Overview

Operation Crossroads was a series of nuclear weapon tests conducted by the United States at Bikini Atoll in mid-1946. It was the first test of a nuclear weapon after the Trinity nuclear test in July 1945. Its purpose was to investigate the effect of nuclear weapons on naval ships.

Crossroads consisted of two detonations, each with a yield of 23 kilotons: Able was detonated at an altitude of 520 feet (158 m) on July 1, 1946; Baker was detonated 90 feet (27 m) underwater on July 25, 1946.

The test resulted in the radioactive contamination of all the target ships by the underwater Baker shot. It was the first case of immediate, concentrated local radioactive fallout from a nuclear explosion. (The fallout from an air burst is global, held in the stratosphere for days and widely dispersed.) Chemist Glenn Seaborg, the longest-serving chairman of the Atomic Energy Commission, called Baker "the world's first nuclear disaster."

References

Operation Crossroads - wikipedia