Energy From Thorium Discussion Forum

It is currently Sep 22, 2018 2:23 pm

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 10 posts ] 
Author Message
PostPosted: Sep 10, 2014 4:50 pm 
Offline

Joined: Jan 21, 2008 9:12 pm
Posts: 317
Location: idaho falls
Does anyone have firm numbers (with refs) for the fractional TRU recoveries (Pu & MA) achieved by the pyroprocessing of IFR-type fuels. I'm of the opinion that the 0.1% TRU loss figure usually assumed is wildly optimistic.

_________________
Darryl Siemer


Top
 Profile  
 
PostPosted: Sep 10, 2014 5:16 pm 
Offline

Joined: Jul 28, 2008 10:44 pm
Posts: 3063
My impression is that 0.1% is very optimistic for the minor actinides. I don't think anyone has tried hard to get to very low escape probabilities for the minor actinides. ORNL did publish numbers on extracting plutonium using 650C fluorine gas and small drops of plutonium containing fuel salt. If you work through the numbers they achieved you come out around 0.1% escaping using two passes. Using 650C fluorine gas was deemed too impractical and the idea was dropped back in the late 60's but perhaps we have better knowledge today (perhaps an amorphous diamond coating to the vessel)?

I'm also not sure of the value of getting that last little bit. I expect that the sensitivity to plutonium is so high that even if you remove 99.9999% you would still have to use deep geological storage due to the residual plutonium. If we can't get clean enough to avoid geo storage then we just want to reduce the plutonium far enough to remove heat load problems and to avoid creating a future "plutonium mine". Seems like 99% should be good enough for those purposes.


Top
 Profile  
 
PostPosted: Sep 11, 2014 4:02 am 
Offline

Joined: Jun 19, 2013 11:49 am
Posts: 1552
If you are going for the intermediate service storage option you can just pull 99% and then later on once the fuel is not a horrendous witches brew of death you might be able to do something sophisticated to it.

Also you have 300 years to do the R&D.


Top
 Profile  
 
PostPosted: Sep 11, 2014 10:36 am 
Offline

Joined: Jul 14, 2008 3:12 pm
Posts: 5045
E Ireland wrote:
If you are going for the intermediate service storage option you can just pull 99% and then later on once the fuel is not a horrendous witches brew of death you might be able to do something sophisticated to it.

Also you have 300 years to do the R&D.


Good points. In fact, even a 90% recovery efficiency would be just fine in this plan. IFR plans on quite high burnup of fuel.


Top
 Profile  
 
PostPosted: Sep 11, 2014 1:44 pm 
Offline

Joined: Jan 21, 2008 9:12 pm
Posts: 317
Location: idaho falls
Cyril R wrote:
E Ireland wrote:
If you are going for the intermediate service storage option you can just pull 99% and then later on once the fuel is not a horrendous witches brew of death you might be able to do something sophisticated to it.

Also you have 300 years to do the R&D.


Good points. In fact, even a 90% recovery efficiency would be just fine in this plan. IFR plans on quite high burnup of fuel.



The point of my question was to see if anyone has actually seen a report documenting the 0.1% TRU loss figure serving as the chief rationale for the USA's espousal of a LMFBR-based (IFR) approach to GNEP which, in turn, assumes ANL's electrochemical-based "pyroprocessing" scheme.

I doubt that any such report has ever been “released”.

Today's best-proven LMFBR is the S-PRISM. GE-Hitachi's reports suggest that its driver fuel would contain about 20% recycled TRU & achieve 10% burn up. At 42 % thermal efficiency, generating one GWE's worth of IFR power requires the burning of about 920 kg of fissile per year. This translates to reprocessing 9.2 tonnes (920kg/10%) of driver fuel plus about the same amount of blanket fuel per GWe year. If 20% of its driver fuel is TRU, this means that 1840 kg of TRU plus whatever's in the blanket must be processed/year.

Six years ago the Director of GNEP's Technical Integration Program (INL's Phillip Finck) gave a talk to "NEAC" in which he indicated that the best-ever U recovery actually achieved by ANL's proprocessing scheme was 97.6 % (this talk is too big to ATTACH). He made no mention of actually achieved TRU recovery but it's pretty safe to say that would be less than that seen for U because TRU is intrinsically harder to "plate out" than is U. 2.4% TRU loss/cycle adds up to about 45 kg of TRU waste/GWe year's worth of IFR generated power - about 10 times more than that discarded by the much simpler, no-reprocessing, MSFR isobreeder scheme that I've described in another thread.

Pyroprocessing is intrinsically complicated & generates a great deal of radwaste - mostly contaminated salts & miscellaneous metals - which must be competently dealt with, not "temporarily" stored until some future generation develops both the will & ability to extract its residual TRU before disposal. We MSR/thorium enthusiasts should keep this in mind too.

_________________
Darryl Siemer


Top
 Profile  
 
PostPosted: Sep 11, 2014 6:06 pm 
Offline

Joined: Dec 24, 2011 12:43 pm
Posts: 219
Location: Newport Beach, CA
darryl siemer wrote:
Cyril R wrote:
E Ireland wrote:
If you are going for the intermediate service storage option you can just pull 99% and then later on once the fuel is not a horrendous witches brew of death you might be able to do something sophisticated to it.

Also you have 300 years to do the R&D.


Good points. In fact, even a 90% recovery efficiency would be just fine in this plan. IFR plans on quite high burnup of fuel.



The point of my question was to see if anyone has actually seen a report documenting the 0.1% TRU loss figure serving as the chief rationale for the USA's espousal of a LMFBR-based (IFR) approach to GNEP which, in turn, assumes ANL's electrochemical-based "pyroprocessing" scheme.

I doubt that any such report has ever been “released”.

Today's best-proven LMFBR is the S-PRISM. GE-Hitachi's reports suggest that its driver fuel would contain about 20% recycled TRU & achieve 10% burn up. At 42 % thermal efficiency, generating one GWE's worth of IFR power requires the burning of about 920 kg of fissile per year. This translates to reprocessing 9.2 tonnes (920kg/10%) of driver fuel plus about the same amount of blanket fuel per GWe year. If 20% of its driver fuel is TRU, this means that 1840 kg of TRU plus whatever's in the blanket must be processed/year.

Six years ago the Director of GNEP's Technical Integration Program (INL's Phillip Finck) gave a talk to "NEAC" in which he indicated that the best-ever U recovery actually achieved by ANL's proprocessing scheme was 97.6 % (this talk is too big to ATTACH). He made no mention of actually achieved TRU recovery but it's pretty safe to say that would be less than that seen for U because TRU is intrinsically harder to "plate out" than is U. 2.4% TRU loss/cycle adds up to about 45 kg of TRU waste/GWe year's worth of IFR generated power - about 10 times more than that discarded by the much simpler, no-reprocessing, MSFR isobreeder scheme that I've described in another thread.

Pyroprocessing is intrinsically complicated & generates a great deal of radwaste - mostly contaminated salts & miscellaneous metals - which must be competently dealt with, not "temporarily" stored until some future generation develops both the will & ability to extract its residual TRU before disposal. We MSR/thorium enthusiasts should keep this in mind too.


Is it fair to say that you and Chairman MacFarlane are on the same page w.r.t. pyroprocessing? If I remember correctly she does not view it favorably because of the large volume of non-fuel materials contaminated in the process. If that's the dominant view it seems the only kinds of SNF reprocessing that avoids this issue are an MSFR or a DMSR (i.e. invitro burnup with fast spectrum, or burnup very slowly with thermal spectrum).


Top
 Profile  
 
PostPosted: Sep 11, 2014 7:49 pm 
Offline

Joined: Jun 19, 2013 11:49 am
Posts: 1552
Which takes us back to simply sitting the fuel in concrete casks.

If any form of radwaste production is unacceptable then the case for reprocessing falls to pieces.


Top
 Profile  
 
PostPosted: Sep 11, 2014 9:13 pm 
Offline

Joined: Jan 21, 2008 9:12 pm
Posts: 317
Location: idaho falls
[/quote]
Is it fair to say that you and Chairman MacFarlane are on the same page w.r.t. pyroprocessing? If I remember correctly she does not view it favorably because of the large volume of non-fuel materials contaminated in the process. If that's the dominant view it seems the only kinds of SNF reprocessing that avoids this issue are an MSFR or a DMSR (i.e. invitro burnup with fast spectrum, or burnup very slowly with thermal spectrum).[/quote]

I agree with her about "pyroprocessing". I don't favor DMSRs for anything other than "special" applications for the reasons given in footnote x of the ATTACHMENT.


Attachments:
BEST MSBR final ESR revised.doc [843 KiB]
Downloaded 236 times

_________________
Darryl Siemer
Top
 Profile  
 
PostPosted: Sep 11, 2014 9:24 pm 
Offline

Joined: Jan 21, 2008 9:12 pm
Posts: 317
Location: idaho falls
E Ireland wrote:
Which takes us back to simply sitting the fuel in concrete casks.

If any form of radwaste production is unacceptable then the case for reprocessing falls to pieces.



Some degree of reprocessing will be required by any fuel cycle/reactor capable of implementing a sustainable nuclear renaissance. However, the "amount" of reprocessing required by today's proposed GEN IV et al reactor options differs tremendously & therefore should be accorded a great deal of weight in decision-making. Please read the ATTACHMENT to my last note (it's just been accepted for publication).

_________________
Darryl Siemer


Top
 Profile  
 
PostPosted: Sep 11, 2014 11:55 pm 
Offline

Joined: Apr 19, 2008 1:06 am
Posts: 2240
Most of the construction of nuclear power plants is now in Asia with limited uranium resources. This calls for:-
a. A closed cycle
b. A low cost recycling.
A fast MSR with pyroprocessing on the lines of IFR or the Fluorex is most likely to meet the needs.
China or India with limited uranium but more thorium may shift to thorium once thorium breeder is developed. Old uranium users would best stick to fast uranium waste burners.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 10 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group