RE: Fast moves for nuclear development in Siberia

Sun, 05 Apr 2015 11:10:05 -0700 

 

 

From: [email protected] 
[mailto:[email protected]] On Behalf Of John Clark
Sent: Sunday, April 05, 2015 9:55 AM
To: [email protected]
Subject: Re: Fast moves for nuclear development in Siberia

 

On Sat, Apr 4, 2015  'Chris de Morsella' via Everything List 
<[email protected]> wrote:>>  

> Also, and this is a major point in its favor LFTR reactor types would be walk 
> away safe. Because the U233 fuel plus fertile thorium is solution in the 
> fluoride salt coolant a simple and effective failure plug could be designed 
> in at the low point of the inner core circulating design. If the reactor ever 
> started overheating the plug would be made of a material with a substantially 
> lower melting point than the vessel. In other words it would fail first; 
> guaranteed. 

And that's not the only inherent safety feature, because the fuel is a liquid, 
Thorium dissolved in un-corrosive molten Fluoride salt, if things get too hot 
the liquid expands and the fuel gets less dense and so the reaction slows down. 
The operators wouldn't have to do anything, it's just physics. A LFTR is 
walkaway safe.

Yes, that as well. The liquid nature of the fuel/fertile/salt mix of LFTR is 
superior in this dimension as well vis vis systems that enclose the fuel in 
rod-shaped encasings and in which the coolant is separate. Being walk-away-safe 
is a critical advantage over other proposed fast breeder reactors that instead 
would depend on critical active safety features that if they should fail would 
lead to catastrophic failure modes.

Also, unlike other proposed high temperature coolants (heat transfer fluids) 
such as sodium, the fluoride slats used in the LFTR design do not react with 
air or water (sodium is very reactive by comparison). Thus, in the advent of a 
catastrophic failure that leads to the LFTR circulating fluid becoming exposed 
to either air or perhaps water (running through a secondary heat exchange 
loop), the accident will not become compounded by the chemical reactivity of 
the heat exchange fluid itself. 

> Another advantage of the LFTR design is that they have a broader neutron 
> bandwidth (being able to utilize both fast neutrons as well as slower 
> neutrons). I guess one could say LFTR has a higher neutron efficiency; being 
> able to use them across a broader spectrum of energies.

 

Actually compared with the Uranium fuel cycle the Thorium fuel cycle is neutron 
poor, a LFTR produces enough neutrons to burn up 100% of the Thorium but there 
isn't a lot of wiggle room, however this is an advantage not a disadvantage. If 
somebody tried to secretly siphon off some of the U233 produced in a reactor to 
make a bomb the reactor would simply stop and it would be hard to keep that 
secret, also fewer neutrons means less damage to the equipment, you already 
don't have to worry about the most important maintenance problem that a 
conventional reactor has, cracks in the solid fuel rods caused by neutrons, 
because a LFTR has no solid fuel rods, it's fuel is a liquid and you can't 
crack a liquid. 

 

Interesting. I was referring to the ability of the LFTR type breeders to 
utilize thermal neutrons. U-233 gives off more than two neutrons per absorption 
at thermal energies, which is more than enough to sustain the fission process, 
whereas the P-239 produced by plutonium breeders (from the U-238 fertile 
material) absorb a significant number of neutrons at thermal energy levels, in 
this manner starving the fission process. In order to keep plutonium breeders 
going it is necessary to go to fast neutron design which does away with the 
graphite moderators (used in the thermal neutron design to slow the neutrons 
down).

Fast breeder reactors raise many more safety, economy, and nuclear 
proliferation challenges than do LFTR variants for this reason.

Chris

 

There is a excellent video about LFTR's, it's not short but it's packed with 
information and well worth your time:

 

/www.youtube.com/watch?v=P9M__yYbsZ4 
<http://www.youtube.com/watch?v=P9M__yYbsZ4> 

 

  John K Clark

 

 

-- 
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

-- 
You received this message because you are subscribed to the Google Groups 
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.

Reply via email to