Radiochemical Verification Technologies for the Detection of Nuclear Explosions – Recent Developments in Radionuclide Monitoring with the Comprehensive Nuclear-Test-Ban Treaty –

摘要

The Provisional Technical Secretariat of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) Organization has established the International Monitoring System (IMS) under its auspices. Through technological advances, the CTBT has achieved nuclear test detection limits of 1 kiloton by the use of CTBT verification technologies. However, radionuclides were not observed clearly by the IMS during the first and second nuclear weapon tests conducted by the Democratic People’s Republic of Korea (DPRK). With the third test carried out by the DPRK, however, they could observe traces of the event using the IMS, noble gas detection stations, and Atmospheric Transport Modeling (ATM) techniques. After the accident at the Fukushima Dai-ichi Nuclear Power Plant in March 2011, the IMS accurately tracked the global movement of radionuclides that originated from this event. In the following report, the current situation and recent problems regarding environmental monitoring of radionuclides by the CTBT are presented and discussed. Focus will be placed on the detection abilities of the IMS and the system used for evaluation of the radionuclides released by nuclear explosions and power plant accidents.