Fission of 1000 kg U-233 produces several chemicals essential for industry, readily extracted from a LFTR or any other Molten Salt Reactor, including 150kg xenon, 125kg neodymium (high-strength magnets), 20kg medical molybdenum-99, 20kg radiostrontium, zirconium, rhodium, ruthenium, and palladium.
MSRs also produce non-fissile Pu-238, that conventional reactors can’t produce isolated from highly fissile Plutonium-239; Pu-238 is needed for radioisotope power such as for NASA deep space exploration vehicles (none left, only Th to U-233 makes Pu-238 w/o Pu-239).
(Extracting these from fuel rods in a solid fuel reactor would be extremely difficult.)
Radioactive isotopes are needed for medical treatment, including highly-targeted cancer treatments. These are currently very rare, since they have half-lives of a few days. LFTRs would produce these as part of the decay of U-233, and they would be easy to remove from the fuel salt.
Iodine-131 is used to treat cancers of the thyroid.
Thorium-229 for cancer treatments, decays to Bismuth-213, which decays through alpha emission (unlike most of the fission products that decay through beta emission). By binding Bi-213 to an antibody, it can be directed swiftly to a cancerous cell. The alpha decay of the Bi-213 then has a high probability of killing the cancer cell. (Very small amount/treatment, but decays fast to Bi-209.)
There are other products of Molten Salt Reactors, that aren’t from fission, but from the heat produced. including making gasoline and diesel fuel, and desalinating water.
Molten Salt Reactors (or other modern reactor designs) are the only power source we have capable of generating enough power to both fuel the world and reduce the ocean acidification from CO2 entering the oceans. The specific acid created by CO2 in the oceans dissolves sea shells, including the cell walls of plankton, killing them. We have already put enough CO2 into the air to make the oceans acidic enough to make most species of plankton extinct. Making materials to remove the acid and/or remove the CO2 will take about the amount of energy the world currently uses, for over a decade.
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I am doing a report on LFTR and I truly believe in it but I need to know per 1000kg of thorium (or uranium 233) how many kg of radioactive material is produced and can this number of kg of nuclear waste be reduced by running it back through the LFTR, if so how.
See the section on this blog on nuclear waste, I’ve covered it in enough detail for most people (but not enough for regulators, LFTR designers, etc). 300lbs of 350-year waste per GW-year.
All the transuranic materials simple remain in the reactor until they fission.
Some of the 350 year waste can absorb neutrons to become shorter term waste, but I’m not sure if that could happen inside the LFTR (neutron economy is a concern) or if it would take an external neutron source.
Ask at the Energy from Thorium Forum, http://www.energyfromthorium.com/forum/index.php
So if I’m reading your reply correctly there are no ‘major’ technological hurdles to overcome (such as fusion) to bring this to market, just a concerted effort? It really does sound like it could be the answer to most of our power needs, now and in the future. Interesting blog you have here, must say I stumbled upon it by seeing a couple of your posts on the EEstor blog, as I have been following that blog off and on for a couple of months now. I will admit that I never heard of Thorium used as a nuclear fuel, being that I’m a newbie to all this. I’ve been going through some of your old posts and have also checked out the Thorium energy blog…good stuff! Quite interesting and keep up the good work
Since all the uranium and other transuranic elements are easily left in the reactor, circulating through the core until they fission, essentially all of the long-term waste is “reduced by running it back through the LFTR”.
The fission byproducts from 1000kg of Th converted to U233 (or 1000kg U235, U238, or Pu239) would be 1000kg, 83% has half-lives under 1 year, 17% has half lives 35 years (10 half lives is a good guideline for how long needs to be stored, 1/1024 the radioactivity).
I don’t know the details on each isotope of each element that could be produced in a LFTR (or by a LWR and put in a LFTR).
There are some isotopes that if absorb another neutron have shorter half lives. Whether those would be left in the reactor to absorb a neutron, or taken out so the neutron would be captured for example to breed fuel, is an engineering decision. Cesium is one of those that might get neutron bombarding to shorten the half life, either in a LFTR or from another neutron source.
As said on other pages, the LFTR waste, or any MSR waste, would be 1000kg (the original 1000kg minus a very tiny amount of mass converted to energy). The fission byproducts of U-233 and U-235 are similar, Wikipedia has lists of the decay chains and the fission byproducts. The probabilities of each fission byproduct are known, just need to crunch those numbers.
But the MSR waste would not contain uranium like LWR waste; 83% below safe radiation levels in under 10 years; 17% (about 375 lbs, low radiation, non-fissionable) store for 350 years. Depending on the specific MSR design used, and type of electric generator, about 800kg-1000kg fuel would produce 1 giga-watt electricity.
Remember, in any MSR, the fuel salt is molten, so uranium, transuranic elements, and elements with isotopes with long half-lives can be separated and would be returned to the reactor core (for fissioning, or for decay by neutron bombardment). Depending on the MSR design (in-reactor or external batch fuel processing), they never leave the reactor.
In LWR waste, uranium is by far the largest by kg (over 95%); that uranium could be used as MSR fuel, no “reprocessing” needed, no “enrichment” needed, the hard part would be mechanically/chemically removing the uranium from the fuel rods & pellets: U235 would fission, U238 would absorb a neutron and become Pu239 which fissions, fission byproducts could be removed by the same processes the MSR uses, either in the reactor or separate equipment at the LWR waste storage site.
A LFTR could handle small amounts of LWR waste (just add less thorium, the reactor self-adjusts since the fuel expands/contracts with changes in heat); a “waste burning” MSR would be configured for LWR waste as fuel, neutron economy adjusted, no thorium-to-uranium blanket.
Using he fission products is a nice idea, but for most of them it currently is not economic, at least when reprocessing LWR fuel.
Reusing the xenon probably will work, since it more of less needs to be separated anyway. However the value is not really significant.
The radioisotopes that are used in medical applications need a high purity – the wast from the LFTR just delivers a mixture of isotopes. There is essentially no alternative to irradiating target materials of high purity. Even the Pu-238 may not be pure enough to be really valuable – so it’s likely better to remove the neptunium before it becomes Pu-238. Than a second dedicated reactor can make pure Pu-238 from this.
Neodymium is mainly expensive because it’s hard to separate from other rare earth elements and thorium. So it’s likely not a good idea to do the rather dirty chemical separation with a highly radioactive mixture of rare earth material.
The one really valuable isotope, worth selling it may be tritium – it’s only some 100 g a year, but quite expensive.
[Several of the fission products are single-isotope, only chemical separation needed. Pu-238 and other isotopes are useful in reactors, Pu only needs to be single-isotope pure to a few parts per million for nuclear bomb use. Most of the fission products have very short half lives, only need to be stored a few years before can be used for industrial purposes. — George]
I’m not a chemist, but seems to me there are very few elements generated in LFTR, whether using Th-U233, U235 or U238-Pu239. Should be standard chemical methods for separating them from the molten salt.
Reprocessing LWR fuel seems much harder, including the fuel rod is designed to trap all fission byproducts (and TRISO adds several more layers of trapping). Read more on the fluoride volatility and distillation processes a LFTR would use, and ask questions on the Energy From Thorium boards.
But if it isn’t economical to separate some of the elements, it would still be simple to let them decay for the few years needed to not be radioactive, and then just drop them into whatever storage container is appropriate.
All the discussions I’ve seen talk about this like it is easy to separate these chemicals, and molten salt reactors are the Only way to get some of them (aside from very expensive specialty reactors).
I will be teaching a course “Energy and Environment” next term, and want to include a section on thorium. The one part I can’t seem to find details on is the exact process of chemical separation of fission products. It seems to me (have not calculated this) that they MUST be removed eventually, if not continuously, otherwise the radioactivity would increase without limit, and fuel concentration would decrease (as well as xenon poisoning the reactor due to neutron capture). However, I can’t find any diagrams of what the waste removal facility would actually look like. What I really want is to tour a working thorium plant and take pictures! :()
[Mark, Not “without limit”, which you know isn’t possible; search for radiation charts for LWR fuel over time, which trap all fission products in the fuel pellets. Xenon is a gas, it bubbles out of the circulating molten fuel, easily collected. There are designs of MSR, e.g. for “non-nuclear states” like Iran, where you put in enough fuel for 30 years, do no chemical processing, install the normal monitoring and security devices with remote communication, seal the entire reactor, bury it underground, and 30 years later extract the entire reactor and replace it; the entire reactor would be shipped to a central location that removes the fission products and puts the remaining fuel into the next reactor. Make sure you specify “working molten fueled thorium plant”; I want a tour too! — George]
The point of the MSR is that you don’t NEED or even _want_ to separate the products in question out (and there’s an unholy mix of isotopes in there, so anyonme attempting to pull them out for weaponsmaking will probably find it too much trouble thanks to some of them being white hot, radioactively speaking)
All your fisionables and products just keep circulating until they fission or grab enough neutrons to become fissionable. The only question is ensuring your neutron economy doesn’t go negative – this is helped inasmuch as the most copiously generated neutron poison is xenon – a gas – which comes out easily without any chemical processing in the circulating pump sparge space (store it for 6 months and then sell it)
Other neutron poisons may be better left in the loop and just tolerated
Remember: The MSRE was shut down on friday afternoons, restarted on Monday mornings and tests running it down to minimum output and back up to maximum power were conducted to assess its susceptabliity to neutron poisoning or a SL1 type incident (other incidents being far in the future) – it didn’t even miss a beat in these tests
Regarding LWR fuel rods, most of the proposals I’ve seen boil down to “dunk them in the melt and let the contents dissolve”. You don’t need to preprocess or separate out any of the rod’s contents before introducing them to the MSR loop
Actual out-of-reactor reprocessing of the loop content is intended to be as absolutely minimal as possible (only enough to prevent poisoning of the reactor) and restricted to _chemical_ processes. (Weinberg’s “Chemical Kidney”) This was never tested at Oak Ridge as far as I know.
Extracted gasses and noble metals are all separateable fairly easily. The most problematic appears to be Kypton – which needs several decades storage – most of the rest have “decay to safety” levels measured in months at most.
The point someone else made about tritium is an interesting one.
In a LFTR, the single largest source of tritium will be 6% of the lithium in the salts. Tritium is held up as one of “The Reasons” that lithium must be isotopically pure and when you point it it’s valuable all kinds of handwavery then start going on about how it will escape from the loop and people start raving on about metal embrittlement/high pressures. Circulation speeds are such that it will come out in the sparge space where it can be extracted, it’s a low pressure system and once captured, tritium can be chemically bound so that it doesn’ perform the usual annoying molecular hydrogen tricks
The problem is that the MSRE didn’t get a chance to perform many of the more indepth tests needed to assess costs of long operation and so much has been buried that all this research is having to be done again – but always bear in mind that the intent of a LFTR (and more other MSRs) is “Zero reprocessing, or as little as technically possible – if it’s problematic, leave it in the loop” – anything coming out that’s seriously radioactive is a fuel source better left inside.
Alvin Weinberg spent a lot of time working out the best and safest way to handle breakdown products. He regarded intrinsic safety as paramount and part of that safety is deigning to ensure that you don’t _need_ to pull nasty stuff out where it can pollute the biosphere or hurt people.
Very interested in Thorium 229 for cancer treatments. I URGENTLY need any information you have on potential cancer treatments available. I am writing in 2014 – have there been any updates on this? Any progress?
I would appreciate any information!