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Thorium Instead Of Uranium: Solution To Our Energy Woes?

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Re: Thorium Instead Of Uranium: Solution To Our Energy Woes?

#51

Post by terra_t »

uvdiv wrote: post #38
terra_t wrote: post #19

Earlier quoted context omitted.

The trouble with fast breeders is that you need a huge fissile inventory to get one started. A study of the PRISM design, a modern fast breeder that uses integral reprocessing to reduce the inventory of plutonium that's sitting around, not fissioning, indicates that if we reprocessed all spent fuel in the U.S. today, we'd have enough Pu to power about 33 MWe worth of breeders, about 1/3 of the current fleet. It comes…

> if we reprocessed all spent fuel in the U.S. today, we'd have enough Pu to power about 33 MWe worth of breeders, about 1/3 of the current fleet. That should be "GWe" not "MWe". Also, I dispute your choice of statistic. Why not show what happens if you start fast breeders on mined uranium, just like LWRs?

Sorry I missed a factor of 1000. Fast breeders on mined uranium have the same problem as plutonium breeders... Except you can breed plutonium faster (but less efficiently) in LWRs!

Re: Thorium Instead Of Uranium: Solution To Our Energy Woes?

#52

Post by protomyth »

pjscott wrote: post #43
wtallis wrote: post #35

Earlier quoted context omitted.

As soon as the market has to bear the cost of long-term storage of waste, they'll be interested in thorium.

That "waste" is still perfectly usable fuel. You could extract the plutonium and uranium and use that to make more fuel rods. You could burn it in fast breeder reactors, in a hypothetical future where mined uranium becomes expensive enough to warrant the use of fast breeders. Or you could just ship it to Canada, where they have heavy-water-moderated reactors that can use regular nuclear waste directly as fuel, withou…

To add, http://en.wikipedia.org/wiki/Nuclear_reprocessing - see the last two paragraphs in history for some problematic decisions.

Re: Thorium Instead Of Uranium: Solution To Our Energy Woes?

#53

Post by olegkikin »

Retric wrote: post #40
olegkikin wrote: post #27

Earlier quoted context omitted.

Your 100 and 1000 year assumptions are just silly. You assume energy demands will remain constant, while they are exponential. Just think what will happen if electric cars become popular. We will need a lot of electricity.

Resource usage tends to follow a http://en.wikipedia.org/wiki/Logistic_function not pure exponential growth. Picking a good limit is hard but assuming energy use per person is stays around 5x our current value and US population is limited to 1 billion people 1000 years is an extremely conservative estimate. Conceder: Between 1980 and 2006, the worldwide annual growth rate was 2%. ( http://en.wikipedia.org/wiki/World_…

Your assumption that we will stay exclusively on this planet for the next 1000 years is even more silly.

Re: Thorium Instead Of Uranium: Solution To Our Energy Woes?

#54

Post by tkeller »

pjscott wrote: post #20
CWuestefeld wrote: post #9

Earlier quoted context omitted.

From the OP: You will hear that we can’t make bombs out of U-233 because it is a virulent gamma-ray emitter. This is not true, and I find it curious that it is used as a reason. U-233 has a 158,000-year half-life. What they are referring to is the protactinium-233 contaminant, which has a 27-day half-life, beta-decaying into U-233 with gamma-ray involvement. Chemically scrub the protactinium, of course, or just wait…

No, that's wrong. The claim is that the bred U-233 will be contaminated with U-232, which is very hard to get rid of, and has the hard gamma emitter Thallium-208 in its decay chain.

Where would the U-232 contamination come from, if it's bred U-233? Does thorium also just sometimes decay into the lighter isotope?

Re: Thorium Instead Of Uranium: Solution To Our Energy Woes?

#55

Post by pjscott »

tkeller wrote: post #54
pjscott wrote: post #20

Earlier quoted context omitted.

No, that's wrong. The claim is that the bred U-233 will be contaminated with U-232, which is very hard to get rid of, and has the hard gamma emitter Thallium-208 in its decay chain.

Where would the U-232 contamination come from, if it's bred U-233? Does thorium also just sometimes decay into the lighter isotope?

Sometimes the thorium, when it absorbs a neutron, will emit two neutrons and turn into thorium-231, which decays (though a couple more isotopes) into U-232. It can also be formed when U-233 absorbs a neutron and emits two, forming U-232.

How hard this would be to separate depends on the type of LFTR design you're using. However, you could also include some thorium-230 in the fuel mix to denature any protactinium produced, so there's really no way around having U-232 mixed with the bred U-233. Here's a blog post with more details on the entire process:

http://energyfromthorium.com/2006/10/06/denaturing-thorium-w...

Re: Thorium Instead Of Uranium: Solution To Our Energy Woes?

#58

Post by Retric »

olegkikin wrote: post #53
Retric wrote: post #40

Earlier quoted context omitted.

Resource usage tends to follow a http://en.wikipedia.org/wiki/Logistic_function not pure exponential growth. Picking a good limit is hard but assuming energy use per person is stays around 5x our current value and US population is limited to 1 billion people 1000 years is an extremely conservative estimate. Conceder: Between 1980 and 2006, the worldwide annual growth rate was 2%. ( http://en.wikipedia.org/wiki/World_…

Your assumption that we will stay exclusively on this planet for the next 1000 years is even more silly.

At no point did I assume that. If, I extrapolate based on something that is not true (aka we stop mining uranium) and look at it in a given area (aka the land area currently occupied by the USA or the Earth) then clearly I am not trying to predict human behavior in some other location.

If you want a prediction of human behavior, fine. I suspect that we will move to a mixture of fusion, wind, and solar power long before our supply’s of fissile materials become an issue. I also expect that our initial expansion into space will primarily involve exporting technology into space and collecting raw materials from space. However, initial space exploration is going to have minimal impact on life on earth with few material goods being sent back and forth. I also suspect that it’s going to take far longer than 1000 years before 1 billion people live outside the earths atmosphere.

Edit: The Americas where "discovered" 518 years ago and dispite being there for the taking and far more hospitable than space 200 million more people live in India than all of the Americas put together.

Re: Thorium Instead Of Uranium: Solution To Our Energy Woes?

#59

Post by cromulent »

DanielBMarkham wrote: post #21

I'm a big fan of Thorium, but I'm also a big fan of nuclear in general. It just makes sense. In fact, this is a lot like the issue of not building any oil refineries in the United States since the 1970s. While I'm sure there are good reasons for our lack of needed nuke plants, at the end of the day it looks like the system has let us all down. I hate to sound like old cranky guy again, but frack, if you really wanted…

Patrick Moore (Greenpeace founder) and James Lovelock (Gaia theory) must also be "cranky old guys" as they also believe nuclear makes sense.

http://www.washingtonpost.com/wp-dyn/content/article/2006/04...

It is super frustrating. And we aren't building enough to replace the old ones!

http://www.nytimes.com/2009/05/29/business/energy-environmen...

Sometimes it seems as though Western civilization has peaked, simply because we've lost our mojo.

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