EnergyUnlimited wrote:Dezakin wrote:They form equilibrium concentration because they form at low concentration. They're at worst annoying.
http://energyfromthorium.com/2010/06/20 ... n-poisons/
It is big annoyance.
Salt distillation would not be needed, if you don't have to remove neutron poisons other than Xe135.
There are other neutron poisons that form with much smaller cross sections yet aren't in equilibrium. If we could get rid of Samarium for instance then we have more neutrons to play with, which in thermal and epithermal spectra are always precious.
You can via brute force remove everything but the uranium using fluoride volatility of UF6 to my knowledge. I humbly bow to those more experienced in molten salt chemistry, but wasn't aware of any real showstopping problems with molten salt reprocessing. Things we'd like to do better sure.
I don't understand your argument.
Molten fluoride Thorium reactor converts Th232 into U233 (and a bit of U232).
Thorium doesn't form volatile hexafluoride like Uranium (and with some pain Plutonium) does.
Essentially you would isolate fissile isotope (and you may end up with excursion, if you try it in naive fashion).
However bulk of initial thorium input will still remain mixed with fission products (neutron poisons) and so you will have to dispose this thorium - antithesis of thorium breeder concept.
That's where some misunderstanding may be. In a two fluid breeder, there is no thorium in the core. You're probably thinking of one fluid designs (like the one prototyped at ORNL), which has much more complicated reprocessing. There's two separate fluids, the outer blanket which is thorium fluorides where the uranium is extracted by fluoride volatility, and the inner core which doesn't have any thorium in it.
The two fluid core and blanket design is my favorite for several reasons. First the reprocessing is much simpler of course. But the other is that in a two fluid design the outer vessel is insulated from most of the neutrons by the blanket, and so can be selected much more for its chemical compatibility with the salt rather than its resistance to neutron damage. I believe that you still have to be aware of different electrochemical potential between the core/blanket barrier and the outer vessel wall, but it does open up more options.
Another advantage is breeding doesn't explicitly require protactinium partitioning in a two fluid system, and so you can decide weather to do partitioning or pay for a larger salt volume.
The downside is the barrier between the core and blanket is in a hell of neutron radiation, and so there's some question on weather it will have to be replaced every so often.
This is David Leblanc's exploration of the various molten salt reactor concepts, along with his modified geometry two fluid design for a full breakdown of the issues with liquid halide breeders. Its quite helpful, and I think you might enjoy it:
http://energyfromthorium.com/2007/08/23 ... t-breeder/
I'll forward your concern to the LFTR community forum relating to vacuum distillation material, as there are several chemists and nuclear engineers there with far more experience than I. I read something about tungsten being an appropriate tubing material
Would be nice if you let me know, what they think about it.
We have still some considerable problems with fabrication of bulk tungsten items (you will need long sections and significant diameters of tubing).
I don't know how relevant these can be though.
Which forum do you have in mind?
Kirk Sorenson maintains a forum relating to liquid halide reactors:
There's some discussion of using tungsten tubing in this thread:
http://www.energyfromthorium.com/forum/ ... &sk=t&sd=a
There wasn't anyone pursuing liquid halide cooled reactors at this time besides the US, so there was no program to abandon. Much of the blame for abandoning this program lay at the feet of one Milt Shaw.
Indians are meddling with Thorium for quite a while.
It seems sensible to explore molten salts reactors in this context, but they didn't (please correct me if not true).
You may dismiss them, saying that Indians are stupid and don't know what to do, but I don't think it is that simple.
There may be more reasons...
I think that outside of the US, France, Britain, and the Soviets, the world has largely been following nuclear innovation rather than engaging it during the twentieth century. And yes, you could say I'm a bit disappointed in the strategic decision making of the Indians with regard to nuclear power. They should be willing to pay a 100% premium on uranium from their mines as a nonsignatory of the NPT, and recover it from the poorer ore grades in India, but they don't and uranium shortage in India is a worry.
Sure, this reactor is gaining awareness, but I think its going to take a large government investment to develop it, and that is at least a decade away.
I always wonder why it seems impossible for private corporations to invest these few $ billions?
This is not a lot for many firms.
I don't know about that. The timescales are awfully long for firms that want to see a return inside of a decade. I don't know what the solution is to encourage corporations to invest in very long term development. These large engineering challenges always seem to be driven by government. Maybe if everyone was forced to pay for the externalities of coal and natural gas...