Energy From Thorium Discussion Forum

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PostPosted: Feb 24, 2013 11:40 am 
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Lars wrote:
Kirk Sorensen wrote:
I highly doubt that an MSR would end up being a superior reactor for a military submarine, mostly due to space constraints and noise issues. For a civilian (or even military) surface vessel, on the other hand, an MSR might be a very attractive choice.

Why should pumping the fuel salt around generate more noise than pumping coolant water?


At lower power levels a submarine pwr uses natural circulation and no pumps at all.


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PostPosted: Feb 24, 2013 11:42 am 
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Joined: Jul 14, 2008 3:12 pm
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KitemanSA wrote:
Kirk Sorensen wrote:
KitemanSA wrote:
Aren't MHD pumps viable for molten salts?
No, insufficient electrical conductivity.
Really? Molten salt? aluminum smelting? Hmm...


This was discussed previously. Yes, the thermal conductivity is sufficient for an electrolyte... but way too low for electromagnetic pumping. You could try, and get some pushing; but it'd be almost incidental.

Even sodium, with its high electrical conductivity, has a net pump efficiency of <60% in large pump units. With molten salt, you'd be getting well under 1% pumping efficiency. Basically this wouldn't be a pump... it would be a heater with some self-pushing. :lol:


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PostPosted: Feb 24, 2013 12:56 pm 
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Joined: Jul 28, 2008 10:44 pm
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Marcus wrote:
Lars wrote:
Kirk Sorensen wrote:
I highly doubt that an MSR would end up being a superior reactor for a military submarine, mostly due to space constraints and noise issues. For a civilian (or even military) surface vessel, on the other hand, an MSR might be a very attractive choice.

Why should pumping the fuel salt around generate more noise than pumping coolant water?


At lower power levels a submarine pwr uses natural circulation and no pumps at all.

Is there a reason the same wouldn't apply to a molten salt coolant?


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PostPosted: Feb 24, 2013 6:04 pm 
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Molten salt reactors are much more restricted in their coolant volume. It means more fissile. Natural circulation requires a lot of coolant volume per kWe, so high fissile cost per kWe.

Perhaps with a naval reactor you care so little about that, that it is feasible. But it has to fit in a tight space and molten salt is just never going to be as good as water in terms of natural circulation capability (just look up heat transfer figure of merits for molten salt and water in natural circulation).


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PostPosted: Mar 02, 2013 1:31 am 
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Joined: Feb 05, 2013 5:24 am
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But, the delta T also factors in to natural circulation and molten salts are capable of much higher delta T's across the "core" than water. Barring materials issues and reactivity issues.

Sounds like Hastelloy N WOULD be a significant materials problem based on the material specs. & reading in the safety thread.


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