How Much Do You Know About Nuclear Weapons?

The news most days has something in it about the world's current nuclear weapon situation. We all see it almost everyday, whether it is on television or in the paper. How much do you really know about nuclear weapons?

How the Bomb Works
Nuclear weapons are similar to conventional bombs, they are designed to cause damage through an explosion (the release of a large amount of energy in a short period of time). In a conventional bomb, the explosion is created by a chemical reaction; this involves atom rearrangement to form new molecules. The amount of energy released is proportional to the binding energies of the molecules. The explosion in nuclear weapons is created by changing the atoms themselves - they are either split or fused to create atoms.

There are two main types of nuclear weapons:
· Atom bombs- which use fission as the main reaction (the atoms are split)
· Hydrogen bombs- which use fusion as the main reaction (the atoms are fused together)

Effects of a Nuclear Weapon on a Target

The Blast
The rapid release of energy in an explosion creates a shock wave of overpressure. Very close to the center of a nuclear explosion, overpressure is the equivalent to several thousand pounds per square inch (psi). This is hundreds of times greater than the pressure of a pressure cooker.

The overpressure crushes objects; the human lungs are crushed at about 30-psi overpressure. At 10-15 psi, brick houses are turned to rubble. The blast also will generate very strong winds that can turn a person or objects into missiles.

Thermal Radiation

Thermal radiation includes light and heat. Huge amounts of energy as light (ultraviolet, visible and infrared) are released by nuclear weapons. This light is so intense that can make sand explode, blind people for many miles, burn shadows into concrete, burn skin and ignite flammable materials at large distances.

Initial Nuclear Radiation

Initial radiation is composed mostly of gamma rays and neutrons that are generated in the nuclear which can enter the human body directly. A radiation dose of 400 rads will be lethal to half or more of the population exposed. These deaths occur within about 6 - 7 weeks.

Fallout
This consists of large numbers of particles, from the earth, buildings and other ground objects that are irradiated by the explosion itself and then being distributed over a wide area by wind. The effects of fallout (internal damage to the human body) persist for hundreds of years, although the relative risks reduce over time.

Electromagnetic Pulse
A nuclear explosion also sends out an electromagnetic pulse, similar to a thermal pulse. It does not directly harm humans, it can indirectly though. It disables all electrical devices in its path such as medical equipment and microchips found in newer cars.

Extent of Damage
This will be dependant on the size of the nuclear weapon, the terrain and height at which it is detonated. A ground level detonation of a nuclear weapon will generate more fallout as a result of ground material which is irradiated by the explosion and thrown in the air, but the effects of thermal radiation and radioactive waves is less than in an air blast.

The nuclear weapon detonated in Hiroshima was the equivalent of 12,000 tons of TNT. The combined effects of the blast, and radiation killed about 300,000 people. Current nuclear weapons range in size from 1 kt to over 1000 kt. Most are about 100 kt, which is about 10 times the force of the Hiroshima bomb.