Page 1: Types of Nuclear Weapons Tests

Nuclear explosions have been detonated in all environments: above ground, underground and underwater. Bombs have been detonated on top of towers, onboard barges, suspended from balloons, on the earth's surface, underwater to depths of 600m, underground to depths of more than 2,400m and in horizontal tunnels. Test bombs have been dropped by aircraft and fired by rockets to altitudes of over 500 kilometres.

Atmospheric testing

Atmospheric testing refers to explosions which take place in the atmosphere.

All told, of the over 2,000 nuclear explosions detonated worldwide between 16 July 1945 (United States) and 29 July 1996 (China), 25 % or over 500 bombs were exploded in the atmosphere: over 200 by the United States, over 200 by the Soviet Union, about 20 by Britain, about 50 by France and over 20 by China.

International concern over radioactive fallout resulting from atmospheric tests escalated in the mid 1950s. In March 1954, the United States tested its hydrogen bomb Castle Bravo in the Pacific’s Marshall Islands. The Bravo test created the worst radiological disaster in the United States’ testing history. By accident, local civilians on the Marshall Islands, U.S. servicemen stationed on Rongerik atoll, and the Japanese fishing trawler Lucky Dragon, were contaminated with the fallout.

Nuclear weapon tests have been carried out in all environments: above ground, underground and underwater.
Signing of the Partial Test Ban Treaty, 5 August 1963. Secretary of State Dean Rusk signing for the United States; Foreign Minister Andre Gromyko, signing for the Soviet Union; and Lord Hume signing for the United Kingdom.

Atmospheric testing was banned by the 1963 Partial Test Ban Treaty. Negotiations had largely responded to the international community’s grave concern over the radioactive fallout resulting from atmospheric tests. The United States, the Soviet Union and the United Kingdom became Parties to the Treaty; France and China did not. France conducted its last atmospheric test in 1974, China in 1980.

CTBTO's infrasound IMS stations are used to detect nuclear explosions by monitoring low-frequency sound waves in the atmosphere. CTBTO Radionuclide IMS stations are designed to detect radioactive particles emanating from an atmospheric test.

High-altitude nuclear testing

Artificial aurora over Honolulu created by the 1962 Starfish Prime test.

Around 20 nuclear tests were conducted by the United States and the Soviet Union in high altitudes or lower outer space between 1958 and 1962. The main aim of these explosions, detonated at heights between 40 and 540 kilometres, was to determine the feasibility of nuclear weapons as anti-ballistic missile defense or anti-satellite weapons. The largest such test, the 1.4 megaton U.S. Starfish Prime test in 1962, damaged and destroyed several of the satellites in orbit at the time and led to wide-spread power outages on the ground. High-altitude or outer space nuclear testing is equally banned by the 1963 Partial Test Ban Treaty as well as by the 1967 Outer Space Treaty.