What's Inside the Atomic Bomb? | Insane Engineering of the Atomic Weapons | CURISM

Introduction

• "Fat Man" is the code name for the second and last nuclear weapon ever used in war .

• It ended World War II, killing almost 40,000 people .

"This is Fat Man, the bomb that ended World War II, killing almost 40,000 people."

Description of the Atomic Bomb

• Fat Man was one of the two nuclear bombs that exploded over Japan .

• It showcased the destructive and devastating power of nuclear weapons .

• This video provides a detailed tour of the inside of the plutonium implosion bomb and explains the science and engineering behind it .

"The world witnessed the destructive power of the atomic bomb when Fat Man exploded over Japan."

Nuclear Fission and Fissile Materials

• Elements heavier than lead, like uranium-235 and plutonium-239, are usually unstable and undergo nuclear decay to lower their internal energy .

• Uranium-235 and plutonium-239 are called fissile materials because their atoms can be split .

• In the case of plutonium, when it is supplied with a small energy by colliding with a free neutron, its unstable nucleus splits into two smaller atoms, xenon and zirconium .

"More unstable atoms with a higher number of protons and neutrons can undergo nuclear fission. Uranium-235 and plutonium-239 are examples of fissile materials."

Critical Mass and Compression

• The critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction .

• To make the plutonium sphere critical, it must be compressed and increased in density by two and a half times .

• The compression is achieved by surrounding the sphere with explosives and detonating them simultaneously .

"To achieve a sustained chain reaction, the plutonium sphere must reach critical mass, which requires compression and increased density."

Explosive Lens and Supercritical State

• The explosives surrounding the plutonium sphere are arranged in layers of fast and slow explosives, creating an explosive lens .

• When detonated, the explosive lens compresses the plutonium sphere, increasing its density by two and a half times .

• This state, known as the supercritical state, allows for the sustained chain reaction .

"The explosives surrounding the plutonium sphere are arranged in an explosive lens, which compresses the sphere and brings it to a supercritical state."

Chain Reaction and Energy Release

• Polonium-210 releases alpha radiation, which is absorbed by beryllium .

• Beryllium emits neutrons, which, when injected into the supercritical sphere of plutonium, initiate a chain reaction .

• The chain reaction releases a tremendous amount of energy .

"Polonium-210 releases alpha radiation, initiating a chain reaction that leads to the release of tremendous energy."

Components of the Atomic Bomb

• The core of the assembly houses the internal neutron initiator or urchin, responsible for emitting neutrons for the chain reaction .

• Surrounding the neutron generator is the main fusion material, a 6.19-kilogram plutonium sphere enclosed in a sphere of uranium-238 to reflect neutrons .

• A boron plastic shell absorbs slow-moving neutrons and avoids pre-detonation .

• The fission reaction components are enclosed in a thick layer of aluminum called the aluminum pusher .

• The aluminum pusher is surrounded by blocks of fast explosives making up the explosive lens for compression .

• Detonators are inserted into each explosive block, and the entire assembly is called the physics package .

• The physics package is enclosed in a thick steel case to contain the explosion .

"The atomic bomb consists of various components, including the core, fusion material, reflector, explosive lens, and the physics package."

Bomb Structure and Deployment

• The bomb has a length of 3.3 meters, a diameter of 1.5 meters, and weighs about 4.6 tons .

• The bomb is fitted with a cover and a California parachute at the tail to stabilize it in the air .

• On August 9, 1945, Fat Man was lifted and fitted into the belly of the Boeing B-29 bombing plane named Boxcart .

• The B-29 flew to the primary target of Kokura but proceeded to the alternative target of Nagasaki due to obscured visibility .

• After 15 seconds of the bomb dropping, barometric sensors and radar systems were enabled .

"Fat Man, with its massive structure and complex components, was dropped from a B-29 plane to its targets."

Conclusion

• The detailed tour of the internal components of Fat Man provided insights into the science and engineering behind atomic weapons .

• The engineering challenges of achieving critical mass and compression were overcome to unleash the destructive power of the weapon .

• Understanding the components and functioning of the atomic bomb helps in comprehending the devastating effects of nuclear weapons.

"By exploring the inside of Fat Man, we gain a deeper understanding of the science and engineering behind atomic weapons."

Radar system and firing circuit

• The radar system detected a distance of 500 meters after 28 seconds.

• The firing circuit closed, initiating the bomb's detonation process.

"The radar recorded a distance of 500 meters and the firing circuit closed."

Detonation process and shockwave

• The x unit discharged high current at 5000 volts to the detonators.

• The outer ring of 32 detonators detonated, followed by the inside ring of 32 detonators.

• These detonations created a concave shockwave with a pressure over 300,000 atmospheres.

• The shockwave's intense pressure was transferred to the uranium and plutonium spheres by the aluminum pusher, reducing the plutonium sphere's volume and increasing its density.

"The detonators in the bomb discharged high current and triggered a series of detonations, creating a concave shockwave with immense pressure."

Neutron generation and chain reaction

• The plutonium core became supercritical due to the increased pressure.

• The gold-plated beryllium neutron generator was crushed, mixing the polonium and beryllium together.

• The absorption of alpha radiation by beryllium emitted free neutrons.

• These free neutrons were sufficient to initiate a chain reaction inside the supercritical plutonium.

• A sustained fission reaction started within the six-kilogram plutonium sphere, releasing a tremendous amount of energy, equivalent to 24.5 gigawatt-hours.

"The supercritical plutonium core underwent a sustained fission reaction, releasing a massive amount of energy."

Effects of the explosion

• The explosion generated a fireball with temperatures exceeding 4000 degrees Celsius.

• Powerful shockwaves with velocities over 1000 kilometers per hour were produced.

• A burst of gamma radiation was emitted.

• The explosion resulted in the death of 40,000 people, with an additional 20,000 to 30,000 people succumbing to blast, burn injuries, and long-term health effects.

"The explosion created a fireball, shockwaves, and a burst of gamma radiation, causing widespread destruction and casualties."

Richard Feynman's perspective

• Richard Feynman, a physicist involved in the development of the atomic bomb, acknowledged the power of science to do both good and bad.

• He believed that the power to do something holds value, but the outcome depends on its application.

"Richard Feynman recognized the value of power in science, emphasizing its potential for both positive and negative outcomes."