Liquid Salt Nuclear Reactors

CasualBystander

CasualBystander

Celestial
https://www.nextbigfuture.com/2017/...lt-reactors-starting-with-2021-prototype.html

https://www.nextbigfuture.com/2017/...reactor-will-be-cheaper-than-natural-gas.html

A Thorium-Salt Reactor Has Fired Up for the First Time in Four Decades

Just a thread for Molten Salt reactor news.

A pre-manufactured molten salt reactor looks to be the future of energy production in the third world.

Given that liquid salt reactors are starting to be fired up again, look to see a reactor deployed in the next 5 years.

A liquid salt reactor is superior to renewable energy from any angle you look at it.
 
3FEL9

3FEL9

Islander
I did some reading on the topic, a few months ago.. There was a U.S prototype reactor in the 60-70 ties running experiments
and producing lots of hot air ( no kiddin ). It worked perfectly as designed, but was killed by the top gov.

FLiBe - Wikipedia


Using the right salts makes them inherently safe.
 
nivek

nivek

As Above So Below
I didn't know about this technology, very ingenious concept, should it not be used more so that it is?...
 
CasualBystander

CasualBystander

Celestial
nivek said:
I didn't know about this technology, very ingenious concept, should it not be used more so that it is?...
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I've talked about this before on the UFO pages and you just didn't realize it.

The Oak Ridge Molten-Salt Reactor Experiment (MSRE) that they refer to was intended as an aircraft reactor.

It got shutdown when one of Rickover's toadies was appointed to the DOE predecessor, because as a Naval Nuke man Rickover wanted all commercial reactors to be Navy derived (water based) and didn't give a damn about other considerations or the Air Force.

Water is a dumb thing to use as a reactor medium. A radioactive core should be operated at standard atmospheric pressure or less, not at pressures exceeding that of scuba tanks. That's just nuts.

Molten Salt Reactor (MSR). Operates above the melting point of various Fluorine and Uranium/Thorium Salts (other things could be used but Fluorine salts meet the requirements the best). Very high temperature. Can use the Brayton cycle and be 50% more efficient than PWRs (Pressurized water reactor) which use the Rankine cycle. Reactor design is basically a large soup kettle to hold the liquid salt/uranium soup. Failsafe in case of runaway is a larger soup kettle below the first one. The reactant has to be in a roughly square shape to be critical and if dumped into a larger container, ceases to be critical.

There isn't much chance of runaway period, since overheating increases the volume of the reactant that makes it less critical.

LFTR (Liquid Fluoride Thorium Reactor) is a molten salt reactor.
 
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3FEL9

3FEL9

Islander
I like the idea with the freeze plug. If the plant goes blackout, a small fan stops blowing air onto a pipe section, the plug melts
and lets the salt dump down into the underground drain tank..

Thats ingenious !
 
CasualBystander

CasualBystander

Celestial
The liquid salt reactor will do just about anything to keep the volume constant since the rate of reaction depends on the nuclear cross-section.

This makes it a little dangerous for shipboard use. The coolant is at about 700C (973K). A water leak onto the core disassociates (explosion hazard) and an overcooled core will produce near supercritical amounts of heat to keep itself warm.

The sub could be steam baked by a water leak into the core.

The MSR isn't as bad as liquid sodium fast reactor would be, but that is a low target.

The good news is you can clean up pipe leaks with a shovel.
 
3FEL9

3FEL9

Islander
CasualBystander said:
The liquid salt reactor will do just about anything to keep the volume constant since the rate of reaction depends on the nuclear cross-section.
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How is reactor power controlled ? Is it done by regulating the volume or mass reacting in the "core", or massflow through the system's primary loop ?
 
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CasualBystander

CasualBystander

Celestial
3FEL9 said:
Why ? :)
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The neutron cross section (probability of a reaction) increases with reactant density.

So a thermally expanding distributed core produces less heat the warmer (and larger) it gets, and more heat the cooler (and smaller) it gets.

Will see if I can find LiF and BeF2 coefficient of expansion data for the liquid. (LiF is actually used for optics as a solid).

But if memory serves once a reactor gets beyond critical it runs away pretty quickly..

3FEL9 said:
No change from HFO then, lol
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Don't know what the hell HFO is.

Finally, a correction:
The Air Nuclear Propulsion program (1954-1961) and the MSRE (1965 to 1969) were two separate programs led by Alvin M. Weinberg at Oak Ridge that operated MSRs.

Until recently this was the only actual experience running an MSR.
 
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3FEL9

3FEL9

Islander
CasualBystander said:
It took a while but I finally get it.

Some days I'm a little slow, and some days I'm outright impaired.
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No worries. I was about to ask you what MSR stands for :laugh8::laugh8:

You know about the russians operate MSR ?, not the kind discussed here thoo.. sodium or was it natrium salts alloys ?
 
CasualBystander

CasualBystander

Celestial
3FEL9 said:
How is reactor power controlled ? Is it done by regulating the volume or mass reacting in the "core", or massflow through the system's primary loop ?
Click to expand...

This is like asking "what does a house look like".

At least one of the current approaches is pumped reactant. They would just increase pump velocity to increase heat transfer and the small increase in core density from slight cooling would compensate for the increased heat transfer.

But they did have graphite as a moderator in the MSRE so there would be a couple of ways to tune reactor output to match output requirements. Have to look at what the logic of moderator use is in an MSRE. The ΔT = NOT ΔE (where E is energy output) means I would have to research it or think it through.

Haven't seen any reference to pumping reactant to an auxiliary pool (direct volume control). But once reactant cools to 670K+/- 30K it hardens. The BeF2 is used to bring the LiF 1,118 K+ melting point down to about 670K. But it wouldn't be that hard to freeze the reactor solid.
 
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CasualBystander

CasualBystander

Celestial
3FEL9 said:
No worries. I was about to ask you what MSR stands for :laugh8::laugh8:

You know about the russians operate MSR ?, not the kind discussed here thoo.. sodium or was it natrium salts alloys ?
Click to expand...

Liquid Metal fast reactors are different. Solid core, metal coolant. Generally self-breeding.

They use something other than sodium in their nuclear subs. Sodium in a nuclear sub is one leak away from detonation.

A liquid metal with low vapor pressure is the best choice. Mercury turns out to be very problematic because of the high vapor pressure among other things.
 
CasualBystander

CasualBystander

Celestial
CasualBystander said:
Liquid Metal fast reactors are different. Solid core, metal coolant. Generally self-breeding.

They use something other than sodium in their nuclear subs. Sodium in a nuclear sub is one leak away from detonation.

A liquid metal with low vapor pressure is the best choice. Mercury turns out to be very problematic because of the high vapor pressure among other things.
Click to expand...

I saw a reference to the Soviets using metal fast reactors in their subs but Wiki thinks all their current sub reactors are pressurized water.

Ah, the Alfa subs used a BM-40A Liquid Metal Lead-Bismuth Fast reactor.
 
3FEL9

3FEL9

Islander
CasualBystander said:
Liquid Metal fast reactors are different. Solid core, metal coolant. Generally self-breeding.

They use something other than sodium in their nuclear subs. Sodium in a nuclear sub is one leak away from detonation.

A liquid metal with low vapor pressure is the best choice. Mercury turns out to be very problematic because of the high vapor pressure among other things.
Click to expand...

I was thinking of this type. As you say not a MSR.. Sorry for the confusion. My bad

BN-800 reactor - Wikipedia
 
CasualBystander

CasualBystander

Celestial
3FEL9 said:
I was thinking of this type. As you say not a MSR.. Sorry for the confusion. My bad

BN-800 reactor - Wikipedia
Click to expand...
Well...

All the metal or halide reactors (as far as I can tell) operate at close to atmospheric pressure. All that has to be constained is the vapor pressure which is a few PSI.

This is different that the water cooled reactors which are large bombs operating at 2500 PSI or more.

They are a scuba tank larger than your living room (probably several times as large) with 6-8 inch steel walls.
 
CasualBystander

CasualBystander

Celestial
3FEL9 said:
Kirk Sorensen seems to be the MSR guru worth listen to

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Water reactors never made sense.

Biolabs run at negative pressure to keep the critters from getting out.

Deadly radiation??? We'll put it under scuba tank pressures. That will keep it in!

With that reasoning we were lucky to make it out of the caves alive.

Plus the PWR fuel elements are an insulator. Trying to extract heat from inside an insulator?

If you look at PWR design you go, "this might make sense at some deranged level in a sub, but it should not be allowed to crawl onto land."
 
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