MadSci Network: Earth Sciences

Re: How do you turn uranium into power?

Date: Sun Oct 8 19:48:52 2000
Posted By: Donald Howard, Staff, Nuclear Engineering, Retired
Area of science: Earth Sciences
ID: 970016417.Es

How do you turn uranium into power?

When you heat something, down at the atomic level the heat energy makes 
the atoms move faster.  How fast they move depends on how hot they are.  
When Uranium fissions, inside the fuel in a nuclear power plant, it emits 
energy in the form of radiation.  That radiation doesn't travel far before 
it hit other atoms.  When it hits, it will give up all or part of its 
energy to those other atoms.  

The atoms that are hit gain energy.  They move faster.  That faster 
movement means that their temperature has increased.  

With high levels of fissioning, the overall temperature of the nuclear 
fuel increases.  The fuel is surrounded by water that is used as a coolant 
the same way water is used to cool a car's engine.  Heat is transferred to 
the water making it boil into steam.

The steam is used to drive a turbine.  A turbine is just a high tech 
pinwheel.  When the steam blows on it, it spins.  It is connected to an 
electrical generator.  When the generator turns, it literally "pumps" 
electricity through those wires that run to houses, stores, and schools.  

So the faster the Uranium fissions, the more heat it generates.  The more 
heat, the more steam.  The more steam, the more electrical power.

To go back to the beginning, if you are interested in the details of how 
Uranium fission creates the energy to start the process of making 
electrical power, that is tied to how atoms are formed.  The core or 
nucleus on an atom is formed by assembling neutrons and protons.  When the 
atom is formed, energy called "Binding Energy" is given off.  In other 
words, the atoms, once formed are reasonably stable.  If we wanted to 
break them up, we would have to replace that Binding Energy by putting 
energy into the nucleus.

But the larger atoms, because of the close grouping of positively charged 
protons in their nucleus that repel each other, are easier to break 
apart.  The isotope of Uranium of atomic weight 235, it was found, can be 
broken up if it is hit with a neutron.  When it breaks, it forms two 
other, smaller atoms, and these new atoms always have a higher Binding 
Energy.  Because of their higher Binding Energy, the difference between 
the binding energy of the original Uranium atom and these two new atoms is 
emitted at the time the Uranium splits.  And, that is the energy that 
causes the events mentioned above that leads to the generation of 
electrical power. 

MadSci note: an excellent site to visit for more information on fission is the 

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