ON THIS DAY

March 1, 1954:

On this day in 1954 the US exploded Castle Bravo, a 15 megaton hydrogen bomb at Bikini Atoll, which accidentally became the most powerful nuclear device ever detonated by the US.

The scientists testing the first lithium deuteride-fueled thermonuclear weapon expected an explosion with a yield of 6 megatons. Instead, the detonation was 15 megatons - 1000 times more powerful than the bomb dropped on Hiroshima - inadvertently making it the fifth-largest nuclear explosion in history, and causing serious problems in the area where the test took place.

Bikini Atoll had been selected for the test, having had its native population relocated in the late 1940s in preparation for the creation of a nuclear test zone. When Castle Bravo was detonated on March 1, 1954, the radioactive fallout from the test spread as far as 100 miles (160 km) east of the atoll into areas that were inhabited. In addition a Japanese fishing vessel called Daigo Fukuryū Maru with 23 people on board came into direct contact with the fallout and the crew suffered from acute radiation sickness for weeks afterward. 15 atolls were affected, and residents of some were evacuated 48 hours after the detonation.

Even the test crew took shelter for several hours once they realised the explosion was much larger than anticipated. Trace amounts of radioactivity were recorded as far away as Australia, India and parts of Europe. In the years after the test several Marshall Islanders began to experience health issues, including birth defects and tumors, as a result of the test, and the US government eventually paid them compensation.

The incident caused controversy about nuclear testing in the atmosphere, and eventually the United States, the UK and the Soviet Union agreed to ban tests in the atmosphere in 1963.

Castle Bravo detonation.

By the Way:

An atoll is a ring-shaped island, including a coral rim that encircles a lagoon. Atolls are located in warm tropical or subtropical parts of the oceans and seas where corals can develop. Most of the approximately 440 atolls in the world are in the Pacific Ocean.

Bikini Atoll is a coral reef in the Marshall Islands consisting of 23 islands surrounding a 594 sq k / 229 sq mile central lagoon.

The United States used the islands and lagoon as the site of 23 nuclear tests until 1958, when it was discovered that the fallout from nuclear testing was much more dangerous than was previously thought.

To this day, the Bikini islanders have not been able to return home due to nuclear contamination. There are some signs of recovery as the amount of radiation slowly decreases.

In the 21st century, the atoll is a World Heritage Site, remembered for its role in the Cold War and the post-nuclear age.

The island's English name is derived from the German colonial name Bikini given to the atoll when it was part of German New Guinea. The German name is transliterated from the Marshallese name for the island, Pikinni, "Pik" meaning "plane surface" and "Ni" meaning "coconut tree", or surface of coconuts.

Louis Réard, a French automotive and mechanical engineer who was running his mother's lingerie business, released a two piece swimsuit design in 1946, 5 days after the first test of a nuclear device over Bikini Atoll. Reard named his design ‘the Bikini’.