You must know about Hiroshima, and for a nuclear chain reaction to occur, there should be nuclear fuel and sufficient quantities. Nuclear fuels like plutonium and uranium should be brought together to form a critical mass. For a chain reaction, there should be some standard and adequate amount of fissionable material that is required. So, for the chain reaction to begin, neutrons should strike heavy plutonium or uranium nucleus. This action can result in the release of the unimaginable and a tremendous amount of energy.
It also releases few more neutrons that, in turn, can slit into more nuclei, and there is no end.
Understand the above reaction as a gun-type device. Here, to achieve the critical mass, you need uranium projectile, and that should be fired using a gun barrel. However, the uranium projectile is considered to be subcritical and the target should be at a uranium target, and that is also subcritical.
The result will be uranium mass that comprises of both of this projectile. Hence, the target also gets critical. It is the main reason behind the starting of a chain reaction. So, this is the same thing that happened on August 6, 1945, at Hiroshima City in Japan. It was the first time when a nuclear weapon was utilized in a war.
Here are some details about this nuclear chain reaction that happened in Hiroshima.
- The weight was 9,700 pounds
- The length was 10 feet
- The diameter was 28 inches
Other than this, there are many things that you should dig in and understand about this nuclear reaction. The fuel used was completely enriched using the uranium. However, the uranium fuel utilized was nearly 140 lbs. Eighty-five lbs were the defined target, and 55 lbs were the actual projectile used.
The materials used such as barrel, uranium projectile, target case, and the entire set of main parts were ferried through USS Indianapolis to the Island Tinian. The uranium target components were ferried through C-54 aircraft to Tinian. The was the aircraft that belonged to the 509th composite group.
The actual efficiency of this weapon was said to be poor. Hence, among the available quantity, nearly 1.38 percent of the total uranium was actually fission. Fifteen thousand tons of TNT equivalent was the actual explosive force. It was dropped on Hiroshima that is one of the Japanese cities on August 6, 1945.
It is nothing but the second plutonium and is one of the impulsion type bombs. The first one was called gadget, and that was detonated at Trinity site on July 16, 1945. So, if you want to understand the impulsion type device, here the core of the sub-critical plutonium will be surrounded by thousands of pounds of high explosives. These are designed in a way so that the explosive force that is resulted from HE should be directed inwards.
However, this will result in crushing the plutonium core, and that leads to a supercritical state. It was dropped on August 9, 1945, in the Japanese city of Nagasaki. It was the second time when a nuclear weapon was used for war. 10,800 lbs was the weight, it was 10 feet long, and 60 inches in diameter. The fuel used was plutonium 239.