mos6507 wrote:I'm all for thorium breeder reactors. Not enough talk about it right now.
Here is a good doomer blog site that covers the technology as a mitigator:
Energy From Thorium
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
josephmoore wrote:I think that the Liquid Fluoride Thorium Reactors are designed in such a way that the partitioned waste can be harvested for the valuable byproducts.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
Tanada wrote:josephmoore wrote:I think that the Liquid Fluoride Thorium Reactors are designed in such a way that the partitioned waste can be harvested for the valuable byproducts.
They can be, however in all the ubnits built so far they have either not partitioned anything or only partitioned neutron poisons, volitile fission fragments and Protactinium/Uranium.
Thorium is plentiful and can be turned into energy without generating transuranic wastes. Thorium's potential as fuel was discovered during WW II, but ignored as it was unsuitable for bombs. A liquid-fluoride thorium reactor (LFTR) is the optimal approach for harvesting energy from Thorium, having the potential to solve today's energy/climate crisis. This 10 minute video is summarizes 197 minutes worth of Google Tech Talks on the subject of Thorium & LFTR.
Dr Rubbia says a tonne of the silvery metal – named after the Norse god of thunder, who also gave us Thor’s day or Thursday - produces as much energy as 200 tonnes of uranium, or 3,500,000 tonnes of coal. A mere fistful would light London for a week.
Thorium eats its own hazardous waste. It can even scavenge the plutonium left by uranium reactors, acting as an eco-cleaner. "It’s the Big One," said Kirk Sorensen, a former NASA rocket engineer and now chief nuclear technologist at Teledyne Brown Engineering.
"Once you start looking more closely, it blows your mind away. You can run civilisation on thorium for hundreds of thousands of years, and it’s essentially free. You don’t have to deal with uranium cartels," he said.
wisconsin_cur wrote:http://www.telegraph.co.uk/finance/comment/7970619/Obama-could-kill-fossil-fuels-overnight-with-a-nuclear-dash-for-thorium.html
-Ambrose Evans-PritchardDr Rubbia says a tonne of the silvery metal – named after the Norse god of thunder, who also gave us Thor’s day or Thursday - produces as much energy as 200 tonnes of uranium, or 3,500,000 tonnes of coal. A mere fistful would light London for a week.
Thorium eats its own hazardous waste. It can even scavenge the plutonium left by uranium reactors, acting as an eco-cleaner. "It’s the Big One," said Kirk Sorensen, a former NASA rocket engineer and now chief nuclear technologist at Teledyne Brown Engineering.
"Once you start looking more closely, it blows your mind away. You can run civilisation on thorium for hundreds of thousands of years, and it’s essentially free. You don’t have to deal with uranium cartels," he said.
Among the things I will proclaim in an ideological manner is a disbelief in "magic bullets" but this could be useful and there does not seem to be a more recent thread on the issue.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
Tanada wrote:I'm sorry to have to do it but this is a blatant lie. Thorium 232 or regular Uranium 238 can both be used in a liquid fluoride reactor, the statement that 1 ton is equal to 200 tons is a lie, nothing less.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
EnergyUnlimited wrote:There are still plenty of issues related to molten salt reactor left to resolve and perhaps the most important one is related to removal of lanthanide fission products of high neutron crossection from salt melt.
Failing that our reactor will work for few months at best and remaining mix will become to be just intractable mess.
Need of reprocessing of such mess would easily kill commercial advantages of such project.
Salt distillation process might come to a rescue (it is possible to run it at ~1500*C because LiF and BeF2 are volatile at these temperatures and fission products fluorides are not volatile) but halide induced corrosion (pitting) of vessel construction materials and also its thermal stress related deterioration are still not resolved.
For sure there were good reasons for its abandonment in the past.
It may prove successful but it may also fail like commercial FBR did - due to intractable engineering difficulties.
Dezakin wrote:EnergyUnlimited wrote:There are still plenty of issues related to molten salt reactor left to resolve and perhaps the most important one is related to removal of lanthanide fission products of high neutron crossection from salt melt.
Failing that our reactor will work for few months at best and remaining mix will become to be just intractable mess.
That simply isn't true. If that were the case you would have to have refueling times in light water reactors themselves on the order of months rather than ever year or two. The lanthanide fission products aren't significant neutron poisons compared to xenon (which is continuously removed) and certainly can be overcome with higher fissile load and harder neutron spectra.
Because of uranium's particularly high affinity to fluorine, fluoridation can remove most of the neutron poisons. Removing these neutron poisons in a design is an obvious goal, but not necessary as you're implying.
Salt distillation process might come to a rescue (it is possible to run it at ~1500*C because LiF and BeF2 are volatile at these temperatures and fission products fluorides are not volatile) but halide induced corrosion (pitting) of vessel construction materials and also its thermal stress related deterioration are still not resolved.
That's news to me. There never was much question as to what to do for the vessels for reprocessing, there's a whole range of materials that would be appropriate for running high temperature molten salts, from graphite to certain types of Hastelloy. That's easy stuff, as aluminum refining deals with these sorts of conditions regularly.
For sure there were good reasons for its abandonment in the past.
It may prove successful but it may also fail like commercial FBR did - due to intractable engineering difficulties.
It was abandoned because of a political battle between Milt Shaw and Alvin Weinberg.
I'm not unrealistic. If we started doing large scale prototypes (larger than the research reactor at ORNL) we might not have a commercial power reactor for several decades given the timescale of engineering cycles. But if we don't pursue it, it will certainly take longer to develop.
There are a whole host of different designs. Graphite moderated thermal, salt only moderation epithermal, D2O moderation extremely thermal, liquid chloride fast reactors. All different types of geometries, from pan in pan, tube in tube, single fluid, two fluid, a 'one and half' fluid design, all with their different advantages and challenges. Different salt prefrences from FLiBe, FLiNaK, chlorides, etcetera. We have many options.
EnergyUnlimited wrote:Dezakin wrote:EnergyUnlimited wrote:There are still plenty of issues related to molten salt reactor left to resolve and perhaps the most important one is related to removal of lanthanide fission products of high neutron crossection from salt melt.
Failing that our reactor will work for few months at best and remaining mix will become to be just intractable mess.
That simply isn't true. If that were the case you would have to have refueling times in light water reactors themselves on the order of months rather than ever year or two. The lanthanide fission products aren't significant neutron poisons compared to xenon (which is continuously removed) and certainly can be overcome with higher fissile load and harder neutron spectra.
Lanthanides (notably Sm149; 74500 barns and Gd 157; 200 000 barns) are still a major trouble. They are an order of magnitude less problematic than Xe 135 is but they are accumulating in the mixture (Sm 149 is not radioactive) and with progress of time they can wipe out enough neutrons to prevent further fission.
Harder neutron spectrum in LFTR may not be achievable.
Fluorine itself has some moderator properties as well (what is often overlooked in on-line discussions).
Perhaps chlorine is better here (in chloride salt melt) but there are other troublesome issues with it.
Because of uranium's particularly high affinity to fluorine, fluoridation can remove most of the neutron poisons. Removing these neutron poisons in a design is an obvious goal, but not necessary as you're implying.
How so?
These poisons will form nonvolatile fluorides.
Nothing will change.
Salt distillation process might come to a rescue (it is possible to run it at ~1500*C because LiF and BeF2 are volatile at these temperatures and fission products fluorides are not volatile) but halide induced corrosion (pitting) of vessel construction materials and also its thermal stress related deterioration are still not resolved.
That's news to me. There never was much question as to what to do for the vessels for reprocessing, there's a whole range of materials that would be appropriate for running high temperature molten salts, from graphite to certain types of Hastelloy. That's easy stuff, as aluminum refining deals with these sorts of conditions regularly.
For sure there were good reasons for its abandonment in the past.
It may prove successful but it may also fail like commercial FBR did - due to intractable engineering difficulties.
It was abandoned because of a political battle between Milt Shaw and Alvin Weinberg.
There is a world beyond America.
Weird but true.
I'm not unrealistic. If we started doing large scale prototypes (larger than the research reactor at ORNL) we might not have a commercial power reactor for several decades given the timescale of engineering cycles. But if we don't pursue it, it will certainly take longer to develop.
I don't dismiss this technology.
There is a good chance that working commercial installations can be made.
I am just more cautious than you are.
There are still unresolved technological issues there.
There are a whole host of different designs. Graphite moderated thermal, salt only moderation epithermal, D2O moderation extremely thermal, liquid chloride fast reactors. All different types of geometries, from pan in pan, tube in tube, single fluid, two fluid, a 'one and half' fluid design, all with their different advantages and challenges. Different salt prefrences from FLiBe, FLiNaK, chlorides, etcetera. We have many options.
True.
But up to date we commercialized none.
As per my taste FLiBe is most promissing.
Chloride based designs come next.
Sodium & Potassium based designs are even more difficult to reprocess by salt distillation and less promising by the same.
Reactor grade chlorine needs isotopic separation (tedious, expensive).
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/
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'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
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.
I honestly invite you to ask some of your questions and raise your concerns on Kirk's forum, there are plenty of professionals there who would be better able to answer than me.
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.
Users browsing this forum: No registered users and 11 guests