It is now more than a week into the integrated on-site inspection (OSI) field exercise conducted by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) and the first phase of an OSI in the fictitious State of Arcania has been completed. The CTBTO inspection team handed over its progress inspection report to the Director General after review by the inspected State Party on 12 September, which indicated that the inspection techniques used during this initial period did not bring to light any evidence of a recently conducted nuclear explosion.  The team did, however, identify a number of areas of interest that required further study using advanced methods.

Consequently, the inspection team proposed that the inspection be continued into the second phase – the so-called continuation period – when an additional number of techniques, mostly geophysical methods, would be used. The inspection techniques which had been employed previously, including seismic aftershock monitoring, gamma radiation monitoring and visual observation, would continue during the second phase, complementing the geophysical inspection techniques.

Over the last ten days, the small tent town just outside the confines of the former Soviet Union nuclear test site has settled into a daily routine.  The 180 experts from all over the world have become accustomed to play their part in this simulation of an on-site inspection in the fictitious State of Arcania.  In the scenario for this exercise, the CTBTO registered an event on the territory of Arcania which – according to relevant analysis – may have been a nuclear explosion, thus triggering an OSI, the ultimate verification measure of a global alarm system being built by the CTBTO to detect nuclear explosions.