PROS and CONS List

PROS

  1. No Greenhouse Gas Emissions
  2. Near Complete Fuel Usage – less than 2% unused fuel is a significant source of valuable substances- Current reactors use only 5% of the fuel. So LFTRs leave 2% behind and can effectively manage the left over fuel. Far shorter half life (a few hundred years) The current reactors leave 95% behind and leave it for storage and the half life amounts to thousands of years. The storage is handled well but the full elimination of “waste” is more desirable for political reasons.
    • energy density is much greater than Uranium largely because of complete fuel usage being possible in a liquid state.
    • the more toxic fission products such as plutonium never get produced
    • 2 or more plants in one – reprocessing and energy production and secondary applications are all feasible
  3. Lower Pressure so less expensive – runs at atmospheric pressure
  4. Some designs can run them selves without humans
    • underground designs have been suggested
    • underwater designs are a favorite of Kirk Sorensen
  5. Cheaper to build than coal plants – after initial short R&D period costs will come down
  6. are nearly impossible to produce nuclear weapons – main reason it was unpopular in 1960’s
  7. deterrent to fossil fuel usage – can provide abundant and reliable electricity
  8. can be effective as heat source for numerous application
    • water desalinization
    • hydrogen production
  9. thorium supply is plentiful
  10. Robert Hargraves makes a convincing argument that it will lower the worlds population.
    energy=industry=jobs=education=birth control=population control
  11. better than renewables – will produce far more energy than wind or solar power ever could
  12. eliminates war and poverty

CONS
Quoted from Charles Barton’s Nuclear Green Blog post on Single Fluid MSR Design Disadvantages

“David LeBlanc notes some of the disadvantages of the Single-fluid breeder:
Disadvantages

1. Fission product processing greatly complicated by the presence of Thorium
2. Higher neutron leakage
3. Weakly positive temperature coefficient, can be fixed but at large cost
4. Pa removal needed unless both thorium and 233U loading increased substantially

David notes,
Point 3 above is important to discuss. A positive temperature feedback coefficient is generally a bad thing for any reactor design. It is not as serious as may be thought however since the positive term results from effects of the graphite which will lag behind any temperature increase in the salt by tens of seconds at least. Original ORNL work thought it to be slightly negative, recent French studies have shown that to be mistaken. This was mainly due to older calculations treating the graphite and salt mix as homogeneous. In order to solve this problem without destroying the ability to breed, French proposals have gone the route of having an extra Thorium blanket around the core (radial only, not axial). This make it a partial 1 and 1/2 Fluid reactor.

The problem which has been the focus of much attention by French researchers, is that ORNL’s single fluid MSBR had a safety flaw in the ORNL one fluid design that if not corrected, could cause loss of control in the ORNL designed one fluid MSBR. This flaw is probably not fatal, but the French seem anxious to not simply replicate ORNL research, so they have made a big deal of it, and at any rate some, but by no means all, reactor design specialists are concerned enough to write off the one fluid graphite moderated MSRs.


ORNL reactor scientists were not all in agreement on the superiority of the single fluid MSBR design. Many continued t0 believe that the two fluid approach offered advantages.

More Cons for the Dual Fluid Design also post at Nuclear Green

“Disadvantages

* Interlacing of fuel and blanket salt within core is the “Plumbing Problem”
* Blanket salt has positive temperature/void coefficients
* Need for extra heat transfer loop for the blanket salt (5-10% of heat load)”

in the meantime Charles Barton has started a series on Molten Salt Reactors which in general are about Thorium Molten Salt Reactors. He covers the PROS and CONS of each.

  • Molten Salt Reactor Family: Fuel April 25, 2011
  • Molten Salt Reactor Family: Uranium Fuel April 27, 2011
  • Molten Salt Reactor Family: One Fluid May 2, 2011
  • Molten Salt Reactor Family: Two Fluid May 4, 2011
  • Molten Salt Reactor Family: ConvertersMay 6,2011
  • 21 Comments

  • Joe Heffernan
    May 3, 2011 - 6:16 pm | Permalink

    Dear ThoriumMSR,

    I think that Thorium MSR reactors are a great idea. I see that you haven’t completed the cons list yet. I am still fairly new at Thorium MSR but I might bring a fresh view of the cons of Thorium MSR.

    Cons:

    In some Thorium MSR Protactinium 233 will be removed and sequestered for a period of time until it decays to Uranium 233. I understand that this would make it possible to have a pure quantity of Uranium 233 which is fissile and could be formed into an atomic bomb.

    In my opinion a significant reason that the Thorium MSR is not going forward is that once it is built the vendor is unlikley to be able to have long term recurring revenue. Current PWR vendors have significant recurring revenues related to selling new fuel elements.

    Corroion issues are likely to be probematic

    How to keep the rediactive gases produced such as Xenon from escaping before they have decayed to stable elements.

    As I say I am a keen supported of Thorium MSR. I am also a University Lecturer and I know how difficult it can be to write things up.

    I hope you have found the above useful.

    Joe Heffernan

    • Russ Ilk
      April 5, 2014 - 2:07 am | Permalink

      I too am very new to the pros and cons of TMSR as a source of energy. However as you might guess from my e-mail address I am no stranger to pros and cons of using various contoversial materials (pesticides) and processes.

      However when you look at the extensive list of pros you mentioned I think like you probably, wow why hasn’t this process been studied and restudied over and over since the early 60’s. Well that apparently becomes a political and economic issue more so than whats good for the country as a whole issue. This seems best illustrated by some of the materials and tapes available regarding how Pres Nixon and the I think, Adm, in charge of the Nautililus Sub project were able to stop the TMSR research in its tracks.

      Additionally your con regarding long term revenue is quite telling. While this most likely is true I ask is it right? Should the welfare of our planet be looked at in profit and loss terms. Don’t we at the very least risk putting off implementation of programs that will greatly improve our planet until it is to late or very difficult at best to reverse the effects of continued population growth and the negatives associated with this growth.

      So yes there are cons but when I consider the density of energy produced I to become a big supporter of TMSR. And the potential contained in the list of pros only strengthen that support. Add to it the options of continued reliance on fossil fuels or the misguided belief that renewable solar or wind power can be relied on to impact future energy demands I say lets get going on overcoming the cons while making TMSR a significant contributor to the world energy solution.

  • thoriumm
    May 3, 2011 - 11:02 pm | Permalink

    @Joe Heffernan Yes. The cons are not so clear. Partly because of the nature and wide array of design solutions that have been discussed among the engineers and advocates. I was thinking that contributors like your self might pitch in some ideas. And you have. Thanks.

    The Protactinium decays naturally in 27 days to U233 and that is considered one of the admirable outcomes of the Thorium Cycle. The design would need to include ways to process that and most of the community I have exchanged ideas with agree it is easy to manage. Kirk Sorensen has also suggested that a second Chloride molten salt fast reactor could accompany the Fluoride molten salt thermal reactor to enable fuel preparation since the Thorium Cycle does require a fissile startup fuel such as U233.

    One other con is that so few people exist who are trained in this specific aspect of creating nuclear energy. A significant workforce would take time to create.

    Corrosion has various solutions too such as the Big Lots Reactor concept of burning the fuel at lower temperatures to give more life to the core and moderator however the trade off is less efficient output. But since the output is already 200 times greater than those running the Uranium Cycle this is not such a big sacrifice.

  • Michael
    July 11, 2011 - 7:39 am | Permalink

    Cons.
    Nuclear Engineering graduates have not even heard of the concept so bad luck if you were hoping to employ them direct- but there would be quite a few chemical engineering graduates with at least a similar background.

    Complying with strict Tritium emission requirements is tough as it get into the heat fluid chain.

    Hard to get past politicans and bueacrats understanding of nuclear=uranium=solid fuel or perhaps plutonium- i.e. what’s this thorium stuff?

  • Jonathan Wyers
    November 10, 2011 - 3:08 am | Permalink

    @Michael
    I’m a nuclear undergrad, and I’m for LFTRs. Hire me!

  • fmg
    May 30, 2012 - 8:22 am | Permalink

    how does one get in contact with you
    mgawronski3@hotmail.com

  • Ulli
    May 30, 2012 - 1:58 pm | Permalink

    There is one big open point:
    The concept requires a well working reprocessing – currently there are mainly untested concepts. So the question is still open if it is possible to make reprocessing work at reasonable costs and without producing lots of waste. It has to be very much better than the currently used PUREX process – if not, performance of a LFTR would be awful. And don’t think reprocessing is just a small chemists lab: having the whole fluid go through several times a year, so it has to be quite powerful – maybe comparable to something like the half the Sellerfield plant in the UK. So the reactor may be cheap, but we just don’t know how much the reprocessing will cost. On the other hand, if reprocessing really works as well this may be a major proliferation concern – not only getting Pa233 but also Pu239 from a reactor running on normal LEU.

    p.s. Running a LFTR under water or even on board a ship is a really bad idea: the reactor may be a good design on land, but it is just not compatible with water. Much of it’s advantages come from avoiding water. The fuel salt is not suited for long term or intermediate storage: like in the MSRE reactor experiment it would disintegrate and very likely get set free in case such a ship would sink. Keep in mind: the U-233 is about as nasty stuff as plutonium is.

  • Jonathan Wyers
    May 31, 2012 - 9:16 pm | Permalink

    @fmg
    My email is jwyers@ufl.edu

    I’m at the Thorium Energy Alliance conference in Chicago right now. Are you as well?

  • July 26, 2012 - 5:09 pm | Permalink

    Reprocessing LWR waste to use it as LFTR fuel has been mentioned by several of the scientists. It is simpler than the LWR industry is using.

    Fast Spectrum Molten Salt Reactor Options ORNL July 2011 has a section on “Front–end processing system options for used LWR fuel”, covering the chemistry. (Yes, MSRs can be thermal or fast spectrum.) The Executive Summary section says:

    “A light-water reactor (LWR)–transuranic burner can either make use of centralized fuel reprocessing or use much of the infrastructure of its fuel processing system to directly accept used LWR fuel, avoiding the need for a separate reprocessing plant. In addition to helium sparging to extract the gaseous fission products and mechanical filtering to remove the noble metal fission product particles, a fluoride salt–based FS-MSR would employ fluoride volatility and reductive extraction processes to separate the fission products from the fuel salt. Chloride salt–based reactors would employ electrochemical separation, zeolite ion-exchange capture, and chloride volatility processing. In either case, longer-lived fission products could be returned to the salt for fast neutron destruction, albeit with relatively low efficiency because of their primarily thermal absorption cross sections. As the separated fission products have relatively small volume, they can be left in salt form and allowed to solidify and decay in short-term storage.”

    Your “proliferation” comments are a valid concern, but technically not how things work. The Pa and Pu always stay in the reactor, too radioactive and temperature hot to easily steal, and stealing fuel would shut down the reactor. There is never a Pu stockpile produced. “In the context of proliferation resistance, FS-MSR fuel has a uniform isotopic concentration of actinides, including highly burnt plutonium or uranium isotopes along with other minor actinides and fission products. The local fuel processing of the breeder and burner configurations eliminates the possibility of diversion during transport. The fission-product–saturated fuel salt of the minimal fuel processing converter reactor is highly self-guarding during transportation. Further, the transport casks are massive because of the required amounts of shielding. In general, diversion of molten salt materials is difficult. The reactor operates as a sealed system with an integrated salt processing system that is technically difficult to modify once contaminated. The hot salt freezes at relatively high temperatures (450–500°C), so it requires heated removal systems. FS-MSRs operate with very low excess reactivity. Loss of a significant amount of fuel salt would change the core reactivity, which could be measured by a well-instrumented reactivity monitoring system. During operation (with the exception of deliberate fissile material removal for a breeder or addition for waste burner), the fissile materials always remain in the hot, radioactive salt.”

    Anybody with the technical ability to handle molten fuel could more easily make plutonium the way the USA made the first usable amounts of plutonium, (see Wikipedia “X-10 Graphite Reactor”), hidden away somewhere.

    You don’t remove Pa from a 2-fluid MSR, such as LFTR. The % of Pa that would absorb extra neutrons in the blanket salt is low enough to ignore. Only a problem in a 1-fluid MSR.

    When you say things like “if not, performance of a LFTR would be awful”, maybe you could say “compared to what”. Awful compared to a LWR’s 1% use of the fuel? I dont think so. Remember, fluoride volatility extracts uranium very effectively, and is currently used in making LWR fuel (it works, and equipment is NRC-approved). The entire LWR-waste processing system isn’t tested, but the components are, in different industries; the LWR industry isn’t close to handling nuclear waste the “best way”, they make too much money making nuclear waste and storing it.

    We would want to also take care of the remainder of the LWR waste, but getting the uranium is all that is needed for fueling the LFTR. (Also take out the transuranic elements, and store LWR waste for 400 years not 400,000 years. Then separate the short-halflife elements, and over 80% of the LWR waste only needs to be stored for 10 years.)

    I don’t know what you’re referring to by “not compatible with water”; I have seen several scientific reports showing the fuel salt doesn’t react with water, and “normal salt” NaCl from sea water is one of the possible MSR salts.

    Short term the fluoride salt contains the fuel and most of the fission products well; several scientists mention the actinides are strongly chemically bound to the fluoride salts. I don’t know if LFTRs would be better or worse than LWR if the fuel came into contact with sea water, but LFTR would be much less likely to have major problems than LWR (e.g. no loss of coolant accidents, no hydrogen explosions), and at least Navy-level LWR safety and operation procedures have had no problems, but fine, let’s keep LFTR away from commercial ships. (We can power ships with LFTR-produced gasoline or diesel, since high heat + CO2 + H20 = gasoline).

    Corrosion could be an issue if the chemical balance is incorrect. But we do know how to keep several of the candidate salts from corroding the metals that would be used. That’s not a “problem”, just part of proper operation of the reactor. (The corrosion problems noticed in the MSRE were solved before the experiment was ended. One of the corrosion “problems” was micrometers a year, the solution is “make the metal thick enough”.) Plus there are numerous modern materials that should be even better, but need to be tested.

  • Ulli
    October 4, 2012 - 3:11 pm | Permalink

    At the current state of development pyro-reprocessing highly radioactive waste is very expensive and not perfect. The process used for the EBR metal fuel also rather simple and somewhat similar to that planed for a MSR. The estimated cost are about $3000 per kg of heavy metal. You can do the math what it costs to process 10 t a day. There is certainly some improvement possible, but we would need a lot of it.
    Also separation is far from perfect: if 1 % of the thorium is going to waste every cycle (a value the Russians (more advance than the US in this field) hope to reach in the near future) roughly 30% of the thorium goes to waste every year when a 10 days cycle is used. With an inventory of some 60 t for 1 GW plant that is 18 t going to waste and about 1 t is used. That is about the same 5% fuel usage as claimed for the uranium cycle.

  • brendan
    October 14, 2012 - 12:31 am | Permalink

    Ulli,

    the EBR reprocessing you refer to is not even vaguely similar to the reprocessing planned for any MSR, making your first statement a simplistic fabrication. As your first statement is the assumption upon which the remainder of your argument rests, quite simply the argument makes no sense at all.

    As to the rather fantastic claim that 1% of the thorium would be lost in each reprocessing cycle, the thorium is not reprocessed at all in a 2 fluid MSR (the only design with fast paced processing cycle), making your claim an absolute fantasy. Thorium is only ever added to the system. Only 233Pa is extracted from the blanket & later added back following its decay to 233U.

    In a single fluid MSR, there is a choice to employ fuel cleaning, or not. In the DMSR concept, that cycle if employed would be on a cycle of longer than 10 years, making your estimate grossly over the top. The usual suggestion is a once only reprocessing with this type of converter reactor, reprocessing all the heavy metals to the next reactor cycle, with loss of 0.1% to waste.

  • Ulli
    October 26, 2012 - 5:26 pm | Permalink

    The EBR processing is similar in the way of using molten salts for reprocessing. Reprocessing by pure fluorine volatility (FREGATE from Russia + Techeceslovacia) gives similar, maybe slightly lower cost estimates. So hoping for much lower cost is possible, but for now this is wishful thinking. Currently there is not even a plan for working unit, so serious cost estimates are impossible, and we just don’t know how much ends up in the waste. Comparing with other pyroprocessing is about the best we can do for estimates of costs and performance. It’s not that I know that the MSR reprocessing will be so expensive, it is just that we can’t take for granted that is will be so much (e.g. a factor of 1000) cheaper than current technology. The estimate with 1% loss is to illustrate that a low performance reprocessing (still not so far from the current state of the art) will give a poor performance for the whole system. Even with only 0.1% loss and a 10 day cycle something like 2/3 of the thorium would end up in the wast. This is far from the often claimed 98% fuel usage.

    The fast 10 days (or similar) cycle is needed if one wants to effectively separate Pa in a single Fluid LFTR. The 1 fluid MSBR design did specify a 10 day cycle – its just that removal of the rare earth elements was assumed to be only partially effective. Without Pa removal one would either need a rather large fissile inventory (e.g. 3 times more) or some other improvements in neutron economy to archive breeding. The DMSR without reprocessing is such an example: large inventory, still rather far of from breeding and without recovery at the end also sends most of the thorium to waste.
    The French group also turned towards a fast spectrum MSR, and thus much less need for reprocessing – this is because they too have doubt on the feasibility of fast reprocessing
    (see xarchiv 0506004v1).

    A 2 Fluid design could work with relatively slow (e.g. 1 year) and simple reprocessing, but there are other difficulties (barrier and complicated plumbing) – so it was canceled for good reasons.

  • Grant
    November 21, 2013 - 2:35 pm | Permalink

    Looks like the biggest CON is that :-

    The private sector will not fully invest in this technology

    Mainly because it is being presented as a long term Investment (30 Years) & subject to .Gov restrictions that could effectively destroy any profit margins during this time / (they have not fully reaped the initially budgeted profits from fossil fuels yet).

    Does anyone agree?

    Can I ask people just to take a moment & try and imagine what a POST ENERGY SCARCITY Society would look like!!!!.

    Personally I would task/reward/encourage every University in the UK to produce a working Thorium Reactor model every year.

    Take this winner and start building the real thing in such a way as you can swap out the core for any better designs that follow.

    Personally I think Energy Security is too important to leave in the hands of the private sector, they will just end up promoting energy scarcity (increases profits) & holding us all to ransom. (O Wait, they already are)

  • N.S.Rajagopalan M.Sc Physics
    November 27, 2013 - 9:23 am | Permalink

    I wish that Thim based cars are brougt to use ae early as possible.I solicit cooperation of all atomic scientists,

  • Magwoodsman
    April 18, 2014 - 11:24 am | Permalink

    I’m no scientist but I’ve read a great deal about thorium reactors and have come to the conclusion that we have been appallingly betrayed by our politicians, the military, economists and a large section of the scientific community, who all seem to have vested interests in yesterday’s technologies. Given that our world is seriously in need of the kind of generating capacity that a thorium based reactor network could produce, the fact that we are not building these stations right now is one of today’s most heinous scandals.

  • Farook Shah
    September 28, 2014 - 7:28 pm | Permalink

    If LFTR and MSR are such a good idea why do not we see it in practice? Why are the “cons” shrouded in such a mystery? Why is corrosion still a problem despite +60 years when it was first recognized?

    • admin
      September 28, 2014 - 7:44 pm | Permalink

      The cons are not a mystery. There are simply many good things to say. The corrosion was solved when the nickel-hastalloy was developed. I have some cons mentioned.
      With regard to corrosion. Some of the lifetime use will be lower than other kinds of reactors but for example replacing the container every seven years is not too expensive and solves the problem.

      Why it is still not being used? That is related to several factors. The nuclear industry is heavily regulated. New types of reactors have a very expensive licensing process that arguably needs to change but that plus the fact that it is a drastic design change that would require new skills and new training for plant workers. If you want to read more about a recent company that is moving forward nicely is a company called Terrestrial Energy in Canada. Their chance of success is good because of Canada’s less rigid regulator the CNSC.

  • David Lyttle
    October 31, 2014 - 1:09 pm | Permalink

    I agree with Grant and the others who advocate building LFTRs. Pros and Cons? Look at the cons associated with conventional nuclear reactors… high operating pressure and temperature, massive size of containment structures, waste by products, potential for catastrophic systems failure, ad nauseam and they built them anyway!

    I say efforts should be made to get LFTRs up and running in every state so we can get real data and experience. Other wise we run the risk of talking the concept to death as greenhouse emissions rise along with sea levels… and I don’t know how to swim!

  • Ryan
    October 31, 2014 - 9:39 pm | Permalink

    I have researched some on the thorium msr and had some thoughts to modifications that may benefit everyone. First setting up a research reactor adjacent to an inferior lwr that is nearing the end of its life would be extremely beneficial in many ways, first the waste at the site could be used to fuel the msr to start and reach critical, second the heat exchanger should have a build in still or electrolysis tank for seperating deuterium and tritium since the water would be brought above the necesarry temperatures anyway, this still could produce heavy water for candu style reactors as a moderator, but also high voltage plus heavy water makes neutrons which would be beneficial to a beam driven thorium setup, also seperate tritium and use it for research into fusion or for other applications (currently priced at around $30,000 a Gram) this still would also purify sea water to fresh potable water, from water that had run through the lwr and remove any tritium caused by stray neutrons. Water scarcity in places like China are a real problem, lets make water and power systems interconnected therefore available to more people. The deuterium electrolysis isnt normally used due to the high power use, not a problem for a reactor station. The old lwr infrastructure would assist the fledgling msr until all the bugs and details are worked out, then decommision the old reactor and recycle old waste on site withought transport. There have been hypothesis that a dual fission/ fusion plant might be possible but thats a discussion for another date, but the name of the game is synergy, use the lwr flaws to the msrs advantage. If someone could integrate high efficiency Tesla turbines as the generators output could be maxed, alomg with gravity fed sea water pits to the heat exchange and heat pumps to move the distilled fresh water along water main pipes one could imagine the lwr complex evolving to a lwr, msr, industrial complex with other processes and factories added on as time goes on. If any of this sounds viable im glad to help anf im willing to move for any job offers :) RyanAtkins7786@gmail.com

  • Leave a Reply

    Your email address will not be published. Required fields are marked *

    You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>

  • Quick Facts: [Thorium Element 90 in periodic table] [Burns up fuel much more efficiently than traditional reactors] [leaves barely any waste behind] [3 x more abundant than uranium] [MSRs run at high temp in liquid molten mixture of fluoride - heat useful for purifying water] [looks like blue water] [no pressure needed] [much safer because of passive safety] [Less expensive to build because it is smaller and easier to build with no pressurized containment needed] [can run without water therefore good for dry and remote locations][molten salt is very stable]

    See This Book Reviewed Here!!!

    BOTH BOOKS ALSO IN PAPERBACK