Phys.org reports on Transatomic Power's ambitions to build a better reactor.
"Transatomic Power has focused on an innovative molten salt reactor, which, they said, can safely burn nuclear waste to deliver affordable clean energy. Molten salt reactors are not a new discovery.
The main technical change [Transatomic Power] make is to change the moderator and fuel salt used in previous molten salt reactors to a zirconium hydride moderator, with a LiF-based fuel salt. During operation the fuel in the salt is primarily uranium. Together, these components generate a neutron spectrum that allows the reactor to run using fresh uranium fuel with enrichment levels as low as 1.8% U-235, or using the entire actinide component of spent nuclear fuel (SNF). Previous molten salt reactors such as the Oak Ridge National Laboratory (ORNL) Molten Salt Reactor Experiment (MSRE) relied on high-enriched uranium, with 33% U-235. Enrichments that high would raise proliferation concerns if used in commercial nuclear power plants."
(Score: 2) by SlimmPickens on Sunday June 22 2014, @09:45PM
What is a LIF-based fuel salt? It presumably doesn't share the corrosive or explosive properties of molten sodium chloride.
(Score: 2, Informative) by kstox on Sunday June 22 2014, @10:03PM
It is actually LiF, Lithium Floride.
(Score: 2) by HiThere on Monday June 23 2014, @06:36PM
Molten sodium chloride isn't explosive, just hot and corrosive. Anything that hot can cause a steam explosion. But holding a lot of heat is necessary for the application, so the potential for steam explosions in case of leak will always be there.
(I think you're conflating molten sodium chloride and molten sodium, but even molten sodium isn't explosive in and of itself. Only after a leak.)
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(Score: 4, Informative) by mojo chan on Sunday June 22 2014, @09:55PM
The problem isn't proliferation, it's economic. Every similar research reactor built so far has had major issues. India has been trying to build a commercial one for the better part of 40 years. What they are asking is for someone to give them tens of billions of dollars in the hope of fixing some major problems and getting it all signed off by the regulator at some indeterminate point in the future. Meanwhile renewables and clean energy are surging ahead with massive growth.
The massive subsidies that got nuclear off the ground are not there any more, so we are not likely to see any more than incremental improvements from now on.
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(Score: 3, Informative) by frojack on Sunday June 22 2014, @10:21PM
Well it might happen if for no other reason then the amount of spent fuel we are storing keeps climbing.
These reactors have the ability to use that "spent fuel" that is stacking up in every reactor in the country, as well as elsewhere. Our inability to agree on a safe affordable disposal method may end up being a godsend if this process can be perfected.
The key here is that "Transatomic's reactor would cost half as much per gigawatt of electricity as conventional reactors". That alone changes the cost equation, it it is true.
The OECD Nuclear Energy Agency (NEA) took a halfhearted attempt at costing estimates [oecd-nea.org] of such reactors last year. While nothing they said backs up the Half as Much, claim, the paper pretty much serves as a good refresher on this subject.
No, you are mistaken. I've always had this sig.
(Score: 2) by Aiwendil on Sunday June 22 2014, @10:01PM
So, instead of using the same moderator as found in RBMK and MAGNOX (graphite [also suggested for LFTR]) they decided to use the moderator used in TOPAZ and TRIGA? :)
And isn't LiF pretty much the standard salt suggested for all MSR these days?
Regardless it is nice to see more ideas entering the playfield to keep the interest active.
Anyone that works/studies in/near the field that can explain the advantages and disadvantages with this moderator over graphite? (preferably with pointers to where one can read up a bit more about moderators and their math)
(Score: 2, Informative) by Anonymous Coward on Monday June 23 2014, @02:47AM
http://transatomicpower.com/white_papers/TAP_White_Paper.pdf [transatomicpower.com]
That's the most detailed information published so far on their design. Gives a good description of what changes they've made and why they matter.
(Score: 5, Interesting) by zeigerpuppy on Monday June 23 2014, @06:14AM
Last time I looked into the molten salt reactor concept, there still appeared some rather difficult technical issues.
The proponents of these reactors often fail to mention that while the core of these reactors is significantly safer than solid fuel reactors, there are dangers introduced by the design because chemical separation of the reaction by-products needs to happen in a side-stream unit.
Fluorides are very reactive and corrosive salts that need to have the neutron poisons (that absorb neutrons and slow the nuclear reaction) removed from the functioning reactor (usually the aim is to do this continuously). These poisons include Xe-125 as well as uranium and transuranic isotopes. The chemical processing is the hardest part of these reactors and has only been tested in short run experiments.
These technologies may have some application in waste management but overall, concentrated solar is a better investment and lacks the significant problems of radiological pollution. While nuclear power is feasible, it now looks overly complicated, expensive and risky. We have a great big fusion reactor in the sky that can provide us with plenty of energy with much simpler systems.
(Score: 5, Insightful) by Covalent on Monday June 23 2014, @07:05AM
Agreed. I'm all for trying to get more use out of nuclear fuels (and potentially using nuclear waste). This is a noble research goal. But you've potentially "solved" this problem by introducing another one - molten corrosive ionic neutron absorber (aka salt).
Chernobyl proved what can go badly when people are not properly trained and stupidity overcomes good judgement...in a standard nuclear reactor. Water plus hot metal --> H2 + O2 which, given a little time to build up, blows your plant to smithereens and contaminates vast swaths of Eastern Europe.
Fukushima proved what can happen mother nature reminds you how small you really are...in a standard nuclear reactor. Nuclear fuel plus a non-functional cooling system --> molten floor and massive fuel leak (also happened at Chernobyl, but the bigger problem there was the explosion).
But in both of these cases, you don't have 800C liquid death exploding out of pipes and starting nearly everything it touches on fire. Now, of course, the liquid death (aka salt) is contained in well-designed pipes that are perfectly safe, etc. etc. etc., but then human stupidity and mother nature have a tendency of blowing stuff up and / or dropping a tornado, small asteroid, or epic tsunami on your plant. In any of those cases, you can have a serious problem on your hand which, of course, can lead to problems with the nuclear reactor, and SERIOUS problems on your hands.
OK...enough doom and gloom. I'm on vacation in Portland, OR this week and this city has solar powered trash cans all around the city that periodically compact the garbage inside of them. Why? So that the trucks only have to pick up 1/6th as often as they used to. This works beautifully in sunny, arid, equatorial...oh, wait, no Portland is one of the rainiest, cloudiest places around. And it STILL works beautifully.
It is solutions like this that will chisel away at the massive amount of energy that we use. Every watt saved is probably 2+ watts that don't have to be generated (storage and transmission losses).
You can't rationally argue somebody out of a position they didn't rationally get into.
(Score: 3, Interesting) by Immerman on Monday June 23 2014, @02:04PM
>you don't have 800C liquid death exploding out of pipes and starting nearly everything it touches on fire
You wouldn't have that in a liquid salt reactor either. Unlike the water in a traditional reactor, the salts are at low pressure so they don't "explode out of the pipes". At best they leak or, if a pipe fails completely, pour quickly. And all the pipes carrying salt are within the reactor containment chamber - that's your hot radioactive fuel after all. And there shouldn't be anything flammable in that chamber - the chamber where, it should be mentioned, the last-resort safeguard plan often calls for basically dumping all those hot fuel salts out onto the floor to spread it out enough to quickly and safely stop the reaction. It's basically a high-temperature concrete vault.
(Score: 2) by HiThere on Monday June 23 2014, @06:50PM
Sorry, but though they are low pressure they are high temperature. That means when they touch water you get a steam explosion. (Not as dramatic and dangerous as a core fire in the graphite, but still pretty annoying.)
P.S.: Why was Chernobyl brought into this? This stuff isn't much similar to a graphite modulator. Also I think that the GP is conflating LiF with molten sodium. Now that *was* dangerous if you got a leak, which kept happening. If I remember my chemistry, LiF should be pretty unreactive chemically. Rather like salt. But you've still got a high temperature liquid leaking, which is very nasty, even though it is at low pressure, and if water leaks the other way it doesn't STAY low pressure. (Well, actually it does, because the steam explosion rips a bigger hole in the pipes, but...)
I suppose you could use a different working fluid than water in the heat exchanger, but water has lots of advantages.
P.P.S.: I'm not a nuclear plant designer nor a chemical engineer. This is all based of college chemistry classes of a few decades ago. So don't take it too seriously. But it should be in the ballpark of being correct.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 2) by zeigerpuppy on Tuesday June 24 2014, @03:20AM
Of course it depends on the design, but the chemical separation in this type of reactor is often outside the primary containment.
It's an open system that needs to have extraction of neutron poisons or else the reaction stops.
I do agree that molten salt reactors have some advantages (negative temperature coefficient being an important one). But it's essential not to get rose coloured glasses on about them. They are still working with some truly nasty stuff, a soup of hot, corrosive and radioactive transuranics, fission byproducts, metals in solution and a carrier medium which will happily eat through steel unless properly managed.
Nuclear reactors have a habit of failing in unexpected ways.
The basic premise I return to is a proper understanding of hazard. We often only hear about one coefficient in the equation, risk.
Hazard = risk x impact of event.
The impact of a nuclear accident persists for thousands of years and effects whole biosystems, even beyond human caualties or long term cancer rates. So even if the risk is very small, the hazard can still be quite high.
This is one reason why nuclear power requires such great subsidies, insurance companies know a lot about hazard and will not insure these reactors, the risk falls to government.
I once heard it described that the power generation part of nuclear was the sexy part and no one really wanted to focus on the other end, decommissioning and waste management. I would happily support a nuclear industry that showed the maturity to deal with its own waste and put safety first. However, this does not appear to be the case. An industry that continues to run flawed reactor designs (GE Mark 1) beyond their designed lifetime and is plagued by mismanagement compounded by light touch oversight and financial woe is not the model of who should be managing the most toxic substances known to man.
The first task of the nuclear industry is to vitrify or stabilise the thousands of tonnes of waste in exposed fuel pools and dry cask storage. The reality is that this will be a massive cost to the industry.
If molten salt reactors can be part of this process, great, but the future lies with energy sources that do not involve complex material flows, excess hazards to the environment or labyrinthine management systems to keep running.