What will Iran do with a bomb?

The picture to the left is the "Little Boy Bomb" that was dropped on Hiroshima.

The previous post described this as a uranium bomb. What that means is that it contains two pieces of the uranium isotope with a mass number of 235 that are shot together to make an explosive nuclear reaction.

Uranium is an atom with 92 protons in its nucleus, but with different numbers of neutrons. The mass number is the sum of the protons and neutrons. Uranium-235 makes up less than 1% of the atoms of naturally occurring uranium. So to make a bomb, you need to separate the U-235 from the rest of the uranium, which is mostly heavier U-238, assemble two smaller pieces in a way so that when they are rapidly brought together, they explode. This is not difficult for a country like Iran, which has a huge oil revenues to fund this work.

Separating the uranium is the difficult part of this work, since chemical separations don't work. There are two ways to separate the isotopes. One is to make charged atoms called ions, and send them at a high speed through a strong magnetic field. The magnetic field will cause the flight path of the ions to curve, with heavier ions going in a less curved path. Once the ions hit the a device called a "collector", which is placed at different distances along the flight paths in the vessel, they lose their charge and are converted back to atoms. The collector will accumulate U-235 atoms. When the U-235 concentration in uranium becomes higher than the normal concentration, the uranium is called "Enriched Uranium". When the U-235 concentration is lower than natural uranium, it is called "Depleted Uranium."

The instrument used to enrich uranium using magnetic fields is called a "Calutron". This is an expensive, but not technologically difficult method to produce bomb grade enriched uranium, and was the technique used to make the U-235 that went into the Little Boy Bomb.

Another way to enrich uranium is to react the uranium with fluorine to create uranium hexaflouride, which is a gas at elevated temperatures. This can be spun in a high speed gas centrifuge and gradually enriched, as the lighter U-235 will migrate to the top of the centrifuge tube and the heavier U-238 will migrate th the bottom. This process is repeated many times and requires many expensive centrifuges. This is the technique Iran is using to make bomb grade uranium.

The view that Iran is making enriched uranium for "peaceful purposes" is incredible. There is plenty of lightly enriched uranium available for nuclear power applications, and Iran has only a single nuclear power reactor. They are producing highly enriched uranium for only one possible purpose: to make a bomb. Yesterday, November 20, Iran stated that they were in the process of building 60,000 centrifuges for its nuclear "fuel" needs.

The production of uncontrolled highly enriched uranium with centrifuges is not consistent with nuclear power fuel needs. But it is consistent with making an atomic bomb. A simple atomic bomb will take about 25 kg of highly enriched uranium. Once Iran has this quantity (or any other country that wants to make a bomb), assembling a weapon requires only existing military technology, and is much simpler than making a plutonium bomb.

Iran will build a bomb as soon as they have enough highly enriched uranium. What will they do with it?