Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Hirahara, Toru*; Otrokov, M. M.*; Sasaki, Taisuke*; Sumida, Kazuki*; Tomohiro, Yuta*; Kusaka, Shotaro*; Okuyama, Yuma*; Ichinokura, Satoru*; Kobayashi, Masaki*; Takeda, Yukiharu; et al.
Nature Communications (Internet), 11, p.4821_1 - 4821_8, 2020/09
Times Cited Count：41 Percentile：93.11(Multidisciplinary Sciences)
-ray imaging capability with a Si/CdTe semiconductor Compton cameraTakeda, Shinichiro*; Aono, Hiroyuki*; Okuyama, Sho*; Ishikawa, Shinnosuke*; Odaka, Hirokazu*; Watanabe, Shin*; Kokubun, Motohide*; Takahashi, Tadayuki*; Nakazawa, Kazuhiro*; Tajima, Hiroyasu*; et al.
IEEE Transactions on Nuclear Science, 56(3), p.783 - 790, 2009/06
Times Cited Count：56 Percentile：96.13(Engineering, Electrical & Electronic)Okuyama, Shinichi; Torii, Tatsuo; Suzuki, Akihiko*; Shibuya, Masanori*; Miyazaki, Nobuyuki*
Journal of Nuclear Science and Technology, 45(Suppl.5), p.414 - 416, 2008/06
Times Cited Count：27 Percentile：84.4(Nuclear Science & Technology)In case of a nuclear emergency when a large amount of radioactive substances and/or radiation is released from a nuclear facility, emergency radiation monitoring is carried out from the sea and air as well as from the ground adjacent to the facility to evaluate the influence of the radiation on the surrounding environment. As a means of radiation monitoring from the air, aerial monitoring using a manned helicopter is conducted. Although a manned helicopter can monitor a large area during a short time, flight at an altitude of 300 m or lower is prohibited by the Aviation Law in Japan. Therefore, it is difficult for a manned helicopter to measure the radiation profile near the ground and to measure the radiation level in a complicated terrain. In recent years, technologies for autonomous flying of industrial unmanned helicopters have been developed and applied to natural disasters. In expectation of the application of unmanned helicopters to aerial radiation monitoring during a nuclear emergency, we have developed a remote radiation monitoring system and investigated its possibilities.
Torii, Tatsuo; Okuyama, Shinichi; Nozaki, Tatsuo; Okubo, Koichi; Sugita, Takeshi*; Muraki, Yasushi*
Chimondai Ni Yoru Saiensu; Kyokugen Enerugi Uchubutsuri Kara Chikyukagaku Made, p.211 - 217, 2008/00
The dose rate of the -rays increases in association with the activities of the thunderstorm. They were observed on the ground in the winter season of Japan. In addition to the measurement by the environmental radiation monitors set up around the fast breeder reactor, Monju, the radiation detectors were prepared which consist of the long proportional counters. The results were compared with the results measured at the same time by the environmental radiation monitors. The following two types of the radiation enhancements have been found during the winter thunderstorm activities; the gradual variation of photon intensity with energy up to a few MeV, and the burst type of the radiation that is attributed to the injection of high energy photons with the energy over 10 MeV. In this paper, we present the observed results during winter thunderstorms, and mention the runaway breakdown produced by the incidence of energetic radiation into thunderclouds.
Torii, Tatsuo; Okuyama, Shinichi; Ishizuka, Akihiro
Tokyo Daigaku Uchusen Kenkyujo Heisei-17-Nendo Kyodo Riyo Kenkyu, Kenkyu Seika Hokokushu, P. 129, 2006/00
no abstracts in English
Okuyama, Shinichi; Torii, Tatsuo; Shibuya, Masanori*
Hoshasen Bogo Iryo, (1), p.44 - 45, 2005/11
no abstracts in English
Torii, Tatsuo; OKUBO, Koichi; Okuyama, Shinichi
JNC TN4420 2004-002, 14 Pages, 2004/05
JNC-TN4420-2004-002.pdf:0.36MB
none
Iwama, Toshiro; OKUBO, Koichi; Okuyama, Shinichi
JNC TN4420 2003-004, 30 Pages, 2004/03
JNC-TN4420-2003-004.pdf:3.16MB
This is the investigative report of vegetational observations including some photographs of plants around Monju area in 2003.
Iwama, Toshiro; Okubo, Koichi; Okuyama, Shinichi
JNC TN4420 2003-003, 30 Pages, 2004/03
JNC-TN4420-2003-003.pdf:2.18MB
none
Iwama, Toshiro; Okubo, Koichi; Okuyama, Shinichi
JNC TN4420 2003-002, 30 Pages, 2004/03
JNC-TN4420-2003-002.pdf:2.05MB
none
Okuyama, Shinichi; Torii, Tatsuo
6th International Conference on High Levels of Nat, 84 Pages, 2004/00
Feasibility study of a remote radiation monitoring system using an autonomous unmanned helicopter, mounted the CCD cameras, the GPS sensor, and a radiation detector, has been carried out as measures in a nuclear emergency and for surveying high radiation area in the environment. This system can fly for the destinations and return by the automatic operation, and the radiation data can be measure during the flight. Radiation data measured are transmitted immediately with image data to the monitoring station on the ground. It is possible to monitor these data on the map of the computer display in the real time. As a result of the flight tests, it is confirmed that the fluctuation of the dose-rate distribution on the ground is measured by this system, and it can be used for the radiation monitoring in case of a nuclear emergency.
Torii, Tatsuo; Okuyama, Shinichi; Ishizuka, Akihiro; Nozaki, Tatsuo; Nawa, Yasunori*; Sugita, Takeshi*
no journal, ,
ray dose-rate increases associated with winter thunderstorm activities have been observed at the coastal area of the Sea of Japan. The features are clarified from the measured data obtained by environmental radiation monitors. In order to investigate the generation of energetic radiation which originates in thunderstorm electric fields, we have calculated the behavior of secondary cosmic rays (electromagnetic component; muon) in electric fields with Monte Carlo method. In the calculation, the electron and photon fluxes have increased greatly in the region where the field strength exceeds about 280 P(z) kV/m-atm, where P(z) is the atmospheric pressure (atm) at altitude z (m),.and these energy spectra show a large increase in the energy region up to a few tens of MeV. We have also carried out the Monte Carlo calculations of the beta and rays emitted by radon progenies in thunderstorm electric fields. By the calculation for the radon progeny, the electron flux shows notable increases in the strong electric field region, while the photon flux does not fluctuate significantly. As well as the secondary cosmic rays, the radon progeny products form a large part of the energetic charged particles in the atmosphere. Therefore, they can serve as the source of a considerable amount of runaway electrons, through their ionization process with air molecules. These results indicate that the production of energetic electrons plays an important role in the intensive ionization of the air, and as a result a significant growth of electric conductivity in thunderstorm electric fields. These productions may also induce the lightning discharge by these processes.
Torii, Tatsuo; Okuyama, Shinichi; Nozaki, Tatsuo; Sugita, Takeshi*; Muraki, Yasushi*
no journal, ,
The dose rate might increase when the winter thunderstorm generated in the Sea of Japan coast has been generated. We report on events observed around Monju, and report this case on the radiation behavior in the thundercloud electric field thought about as a source of the radiation.
-ray imaging with a Si/CdTe semiconductor Compton cameraTakeda, Shinichiro*; Aono, Hiroyuki*; Ishikawa, Shinnosuke*; Odaka, Hirokazu*; Watanabe, Shin*; Kokubun, Motohide*; Takahashi, Tadayuki*; Okuyama, Sho*; Nakazawa, Kazuhiro*; Tajima, Hiroyasu*; et al.
no journal, ,
Aono, Hiroyuki*; Takeda, Shinichiro*; Ishikawa, Shinnosuke*; Odaka, Hirokazu*; Kokubun, Motohide*; Watanabe, Shin*; Takahashi, Tadayuki*; Nakazawa, Kazuhiro*; Okuyama, Sho*; Tajima, Hiroyasu*; et al.
no journal, ,
Na and 
Be depositions in Tsuruga cityYoshida, Keisuke; Kato, Shingo; Inoue, Mutsuo*; Ishizuka, Akihiro; Okuyama, Shinichi
no journal, ,
Na is observed for environmental monitoring of Monju fast breeder reactor because Monju reactor contains Na in primary coolant. But Na is produced in upper atmosphere, therefore, Na is detected in assembled deposition sample. To increase accuracy of environmental monitoring, it is necessary to understand transport and supply process of Na and Be depositions from high latitude region where a lot of Na is produced. We collect deposition samples at Tsuruga city to measure Na and collect Be deposition data in 5 sites in Fukui prefecture and Ishikawa prefecture. Because Na and Be shows good correlation, Na have same behavior with Be. Be deposition is maximum at Kanazawa city and minimum at Shika town, but Be deposition is maximum in Winter season at all sites. Be deposition and precipitation shows correlation. From the above, Winter monsoon transport Be and Na from high latitude region and precipitation provide these nuclides to ground surface at Tsuruga city. The deference of Be deposition in Winter season is likely owing to height of mountain and distance of sampling sites.
Kato, Shingo; Ishizuka, Akihiro; Okuyama, Shinichi; Nozaki, Tatsuo; Hayashi, Gaku*; Yasuda, Nakahiro*; Torii, Tatsuo*; Ando, Takasuke*
no journal, ,
no abstracts in English
Kato, Shingo; Yoshida, Keisuke; Inoue, Mutsuo*; Yamashita, Masahiro; Okuyama, Shinichi; Ishimori, Yuu
no journal, ,
no abstracts in English
Be depositions in Hokuriku, JapanYoshida, Keisuke; Kato, Shingo; Uchida, Kengo*; Yamashita, Masahiro; Okuyama, Shinichi; Inoue, Mutsuo*
no journal, ,
In winter, Be deposition profile shows wide variation in Hokuriku region. Temporal and regional variations of Be deposition data during 30 years (Apr. 1991 to Mar. 2021) were analyzed and material transport mechanisms from arctic region were studied. Due to pressure pattern around Japan in winter and inhomogeneous precipitation in Hokuriku region caused by topography, characteristic seasonal variation was found and highest Be deposition was observed in mountainous area in Kanazawa City. In addition, the period of high Be deposition observed approximately agreed with that of minimum sunspot number or maximum precipitation. Therefore, sunspot number and precipitation affect temporal variations of Be deposition.
Hayashi, Gaku*; Torii, Tatsuo*; Ishizuka, Akihiro; Okuyama, Shinichi; Kato, Shingo; Nozaki, Tatsuo; Yasuda, Nakahiro*
no journal, ,
no abstracts in English
