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PostPosted: Oct 10, 2014 3:34 pm 
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Fluoride Salt-Cooled High-Temperature Reactors: The Next Generation in Nuclear Power?
Dr. David E. Holcomb
DOE-NE National Technical Lead for Fluoride Salt-Cooled High-temperature Reactors (FHRs)
Oak Ridge National Laboratory
Oak Ridge, TN
Presented October 8, 2014

(Presentation starts about 5:45 into the video)
https://sf.ites.utk.edu/utk/Play/971759 ... 7a944b481d


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PostPosted: Oct 10, 2014 7:48 pm 
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A smaller modification in the metal cooled reactors-a fluoride/chloride secondary coolant loop-can yield useful results. It could work without Li7 enrichment and could be a useful preliminary (that may or may not be further developed) to FLiBe based reactors.


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PostPosted: Oct 10, 2014 8:31 pm 
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I don't think that FHRs can work without reactor-grade LiF-BeF2. They need it even more than MSRs do.


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PostPosted: Oct 11, 2014 5:45 am 
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Kirk Sorensen wrote:
I don't think that FHRs can work without reactor-grade LiF-BeF2. They need it even more than MSRs do.


There was some work indicating that other salts would be acceptable with lower salt to graphite/TRISO fuel ratio and use of neutron poisons.

But, practically you are totally right since all major FHR work has unanomously settled on FLiBe.


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PostPosted: Oct 11, 2014 8:46 am 
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I guess that means that cheaper FLiBe without isotope separation can be used only outside the reactor vessel. That reduces the benefits.
I wonder if NaF-ZrF4 could be good enough to tranport the heat?
From table A to ( http://web.ornl.gov/~webworks/cppr/y200 ... ion_detail),the viscosity appears to be comparable. May be OK for fast reactors.


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PostPosted: Oct 11, 2014 9:07 am 
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jagdish wrote:
I guess that means that cheaper FLiBe without isotope separation can be used only outside the reactor vessel. That reduces the benefits.
I wonder if NaF-ZrF4 could be good enough to tranport the heat?
From table A to ( http://web.ornl.gov/~webworks/cppr/y200 ... ion_detail),the viscosity appears to be comparable. May be OK for fast reactors.


Earlier work indicated that NaF-ZrF4 is acceptable, with enough neutron poison (I think this was for non pebble design but am not sure if it would be the case for pebble beds with their high coolant fractions).

You lose the significant fuel savings advantages over LWRs though if you go this route.


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PostPosted: Oct 11, 2014 11:33 am 
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The problem is having a coolant sufficiently neutronically transparent that it doesn't give a positive coolant void coefficient. LiF-BeF2 is the only one good enough. Having more neutron absorption in the salt is a BAD thing for FHRs.


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PostPosted: Oct 11, 2014 11:54 am 
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Kirk Sorensen wrote:
The problem is having a coolant sufficiently neutronically transparent that it doesn't give a positive coolant void coefficient. LiF-BeF2 is the only one good enough. Having more neutron absorption in the salt is a BAD thing for FHRs.


Correct. However alpha is made up of different terms and the work I referred to claimed that the increased negative term from burnable poison (erbia) could offset this to produce a decidedly negative total alpha.

You'll find it here:

http://web.ornl.gov/~webworks/cppr/y200 ... ion_detail

The claim of the proponents is further, that rapid voiding is very unlikely in fluoride cooled pool type reactor, as the boiling point of FLiBe is over 1400C (and probably >1450C at operating pressure)


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PostPosted: Oct 13, 2014 1:39 am 
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Use of cheaper eutectics as secondary coolant in fast/MS reactors could minimize the neutron loss and maximize the savings.


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