Chagan was a Soviet nuclear test the during the Soviet atomic bomb project and was equivalent of the US Operation Plowshare to investigate peaceful uses of nuclear weapons. It was an underground test, and was fired on January 15 1965. The site a dry bed of the Chagan River at the edge of the Semipalatinsk Test Site, and was chosen such that the lip of the crater would dam the river during its high spring flow. The resultant crater had a diameter of 408 meters and was 100 meters deep. A major lake (10,000,000 m³) soon formed behind the 20-35 m high upraised lip, known as Lake Chagan or Lake Balapan.

The explosion's power was 140 kilotons of TNT.

The area is still radioactive. The test apparently violated the 1963 Limited Test Ban Treaty, and the United States complained to the Soviets, but the matter was dropped.

Of note, the photo has been twice mistakenly credited (in otherwise reputable works) as the Soviet test, Joe 1 (Richard Rhode's 1995 Dark Sun: The Making of the Hydrogen Bomb and David Holloway's 1994 Stalin and the Bomb). The difference can be seen when comparing it to other photographs of Joe 1 (which look quite different), and also in the fact that the Chagan photograph is clearly coming out of the ground, notable by the amount of dirt and debris in the picture (comparable with photographs of other US "plowshares" shots).

External links

• On the Soviet nuclear program