Nothing is quite as hilarious as when you start talking isotopes, since you are completely clueless about reactor physics, nuclear chemistry and reactor engineering.
Uranium-236 may be viewed as a burnable poison. Anyone who knew anything at all about reactor physics - and let's face it, you don't learn reactor physics in fundie anti-nuke cults like "'Friends' of the Earth" any more than you learn evolutionary genetics in the "science" classes at Liberty University - knows that almost all reactors have burnable poisons. The nice thing about U-236 is the way it burns, particularly in thermal breeding scenarios. For a while the poisoning effect rises as U-236 is converted into Np-237, but as both are depleted as fission poisons accumulate, the situation relaxes.
In fact there are many parts of the fission neutron spectrum at which the "fission to capture" ratio (duh, Mom, what's that?) is as high as 0.3 for U-236. For Np-237, the ratio is nearly 0.4
(Source: Stacey, Nuclear Reactor Physics, Wiley, 2001, pg 235.) The obvious advantage of a parasitic nucleus like U-236 in reactors having slower spectra, is to eliminate the need for boron and other poisons deliberately added to reactors.
This means that by manipulation of the spectra via geometry and materials considerations, the neutron sinks can be easily manipulated. Interestingly enough, for 1 MeV neutrons, U-233 has the highest known value of eta for any actinide other than Pu-241 (which in any case is near 2 MeV.) The engineering implications are obvious.
It can be shown that there are many methods to do these things in situ, as were pioneered by Weinberg more than 3 decades ago.
But, of course, if you're reading some dumb shit rhetoric off of some googled anti-nuke website filled with contempt for science and engineering, none of this matters.
As for U-232, I note that our fundie anti-nukes are pretty loud - when they're not telling us, a la Amory Lovins that nuclear energy is dying - at voicing their illiterate fantasies about weapons diversion of uranium. In the next breath, they're arguing to keep existing weapons materials as dangerous as possible, at least when they're not pushing fossil fuel wars. In fact, a bunch of dumb ass anti-nukes were
essential to whipping up the "Saddam Hussein is buying uranium" hysteria in 2003. There was NOT ONE person with a knowledge of nuclear physics who took one word of this bit of crap seriously.
U-232 has the
advantage of making clandestine weapons diversion of uranium fuels
impossible. The problem is not that we have too much U-232, but that we don't have enough of it. In fact, one might argue that the perfect nuclear fuel for the purpose of
forcing nuclear disarmament would have an admixture of U-232, U-233, U-234, U-235 and U-236.
There is no feasible technology for enriching such a fuel to weapons grade. This fuel composition can
only be achieved through a
rational embrace of nuclear fission
energy plants.
I note that the
first US nuclear reactor - the one at Shippingport - operated for a full cycle on thorium based fuel, that the first molten salt reactor operated on thorium fuel in the late 1960's and that Indian reactors operate on it now.
Thorium fuel does have a moderately higher processing cost that traditionally enriched fuels, but the cost of nuclear fuel is trivial in all cases, the equivalent of gasoline at less than a penny a gallon. However, since there is no shortage of nuclear fuel, there is no reason to exploit these facts - yet.
The cost of nuclear energy is almost entirely the cost of the infrastructure. Fuel is plentiful and cheap.
I note with my usual contempt for ignorance, that we are hearing this disingenuous whining about cost from a yuppie apologist for solar power - affordable only for Mom's drinking class -
http://www.solarbuzz.com/.When the cost of nuclear energy rises to 21 cents
busbar per kw-hour, be sure to come back and whine. Until then, though, your criteria is like the bullshit representations of
every fundie anti-nuke - selective attention.
Somehow when we are distributing point source electronic waste - which is what solar cells will become in about 20 to 30 years - across the face of the earth in the brazillion solar roofs, cost is no object. But when we talk about energy that every person on earth can afford, we suddenly hear whining about costs.
India, which has the world's largest thorium reserves, couldn't care less about the chanting of the yuppie cults who know
no physics,
no chemistry, and
no economics. It fully intends to go with thorium, and this is an extremely wise and informed choice. They can do it; they will do it and to some extent they are doing it.
The reactor at Kamini went critical in the mid 1990's. It is operating now at 30 MWe. Kakrapar 1 and 2 are both loaded with thorium fuel.
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