Energy From Thorium Discussion Forum

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PostPosted: Mar 25, 2015 1:34 am 
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But Terrestrial Energy's is burning in a MSR, or do I miss understand you.


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PostPosted: Mar 25, 2015 9:03 pm 
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Pure LEU MSR burners like the IMSR achieve much higher burnups than LEU solid fuel burners.
1 - The most critical neutron poisons are removed online (Xenon and Krypton)
2 - As extra fuel is added, there's an overflow tank, so old fuel (and non gas fission products) can be kept in the reactor for much longer
3 - Very little excess reactivity means less neutrons wasted from excess fuel
4 - Higher temp outlets increases thermal to electricity efficiency by 1/3 to 1/2
This results in a quoted reduction in around 85% in waste per GWh of electricity produced (1/6th the waste of a typical LWR/BWR), without reprocessing.
With reprocessing fuel can be kept in the reactor for 20 years, which should further reduce waste per GWh of electricity to less than 1/10th compared to typical LWR/BWR.

I would assume that with reprocessing, and using makeup fuel from separated plutonium (and depleted uranium as needed to maintain fissile/fertile ratio) waste levels could be even lower, since less U238 would be inserted per fissile added. Depending on the quality of the plutonium, very little U238 might be needed. France recycles its plutonium once. As MOX bundles are fully spent, plutonium isn't recycled anymore. MSRs don't have those limitations.

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PostPosted: Mar 26, 2015 12:14 pm 
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Shippingport reactor was a breeder or near breeder even if not an MSR. With thorium as fertile fuel, a near breeder using solid fuel could be possible.


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PostPosted: Mar 29, 2015 12:46 am 
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Indians have developed a design of AHWR using solid fuel with LEU and thorium.
http://dae.nic.in/writereaddata/.pdf_31
It has following improved features.
1. A high burn up of 64,000 MWd/ton.
2. Uses 13% less mined fuel than LWR.
3. Has all negative co-efficients ensuring full safety.
4. Used fuel has nearly 8% fissile including 235U and 233U and can be used as fuel in LWR or PHWR. It can be easily separated by chloride or fluoride volatility. Plutonium will require PUREX or similar process to recover from used fuel. It can be used as RG fuel in fast reactors. All these are benefits of thorium.
Slightly modified fuel design is possible for LWRs.
http://dae.nic.in/writereaddata/.pdf_38
Lightbridge are trying parallel development.
These designs could have similar features.
If a core-blanket fuel design is used, 233U can be produced. Th-233U fuel could be a breeder design in LWR or PHWR. Shippingport experiment proved it. If India was not short of fissile fuel, they could have done it by now. Fast breeder, which will only be functional this year, will ensure continued development, unless politics comes into action. Then it is only Russia, who are already operating fast reactors and do not need thorium and China. The Chinese are also working on MSR development.


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PostPosted: Mar 29, 2015 3:26 am 
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jagdish wrote:
Indians have developed a design of AHWR using solid fuel with LEU and thorium.
http://dae.nic.in/writereaddata/.pdf_31
It has following improved features.
1. A high burn up of 64,000 MWd/ton.
2. Uses 13% less mined fuel than LWR.
3. Has all negative co-efficients ensuring full safety.
4. Used fuel has nearly 8% fissile including 235U and 233U and can be used as fuel in LWR or PHWR. It can be easily separated by chloride or fluoride volatility. Plutonium will require PUREX or similar process to recover from used fuel. It can be used as RG fuel in fast reactors. All these are benefits of thorium.

Only 13% less fuel?

This kind of proves the point - MOST of the benefit is in going from solid fuels to liquid fuels. There is is additional benefit from going from Uranium to Thorium.

The UK Atomic Energy Authority rather dismissed Thorium as being of little benefit. They made a lot of errors (as shown by Kirk and others), but the main point was that they only looked at solid fuel reactors.

Why is anyone developing a solid fuel reactor when Molten Salt Reactors can be available in about a decade?


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PostPosted: Mar 30, 2015 4:21 am 
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jagdish wrote:
Why is anyone developing a solid fuel reactor when Molten Salt Reactors can be available in about a decade?
To a man who’s only tool is a hammer, all problems appear as a nail. Enough said? 8)

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PostPosted: Mar 31, 2015 12:32 pm 
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Molten Salt Reactor have been talked about for a couple of generations like the accelerated driven reactors and fusion reactors. Solid fuel fast and thermal reactors are operating. Creation of 233U is required for thorium fueled reactors and has been practiced earlier in the US and currently in India. Use of thorium in current reactors will not only introduce high burn up, low fabrication cost fuel in a short time but also open the way for sustained power from thorium. For the final design, we should have thermal and fast spectrum and solid and liquid fuel choices. The topic, in any case is thorium beyond MSRs.


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PostPosted: Apr 03, 2015 8:04 pm 
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Wilson wrote:
Terrestrial Energy's burner uses low enriched U235. It can burn most of its fuel, its waste, and burn other existing nuclear waste.
No, the IMSR does not burn its own waste nor really the waste of other reactors, AND, while it uses "LEU" it is 20%(-) LEU, not the typical 4%-5%LEU of LWRs. So if you ignore the DU, that makes for about 1/4 to 1/5 the waste right there. The other efficiencies help, but are not as big as the %age fissil to start with.

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PostPosted: Apr 03, 2015 9:05 pm 
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KitemanSA wrote:
Wilson wrote:
Terrestrial Energy's burner uses low enriched U235. It can burn most of its fuel, its waste, and burn other existing nuclear waste.
No, the IMSR does not burn its own waste nor really the waste of other reactors, AND, while it uses "LEU" it is 20%(-) LEU, not the typical 4%-5%LEU of LWRs. So if you ignore the DU, that makes for about 1/4 to 1/5 the waste right there. The other efficiencies help, but are not as big as the %age fissil to start with.


I got this information from http://terrestrialenergy.com/imsr-technology/
under waste

Your point with LEU at 20% I understand as this is not normal LEU % for most nuclear power plants that use LEU fuel.

Can you please explain the burning of own fuel and waste fuel. Is David inaccurate or have missed something here. Thanks.


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PostPosted: Apr 03, 2015 9:11 pm 
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Are you sure ? I recall IMSR using 5% enriched LEU. I just went through the URL you sent, couldn't find anything about the enrichment level.

All MSR designs I read about that need 20% enriched uranium is when the uranium will be mixed with Thorium (4 parts of Th-232 for each part of 20% enriched U, resulting in something like 80% Th-232, 15% U-238, 5% U-235). IMSR used pure Uranium fuel.

ThorCon uses that 80% Th, 15% U-238, 5% U-235 mix. So did the ORNL DMSR design.

The main reason I think your info is wrong is that thermal spectrum reactors tend to use less than 5% fissile concentrations. I think a 20% enriched fuel would result in the reactor overheating and fizzling. The one exception are military reactors, that are very compact and must operate for decades between refuelings, so they use close to weapons grade Uranium concentrations.

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PostPosted: Apr 03, 2015 9:57 pm 
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David dos not rule out thorium

Fuel Material---- LEU as UF4 within liquid carrier salt;----thorium use optional
http://terrestrialenergy.com/wp-content ... -12-ws.pdf

So, maybe David is saying 5% 235U when uranium only is being used, 20% 235U when uranium and thorium is used.


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PostPosted: Apr 03, 2015 11:55 pm 
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Okay, here it is

http://thoriumenergyalliance.com/downlo ... 0TEAC5.pdf Slide 15

If DMSR and IMSR are the same when it comes to fuel, then the above is what David is saying.


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PostPosted: Apr 04, 2015 4:11 am 
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Use of thorium in lieu of burnable poisons makes for more efficient use of fissile fuel in high burn up fuels. If all uranium, as calculated for LEU enriched thorium fuel for AHWR, is extracted by chloride volatility, it will have 8% fissile, 233U and 235U combined. It could make part of refueling. MSR would be even more neutron/fissile efficient.


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PostPosted: Apr 04, 2015 3:25 pm 
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I received a email from David and what I posted is correct.

Wilson,




The IMSR as a graphite moderated MSR-Burner like the DMSR only needs a very low "effective" enrichment. If no thorium is used, then the needed enrichment in the fuel salt is quite low, below 5%. If thorium is used (which improves the fuel economy of the reactor) then one uses mostly thorium along with uranium enriched to higher levels, 19.9% is the legal limit for U235 in U238. We have not declared either way whether we will use thorium or not. It is actually a remarkably long and subtle list of pros and cons to use thorium or not in MSR-Burners.






David LeBlanc

President, CTO

Terrestrial Energy Inc


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PostPosted: Apr 05, 2015 11:45 pm 
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Wilson wrote:
KitemanSA wrote:
Wilson wrote:
Terrestrial Energy's burner uses low enriched U235. It can burn most of its fuel, its waste, and burn other existing nuclear waste.
No, the IMSR does not burn its own waste nor really the waste of other reactors, AND, while it uses "LEU" it is 20%(-) LEU, not the typical 4%-5%LEU of LWRs. So if you ignore the DU, that makes for about 1/4 to 1/5 the waste right there. The other efficiencies help, but are not as big as the %age fissil to start with.


I got this information from http://terrestrialenergy.com/imsr-technology/
under waste

Your point with LEU at 20% I understand as this is not normal LEU % for most nuclear power plants that use LEU fuel.

Can you please explain the burning of own fuel and waste fuel. Is David inaccurate or have missed something here. Thanks.
If you look at the section on "Waste" he divides it into THREE segments, FPs, U, and Pu. It seems that the Pu is the part he is talking about "recycling". You canot "recycle" he U and burn it in a thermal spectrum reactor. So unless he has gone fast spectrum without me knowing it (entirely possible), he will NOT be burning up all of the actinides, only the TRUs.

With a 2.2+ fluid LFTR we can burn up all the actinides from LWR PUFF (previously used fission fuel).

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