Once More from the Top

I figure that before one can make an accurate judgment about the benefits of nuclear power, one should know the fundamentals behind how it works.  I don't want to get into to much technical depth (if you want that, you should enroll in a nuclear engineering program), but I do want to walk through the basics so that those reading this have a basic understanding of a reactor when I talk about them at future times in this blog.

In reality, a nuclear power plant is fundamentally the same as any coal-fired power plant.  In essence, the process is just boiling water to make steam, which is then pressurized and used to turn a turbine.  The turning of the turbine is what creates the electricity.  Below is a diagram depicting the basic process by which power is produced by the means of nuclear power.  Interestingly enough, the blue system consisting of the steam generator, turbine, generator and condenser is exactly the same for coal-fired power plants.

Image borrowed from the NRC

The difference between the two types of plants is how the water is heated.  A coal-fired power plant burns coal to heat the water (I know, the name gives it away).  In a nuclear power plant though, the heating of the water is some what more technical, but much more powerful than the burning of coal.  At the heart of the nuclear power plant is the nuclear reactor.

The idea of a nuclear reactor is quite intimidating to most people.  It conjures images of immense power and to most, it brings thoughts of nuclear explosions.  So what does the phrase "nuclear reactor" actually mean?  Put simply, it is a concentration of special radioactive materials placed into an environment where a fission reaction is sustained in order to produce large amounts of heat.  This brings me to my next point...what is fission?  At this point, an awesome picture can explain better than I ever could, so here it is:

Borrowed From http://www.atomicarchive.com/Fission/Fission1.shtml

Ok, so maybe the picture is not self explanatory, but I do maintain that the concept of fission is quite simple.  To start, there is a parent nucleus (target nucleus in the picture) which has special properties that allow it to fission.  In general, this usually means that it is a large nucleus containing many protons and neutrons.  It is hard to make generalizations about what numbers of protons and neutrons make a nucleus more or less stable.  In other words, it is hard to define what numbers of protons and neutrons give the nucleus the ability to fission.  There seem to be several magic numbered isotopes of various elements, but I can discuss later.

Fission is induced in the target nucleus by adding another neutron to it.  Simply put, this causes the nucleus to become extremely unstable and to split into two pieces known as the fission products.  Also a product of the fission reaction is the release of several more neutrons in the system.  It is important to note these neutrons because they are what go on to cause more fission reactions with other nuclei in the reactor.  They are what enable the chain reaction in the reactor resulting in usable power from the reactor.

So great, now we have a process to split atoms by bombarding them with neutrons...the question is how do we get power from this?  The answer lies in the produced fission products (remember the two nuclei formed after the splitting of the target nucleus).  When the fission reaction occurs, the fission products move away from each other at high speeds.  Their rapid movement means that they carry a large amount of energy, and as they move through the reactor and slow down, they deposit this energy in the form of heat.  Thus, the reactor heats up providing a good source of heat to boil water.

Obviously, this is a very simplified version as to what happens in a reactor, but it is important to understand the basics of fission for nuclear power.  One must note that there are many types of reactors all inducing this reaction differently and taking the power from the reactor differently.  I will be commenting on different types of reactors in the future to showcase different safety features as well as which ones are more efficient and why, but for now I will leave it simple.  If you are interested now in learning about new types of reactors or just seeing the differences between them, I recommend this paper which does a good job introducing the different generations of reactors.

Also, there are many more details to learn about inducing fission reaction and what types of materials require what conditions to undergo fission.  If there is interest in this subject, I will be happy to delve into the subject on my blog in the near future.

On that note, impress your friends at the bar this weekend with what you just learned...never mind, it has yet to work for me.  But if it does work, fill me in!