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PostPosted: Mar 02, 2011 5:27 pm 
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Hi forum,

here is the most recent and detailed SmAHTR report "Pre-Conceptual Design of a Fluoride-Salt-Cooled Small Modular Advanced High-Temperature Reactor (SmAHTR)" by the ORNL group (PDF, 125 pages).

It may be distributed freely, enjoy :)


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PostPosted: Mar 02, 2011 6:45 pm 
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Nice report ! ...thanks !

All that Hastelloy-N in the “Core barrel and other internals” looks a bit puzzling though.

Attached are a couple of NNDC graphs of nickel (n,g) and (n,a) traces (thermal and fast), for anyone concerned about helium production in the metal…..

....there doesn't appear to be any boron coating on the inside, but I haven't read all the details.


Attachments:
Ni-58,59,60_(n,g),(n,a)_fast.gif
Ni-58,59,60_(n,g),(n,a)_fast.gif [ 34.43 KiB | Viewed 6267 times ]
Ni-58,59,60_(n,g),(n,a)_thermal.gif
Ni-58,59,60_(n,g),(n,a)_thermal.gif [ 16 KiB | Viewed 6254 times ]
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PostPosted: Mar 02, 2011 7:30 pm 
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Perhaps they handle that with pebbles that flow only on the outside that are full of thorium. Sort of a blanket.


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PostPosted: Mar 02, 2011 8:30 pm 
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One specific thing I like in the report is the use of Carbon-Carbon Composite (or RCC) in the structure of the "plank fuel bundles".

These RCC components are expected to be good for the life of the core -- some four years.

Although the power density is likely quite different, this suggests that using RCC for MSR fuel channel tubes may be viewed favourably.....


Attachments:
RCC_SmAHTR_plank_fuel_bundle.jpg
RCC_SmAHTR_plank_fuel_bundle.jpg [ 67.21 KiB | Viewed 6283 times ]
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PostPosted: Mar 03, 2011 9:06 am 
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I've also uploaded the document to the repository and created a special section for salt-cooled reactors.


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PostPosted: Mar 03, 2011 3:25 pm 
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Only a chance to skim so far. I notice roughly 2 tonnes of 19.75% starting load and the comment of 4.19 year core life. Anyone notice if this means a complete core change every four years? If so this works out to the equivalent of an 8 tonne U235/GWe fissile starting load and about 2 tonnes/GWe year make up fuel (twice a LWR, not surprizing with a small leaky core?). Perhaps they only replace half the core every 4 years though?
Also, anyone notice the total volume of Flibe needed? Looks like a lot, with the price of Li7 a big unknown this could be an issue.

David LeBlanc

P.S. Jaro, why no comments about them dreaming in technocolor about using 19.75% enrichment?


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PostPosted: Mar 03, 2011 5:06 pm 
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Good observations David.
David wrote:
Perhaps they only replace half the core every 4 years though?
No, the cores are treated as a unit -- illustration shows several cores stored in a spent cores bay. "Pros-and-cons" discussion mentions large shielded transfer flask needed to move spent core to central storage....

David wrote:
P.S. Jaro, why no comments about them dreaming in technocolor about using 19.75% enrichment?
ORNL is a DoE outfit, isn't it ?
They can specify any fuel they want -- including HEU.
Doesn't mean it will fly commercially.


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PostPosted: Mar 06, 2011 12:13 am 
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David wrote:
Only a chance to skim so far. I notice roughly 2 tonnes of 19.75% starting load and the comment of 4.19 year core life. Anyone notice if this means a complete core change every four years? If so this works out to the equivalent of an 8 tonne U235/GWe fissile starting load and about 2 tonnes/GWe year make up fuel (twice a LWR, not surprizing with a small leaky core?). Perhaps they only replace half the core every 4 years though?
Also, anyone notice the total volume of Flibe needed? Looks like a lot, with the price of Li7 a big unknown this could be an issue.

David LeBlanc

P.S. Jaro, why no comments about them dreaming in technocolor about using 19.75% enrichment?


One disadvantage you have with fuel utilization for a reactor this like is the single batch refueling. Just that alone will give you 50% less fuel utilization than a three-batch core. That combined with the small core size and operating with a higher enrichment results in a lower fuel utilization. The intent here was to stretch the time between refueling with one batch.

I'll have to look up flibe volume, don't have that number on the top of my head. We had considered introducing structures above the core to displace salt, but in the end left that open. Certainly the salt volume could be reduced if necessary.


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PostPosted: Mar 06, 2011 12:19 am 
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jaro wrote:
Nice report ! ...thanks !

All that Hastelloy-N in the “Core barrel and other internals” looks a bit puzzling though.

Attached are a couple of NNDC graphs of nickel (n,g) and (n,a) traces (thermal and fast), for anyone concerned about helium production in the metal…..

....there doesn't appear to be any boron coating on the inside, but I haven't read all the details.


The core barrel and other internals can be easily replaced. The primary concern with helium production is in the vessel, which generally will not be replaced (although it certainly could be). We evaluated the lifetime of the vessel this and do not think that it will be a problem.


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PostPosted: Mar 06, 2011 2:54 pm 
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Kirk Sorensen wrote:
I've also uploaded the document to the repository and created a special section for salt-cooled reactors.


Here are some additional documents that you might want to include in your repository:

Status of Preconceptual Design of the Advanced High-Temperature Reactor (AHTR), May 2004
http://www.ornl.gov/~webworks/cppr/y2001/rpt/120370.pdf

Status of Physics and Safety Analyses for the Liquid-Salt-Cooled Very High-Temperature Reactor (LS-VHTR), Dec 2005
http://www.ornl.gov/~webworks/cppr/y2001/rpt/124473.pdf

Trade Studies for the Liquid-Salt-Cooled Very High-Temperature Reactor: Fiscal Year 2006 Progress Report, Feb 2007
http://nuclear.inl.gov/deliverables/docs/status_report_fy06_ornl-tm-2006-140.pdf


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PostPosted: Mar 08, 2011 9:38 pm 
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Jaro,

jaro wrote:
Nice report ! ...thanks !

All that Hastelloy-N in the “Core barrel and other internals” looks a bit puzzling though.

Attached are a couple of NNDC graphs of nickel (n,g) and (n,a) traces (thermal and fast), for anyone concerned about helium production in the metal…..

....there doesn't appear to be any boron coating on the inside, but I haven't read all the details.



The "downcomer skirt" and "core barrel" are discussed in the report as if they are separate components. However, it is quite possible these two components would be a manufactured as a single component. In any event, while Hastelloy-N is indicated as the material of choice, we also discussed C-C and SiC-SiC composites as options. I think we would use either Hastelloy-N or C-C if we were to build SmATHR today. This is one of the many trades to be examined in more detail.

Glad you like the report.

Sherrell


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PostPosted: Mar 09, 2011 2:55 am 
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On behalf of the other forum members and myself, welcome Sherrell.

I presume that you are Sherrell Greene of ORNL. Welcome.


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PostPosted: Mar 09, 2011 6:13 am 
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Welcome Sherrell! We're glad to have you on the forum!


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PostPosted: Mar 09, 2011 9:51 pm 
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Lindsay: Yes, I am one and the same Sherrell Greene from ORNL.

Kirk: I can't tell you how gratifying it is to see the MSR document collection we created together several years ago become available around the globe thanks to your initiative!

Thanks for the greetings Gentlemen. I'm happy to join the most innovative group of nuclear energy advocates on the Web...

Sherrell


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PostPosted: Mar 10, 2011 2:54 am 
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Just finished reading the report and learned a lot. There are several ideas that would be common with a LFTR. Question 2 is applicable in the context of a LFTR and would love to discover that it isn't a problem at all.

I have a few questions.
1) Was thorium considered as a burnable poison - would it work?
2) It seems like Smahtr will have virtually the same tritium production as a LFTR. It seems to me that the main tritium transfer path will be through the heat exchangers especially if a steam turbine is used. What is the forecast tritium release rate?
3) Your fissile consumption of 1600 kg LEU20 every 3 years for 125 MWth => 2.1 tonnes fissile / GWe-yr so at the end of life roughly half the fissile must still be in the fuel. Is it correct that the spent fuel contains roughly 10% enriched uranium? Is the plan that this is treated as once-through or is the plan to recycle the fuel in some form?
4) From the drawings it looks like an aircraft could take out all three passive cooling towers. Is this a plausible scenario? If so, how does the system handle it?


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