LFTR

[Nich]

So it looks like the video is 2 years old.  All I can think is if this is so good is it snake oil like cold fusion?  Is it actually real and has anyone made any progress with it.  I am probably going to have nightmares tonight about the 00.5% usage rate tonight :/

 

 

Edited April 10, 2016 by Nich

[Phoenix1583]

Liquid salt reactors have their place. It's not really snake oil, it's just not quite as amazing as they're making it out to be. The thorium is really just a fertile material that's converted into Uranium (233 actually, an odd isotope) which is then used. Outside of that common misconception, liquid salt reactors are not very well suited to be scaled or modular. They would, essentially, be a small units which are self contained and have everything from the energy generation equipment to the recycling equipment all built into a single unit. As such, you would actually need arrays of these systems to offset the power output of something like a PWR or LWR. 

They're absolutely on track with saying that Thorium is a useful material that we're ignoring though. I couldn't agree more. However, we should also be looking at things like fast breeders and pebble-bed reactors in general.

Also, for the record, it's not snake oil because we've actually made experimental systems. The main reason we didn't go further with it was because the powers that be at the time found that other designs were more useful for producing weapons grade fissile materials. 

https://www.ornl.gov/news/msres-50th

Edited April 10, 2016 by Phoenix1583

[cantab]

So you want your nuclear reactor using a 500 degree C molten highly radioactive salt, and it's going to use graphite as the moderator with all the known problems that has. Doesn't seem like the best idea to me.

[MalfunctionM1Ke]

I think it is very intersting stuff aswell, so I got some Videos highlighted:

 

[Tex]

Moved to Science & Spaceflight because this particular flavor of Science isn't KSP-themed.

[Streetwind]

As far as molten salt reactors go, I'm intrigued by Transatomic Power. It's a startup company that focuses on building reactors that can consume an extremely broad variety of fuels - thorium, uranium, or even nuclear waste from other reactors. They're still pretty new, so they haven't built anything yet, but they've gotten serious research grants and and have been putting out whitepapers that make a refreshing amount of sense in a field that's too often steeped in half-truths and conspiracy theories (I mean, just look at the title of the video linked in the OP. *groan*).

[peadar1987]

Molten Salt reactors are a decent concept with a lot going for them. The man complicating factor is probably the molten salt part. It's the sort of stuff that gives metallurgists nightmares.

Unfortunately, a good concept has been jumped on by the "it's a conspiracy" brigade, which tends to rob anything of any credibility.

[p1t1o]

13 minutes ago, peadar1987 said:

Molten Salt reactors are a decent concept with a lot going for them. The man complicating factor is probably the molten salt part. It's the sort of stuff that gives metallurgists nightmares.

Unfortunately, a good concept has been jumped on by the "it's a conspiracy" brigade, which tends to rob anything of any credibility.

Don't they use a molten salt to manufacture aluminium? Could be a more mature field (molten salt handling) than expected - it can't be worse than reactors running with liquid sodium as a coolant... 0_o

Didn't I also read somewhere that molten salt as a coolant has the advantage (apart from being a very high temperature, giving good thermodynamic characteristics) that it solidifies quickly if there is a leak, reducing the chance of catastrophic release of radioactivity?

Anyway, it seems research and development in the area is alive and well, so there's no real need to worry that it is some kind of lost panacea.

It does also seem though that the nuclear weapons proliferation issue is likely a big deal in whether or not these things are built, which quite frankly I can understand.

[todofwar]

22 minutes ago, p1t1o said:

It does also seem though that the nuclear weapons proliferation issue is likely a big deal in whether or not these things are built, which quite frankly I can understand.

I thought one of the reasons they choose against LFTR in the olden days was it wasn't good for generating material for bombs. Could be wrong about that though. 

[Kryten]

Just now, todofwar said:

I thought one of the reasons they choose against LFTR in the olden days was it wasn't good for generating material for bombs. Could be wrong about that though. 

The U-232 which is bred out of the thorium is usable as bomb material, the US (when they were experimenting with alternate fuel cycles in the 60s) and India (currently the most invested in thorium cycle) have both tested small U-232 bombs.

[todofwar]

3 minutes ago, Kryten said:

The U-232 which is bred out of the thorium is usable as bomb material, the US (when they were experimenting with alternate fuel cycles in the 60s) and India (currently the most invested in thorium cycle) have both tested small U-232 bombs.

I might be thinking the U233 (5?) That they normally use in bombs is also usable in plants, so once you have a centrifuge to enrich for peaceful means you can enrich for bombs too. One of the issues with Iran I believe (not to go political), they might be enriching for peaceful means but just enrich a bit more and you have weapons grade uranium. But I have very little academic knowledge of nuclear technology so this is all from the internet.

[Kryten]

 You can't just enrich reactor-grade 235 'a bit more' to get weapons-grade, you need different technology to get the concentration that high.

[Bill Phil]

On April 10, 2016 at 7:05 AM, cantab said:

So you want your nuclear reactor using a 500 degree C molten highly radioactive salt, and it's going to use graphite as the moderator with all the known problems that has. Doesn't seem like the best idea to me.

Graphite has been a neutron moderator for quite some time. All it has to do is slow the neutrons down.

[peadar1987]

57 minutes ago, p1t1o said:

Don't they use a molten salt to manufacture aluminium? Could be a more mature field (molten salt handling) than expected - it can't be worse than reactors running with liquid sodium as a coolant... 0_o

Didn't I also read somewhere that molten salt as a coolant has the advantage (apart from being a very high temperature, giving good thermodynamic characteristics) that it solidifies quickly if there is a leak, reducing the chance of catastrophic release of radioactivity?

Anyway, it seems research and development in the area is alive and well, so there's no real need to worry that it is some kind of lost panacea.

It does also seem though that the nuclear weapons proliferation issue is likely a big deal in whether or not these things are built, which quite frankly I can understand.

Well the molten salts react more with metals than a liquid metal would. And the plumbing for a reactor is a lot more complex than that used for purification of aluminium, which is essentially a bath.

It's not a deal-breaker by any means, but making a power plant that is going to last for 20+ years while in constant contact with molten salt is a non-trivial material science problem

[kunok]

6 hours ago, p1t1o said:

Don't they use a molten salt to manufacture aluminium? Could be a more mature field (molten salt handling) than expected

If you ever been in a factory of that you would know that you never want a radioactive molten salt, and that only a pool, not a complex system. Yes it will be doable, but I don't want to be close to it by far. And I have serious questions about the materials needed like @peadar1987

I don't feel we need another fission tech for nuclear power plants, we should stop making that. The only place I feel there is sense to it is in big boats, were energy density is important, and has enough place to put a reactor inside.

[Gallopingcamel]

This is my first post here.  I am a physicist/engineer who helped build the world's brightest gamma ray source.  While I am a trained "Radiation Worker" my field is electro-optics rather than nuclear physics so my opinions on nuclear reactors are those of an "Informed Amateur".

I like MSRs (Molten Salt Reactors) in general and LFTRs (Liquid Fluoride Thorium Reactors) in particular.  Here is an update on that video you posted:

One of the engineering problems with LFTRs is finding materials that can withstand high temperatures and high radiation flux.  Hastelloy-N is the best material known for this purpose but it does not have the needed life expectancy in a high radiation environment.  This video explains how graphite can be used as a moderator and as a means of protecting the Hastelloy from radiation damage.

 

While I am a fan of the LFTR the concept is "Vaporware" until someone builds one.  In that respect it is no better than Andrea Rossi's E-Cat.

 

I am highly sceptical of LENR (Cold Fusion?) in general and scam artist Andrea Rossi in particular.  Even so there are Nobel prize winners who take Rossi seriously:

While I respect Brian Josephson as a physicist and a fellow Welshman I am not convinced by his arguments.

[Gallopingcamel]

I may be pushing my luck here. 

On Monday I emulated Dorothy and got "Behind the Curtain" at the Kennedy Space Center.  I visited the control room in Hangar AE where the managers oversee most of the launches.  This stuff is beyond cool!

Recently Stephen Hawking has been talking about interstellar space travel using micro robots.  Let's hope we will do much better:

https://diggingintheclay.wordpress.com/2013/06/17/bussard-revisited/

[NuclearNut]

On 4/10/2016 at 5:05 AM, cantab said:

So you want your nuclear reactor using a 500 degree C molten highly radioactive salt, and it's going to use graphite as the moderator with all the known problems that has. Doesn't seem like the best idea to me.

Actually it is a great idea.  The salt is the fuel as well as the coolant, when it expands due to heating it ultimately becomes sub critical, giving it a strong negative temperature coefficient of reactivity, negating the problems with graphite as a moderator (graphite actually makes a great moderator).  The biggest problem is not the hot salt, that is actually good, but rather the fact that this will need onsite reprocessing, so each unit will have to be larger than micro, at least 200 MW to be reasonably profitable.

[RainDreamer]

So how practical is this for space use? Seems like it is rather useful for satellites.

[peadar1987]

@Gallopingcamel, it's far better than the E-cat, because it's not an obvious scam from a convicted fraudster!

 

[Gallopingcamel]

@cantab

My degree is M.A. (Cantab).  I studied at Pembroke college and was able to walk to work at the Cavendish laboratory.  The Cavendish has relocated but the plaque showing where J.J Thomson discovered the electron in 1899 is still there.

[Gallopingcamel]

@RainDreamer,

"So how practical is this for space use?"

The first MSR was intended to power an aeroplane so it had to be small and light.  Sorensen worked at NASA designing reactors for use in space or on the surface of the Moon.   He picked the LFTR and IMHO this still looks like the best choice when it comes to MW/kg.

Can you imagine what it would take to build a BWR on the Moon?  In contrast a 100 MWe LFTR would weigh less than 20 tonnes.

Edited April 23, 2016 by Gallopingcamel

[Gallopingcamel]

@todofwar

"I thought one of the reasons they choose against LFTR in the olden days was it wasn't good for generating material for bombs. Could be wrong about that though."

Sorensen says that the LFTR will have a positive effect on "Proliferation".  He points out that the plutonium produced by LFTRs is mostly Pu238 which is not fissile and is the most valuable element on earth (~$8,000,000 per kilogram).

Sorensen explains that LFTRs breed fissile U233 which can easily be extracted from the reactor salts by bubbling Fluorine through the FLIBE.  This U233 would be a superb material for making bombs but for the fact that it is contaminated with U232 which emits energetic gamma rays that are easy to detect.  These gamma rays destroy sensitive electronics based on semiconductors.

What Sorensen does not mention is that one can get weapons grade U233 from LFTRs using (inexpensive) chemical separation.  LFTRs are superb reactors for creating nuclear bombs.  LFTRs create Protoactinium 233 which can be chemically separated from the FLIBE.  Pa233 converts to U233 with a half life of 27 days.  

While I like Sorensen, I would like him much more if he did not try to sweep this problem under the rug.