIN will be presented at the meeting, together with the recent improvements of the system such as the implementation of the function for estimating neutron spectra using the unfolding technique.
Torii, Tatsuo; Sugita, Takeshi*; Tanabe, Sachiko*; Kimura, Yoshihisa*; Kamogawa, Masashi*; Yajima, Kazuaki*; Yasuda, Hiroshi*
Geophysical Research Letters, 36(13), p.L13804_1 - L13804_4, 2009/07
Times Cited Count：57 Percentile：80.7(Geosciences, Multidisciplinary)Fluctuations of energetic radiation that seemed to be caused by a summer thunderstorm were observed at the top of Mt. Fuji. The largest of such fluctuations was gradual and lasted for about 20 minutes, and was found to be high-energy 
rays having a continuous energy spectrum up to 10 MeV or more. As for the feature of these fluctuations, it seems naturally that such fluctuations are caused by the bremsstrahlung photons generated by the energetic electrons produced continuously with an intense electric field in the thundercloud rather than originated in the process of lightning discharge.
