Applications for Nuclear Reactions

Weapons

Since the end of World War 2, we have come to fear nuclear reactions. The destruction that was inflicted upon Nagasaki and Hiroshima, Japan upon the first use of the atomic weapons Little Boy and Fat Man on an enemy target. Both of these nuclear warheads were fission weapons, using Uranium-235 and Plutonium-239 respectively, which as stated before are far too large of atoms for fusion. However, given a free neutron, these both become unstable isotopes that release more free neutrons that continue this chain reaction until the fuel of the explosion is finally consumed by the reaction. A video of the devastating force that a fission bomb unleashes is given on the left and is a scary reminder of this weapons capabilities. Time does not stand still however, and an even more powerful nuclear device was discovered using fusion rather than fission. This Hydrogen Bomb or H-Bomb is a fusion warhead that eclipses the fission warhead in destructive reach, estimated as being 100 times more powerful than the conventional fission bomb. Fortunately for the world, none of these fusion powered warheads have been used to harm anyone as of writing this, but the fear of such an event has lead to many books and even video games such as the Fallout series.

Courtesy of: Fundamentals of Physics 8th Edition by Halliday & Resnick

Power Generation

A much more humane and useful application for nuclear fission is using it to run a power plant. This has been a reasonably common practice in many countries for several decades now, especially in France where approximately 78% of their total electrical energy comes from nuclear power plants. This is a relatively simple process as the fuel pellets, normally uranium, are placed into initially hollow fuel rods that are placed into the reactor core. A moderator is placed around this reactor, which in many cases is just water. The moderator is a way in which to slow the initially fast moving neutrons that are released to allow for proper absorption of neutrons by the fuel and control rods to prevent the reaction from becoming unstable (think nuclear explosion). The moderator becomes superheated and pushed out into pipes that heat surrounding cooler water, turning it into steam which rotates a turbine and generates power. The steam pressure can be released from the top of the generator which is what the large "smoke" stacks of the classic nuclear power plant are actually expelling. Some of the steam can also be condensed in a cooler portion of the reactor to be reused again. To the left is a picture of this process taken from our physics book. Unfortunately as of yet, we have not achieved fusion generated power that is self-sustaining or in a state of "ignition". In fact, fusion generators in present day have not even achieved the critical step of breaking even with the amount of power required to create the reaction and the amount of power that comes out of the reaction. This has not stopped the research by any means though, as many physists, engineers, and scientists around the world are working to achieve this. In the following pages, you will find a couple of possible designs for the confinement of the superheated plasma needed for fusion to occur and fuel choices along with their drawbacks.