A team of researchers from Columbia University has found that the Marshall Islands are becoming habitable except Bikini Atolls. The radiation there remains 184 mrem/year. This is after 66 years of Castle Bravo explosion test. More study needs to be conducted regarding the Island in terms of food it can grow and drinkable water, before any talk of rehabilitation can start.

During 1946-58, the US undertook an ambitious project of producing powerful nuclear devices. They detonated around 67 nuclear devices. Castle Bravo explosion was the first of the thermonuclear bombs of the series of “Operation Castle”. It was one of the biggest nuclear tests of that time, 1000 times larger in effect than the bombs dropped on Hiroshima and Nagasaki. The experiment of Castle Bravo, however, did not go according to the plan. There were some miscalculations which led to devastating impacts.

Let’s look at the story of Castle Bravo explosion in detail.

How did it all start?

The Marshall Islands lie between Hawaii and Australia in the Pacific Ocean, above the equator. It is a two-chain, low lying artificial Island. It was initially controlled by Germany during World War-I; the power was later seized and maintained by the Japanese. During World War-II, after the bombs were dropped on Japan (in 1945), the US military took over the Islands.

Due to its remote location, scarce population and stable weather, it became an ideal site for the US to test its nuclear weapon. The natives of the Island were regularly moved by the military to nearby Islands to prevent them from falling under the radiation zones. Their initial tests killed a huge number of land and marine animals. The islands where the people were usually shifted did not have enough food to sustain its “temporary population”. After 1947, operations in Pacific Proving Ground shifted from the US military to US civilians under the newly formed Atomic Energy Commission. This led to a new cloud of secrecy in their future plans.

The era of the Cold War started, leading to an arms race between the US and Russia. Many series of tests for powerful weapons started taking place like Operation Sandstone, Operation Ivy, Operation Greenhouse, and Operation Castle (The first bomb that was tested under the Operation Castle series was ‘Castle Bravo’). The secrecy of the project was a major reason that it led to a disastrous impact. That’s how it all began.

What went wrong with Castle Bravo?

On 1st March 1954, at 6:45 AM, as soon as the nuclear explosion took place the scientists knew something had gone wrong. The blast was overwhelming creating a fireball that was rising at 1000 feet per second. The explosion created a mushroom cloud 130,000 feet above the sea level, leaving a crater on the ocean floor of about 6,500 feet diameter and depth of about 250 feet. It was the US’s most powerful nuclear weapon at the time but also most disastrous. Some witnesses even said that the light was so powerful that they could see the shadows of the bones of other men through their flesh. The shockwaves destroyed buildings outside the area predicted and almost knocked off the surveillance aircraft. People in the forward observation bunker felt that their bases had been completely eroded off and that they might have flung somewhere else.

The impact of the explosion was 15 megatons of TNT while the prediction was about 6 megatons, which is about 2.5 times more. This was due to the use of lithium-7 isotope as fuel, relating to which the designers of the device (Los Alamos National Laboratory) had made an error in calculating the yield. The use of the fuel led to some unforeseen reactions leading to high radioactive contamination of the Island Bikini Atolls and the area east of it.

The aftermath of the explosion:

The explosion may not have gotten international coverage if the Japanese fishing ship named “Lucky Dragon 5” with 23 crew members wasn’t caught in the contamination zone. A surviving crew member described the blast as “It felt like our bodies were being burned by a blowtorch”. One of the members died with radiation sickness due to the contaminated tuna which was bought by them was circulated in the fish market of Japan. This incident created a strain in the relations between Japan and the US. Finally, some compensation was provided by the US to the surviving crew members and the news of Bravo explosion became huge.

The Marshall Islanders were taken as a test subject of the US study called “Project 4.1” to know the effects of radiation on humans without their consent. None of the people knew what kind of drugs they were given and what for they were being studied. 55% of the Marshallese suffers from thyroid cancer or blood poisoning. The women exposed to radiation gave birth to deformed babies- some with anomaly large heads or translucent skin. Most of them died within a few days. The Islanders who were relocated had trouble finding livelihoods as they were not proficient in English and they continue to demand adequate compensation for their land and health and for the sake of justice.


Castle Bravo was not the last test conducted on the island even after its large scale impact. It’s been 66 years since the explosion took place, however, the islands are still contaminated beyond the safe level for the Marshallese to return. One of the Bikini representatives, Tomaki Juda said in a press conference in 2014 for the 60th anniversary of the Castle Bravo, “We are sadly more akin to the Children of Israel when they left Egypt and wandered through the desert for 40 years, we left Bikini and have wandered through the ocean for 32 years and we will never return to our Promised Land.” Science has progressed by leaps and bounds but living in a world where arm race has only intensified and a full-blown nuclear war is a possibility, one might wonder- at what cost?

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