
Kazakhstan and Chain Reaction 2016 – from nuclear tests to a nuclear-weapon-free world
On 29 August 1949, the Soviet Union detonated their first nuclear weapon, code-named First Lightning, a nuclear chain reaction that caused radioactive contamination over a large area of Kazakhstan. Over the next 40 years, the Soviet Union detonated another 455 nuclear weapons in Kazakhstan, 115 above ground and 340 underground.