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Thursday, February 24, 2011

Nuclear Waste Equals Nuclear Resource?

Nuclear waste is the Achilles heal of the nuclear power industry...or is it?  It is true that what comes out of nuclear power plants is not safe for humans to live with nor is it something that we want to encounter in our every day lives.  In this way, nuclear waste is a major hassle and is something that we need to figure out how to deal with if we are going to continue on with the building of the industry.  Katie Couric gets this idea across in a short clip that she did on CBS news when the Yucca Mountain project was still underway.


As you guys probably know, Yucca Mountain was shut down recently by the Obama administration through reasoning that according to anybody involved with the project was just insane.  That is another issue though, and perhaps I will talk about this in another post.  The fact is that nuclear power lost its deposition place for its high level waste.  This would seem like the end of nuclear power.  How could the plants operate if they had no place to put the waste?  They would be over run with dangerous waste right?  This was what environmentalists groups such as Green Peace was hoping for, and as soon as Yucca Mountain was shut down, they began calling for halt on all construction of nuclear power plants in the United States as well as the closing of all reactors currently running.  Have they finally won the debate over waste?

Thankfully they have not won the debate and nuclear power will continue.  Nuclear waste seems to be a highly misunderstood area which has been reflected in policy decisions as early as the Ford administration.  There has been a popular article circulating around the internet, even showing up in the Wall Street Journal, giving a totally different perspective on nuclear waste.  Could the failure of Yucca Mountain actually be a good thing for the nuclear industry?  Well, it seems that it can!

First, let's understand how we currently treat our high level nuclear waste.  As an aside, high level nuclear waste simply refers to the radioactive materials which are emitting radioactivity at a high rate, such as spent nuclear fuel rods.  Today, these types of waste are stored at the nuclear power plants themselves.  This type of storage is referred to as "interim storage," meaning we are storing it there until we find something better to do with it.  The storage facilities are basically lead boxes filled with water.  The lead is used to stop the gamma radiation put off by the stored contents, and the water is necessary to stop the neutrons being emitted.  We have to use water for this because it turns out that hydrogen is the best way to slow down a neutron with lots of energy.  Think of it like a pool ball.  It is possible to hit the pool ball at another pool ball and transfer all of the energy from the pool ball you hit to the one you hit it at.  I am sure all of you pool playing people out there will agree.  No replace the second pool ball with a bowling ball.  Hitting the pool ball at the bowling ball will simply result in the pool ball bouncing off in a different direction without slowing it.  The same is true with neutrons.  Lucky for us, hydrogen has roughly the same mass as a neutron and we have a substance on Earth that is easy to work with and full of hydrogen.  Good old water!  Sorry for getting side tracked, but I though you might find that interesting.

As the article points out, it seems that it is a good thing that we have kept our spent fuel out of permanent disposal.  Why?  Because it is not really waste.  In fact, waste is possibly the most inaccurate term you could use to describe the stored spent fuel.  Remember that the spent fuel is not used completely.  I discussed this in my article on reprocessing nuclear fuel.  When the nuclear power plant is done with the fuel, roughly 95% of the energy remains in the spent fuel.  We just have to install new fuel because fission is inhibited by its own fission fragments.  If we clean these out through reprocessing, there is much more energy that we can harness from the fuel.

I said earlier that we do not yet need to reprocess in the nuclear power industry because uranium is currently so abundant that it is cheaper to mine more of it than to reprocess the spent fuel.  I still do hold to this argument, though in the future this might not be the case in which putting all our spent fuel in a permanent repository would be a huge mistake.

There is an economical reason to process the fuels today though.  Many industries use nuclear materials including the medical industry and the exploratory oil industry.  The nuclear medicine industry is a four billion dollar industry, so the demand for the materials in the fuel is there.  And as a byproduct of the reprocessing, we regain the U-238 from the fuel rods which can be used for new fuel as well as retrieve the important stuff:  the fissile materials such as U-235 and Pu-239.  France does not reprocess fuels for the nuclear power industry, but they do to meet the demand of other industries.  The parts of the spent fuel that are left over that we don't have a current use for can then be placed into "interim storage" until we do have a use for it.  This is such a small amount of material that it really doesn't need to be taken anywhere.  It can be stored right at the reprocessing plant thus avoiding the transportation of nuclear materials on our highways.  Sounds like the way to minimize risk to me!

I guess really what I want to point out, just like the article, is that the term nuclear waste is a misnomer.  I don't think there is such a thing as nuclear waste.  We have uses for almost all of the nuclear material in one way or another.  To give you some perspective, to bury the 70,000 metric tons of spent nuclear fuel that the U.S. currently would, just in the energy capacity alone, be the equivalent of burying five billion gallons of oil!  That is a lot of energy!  And the 70,000 metric tons of spent nuclear fuel will fit roughly on a single football field stacked five meters deep.  That is a lot of bang in a relatively small volume!  I don't think we can begin to call this waste.

6 comments:

Michael Musso said...

The relatively small volume of nuclear waste is definitely a plus. So how much of this 95% of energy remaining in spent fuels can actually be reprocessed? I couldn't quite gather this from your reprocessing post

Aaron Ackerman said...

Michael, we can reprocess all of the good material back out of the spent fuel. Actually, we aren't really reprocessing the good material out as much as we are taking away the waste material. When we do this, we can make more fuel just like we had initially. This will be used up the same as the initial fuel was. We then repeat the process to keep getting the good fuel back so that we can use it. Thus, we don't really just use up all the available fuel. We just have to mine less as we keep making new reactor fuel since we are getting the usable fuel back out. Does that make sense?

Jen Schneider said...

Interesting, and a good counter to the conventional wisdom that geological disposal is the only answer.

Of course, it will be no small thing to get a reprocessing industry up and running...

Michael Musso said...

Yes, thanks Aaron

Dan said...

From what I understand, nuclear waste has military applications (armor and armaments.), some for civilian applications (food irradiation). But it seems we are focusing mainly on disposal. Are there other proposed uses of nuclear waste?

Aaron Ackerman said...

Jen, the good thing about reprocessing is we don't need it right now. We have lots of time to develop the industry, so we should do it right. For now though, I think that it is ok to store the waste on site. Really, there isn't much of a better place.

Dan, there are tons of other applications for nuclear material, but not all has to come from spent fuel. Though we could use the spent fuel for such applications, currently we just don't reprocess enough to have enough of the material available from the nuclear power industry. There would be many other applications that would be opened up if we had such a program though!

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