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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.
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.
