America’s Disastrous Miscalculation: The Castle Bravo Nuclear Test

During the Cold War, the United States and the Soviet Union were involved in an intense nuclear arms race. This involved the testing of atomic weaponry by both sides.

On 1 March 1954 the United States military detonated its most powerful nuclear explosion ever. The test came in the form of a dry fuel hydrogen bomb.

An Error of Nuclear Proportions

castle bravo bikini atoll

The Castle Bravo explosion

Due to a theoretical error by the bomb’s designers, the device resulted in measured yield of 15 megatonness of TNT. This was far far more than the 6 – 8 megatonnes it was expected to produce.

The device was detonated on a small artificial island off of Namu Island in the Bikini Atoll, part of the Marshall Islands, which are located in the equatorial Pacific.

Code named Castle Bravo, this first test of the Operation Castle test series was 1,000 times more powerful than either of the atomic bombs the US dropped on Hiroshima and Nagasaki in World War Two.

Within a second of detonation Bravo formed a 4.5-mile-high fireball. It blasted a crater some 2,000 metres in diameter and 76 metres deep.

Destruction and Fallout

An area of 7,000 square miles was contaminated as a result of the test. Inhabitants of Rongelap and Utirik atolls were exposed to high levels of fallout, resulting in radiation sickness, but they not evacuated until 3 days after the blast. A Japanese fishing ship was also exposed, killing one of its crew.

In 1946, long before Castle Bravo, residents of the Bikini Islands were removed and resettled to Rongerik Atoll. Islanders were allowed to resettle in the 1970s, but left again due to contracting radiation sickness from eating contaminated food.

There are similar stories concerning the residents of Rongelap and Bikini Islanders have still yet to return home.

The Legacy of Nuclear Testing

All in all the United States performed 67 nuclear tests in the Marshall Islands, the last of which was in 1958. A UN Human Rights Council report stated that the environmental contamination was ‘near-irreversible’. Islanders continue to suffer due to a number of factors relating to their displacement from their homes.

The most powerful nuclear explosion in history was the Tsar Bomba, detonated by the Soviet Union on 30 October 1961 over the Mityushikha Bay nuclear testing range in the Arctic Sea. The Tsar Bomba produced a yield of 50 megatonnes — over 3 times the amount produced by Castle Bravo.

By the 1960s there was not one place on Earth where fallout from nuclear weapons testing could not be measured. It can still be found in soil and water, including even the polar ice caps.

Exposure to nuclear fallout, specifically Iodine-131, can cause a number of health problems, especially thyroid cancer.

Graham is an editor and contributor at Made From History. A London-based writer originally from Washington, DC, he holds a master's degree in Cultural History from Malmö University in Sweden. Graham also contributes environmental news articles to asiancorrespondent.com and latincorrespondent.com.