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Thursday, February 25, 2010

Thorium Power

At the outset, I must say that I am sceptical about what I have written below. It seems too ridiculous that it isn't being acted upon - especially considering the last paragraph. I am trying to get some input from a reputable nuclear physicist to see if I am off base and will add to this blog anything that seems relevant.
 

It would appear that there is an alternative to producing electricity using enriched Uranium. One can use un-enriched Thorium. Why Bother? The reason is that the use of Thorium has some definite advantages over the use of Uranium. For instance:



1. Thorium is more abundant in the earth's crust, easier to find and easier to process. It is therefore less expensive to obtain purified Thorium, leading to cheaper electricity.

2. Thorium is only slightly radioactive (It has a half life of over 14 billion years - hence is only slightly radioactive*) making it safer and hence less expensive to handle. Again cheaper electricity.

* The longer the half life, the slower the release of radioactivity which occurs when an atom disintegrates, to produce a new isotope.  During the transmutation to a new isotope alpha or beta radiation is given off and always gama radiation.

3. Thorium has no critical mass, above which it will explode. It therefore needs less special precautions to ensure that you never have too much of it in one place. (Thorium is fertile, not fissile) Cheaper electricity.

4. The isotope of thorium which is used for power production is the most common isotope Th232  (More than 99% of the naturally occurring Thorium is Th232).   By contrast Uranium piles use the rare U235. With Thorium generation no expensive enriching is needed. Cheaper electricity.

5. The waste from a Thorium reactor is less in quantity, less radioactive and shorter lived than waste from a conventional nuclear power plant, and hence cheaper to handle, transport and dispose of. Once again, cheaper electricity.

6. Because of it's physical and chemical characteristics, it is possible to build a Thorium reactor which is inherently stable. Far less control systems are needed to ensure that a melt down does not occur and a containment building is not even needed. A thorium plant is cheaper to construct than a uranium plant. You guessed it - cheaper electricity.

7. Thorium reactors produce no bomb making material as do Uranium reactors. Once the technology is mature, there will be no excuse for anyone to use Uranium. States which persist in the use of Uranium will clearly be doing this in order to make atomic bombs. The case against such states will be exceedingly clear.

8. Mining and purifying Uranium provide many points at which Uranium can be sidelined for nefarious purposes. Stopping the production of new Uranium reduces the chance of uranium falling into the wrong hands. If Thorium falls into the wrong hands, it is of no use to them, it is not fissile. Less expensive security is needed. (electricity price??? ---  you guessed it)

10. You get far more energy from a kg of thorium than from a kg of Uranium. You guessed it.


You would think, therefore, that the switch to Thorium is a no-brainer. This conclusion would completely ignore the forces arrayed against such a move.


1. It is very likely that electricity from a Thorium powered plant will be less expensive than the electricity from a coal powered plant. The coal industry - from exploration to mining to transport to use in Coal fired power stations and even disposal of the ash will wither and die from simple economic considerations. Guess who will be lobbying against the use of Thorium.

2. Since the military of the world already has the power to blast the top meter of the earth into space,(only slight hyperbole) you would think that not producing more bomb making material would not be a problem. However the military, being what it is, wants to be able to blast the top two meters of the earth into space. Guess who will be lobbying against the use of Thorium.

3. The Uranium industry which explores for new Uranium deposits, refines the uranium, enriches the uranium builds it into rods and transports it and finally reprocesses the waste will wither and die. Guess who will be lobbying against Thorium.

4. Even the anti-nuclear industry will be out of work. If the literature is correct, they won't have any logical reasons to object to thorium power (that may not stop them)  I bet even they will be lobbying against Thorium. It will be interesting to hear their ingenious ingenuous arguments.

Once again there exists a simple technical solution to a problem which is stymied by vested interests. Technically, climate change, greenhouse gases, overpopulation, species extinction and so forth are no problem at all. The technical solutions are obvious. Any grade 12 student could tell you what must be done.  As usual the problems are ones of vested interests. We need to focus in on the true problem. Namely how to get around vested interests and initiate the necessary technical solutions.

News Flash
Forget Thorium. We will save it for energy in the next Milena. I just read James Hansen's book, Storms of my Grandchildren and since what he said was simply unbelievable, I checked it out as well as possible using the Web. Insofar as I can tell he is right on the mark. It turns out that there is another source of fuel which can be used in 4th generation type nuclear reactors and it is lying around all over the place. This fuel is the waste from generation 1,2 and 3 nuclear reactors and the waste from bomb making reactors. All the benefits listed for Thorium still hold plus we get rid of by far the larger part of nuclear wastes that have been hanging around since the Manhattan project. As with Thorium reactors, the waste is far less in quantity, less in radioactivity and far shorter lived. Unless all the above is simply a pipe dream - an urban legend - then some people have a lot to answer for. We could slash our use of fossil fuel, have cheaper safer electricity, get rid of huge dangerous accumulations of nuclear waste and completely eliminate the threat of rogue states making atomic bombs. Am I missing something.  If you are a nuclear physicist, please feel free to debunk what I have written.  I guarantee, I will allow your comments, however scathing.

I received a reply from a nuclear physicist.  I haven't got permission to put his name to the following but if he agrees, I will add it.  This is what he said.  If I get any other replies from other physicists, I will print them as well.

1. Thorium is more abundant in the earth's crust, easier to find and easier to process. It is therefore less expensive to obtain purified Thorium, leading to cheaper electricity.

Yes is it 4x more abundant.  But the less expensive comment depends upon in what its concentration is as an ore.  My memory is that it is in more concentrated ore bodies than uranium so your comment would be true but you might want to check that – I’m not a geologist!

2. Thorium is only slightly radioactive (It has a half life of over 14 billion years - hence is only slightly radioactive*) making it safer and hence less expensive to handle. Again cheaper electricity.

You are comparing the half life of Th-232 half life 14.05 billion years with U-238 half life 4.47 billion years.  Frankly both as so long it makes little difference.  But you need to think about the daughter products.  In the case of Th the crucial one is Radon gas which is breathed in and is an alpha emitter of some concern.  My memory is that U does not have this problem.  So actually Th is not better but worse.  This will make the fabrication of Th fuel slightly more expensive.

3. Thorium has no critical mass, above which it will explode. It therefore needs less special precautions to ensure that you never have too much of it in one place. (Thorium is fertile, not fissile) Cheaper electricity.

You are right it has no fissile isotope so it cannot be used as a fuel until it is in a reactor and some of the Th-232 has bred U-233.  But this definitely does not translate into cheaper electricity.

4. The isotope of thorium which is used for power production is the most common isotope Th232  (More than 99% of the naturally occurring Thorium is Th232).   By contrast Uranium piles use the rare U235. With Thorium generation no expensive enriching is needed. Cheaper electricity.

Sorry, not that simple I’m afraid.  It is swings and roundabouts.  U-235 constitutes about 0.7% of the total uranium and while some reactors can use natural uranium (CANDU and MAGNOX for example) most need the uranium isotopic ratio to be increased to about 4% U-235.  With Th fuel there is zero % fissionable content and so it is necessary to either have a central core of fissionable material to start the reaction in the Th fuel and breed U-233 or to have a mixture of U-233 or U-235 or Pu-239 with the Th-232.  Either way you cannot get away from a fission fuel or a more complex reactor core design.

5. The waste from a Thorium reactor is less in quantity, less radioactive and shorter lived and hence cheaper to handle, transport and dispose of. Once again, cheaper electricity.

While it is not less in quantity (one fission event produces two fission products what ever the fuel) it is totally true that the waste has a much smaller proportion of the long lived so-called transuranic elements within it (that is Pu, Np, Cu, Am).  So the waste poses a radioactive burden for a much shorter time.  This is one of the true advantages.  It is potentially important.

6. Because of it's physical and chemical characteristics, it is possible to build a Thorium reactor which is inherently stable. Far less control systems are needed to ensure that a melt down does not occur and a containment building is not even needed. A thorium plant is cheaper to construct than a uranium plant. You guessed it - cheaper electricity.

I cannot see why this is the case.  It will definitely and definitively need a containment building.  Sorry.

7. Thorium reactors produce no bomb making material as do Uranium reactors. Once the technology is mature, there will be no excuse for anyone to use Uranium. States which persist in the use of Uranium will clearly be doing this in order to make atomic bombs. The case against such states will be exceedingly clear.
Mostly I agree with the bomb comment.  It is all about those transuranic elements again – which includes Pu.  But remember you do use uranium in Th fuel it is just U-233 not U-235 and it is created within the Th fuel via the breeding process.

8. Mining and purifying Uranium provide many points at which Uranium can be sidelined for nefarious purposes. Stopping the production of new Uranium reduces the chance of uranium falling into the wrong hands. If Thorium falls into the wrong hands, it is of no use to them, it is not fissile. Less expensive security is needed. (electricity price??? ---  you guessed it)

Well with Th fuel you do still have to reprocess to some extent and that has potential to be used for other purposes.  Yes no enrichment of U is necessary and that is an advantage.  Again swings and roundabouts (hope you have the same saying).

10. You get far more energy from a kg of thorium than from a kg of Uranium. You guessed it.

That depends on what reactor system you are using.  Fast reactors use up both types of fuels to about the same extent.

In conclusion, I am very keen to see Th fuel exploited but mostly because of the long-lived waste issue.  I do not think it will be cheaper, in fact it will be a bit more expensive but the extra cost may well be worth while.

Have a look at the Indian programme on nuclear to see what they are doing.

1 comment:

Jon said...

I believe Thorium 'feeds' off of the waste of old nuclear plants.

from thestar.com
"it actually feeds on radioactive plutonium waste, one of the nastiest substances on earth, as part of its power-generating process. That’s important because the disposal of plutonium is probably the nuclear industry’s most vexing problem."

Better to move those spent rods from nuclear facility to nuclear facility. The alternative is moving it to the small towns where they are proposing these fusion-fission plants. It would also give the DOE some incentive to clean up their already radioactive sites ...easily ignored when you can plop another 'nuclear' facility right on top.