- Hypothesized dispersion of radioactive noble gas Xenon 133 shown one (a), two (b) and (c) 10 days after the declared nuclear test.
The findings based on the so-called waveform technologies - seismic, hydroacoustic and infrasound - are used to identify the area for a possible on-site inspection. This final verification measure can be invoked by the future Executive Council once the Treaty enters into force. Under the Treaty, an on-site inspection area is to be no more than 1000 square kilometres. In the case of the event of 9 October 2006, analysis of all available data allowed for the identification of a potential inspection area of considerably less than 1000 square kilometres.
The radionuclide technology, measuring radionuclide particles or noble gases in the air, is applied to provide ultimate proof of a nuclear explosion. Radioactive noble gases are of particular interest. Due to their ability to seep through layers of rock into the air, they would be the only evidence of a well-contained underground nuclear explosion. Dispersed by the winds, traces of noble gases would eventually be registered at a radionuclide station equipped with the relevant technology.
- Seismograms for the declared nuclear test and from an earlier earthquake, recorded at primary seismic station PS31 at Wonju, Republic of Korea.
Two weeks after the event, the radionuclide noble gas station at Yellowknife, Canada, registered a higher concentration of Xenon 133. Applying atmospheric transport models to backtrack the dispersion of the gas, its registration at Yellowknife was found to be consistent with a hypothesized release from the event in the DPRK.
At the time of the announced nuclear explosion by the DPRK, only ten out of the planned forty stations with noble gas measuring technology were operational in test-mode. The contribution of this technology to the analysis of the event on 9 October demonstrated its significant role in the CTBT verification system.
The event in the DPRK was a test for the CTBT verification system, for its reliability and technical capabilities. The system has proven its value for the purpose for which it was designed - receiving and reviewing data on a specific event and providing highly qualitative information to States Signatories, enabling them to make their own judgments.
The event underlined the need for early entry into force of the Treaty and the rapid completion of the CTBT verification regime's build-up. Those States that have not yet joined the CTBTO family are encouraged to make that step in order to have the Treaty enter into force.
