Nuclear weapons review:

During the 2004 US Presidential election debates, both challenger Senator John Kerry and President George W. Bush stated for the record that nuclear proliferation was the greatest threat to the national security of the United States. But how many people really understand this threat, and how fearfully realistic it is? This posting intends to explain some of this in laymen’s terms (questions may be posed via comments on this post, or though doing your own research via the internet. See below for a list of suggested web sites to visit to learn more).

(Author's note: I would have included pictures in this entry to better explain the topics discussed, but chose not to as the links below will guide readers to all necessary imagery)

Unfamiliar terms you might have come across:

• Highly Enriched Uranium (HEU)

HEU is one of two types of radioactive material that can be used to construct a working nuclear bomb, the other being plutonium. HEU is a sample of uranium, usually described as a percentage, that contains X% of the uranium isotope U-235. U-235 is preferred for its nuclear properties and can be used in both nuclear reactors and weapons. For the purposes of a nuclear bomb, it is necessary to enrich uranium to around 90% HEU (read as a sample of uranium that is 90% U-235), while reactors require a far less potent sample. Uranium can be enriched through the use of centrifuges and lasers.

• Gas Centrifuge

The centrifuges used in the process of enriching uranium operate on the same principle as the centrifuges one might have seen in a chemistry class or at a doctor’s office. A centrifuge spins at very fast speeds creating centrifugal force. That is, creating a situation in which heavier particles will move to the outside of the centrifuge chamber leaving the lighter particles closer to the middle.

In the case of uranium enrichment, the centrifuges operate on this same principle, but instead of the horizontal spin of a typical centrifuge, those used in nuclear enrichment stand vertically and use a combination of motion, temperature alteration, and magnetic forces to create a more significant effect on the substance being separated.

Uranium destined for enrichment using centrifuges must be converted into a gaseous form of uranium, known as uranium hexafluoride (UF6). UF6 is fed into the vertical centrifuges, which then operate and separate heavier particles of uranium (usually U-238) from lighter particles (generally meaning U-235). The lighter particles are then siphoned out of the centrifuge chamber, resulting in enriched uranium. Enrichment plants that are set up to enrich large quantities of uranium use what is called a cascade, which is a series of tens, hundreds, or even thousands of these centrifuges through which weapons-grade uranium can be produced, or substantial amounts of uranium can be enriched to lower levels for use in reactor cores as fuel.

• Plutonium

Plutonium is an element that does not occur naturally on Earth, and so requires the use of a nuclear reactor to create. Once created through a procedure known as reprocessing, plutonium is a highly radioactive element that makes excellent core material for nuclear weapons. Plutonium is generally not used as reactor fuel.
Reprocessing plutonium is a complicated and expensive process. Essentially it involves removing nuclear reactor core material that has been spent, in other words it can no longer function as core material as its radioactivity has decreased through the slow and controlled nuclear reactions of the reactor core. Once removed, plutonium particles are extracted from the spent sample and stored. I admittedly know less about this process than about uranium enrichment, though if you care to learn more there is, I am sure, ample information on the internet.

• Nuclear weapons

While virtually everyone today knows what a nuclear bomb is, fewer people know precisely how they work. Nuclear weapons can take a variety of shapes, come in a variety of sizes, and have destructive effects ranging from ridiculous to unfathomable, including single warheads powerful enough to wipe out an entire city and much of the surrounding area.
Nuclear weapons are highly sophisticated explosive devices that slam unstable, radioactive ‘blocks’ into each other, initiating a process known as nuclear fission. Nuclear fission is the destruction of the nuclei of the atomic particles of a given material. Because of the relative instability of HEU and plutonium, these substances, used in large enough quantities, form the core of nuclear weapons.

While I cannot pretend to have working knowledge of the most sophisticated designs that exist, the basic principle of a nuclear weapon involves accelerating 2 ‘blocks’ of radioactive material, either HEU or plutonium, into one and other using conventional high explosives. The result is the destruction of the nuclei of the atomic particles in the sample of either HEU or plutonium, and the release of incredible amounts of energy.

Links:

http://www.iaea.org
http://cns.miis.edu/
http://nuclearweaponarchive.org/
http://www.fas.org/nuke/
http://www.sandia.gov/programs/nuclear-weapons/
http://www.un.org/Depts/dda/WMD/treaty/
http://www.brook.edu/FP/PROJECTS/NUCWCOST/50.HTM
http://www.cnn.com/2005/WORLD/asiapcf/02/10/nkorea.talks/