LS: Speaking of Science Column September 08, 2008

How about recycling ... energy?

What if every time you filled your gas tank, you put 1 quart of gas in your vehicle, and poured 16 gallons of gas on the ground? (You have to pay for all the gas, of course.)  With the price of gasoline now, this kind of waste would be unforgivable.

Yet America has placed itself in exactly this situation when it comes to the generation of electrical power. How can this be, since so much research is going into developing energy sources, especially those that don’t generate greenhouse gases?

Nuclear power has provided electricity for America for over 50 years, and currently provides about one-fifth of the electricity generated in America. This energy is clean, requires much less mining than coal-generated power, and doesn’t emit carbon dioxide.

And uranium provides the fuel for this energy.

But only a small part of the uranium mined is used as fuel. This is because the isotope that actually undergoes fission and creates energy is uranium-235, which makes up less than 1 percent of naturally occurring uranium.

The other 99 percent is comprised of the isotope uranium-238, which usually does not fission, therefore
contributes almost nothing to the energy produced.

But what if you could transform the relatively useless uranium-238 into useful fuel? Then, theoretically, you could multiply the energy you obtain from every pound of uranium by almost 100 times (an increase of 10,000 percent!).

Rather than wishful thinking, this is exactly what happens when the “useless” uranium-238 is exposed to the neutrons produced in a nuclear reactor. In this process, some of the uranium-238 is converted to plutonium, which also can be used as fuel for nuclear reactors.

In fact, in reactors of a certain design, called breeder reactors, the amount of usable fuel created by transforming uranium-238 to plutonium can be greater than the amount of fuel consumed to make energy. (Although this may sound like some kind of “perpetual motion” machine, it is not, because you always have to supply more uranium-238 to keep the process going.)

Of course, if the usable fuel created by this process is never retrieved, then no benefit is obtained. It is like pouring gasoline on the ground instead of into your car.

The retrieval of the newly created fuel is called reprossessing. Reprossessing was one of the planned components of the U.S. nuclear power program until its development was ended by the Carter administration in
the late 1970s, primarily over proliferation and cost concerns.

If this move was intended to set an example for the rest of the world, the rest of the world didn’t pay attention. France, England, Japan, Russia and India reprocess nuclear fuel, with no apparent economic drawback.

The concern with proliferation (i.e., the theft of the retrieved plutonium by those who would make nuclear weapons out of it, or the spread of the technology itself) also seems to be questionable now. The technology is out there and being used by other countries, even though the U.S. has decided not to implement it (or benefit from it).

And as far as stealing material for nuclear weapons, Iran and North Korea seem to have decided that it’s easier to just develop their own nuclear capability, without worrying about diverting materials from other countries. So we have put ourselves in the position of burying a fuel source that could extend our resources by 60 fold, calling it “waste” instead.

This brings up another irony in our current position: When we dispose of nuclear materials after they have been used in a reactor, there is an outcry about disposing of the plutonium, with a radioactive half-life of 24,000 years. But if that same plutonium is seen as a resource and used as fuel (instead of calling it a “waste”), the fission process splits the plutonium atoms into other materials with much shorter half-lives.

At the end of the process: no plutonium is left!

So the next time you hear the consistent objection to nuclear power, “But what do we do with the radioactive waste?” you might be able to answer, “Stop calling it waste, and use it as the energy resource it can be.”

Vincent King is a volunteer at the Western Colorado Math & Science Center.


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