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May i please open this question by asking that if you intended to answer this please could you provide links based on your answer. I have read ( and posted one ) on thorium and a lot of the answers are contradictory to what i have read with no scientific papers of links to back up what is being said. I am sure some of you are extremely intelligent but i do not know you. I am very interested in this topic and just want to learn more.

why am i asking this

I am very curious as to why ( and this not being the question, is somewhat political in nature ) the governments has not given more research time or scale development to using thorium as an alternative to are current energy crisis, not so much in that we do not have enough energy but how energy production is having a very negative effect on the environment. So this question is just to understand one side of the larger question, not meant for this board.

Traditional nuclear power radioactivity

Neptunium-237 Plutonium-239 (tried to provide links but i do not have enough point yet)

Those 2 elements being the largest factors in organic destruction

The amount of HLW worldwide is currently increasing by about 12,000 metric tons every year, which is the equivalent to about 100 double-decker buses or a two-story structure with a footprint the size of a basketball court. marathonresources.com.au/nuclearwaste.asp

A 1000-MW nuclear power plant produces about 27 tonnes of spent nuclear fuel (unreprocessed) every year. world-nuclear.org/info/inf04.html

I don't think i need to outline the physics of why this is a very serious problem. Yeah maybe not for us, in our life time (besides the event of meltdown , in the case of Japan having +22 nuclear plants in a region of the earth that has 3 highly active tectonic plates), but for humanity this is really grim. If anyone is interested in a very good documentary on the matter please see http://en.wikipedia.org/wiki/Into_Eternity_%28film%29 note:This is not your run of the mill documentaries.

I don't want to get into the whole nuclear weapon debate, what i am asking has nothing to do this that. This is primarily the radioactive waste produced by these two different forms of electrical generation and the physics with the long term effect on nature.

Can we be certain that with traditional means we are not creating a pandora's box for future generations to come. One that could alter life on this planet to the point of complete destruction?

Thorium radiation 

http://imgur.com/a8TDT <-- poster outline of Thorium

"Thorium produces 10 to 10,000 times less long-lived radioactive waste;" wikipedia.org/wiki/Thorium#Benefits_and_challenges

yet in the same post it states

"potential problems in recycling thorium due to highly radioactive " ( under thorium energy fuel cycle ) due to Th-228

So yes there is still radioactivity in its production but the radioactivity ratio between the two technologies, from what i have read , makes thorium a cleaner waste disposal process with less harmful effect in every area of concern from production, meltdown and disposal.

With Thorium harmful decay is gone in 10 years for 83% of materials and 300 years for 17% compared to 10 000 years with conventional nuclear energy. With what little research has been done, it can also prevent a complete core meltdown. I cannot even imagine how amazing this technology can become with more funding and research into production development and disposal.

In conclusion: 

Am i missing something in the research that i have done that does not make thorium an cleaner alternative to nuclear energy by a factor of a lot? And if i have not missed anything, why is this single difference not driving the research and development into this energy system ( Please i do not want to get political in this answer, if it is political please keep the answer very short, although i am interested i do not want to side line the main topic of this question )

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I've changed the title - there is nothing different about the radioactivity: See also physics.stackexchange.com/questions/20034/… and physics.stackexchange.com/questions/44351/… –  Martin Beckett Dec 1 '12 at 15:53
    
Can you please cite a scientific paper –  gerdi Dec 1 '12 at 15:57
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it was a comment on the English. Uranium isn't "traditional" radioactivity anymore than Thorium is. It's like saying dropping an apple is traditional gravity but dropping an Apple iPhone is different gravity –  Martin Beckett Dec 1 '12 at 15:59
    
Ok that is correct to a degree but you stated in your reason that there is nothing different about radioactivity. This question is about the difference in the release of radioactivity by these elements, which are fairly different, from what i have read. –  gerdi Dec 1 '12 at 16:04
    
@gerdi: as far as I can tell from Wikipedia, (1) thorium fission products are shorter-lived than uranium fission products, so that the radioactivity is no longer highly dangerous after hundreds of years (rather than ten thousand). (2) you get U-233 rather than Pu-239 as an actinide product. This is good because it's easier to convert U-233 into stuff it's hard to make nuclear bombs out of. These are both very good reasons to use thorium reactors, but they're not magic. You seem to believe there is some further difference between thorium and uranium. There's not. –  Peter Shor Dec 1 '12 at 16:10
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5 Answers 5

The relevant physics is this:

Th-232 (non-fissile) can be bred into fissile U-233. Because of side reactions, some U-232 always appears in the creation of U-233. For those wishing to make nuclear bombs, two problems emerge:

1) U-233 is very tricky to detonate.

2) U-232 rapidly decays down to Tl-208, a strong gamma emitter

Strong gamma rays are not just deadly to engineers, making it difficult to fashion, but gammas are also deadly to electronics and semi-stable materials one might put into a bomb. Moreover, the gammas' precise energy and penetrating power announce and identify their source from distance.

So why are bomb-making consideration relevant to nuclear energy? You asked why governments do not research thorium more. Historically, governments have invested more time and money seeking bombs rather than energy. With better alternatives out there, nobody wants to develop unreliable bombs with a shelf life measured in weeks. Consequently, thorium research was cut short back during the cold-war. It is only recently receiving some renewed interest for commercial energy production, but it now must overcome decades worth of cumulative bureaucratic inertia and paid-for uranium industry that are well beyond the scope of this forum.

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In your opinion do you thing that there is an environment advantage to thorium over uranium? Could it be a safer way in which to produce large amounts of energy? thanks –  gerdi Dec 10 '12 at 9:36
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Radioactivity from nuclear waste has two major components, (1) the fission products that result from splitting the uranium or plutonium atom, and (2) transuranic waste, metals heavier than uranium that result from neutron absorption without fission. The fission product waste is almost identical from both the thorium/uranium-233 and uranium-235/plutonium fuel cycles. It decays in a few hundred years. The transuranic elements (TRUs) decay in many thousands of years, so a repository must be able to accept the heat that long. Creating a TRU such as Pu-239 from U-238 in LWRs takes one neutron absorption. Creating Pu-239 from Th-232 in a LFTR (liquid fluoride thorium reactor) takes 7 neutron absorptions, so much less is generated. There are lots of references in the website for my book; see http://www.thoriumenergycheaperthancoal.com

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On average, the shorter-lived a radioactive substance is, the more radiation it generates. This is because for shorter-lived radioactive elements, roughly the same amount of radiation total is generated, but spread out over a much shorter period of time. Exactly how long-lived and how radioactive the waste from a thorium reactor is depends on what radioactive fission products are generated, which is very complicated physics; but there is no contradiction in thorium waste being both highly radioactive and relatively short-lived.

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With thorium, the U233 is isolated and the result is far fewer highly radioactive, long-lived byproducts. So no firstly this is not highly radioactive ( with respect to current nuclear tech ) and its actually not short-lived, its only "short-lived" in that the harmful radioactivity is in a short time span. The half life is much longer,14.05 billion years) with uranium at 4.47 billion years. both are not short-lived with regards to harmful radiation. Unless you know of some research you can cite? –  gerdi Dec 1 '12 at 15:44
    
From Wikipedia: According to some toxicity studies,[17] the thorium cycle can fully recycle actinide wastes and only emit fission product wastes, and after a few hundred years, the waste from a thorium reactor can be less toxic than the uranium ore that would have been used to produce low enriched uranium fuel for a light water reactor of the same power. Other studies assume some actinide losses and find that actinide wastes dominate thorium cycle waste radioactivity at some future periods.[18] How is this different from what I said? –  Peter Shor Dec 1 '12 at 15:53
    
Well its a little different. –  gerdi Dec 1 '12 at 16:10
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It is not a matter of a lot of research needed, since some countries are already planning to make thorium reactors, as India.

It is a matter of economic costs and benefits,( existing uranium mines and processing for example versus new explorations for thorium) radiation costs and benefits .

In effect the world community is betting that fusion, now a world project at ITER, will be the solution for energy in the future, say in fifty years, and most of the radioactivity problems will become moot either with thorium or uranium reactors as they will become obsolete.

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"radiation costs and benefits ." yes that was the nature of my question, but the costs and benefits far out weight the current uranium based tech by a large factor. Fusion does create radioactive waste actually comparable to thorium ( dangerous for only 50 years, ok a bit less then 300 years for 17% of material ) wikipedia but there are some seriously large problems in creating fusion. If we can get it to work ,awesome , but a 50 year projection seems like a good number to market for funding. –  gerdi Dec 1 '12 at 11:30
    
Fusion is an engineering problem, the current design at ITER will lead to a prototype commercial reactor, and then it is over for nuclear reactors. The radioactivity is the one induced on the walls and surroundings of the fusion reactor, but no radioactivity in the burning fuel to be disposed. When a fusion reactor is finished, the place will be off bounds for some centuries and that is all. –  anna v Dec 1 '12 at 12:02
    
This is a fairly off topic but i really hope fusion does work but at the moment it is not looking good and it is not just "An engineering problem" . Dr Michael Dittmar, a physicist at CERN working for the Swiss Federal Institute of Technology thinks this is a comforting folly, a process fraught with problems in physics, mathematics and engineering. BBC Thorium reactors do work, global warming and the negative impact we have on our planet is happening right now. –  gerdi Dec 1 '12 at 12:44
    
Well, global warming has stopped the past 15 years, though the fact is not advertised and only that it has stopped at a high point is emphasized, so that need not be of any concern. A culture that has set a man on the moon and satellites buzzing around the earth will surely as the sun rises solve the problems of controlled fusion. It needs money, dedication and patience.Countries that already have uranium reactors will keep on amortizing their investment. Countries like India may choose thorium because they have the mines. The negative impact on the planet is hype mostly. –  anna v Dec 1 '12 at 12:50
    
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See this report from MIT. Appendix A specifically discusses the use of thorium in commercial power generation and concludes:

However, the technology of thorium fuel does not offer sufficient incentives from a cost or waste point of view to easily penetrate the market. Only if reduction of Pu content of the fuel cycle, and acceptability of U-233 instead, are favored by the proliferation evaluation community would there be a reason to move in the near future to apply the thorium cycle.

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Interesting read thank you. That to me sounds like a political answer though. Please correct me if i am wrong but they are saying you can make basically make weapons out of this process so its not really viable. I am not sure sure how they "view" the waste cost but that seems a bit ignorant compared to the current costs. " it [Thorium Reactors] can burn up plutonium and toxic waste from old reactors... telegraph 20-03-11 –  gerdi Dec 1 '12 at 11:18
    
@gerdi - they are saying you CAN'T make weapons out of this stuff, so it may be more viable for countries that want nuclear power but don't want to make enemies. –  Martin Beckett Dec 1 '12 at 15:56
    
@gerdi - as detailed in the dupe posts, the waste benefits of Th are marginal and there are U reactors that are both inherently safe and can burn Pu waste. –  Martin Beckett Dec 1 '12 at 15:57
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