Nuclear Weapon: The Manhattan Project

The Manhattan Project was a concealed military project launched in 1942 to build a nuclear weapon that would assist the Allies in World War II. The project, which costed 2 billion dollars (about 26 billion of today’s dollars), was led by the United States with the backing of Canada and the United Kingdom. It took place in various sites across the United States and because those sites had high security, not many knew of the project while it was in progress. The people placed in charge of this project were General Leslie R. Groves and U.S. physicist Robert Oppenheimer. These directors had recruited many excellent scientists, mathematicians, and engineers to reach their objective. There were over 125,000 people who took part in this project, and

One type was the gun-type bomb, which has the shape of a capsule. Gun-type assembly involves conventional explosives, a gun barrel, a neutron initiator, a hollow, subcritical fissile “bullet,” and a subcritical fissile core. In this type of bomb, the core, which is made up of the same material as the bullet, is secured at the opposite end of the bullet and the conventional explosives. Near the core lies the neutron initiator. The gun barrel is used as a path that leads the bullet to the core. When conventional explosives are detonated, the bullet is fired down the gun barrel at the core. When the bullet and the core are driven together, a critical mass is formed. Simultaneously, the neutron initiator fires some neutrons into the critical mass. When this happens, some atoms of the mass are split, and the neutrons produced by those splitting atoms strike nearby nuclei of other atoms, causing additional fission to occur. (This is known as a chain reaction.) When these atoms split, immense energy is released as the devastating explosion of the bomb. The gun-type bomb can only be fueled by the uranium isotope, U-235. Little Boy was one of the atomic bombs that were assembled this way and was powered by U-235. Thin Man was also a gun-type bomb, but unlike Little Boy, scientists strived to construct this bomb with a plutonium core (Pu-239), which did not work, so it was never

The assembly of this type of bomb includes a hollow sphere that contains explosives, detonators, a neutron initiator, a pusher, and a subcritical fissile core. In the implosion-type bomb, the neutron initiator is positioned at the center of the sphere. The core surrounds the neutron initiator, and covering the core is the pusher. (The core has a shape of a sphere and has enough space in the middle of it for the neutron initiator to be placed.) Meanwhile, the explosives and detonators are placed around pusher. When the detonators set off the explosives, the pusher compresses the core with the spherical shockwave of the explosions to a high density, triggering the core to become critical. The neutron initiator inside the core is crushed as the core compresses and releases neutrons. These neutrons cause a chain reaction to occur in the core, which makes the bomb explode with overwhelming power. This type of bomb can carry either a uranium core or a plutonium core and is much more destructive than the gun-type bomb. Both the Gadget and Fat Man were implosion-type bombs that were fueled by the plutonium isotope,