Sunday, November 16, 2014

What Is Nuclear Energy and How Is It Produced in Power Plants?

Click for photo credit.

As I mentioned in yesterday's post, this coming Thursday, Hofstra will host a debate as to whether or not nuclear energy should be expanded to create a more sustainable future.  Many in the sustainability field argue that nuclear energy should be rapidly expanded to get us off of fossil fuels.  Others counter that nuclear energy is too dangerous and costly.

In the coming week, I will have several posts on this issue.  Here's what to expect:

Today:  What is nuclear energy and how is it produced in power plants?

Monday:  The distribution of nuclear power plants around the world and the amount of nuclear energy produced.

Tuesday:  The pros of nuclear energy expansion.

Wednesday:  The cons of nuclear energy expansion.

Thursday:  Introduction of the debaters.

Friday:  Debate redux.  My reaction to the debate.

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Today's post focuses on the details about how we get nuclear energy from atoms and how nuclear power plants work to produce electricity.

Enrico Fermi developed the first self-sustaining
nuclear chain reaction.  This led to the development
of nuclear power plants.
Image courtesy of the Argonne National Laboratory.
Most of the nuclear power plants in the world work through nuclear fission.  What happens in these reactors, is that a high atomic mass isotope (usually uranium-235) is bombarded with a neutron.  The neutron is absorbed to create a new isotope (usually uranium-236) that is unstable.  The unstable element splits into lighter elements, thereby releasing tremendous amounts of energy.   In a nuclear power plant, this chain reaction can be controlled to produce a steady, reliable source of energy.  However, this same reaction is used to create nuclear weapons in an uncontrolled environment.

What makes nuclear energy so attractive as an energy source is that on a per mass or volume basis, nuclear energy produces millions of times more energy than conventional energy sources.  In other words, a small amount of nuclear fuel goes a very long way.

Most of the fuel used in nuclear reactors is uranium-235.  It is estimated that there are about 100 years of uranium available if used at the present rate and with no new discoveries.  However, it must be noted that uranium-235 is used in older reactors.  New reactors use other fuels or reprocessed uranium.  This new breed of power plants has enough fuel for hundreds of years.

As we will see in tomorrow's post, many countries of the world rely heavily on nuclear energy to produce the majority of their power.  In the United State's we get roughly 20% of our electricity from nuclear power plants.

While nuclear energy may seem like a very high-tech operation, the electrical generation is relatively conventional.  The fission chain reaction is used to produce heat.  This heat is used to boil water to create steam.  The steam is then used to turn a turbine which in turn produces electricity.  In conventional power plants, oil, natural gas, and coal are used as the energy sources.

There are emerging technologies (fusion and fision fusion power plants) that improve the efficiency of nuclear energy and reduce waste.  It must be noted that, at least in the United States, nuclear power plants are not built that often.  The last one was built in 1996.  As we will see tomorrow, many countries are moving forward rapidly to develop conventional fission nuclear power plants and some of the newer technologies.


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