1.18.2007

Uranium's Peaceful Cousin

This is a pretty interesting article about Thorium being almost the ideal fissile material for nuclear power generation. (Yes I read Treehugger. It's the reason our house is down to 6 incandescents. A renaissance man am I...)

Basically the only reason nuclear energy is based on Uranium (and byproducts of Uranium) is because controllable nuclear fission technology was just a byproduct of the Manhattan Project. It's very possible in some parallel universe where WWII or the Cold War never happened some university developed a Thorium based fission process and they're fossil fuel free -- or very much reduced. The reason the Hippies would desist in the banner making is that the Thorium atom breaks apart much more gracefully than ol' #92:

In today's "once-through" uranium-fueled reactors, we mine uranium, enrich it a
little in uranium-235, burn-up some of that U-235, and then throw it away,
supposedly in Yucca Mountain. (very much in the model of a ‘throw away society’)
When we start out with pure uranium oxide, (roughly 97% U-238 and 3% U-235) and
run it though current methods we end up with three broad categories of "stuff"
in the fuel.
First, there’s the unburned uranium-238 and uranium-235. This
uranium is no more dangerous after being in the reactor than it was before
(except that now it’s mixed with other products). It has billion-year
half-lives, which means it practically never decays (which is why it's still
around to dig up five billion years after it formed in a supernova). So the
uranium’s not a risk.
Then second group of leftovers are the fission products
(the actual waste of fission). These fission products are very radioactive, and
give off dangerous radiation. We have to keep these fission products away from
people and the environment. But because the fission products are so radioactive,
they decay quickly. Most decay to stable elements in a few hours, some take
days. And a very few take years or decades. But, if we leave the fission
products alone for a few hundred years, they will decay to normal background
levels of radiation (Safe enough we don’t need to worry about them as
much).
Finally, there are the transuranic isotopes. These are formed when
uranium absorbs a neutron and doesn’t fission, and include some nasty elements
like neptunium, plutonium, americium, curium. The transuranics are radioactive
for hundreds to tens of thousands of years, and as they decay they give off
different kinds of radiation. It's the transuranic waste that is the reason why
you have to build a place like Yucca Mountain that must remain geologically
isolated for tens of thousands of years.
In contrast Thorium byproducts are highly energetic with half-lives measured in human timescales:
Thorium is better because it has to absorb five neutrons before it will turn
into a transuranic isotope, whereas common uranium only has to absorb one- a
built in buffer. So by operating a reactor on pure thorium and uranium-233, you
can avoid producing the kind of long-lived waste that needs a place like Yucca
Mountain.
Thorium is a great possibility- it could be a high density source
of clean energy. The fluoride salt thorium reactor can produce nuclear wastes
that consist only of fission products, which quickly decay to stable elements -
in fact some elements like xenon or rhodium represent valuable commercial
products after a few months 'cooling down'.
The best part is that Thorium is three times more common than than Uranium. Easily exploitable reserves could last for tens of thousands of years.
Maybe instead of attempting to transform anthropogenic climate change from an engineering problem into a moral/religious issue the Pelosi posse could annouce reasearch into this.

2 comments:

Ben said...

Good find! I don't recall if the article covered it, but could Thorium be used to build a weapon? If not, and a given country opts for Uranium, that would seem pretty clear that they have a nefarious dual use in mind. Either way, it would be a good litmus test to determine a governments intent.

Andrew said...

I don't think Thorium is a suitable fission weapon material. Like anything radioactive I think it's byproducts could be used in a "dirty bomb" that could kill/injure people in a very localized area but the effects would probably be more like the Polonium that killed that British KGB guy (quick, painful death) rather than the long term contamination of a Chernobyl(babies with 3 arms).

You bring up a good point though. If, for example, GE or Westinghouse had working Th technology, the US could have given it to Iran and DPRK and not worried about proliferation.