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Yamamoto, Yoichi
Isotope News, (736), p.31 - 33, 2015/08
The Takasaki radionuclide (RN) station for the Comprehensive Nuclear-Test-Ban Treaty (CTBT) has been in operation for monitoring of radioactive noble gases (radioxenon) by the Japan Atomic Energy Agency (JAEA) since 2007, first as a test run prior to receiving the certification. The noble gas system in the station was certified by the CTBT Organization (CTBTO) on December 19, 2014. Monitoring of radioxenon is expected to have a particularly valuable role in detection of an underground nuclear test. The Takasaki RN station detected radioxenon isotopes simultaneously with radioactive concentration exceeding normal background range in April, 2013. This abnormal event was identified as being associated with the nuclear test declared by North Korea in February, 2013. Since the Takasaki RN station is located at the east end of Asia, it is receiving widespread international attention as the station for radionuclides dispersed by the westerlies.
Shinohara, Nobuo; Inoue, Yoji; Uchikoshi, Takako*; Oda, Tetsuzo*; Kumata, Masahiro; Kurosawa, Yoshiaki; Hirota, Naoki*; Hokida, Takanori; Nakahara, Yoshinori*; Yamamoto, Yoichi
Dai-25-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, p.51 - 58, 2005/00
The Japan Atomic Energy Research Institute (JAERI) conducts researches and developments related to Comprehensive Nuclear-Test-Ban Treaty (CTBT) on the basis of Japan's pragmatic and progressive efforts toward peaceful use of atomic energy and non-proliferation with the goal of realizing a peaceful and safe world free from nuclear weapons. The Treaty aims for the establishment of a global verification regime comprising an International Monitoring System (IMS) and the JAERI has engaged in the following activities: construction and operation of the radionuclide monitoring stations at Okinawa (RN37) and Takasaki (RN38) and the certified radionuclide laboratory at Tokai (RL11) as specified in Annex 1 of CTBT Protocol, and preparation of the National Data Center at Tokai (JAERI NDC). Research activities of JAERI related to the CTBT verification regime are presented in the paper. The subjects of this presentation are (1) an overview of the CTBT verification regime, (2) construction and operation of RN37, RN38 and RL11, and (3) preparation of the JAERI NDC for radionuclide data.
Shinohara, Nobuo; Yamamoto, Yoichi; Inoue, Yoji; Kumata, Masahiro; Oda, Tetsuzo; Uchikoshi, Takako*; Hokida, Takanori; Hirota, Naoki*; Nakahara, Yoshinori; Usuda, Shigekazu
Dai-23-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, p.45 - 52, 2002/12
no abstracts in English
Furuno, Akiko; Kijima, Yuichi; Tomita, Yutaka; Yamamoto, Yoichi
no journal, ,
This research aims at source term estimations of high-concentration detection events of Xe-133, which were observed at the CTBT IMS (International Monitoring System) Takasaki radionuclide monitoring station from the viewpoint of atmospheric dispersion analysis. Japan Atomic Energy Agency operates JPX38 in the Takasaki radionuclide station for noble gas monitoring, and conducts temporary measurement project of radioxenon at Horonobe in Hokkaido (JPX81) and Mutsu in Aomori (MUX88) as a part of the noble gas joint measurement project with CTBTO. The high-concentration detection events were frequently occurred not only at the JPX38 but also at the JPX81from the end of 2020 to January 2021. In the presentation, we will describe the source term estimation analysis of these high-concentration detection events, and discuss the relationship of the events between two stations.
Tomita, Yutaka; Furuno, Akiko; Kurihara, Toshiyuki; Yamamoto, Yoichi; Sakurai, Shinichi*
no journal, ,
There are the two IMS radionuclide stations, RN37 Okinawa and RN38 Takasaki, in Japan. JAEA (Japan Atomic Energy Agency) has been operating both of the stations. RN37 Okinawa has been observing for more than 15 years without long missing periods since received the certification in February 2007. RN37 Okinawa is located in the subtropical zone and close to the sea. Therefore, the station building and equipment are susceptible to corrosion due to high temperature, high humidity, and salt damage. This makes maintenance more difficult than that of RN38 Takasaki which is located inland in the temperate zone. In this presentation, we will report on O&M specific for the RN37 Okinawa, including measures against salt damage, lightning, and humidity, etc.
Yamamoto, Yoichi; Kijima, Yuichi; Oda, Tetsuzo
no journal, ,
The Japanese NDC-2 estimated the movement of virtual radioactive plume by the Atmospheric Transport Modelling (ATM) simulations with regard to the DPRK 2016 event. The simulations were done in two hypothetical cases of coincident and delayed emission of radionuclides. The NDC-2 decided which IMS radionuclide stations should be monitored based on the simulation results. As the result, no radionuclides generated from the nuclear explosion were found in any IMS data obtained from the selected radionuclide stations in January. However, xenon-133 with high activity concentration above the normal background levels was detected 5 times at the Takasaki station in the middle of February. The NDC-2 estimated the location of emission source of the Xe-133 by ATM backward tracking simulations. Some ATM simulations and the analysis results by the NDC-2 are shown in the presentation.
Tomita, Yutaka; Furuno, Akiko; Yamamoto, Yoichi
no journal, ,
Various restrictions under the COVID-19 crisis have been imposed on the operation and maintenance of the radionuclide stations of RN37 and RN38 in Japan. We will report on how JAEA is working with PTS, manufacturers of RASA and SAUNA, and local operators in order to overcome this challenge.
Tomita, Yutaka; Furuno, Akiko; Yamamoto, Yoichi; Kurihara, Toshiyuki
no journal, ,
We are operating the National Data Center (NDC-2) in Japan Atomic Energy Agency (JAEA), and we receive and analyze data from radionuclide stations of Comprehensive Nuclear-Test-Ban Treaty (CTBT) located around the world. These data can be used not only to detect nuclear tests, but also to confirm of the presence of the accidental release of radionuclides from the nuclear facilities. We introduce in this presentation about our results of radionuclide and atmospheric dispersion analyses for a case in which CTBT monitored anthropogenic radionuclides were detected at the Stockholm station (RN63) in Sweden in June 2020. We have also analyzed data from a radionuclide station located downwind from the Zaporizhzhia NPP since its shelling in March 2022 following the Ukrainian conflict. These results will also be shown in the presentation.
Tomita, Yutaka; Kumata, Masahiro; Wakabayashi, Shuji; Kijima, Yuichi; Yamamoto, Yoichi; Oda, Tetsuzo
no journal, ,
Tomita, Yutaka; Kijima, Yuichi; Furuno, Akiko; Yamamoto, Yoichi
no journal, ,
The Japan Atomic Energy Agency (JAEA) has operated two radionuclide stations which are Takasaki radionuclide station (RN38) and Okinawa radionuclide station (RN37) for the CTBT (Comprehensive Nuclear- Test-Ban Treaty) International Monitoring System (IMS). RN38 was built in the Takasaki Advanced Radiation Research Institute of the National Institutes for Quantum and Radiological Science and Technology (QST) in 2002. Radioactivity of particulate radionuclides and radioxenon gases are measured at RN38 by using a Radionuclide Aerosol Sampler / Analyzer (RASA) and a Swedish Automatic Unit for Noble Gas (SAUNA) respectively. It was worthy of special mention that the SAUNA of RN38 detected the radioxenons which were related to the DPRK-3 event in 2013. RN37 was installed in a renovated facility at the Okinawa Tracking and Communication Station of the Japan Aerospace Exploration Agency (JAXA) in 2006. It measures only radioactivity of particulate radionuclides by using a RASA. JAEA contributes to the CTBT international verification regime through these activities. Operation and some monitoring results of both radionuclide stations will be reported in this presentation.
