44 states in Annex 2 and 321 stations in the monitoring system: the Comprehensive Nuclear-Test-Ban Treaty

Background

The Comprehensive Nuclear-Test-Ban Treaty, or CTBT, would ban all nuclear explosive testing, and it has still not entered into force. It was negotiated in the Conference on Disarmament, adopted by the United Nations General Assembly and opened for signature in 1996. Under its Article XIV the treaty enters into force 180 days after all 44 states named in its Annex 2 have deposited their instruments of ratification, but not less than two years after it was opened for signature. Those 44 are the states with nuclear reactors that took part in the disarmament conference session of that year and were its members at the time. The treaty sets up a verification regime, with an International Monitoring System and provision for on-site inspections. When complete that system is to have 321 stations: 170 seismic stations for waves in the Earth, 11 hydroacoustic stations for underwater sound, 60 arrays of infrasound detectors for very low frequency sound in the atmosphere, and 80 radionuclide stations for radioactive particles, half of which also look for radioactive xenon gas, backed by 16 radionuclide laboratories. Data flow to an International Data Center, or IDC, and of the seismic stations 50 are to report continuously in real time while 120 report when the IDC asks. Article II of the treaty creates the Comprehensive Nuclear-Test-Ban Treaty Organization, which will come into existence only once the treaty is in force, so a Preparatory Commission certifies the stations and runs the system in the meantime.