Nuclear Bombs

How Do Nuclear Bombs Work?

Atoms are made up of three subatomic particles

When the ratio of protons to neutrons is 1:1, the atom has a neutral charge

Radioactive Particles

When the nucleus is not neutrally charged, it emits particles called radiation through radioactive decay
Atomic bombs form by destabilizing the particle through fission and fusion

Fission

Splits the nucleus of an atom in two by overloading it with neutrons
As the nucleus splits it ejects neutrons along with bursts of electromagnetic energy
- This energy is called gamma rays
Uranium is the most cooperative in inducing a fission chain reaction
U-235 can be forced to undergo fission by bombarding it with neutrons
As one U-235 undergoes fission, it ejects 2-3 neutrons which cause fission in other U-235 atoms, inducing a chain reaction and bursts of gamma rays
This happens in magnitudes of Picoseconds

Fusion

Critical Mass: the minimum amount of material needed to sustain a chain reaction

In order to harness nuclear power, the nuclear fuel has to be kept in separate subcritical masses so fission doesn’t happen until induced
When detonated, the subcritical masses are brought together to form a supercritical mass
Additional neutrons are also added to kick off the chain reaction
- Polonium and Beryllium combined form a neutron generator used for detonation

Tamper

The entire reaction is contained within this – neutrons bounce back into the core after hitting the walls of this container
As fission happens the neutrons start bouncing faster and faster within the tamper, building up a more dramatic outburst of energy that eventually breaks through the tamper
This material is usually made of U-238

Gun-Triggered Bomb (Fission)

A bullet filled with U-235 is packed on one side of a tube
Explosives fire the bullet down the tube where it collides with the neutron generator
This kicks off the fission chain reaction
Little Boy (Hiroshima bomb) used this mechanism
- It was 1.5% efficient – 1.5% of the material fissioned before detonation

Implosion-Triggered Bomb (Fission)

Contains a sphere of radioactive U-235 as the tamper around a Plutonium-239 core
The sphere is surrounded by explosives
When explosives detonate, a shockwave presses the core and initiates the fission chain reaction

Thermonuclear/Hydrogen Bomb (Fission + Fusion)

Uses hydrogen isotopes Deuterium and Tritium as fuel
Contains a tamper made of U-238
Tamper is packed with hydrogen isotope fuel
The tamper surrounds a hollow rod of Plutonium-239 at the core
An implosion fission device detonates first → this compresses the fuel and causes the plutonium core to fission
The rod starts to fission → it gives off heat and pressure → this initiates fusion in the hydrogen isotopes → leads to the explosion
This process takes 600 billionths of a second and creates 700x the power of the Little Boy

Delivery Methods

Ballistic Missiles: exit the atmosphere and travel long distance before denotation
Cruise Missiles: shorter-range missiles that travel a couple of thousand miles
Tactical Weapons: artillery shells, land mines, etc

Radioactive Aftermath

After detonation, clouds of radioactive particles get carried by the wind to settle in surrounding areas
These radioactive particles poison the water supply, which cycles into vegetation, food sources, biodiversity, etc
Radioactive particles affect human cells that readily divide: hair, gut cells, bone marrow, reproductive organs, etc

Raw Material Supply

Uranium-235 is needed for nuclear weapons, but it does not occur naturally
Instead, U-235 can be formed by enriching U-238 (a natural resource)
U-238 can be bought commercially in powders called “Yellow Cake”
To build 1 nuclear bomb, 6.6 tons of Yellow Cake has to be bought, stored, and enriched
To enrich U-238, it has to reach a very fast speed that can only be done through a sophisticated centrifuge
- The supply of this centrifuge is controlled by the Nuclear Suppliers Group
After U-235 is produced, the bomb can be designed and built (this cycle can take years)
After the bomb is designed, water, hydrofluoric acid, and magnesium are used to convert the gaseous U-235 into solid-state metal
This metal is shaped and refined to fit into the bomb