Thursday, July 29, 2010

What Happens at 150 Million Degrees

One of the more exciting developments in the nuclear realm over the last couple of years have been been small reactors, those that generate less than 350 megawatts of electricity. While enthusiasm sometimes translates into a business model and sometimes does not, both the Department of Energy and the Nuclear Regulatory Commission have sponsored workshops and meetings specifically about them and several bills have been floated in Congress to support their development.
There have been a lot of reasons bruited for the interest in small reactors;  two are that they are less expensive than a full scale reactor while providing the same clean air benefits and most of the proposed designs can be built in a factory and sent fully constructed to a site. Oh, and a third reason: the site can serve a locality that would not necessarily benefit from a full-size reactor or even might want to use them off the main electricity grid (think army bases). So all that favors continued interest.
But business is business and small reactor makers have to make deals and show they are serious and make sure we know about it.
Power generation company Babcock & Wilcox Co. said Tuesday it plans to open a testing facility for its new class of mini nuclear reactors at the new Center for Advanced Engineering and Research Center in Bedford County.
“Mini nuclear reactors” sound like flux capacitors to us – they’re small, yes, but not pee-wee.
Bedford County is in Virginia and the testing facility will bring in some needed jobs. I found this detail a bit amusing:
The Virginia Tobacco Commission, which promotes economic growth and development in tobacco-dependent communities, approved a $2.4 million grant for the project.
Well, better a grant for this purpose than for tobacco, yes? In fact, the description tells the tale. The commission moves former tobacco-growing counties to new areas of interest – including small reactor testing. A net good, I’d say.
You can read more about mPower here.
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Well, it will produce energy, but we won't use this energy and make electricity out of it. The energy that we produce will be released into the atmosphere. We won't be using this energy in any commercial way. It's supposed to produce 10 times as much energy as we put into the plasma. That would be about 500 megawatts. That's quite a bit. About enough to feed a medium-sized city.
Indeed. Speaking is Norbert Holtkamp, ITER’s principal deputy director general, and what he’s talking about is thermonuclear energy and the application of plasma physics to electricity-generating nuclear fusion plants.
Whenever I think nuclear fusion, I think hobby, because it’s something you can do at home – if you assemble the pieces and don’t mind watching your electricity meter spin like a top when you flip the switch on your reactor. It takes a lot of energy to generate a little energy through fusion. Well, it does in your tabletop reactor, anyway.
But the ITER project takes a different approach – I think. Read this description by Holtkamp on how it works:
The ITER is a tokamak, and a tokamak is a magnetic confinement device. What that means is big magnetic coils with very strong magnetic fields enclosing plasma. Through the plasma in the tokamak, one has to drive a very high current to heat up the plasma to 150 million degrees Celsius, which is about ten times the temperature of the sun's core. At this temperature the nuclei start to fuse. That's why it's called a fusion reactor. In the fusion process, energy is released (which we can use) later on to produce electricity.
It’s not the “very high current” that arouses curiosity – that’s well understood in the fusion community – it’s stabilizing the plasma once you get there.
Holtkamp doesn’t directly answer that question.
Frankly, I fully expected this statement:
ITER is the first fusion reactor that will produce much more energy than it uses.
to be directly followed with this one:
That still is a step that needs to be proven and there are scientific and technical questions that need to be answered and will be answered through the construction and operation of ITER.
Fusion does not need to be proven only proven practical. Thus has it always been.
Funning aside, ITER is fascinating and full of all kinds of potential – regardless of whether that step is ever proven – and if proven and made practical, would be a tremendous breakthrough in energy generation. I must confess a weakness for big dreams that seem all kinds of impractical – they always seem the firmest basis for human progress.
See here for more – a lot to explore at the ITER site.
A cutaway view of the ITER tokamak. See here for a better cutaway and a description of parts of the tokamak.

3 comments:

Anonymous said...

Small reactors cannot be economical at this point. Today's large reactor designs have trouble competing with traditional power sources because of capital costs. Unfortunately, when you halve or quarter the power output of a large reactor, you don't halve or quarter the capital cost. In fact, the cost is reduced by a smaller factor.

You may argue that their modularity or simplicity may reduce capital costs further, but I would argue that if that simpler/modular technology existed today in a proven usable form, it would be in place in larger reactor designs. Furthermore, you may be able to assemble the reactor pressure vessel and ship that in one piece, but that's such a small (physically speaking) component of a power plant. Everything else is construction on-site.

Anonymous said...

I would not give up on the possibility of modularizing other components of the plant. NSSS components like steam generators, for example. On the balance of plant side, arrays of turbo generators could be mostly fabricated offsite and then moved to the site for completion and integration. The site-specific plant structures (containment, auxiliary building, cooling tower) would still have to be on-site construction.

Inertial fusion is ahead said...

The statement, "ITER is the first fusion reactor that will produce much more energy than it uses," is wrong. The National Ignition Facility at Lawrence Livermore National Laboratory is likely to achieve this goal within the next year, at the same time that ITER is still just a large hole in the ground.