Molten Salt Reactor on a Pancake-Graphite Core Structure

Threads relating to the design of liquid-fluoride reactors.
Torres
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Joined: Dec 13, 2011 9:57 pm

Molten Salt Reactor on a Pancake-Graphite Core Structure

Post by Torres » Feb 11, 2014 10:55 pm

I have an idea for a graphite core in where the fuel (40UF4-60LiF) and coolant (63LiF-30.5BeF2-6.5ThF4) runs in parallel channels through a machined graphite core.

Metalic gaskets can be developed to joint by continuous compression force the different stages of the reactor structure (core, reflectors, absorbers, manifold and thermal isolator layers) in a pancake structure.

Small quantities of fuel are continuously cycled to remove gas and moble metals.

Protactinium is separated from coolant.

What could be the limiting factors on this concept?

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Gilliam
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Location: Amsterdam, the Netherlands

Re: Molten Salt Reactor on a Pancake-Graphite Core Structure

Post by Gilliam » Feb 12, 2014 7:16 am

What could be the limiting factors on this concept?
Your wallet, mainly.

fab
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Joined: Oct 28, 2013 12:24 am

Re: Molten Salt Reactor on a Pancake-Graphite Core Structure

Post by fab » Feb 12, 2014 12:06 pm

I am not an expert but perhaps you may have challenges with 2 things :

- avoiding positive void with your coolant salt
- transfering heat from the fuel salt to your coolant salt (but with tube within tube or other close configuration it may be easy but you need a barrier which resists to the neutron flux and doesn't eat too much neutrons)

Lars
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Joined: Jul 28, 2008 10:44 pm

Re: Molten Salt Reactor on a Pancake-Graphite Core Structure

Post by Lars » Feb 12, 2014 12:39 pm

This is pretty close to ORNL's initial breeder design. They found the challenge of the plumbing and sealing it as the graphite changes dimensions from neutron flux to be too hard. They shifted to a single fluid reactor with very impressive chemical processing plans to achieve much of the same goals.

Torres
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Joined: Dec 13, 2011 9:57 pm

Re: Molten Salt Reactor on a Pancake-Graphite Core Structure

Post by Torres » Feb 12, 2014 8:28 pm

It looks that the heat transfer of the core and the plumbing problem can be big issues on this concept.

The reason for the monolitic core structure design, with metal gaskets and preloaded are for three reasons, the first is to address the issue of the graphite change of dimensions with the neutron flux with a constant preload, the second is to investigate if the stressed graphite change its stucture to a metastable diamond configuration with time and thus providing a more sound elemental cubic structure, and third is that the disassembly of the reactor can be performed in an automated way. This concept has to be proven experimentally.
This is a reference about graphite:
https://web.up.ac.za/sitefiles/file/44/ ... acture.pdf

Somebody know where to find a reference literature for how much power per liter of fuel a molten salt reactor produce?

Included are two netron velocity spectrum graphs showing the fuel and coolant neutronic characteristics. It looks like an excellent neutron economy can be obtained from this reactor configuration.
Attachments
N Graph FisionU235-Li7-F-U238-U235 II.jpg
A fraction of the neutrons will be leaked out of the fuel before being absorbed by the fuel.
N Graph C-Li-F-Th II.jpg
The resonance spectrum of Thorium can be used to maximise neutron absorption.

Torres
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Joined: Dec 13, 2011 9:57 pm

Re: Molten Salt Reactor on a Pancake-Graphite Core Structure

Post by Torres » Feb 14, 2014 7:16 pm

There is a positive reactivity isuue on this concept. The concept reactor will rely on emergency stop bars that fall into the reactor core by gravity in case of power loss.

Torres
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Joined: Dec 13, 2011 9:57 pm

Re: Molten Salt Reactor on a Pancake-Graphite Core Structure

Post by Torres » May 20, 2014 7:18 am

Related to graphite propierties there is a good document to read about it:
http://zb0035.zb.kfa-juelich.de/record/ ... 3_Haag.pdf
This document relates the effect of isotropy with irradiation stability and crack propagation.
Some authors suggest that high temperature conditions helps to release stresses produced by void on graphite
It will be interesting how a beta type isotropic graphite behaves into a continuously loaded and high temperature conditions under neutron irradiation.

Torres
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Joined: Dec 13, 2011 9:57 pm

Re: Molten Salt Reactor on a Pancake-Graphite Core Structure

Post by Torres » May 30, 2014 4:09 pm

I find this document on the internet related to propierties of graphite:
http://web.ornl.gov/sci/physical_scienc ... _Young.pdf

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