Analysis Of The Announced DPRK Nuclear Test

Next Phase In The Analysis Of The Announced DPRK Nuclear Test

Vienna, Austria, 27 May 2009

At a meeting of Signatory States of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) yesterday, 26 May (see press release), the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) informed delegates on the progress in the analysis of its findings on the nuclear test declared by the Democratic People’s Republic of Korea (DPRK) on Monday, 25 May. The CTBTO issued its first information to the Signatory States at 02.24 am (GMT), containing the location, magnitude, depth and time of the event. This information was further updated within two and four hours. On Monday morning, a technical briefing to Signatory States provided additional information.

Complex seismic signals

CTBTO experts explained that they continued to study the signals detected by the seismic stations of the International Monitoring System (IMS). The seismic data seemed to be more complex than from typical explosions: The signals have been recorded by a larger number of IMS seismic stations. CTBTO experts concluded that the recorded signals contain distinct characteristics of an explosion. In addition, they also identified simultaneous signals with earthquake–like characteristics.

Tracking down radioactive particles

Underground explosions typically release radioactive noble gases, which can be detected – depending on the amount released – by certain IMS stations. Noble gas is the “smoking gun” of a nuclear explosion.

The detection of airborne radioactive substances depends on the prevailing meteorological situation. By applying a technique called Atmospheric Transport Modeling (ATM), the three-dimensional travel path of a radionuclide particle or noble gas is backtracked from where it was detected by a monitoring station, to the area where it may have originated – and vice-versa.

After the 2006 nuclear test, traces of the radioactive noble gas Xenon133 – an isotope that does not exist in nature - were detected by a station in Yellowknife, Canada; some 7500 km away from the test site and 12 days after the event. As the network of noble gas-capable stations has grown denser today – up from 11 to 22 systems (40 anticipated at the entry into force of the CTBT), with the higher density of stations now running in the region, it may be possible to detect radioactive noble gas within days rather than weeks.

The system’s capabilities were also boosted through the establishment of a joint response system with the World Meteorological Organization (WMO) last September, which allows the CTBTO to utilise additional atmospheric transport models in order to make more precise ATM calculations.

The CTBTO will provide an update if and when noble gas has been detected and analyzed.

ENDS

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