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How Much Uranium Did It Take to Destroy Hiroshima and Nagasaki?

The nuclear chain induced by the reaction between rare uraniums is all you need to achieve to produce an atomic bomb. This frighteningly simple technology had the power to completely wreck Hiroshima and Nagasaki, causing Japan’s state of surrender in World War II.

The energy-converted matter in the atomic bomb that caused monumental destruction to the cities of Hiroshima and Nagasaki weighed as much as a single butterfly. 

The Uranium Enrichment

Uranium 235 is an extremely rare isotope, comprising only less than 1% of uranium that naturally occurs. Site X, or what we now know as Oak Ridge, Tennesee, served the sole purpose of making uranium 235. The government of the United States primarily built Oak Ridge City to house uranium enrichment plants, like the K-25 and Y-12, while not being spotted in the maps. Soon, Oak Ridge contained the liquid thermal diffusion plant, S-50, and the pilot plutonium production reactor, X-10 Graphite Reactor.

The Y-12 plant used the most advanced method to enrich uranium at that time. Ernest Lawrence, who worked at the University of California-Berkeley, invented the electromagnetic separation procedure. At the start of the Manhattan Project, electromagnetic separation became the most effective way to separate the isotopes of uranium.

One needs uranium 235, or highly enriched uranium, to construct an atomic bomb. This uranium would be cleansed to a pure state and needed to be processed repeatedly to attain an 80% uranium 235 in an atomic bomb. With the 64 kilograms of uranium in the atomic bomb, less than a kilogram was subjected to fission.

The power of the atomic bomb’s entirety emerges from half a gram of energy-converted matter. The bomb’s destructive force roots from the transformed energy that weighs equal to a singular butterfly. (Source: Atomic Heritage Foundation

The Hiroshima and Nagasaki Bombing

The heavily disruptive yet simple technology found in the makings of the atomic bomb led to the American-caused immense destruction known as the bombing in Hiroshima. On the 6th day of August in 1945, during the Second World War, the infamous Hiroshima bombing occurred in Japan with the first deployment of the atomic bomb.

The B-29 bomber named Enola Gay carried the uranium 235 atomic bomb, which weighed a little over 9,000 pounds. Choosing Hiroshima as its first victim, the bomber dropped its load at 8 in the morning, detonating more than 2,000 feet in the skies above Hiroshima. This explosion utterly destroyed five square miles of Hiroshima.

Without the signaling of surrender from Japan, the Americans sent another B-29 bomber, piloted by Major Charles Sweeney. The bomb that Sweeney carried was called the fat man, as it weighed an estimated 1,000 pounds more than the initial atomic bomb dropped on the city of Hiroshima. The fat man induced a 22-kiloton explosion; by 11 in the morning, Nagasaki fell victim to the bomb. Thankfully, the mountainous area that shrouded the bomb’s location heavily reduced the bomb’s impact, only damaging 2.6 square miles of the city.


With the atomic bombings producing more than 120,000 dead, the Emperor of Japan surrendered subsequently. Emperor Hirohito announced Japan’s surrender through the radio, stating the extremely feared strength of the new and cruel bomb. (Source: History)

2 thoughts on “How Much Uranium Did It Take to Destroy Hiroshima and Nagasaki?”

  1. tester

    03-19-1945, revenge for the attack on the USS Franklen had to have been on Truman’s mind !

  2. Si le Japon avait été irradié de la sorte il serait resté inhabité pendant 1000ans et plus non? Il y a quelque chose qui n’est pas logique non?

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