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 Post subject: Economising Uranium
PostPosted: Jun 11, 2014 9:55 am 
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If we are to see a major rollout of nuclear power in the west at any time in the near future it seems likely that we cannot wait for molten salt reactors to be ready - they are at least a decade away from a prototype utility scale reactor, let alone a full scale gigawatt range plant of the type necessary to make any different.

This leaves us with conventional reactors, which will leave us with an acute uranium shortage especially in terms of the West's dependence on external sources of Uranium (we would have to outbid China for Australian production and Kazakhstan is susceptible to pressure from both the Kremlin and from China).
Seawater extraction of uranium will require uranium prices well over $500/kg to even approach viability at the present time, and while such prices would not be crippling in terms of the price of produced electricity it would undoubtedly alter the economics of reactor operation in tways that would benefit efficiency in uranium use.

It appears that the most non-recycling fuel cycle available at the present time is the 'Once Through Thorium' cycle in the EC6 with thorium fuel elements being rotated through the core using dismantleable bundles and SEU driver fuel.

This manages to conserve valuable uranium by converting 25% of the fuel volume to Thorium dioxide and burning that material to nearly 90GWd/t, a very high level for the CANDU.
The remaining fuel is 20% 1.6% driver fuel (used in the first of the five campaigns of thorium irradiation) and 80% 1.3% driver fuel which is used in the remainder of the time.

Assuming an advanced enrichment plant and a 0.1% tails enrichment (as $500/kg would mean enrichment becoming very cheap) it appears that this fuel cycle would obtain an effective natural uranium burnup of roughly 13.6GWd/t/
That marginally beats the straight SEU cycle which reaches 11.7GWd/t, although the OTT cycle also reduces the total mass of spent fuel by roughly 20%.

Does anyone have any non-reprocessing, solid fuel cycles that can obtain significantly higher NU utilisation than the aforementioned ~13.6GWd/t figure.


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 Post subject: Re: Economising Uranium
PostPosted: Jun 11, 2014 12:45 pm 
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I'm not sure I understand your premise. There is no "major rollout" of nuclear power in the West even planned, if anything the near term concern is keeping existing plants operating. Are you expecting a huge increase of Western orders for ESBWR and AP1000? I'd be very glad if that happened, but most wouldn't be operating in less than 10 years.

Kazakhstan and Australia are hardly the only uranium rich mining areas. Western Colorado & Eastern Utah had very productive mines that could be reopened if the demand is there. There are large deposits in Africa. I'd be surprised if there aren't similarly large deposits in the Andes. I don't think there is much basis for uranium supply constraints in a 50 year window.


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 Post subject: Re: Economising Uranium
PostPosted: Jun 11, 2014 1:24 pm 
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E Ireland wrote:
If we are to see a major rollout of nuclear power in the west at any time in the near future it seems likely that we cannot wait for molten salt reactors to be ready - they are at least a decade away from a prototype utility scale reactor, let alone a full scale gigawatt range plant of the type necessary to make any different.

This leaves us with conventional reactors, which will leave us with an acute uranium shortage especially in terms of the West's dependence on external sources of Uranium (we would have to outbid China for Australian production and Kazakhstan is susceptible to pressure from both the Kremlin and from China).
Seawater extraction of uranium will require uranium prices well over $500/kg to even approach viability at the present time, and while such prices would not be crippling in terms of the price of produced electricity it would undoubtedly alter the economics of reactor operation in tways that would benefit efficiency in uranium use.

It appears that the most non-recycling fuel cycle available at the present time is the 'Once Through Thorium' cycle in the EC6 with thorium fuel elements being rotated through the core using dismantleable bundles and SEU driver fuel.

This manages to conserve valuable uranium by converting 25% of the fuel volume to Thorium dioxide and burning that material to nearly 90GWd/t, a very high level for the CANDU.
The remaining fuel is 20% 1.6% driver fuel (used in the first of the five campaigns of thorium irradiation) and 80% 1.3% driver fuel which is used in the remainder of the time.

Assuming an advanced enrichment plant and a 0.1% tails enrichment (as $500/kg would mean enrichment becoming very cheap) it appears that this fuel cycle would obtain an effective natural uranium burnup of roughly 13.6GWd/t/
That marginally beats the straight SEU cycle which reaches 11.7GWd/t, although the OTT cycle also reduces the total mass of spent fuel by roughly 20%.

Does anyone have any non-reprocessing, solid fuel cycles that can obtain significantly higher NU utilisation than the aforementioned ~13.6GWd/t figure.

If there were an immediate pickup in LWR/BWR nuclear projects today, by the time those are operational, the Thorium-Plutonium fuel would be fully tested and available to go (Halden-Sweden fuel qualification tests underway).
Any concerns surrounding reducing uranium usage should be satisfied by using 90% Th, 10% reactor grade plutonium solid fuel instead.

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 Post subject: Re: Economising Uranium
PostPosted: Jun 11, 2014 4:47 pm 
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E Ireland wrote:

It appears that the most non-recycling fuel cycle available at the present time is the 'Once Through Thorium' cycle in the EC6 with thorium fuel elements being rotated through the core using dismantleable bundles and SEU driver fuel.


What are your thoughts on the thorium fuel cycle in India ? India will begin building the AHWR reactor in 2016. The AHWR is a PHWR like the Candu EC6, perhaps even more advanced. Some Canadian nuclear engineers are also busy a developing a supercritical water cooled reactor (SCWR), which will use pressure tubes instead of a pressure vessel.


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 Post subject: Re: Economising Uranium
PostPosted: Jun 11, 2014 7:06 pm 
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macpacheco wrote:
If there were an immediate pickup in LWR/BWR nuclear projects today, by the time those are operational, the Thorium-Plutonium fuel would be fully tested and available to go (Halden-Sweden fuel qualification tests underway).
Any concerns surrounding reducing uranium usage should be satisfied by using 90% Th, 10% reactor grade plutonium solid fuel instead.

And where does the Plutonium come from?
There is only a finite supply, and even the UKs massive stockpile cannot provide enough to support a significant fleet of reactors for very long. And without reprocessing you will not get very much burnup from the material before the fission products poison it out of service.
Quote:
What are your thoughts on the thorium fuel cycle in India ? India will begin building the AHWR reactor in 2016. The AHWR is a PHWR like the Candu EC6, perhaps even more advanced. Some Canadian nuclear engineers are also busy a developing a supercritical water cooled reactor (SCWR), which will use pressure tubes instead of a pressure vessel.

The Indian fuel cycle is going tobe crippled, in my opinion, by a reliance on reprocessing. PUREX plants have enough trouble, the problems from THOREX seem likely to push the price of the fuel reprocessing sky high to something like $1500/kg or even higher.

It appears we need economical once through cycles.


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 Post subject: Re: Economising Uranium
PostPosted: Jun 11, 2014 7:16 pm 
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Cthorm wrote:
I'm not sure I understand your premise. There is no "major rollout" of nuclear power in the West even planned, if anything the near term concern is keeping existing plants operating. Are you expecting a huge increase of Western orders for ESBWR and AP1000? I'd be very glad if that happened, but most wouldn't be operating in less than 10 years.

I am interested in the idea of some sort of crash reactor programme declared under something approaching a 'War Emergency' basis - however a common criticism levelled at such an idea is the shortage of uranium that would cripple any reactor fleet if we were to initiate such a rapid expansion. (The need for a very rapid build up is the reason I am primarily interested in the EC6 as it bypasses the major production bottlenecks inherent in modern LWRs - heavy water is the primary CANDU constraint and it only has to be available at the end of reactor build, giving more time for production capacity buildout to keep up).

Cthorm wrote:
Kazakhstan and Australia are hardly the only uranium rich mining areas. Western Colorado & Eastern Utah had very productive mines that could be reopened if the demand is there. There are large deposits in Africa. I'd be surprised if there aren't similarly large deposits in the Andes. I don't think there is much basis for uranium supply constraints in a 50 year window.

The problem is that the appearance is we trade one foreign fuel dealer for another and we haven't really altered the 'energy independence' score - there is only one deposit of Uranium on British soil that is anywhere close to economic - in the Orkney Islands off Scotland - and attempts to mine that were defeated by local political opposition.

Economising and reducing uranium consumption would allow a significant reserve to be built up at reduced cost - by piling up drums of yellowcake on a disused runway if nothing else.
Thorium is also far cheaper on the international markets and considering the high burnups the EC6 OTT cycle achieves (nearly 10% of the thorium is burned away) its current price of ~$30/kg means that a fifty year reserve would not be beyond possibilities.


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 Post subject: Re: Economising Uranium
PostPosted: Jun 12, 2014 3:35 am 
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Correct me if I'm wrong, but I thought with a conventional LWR or a CANDU it would be economical to use even 100 - 1000 pm low grade "ores" for the uranium or thorium. It's my impression too that 20% of uranium supplies in the US in the 1990s(?) came from such low grade "ores". I was very much under the impression that we'll never run out of uranium or thorium because we'll never run out of rock, (especially with any sort of breeder reactor, but not only with breeders).


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 Post subject: Re: Economising Uranium
PostPosted: Jun 12, 2014 10:47 am 
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Would the tailings from the previous decades' enrichment process, the depleted uranium, be a better source? I believe, at least for the US, that there are very large amounts of DU in yellowcake/UF6 form with 0.02% - 0.03% U235, which could be used in CANDUs & PHWR(?). *IF* the SILEX enrichment process is feasible, then salvaging this U235 seems feasible, if not then perhaps a centrifuge cascade modified for this feedstock could achieve the enrichment goal for a cheaper cost.


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 Post subject: Re: Economising Uranium
PostPosted: Jun 12, 2014 7:42 pm 
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E Ireland wrote:
macpacheco wrote:
If there were an immediate pickup in LWR/BWR nuclear projects today, by the time those are operational, the Thorium-Plutonium fuel would be fully tested and available to go (Halden-Sweden fuel qualification tests underway).
Any concerns surrounding reducing uranium usage should be satisfied by using 90% Th, 10% reactor grade plutonium solid fuel instead.

And where does the Plutonium come from?
There is only a finite supply, and even the UKs massive stockpile cannot provide enough to support a significant fleet of reactors for very long. And without reprocessing you will not get very much burnup from the material before the fission products poison it out of service.
Quote:
What are your thoughts on the thorium fuel cycle in India ? India will begin building the AHWR reactor in 2016. The AHWR is a PHWR like the Candu EC6, perhaps even more advanced. Some Canadian nuclear engineers are also busy a developing a supercritical water cooled reactor (SCWR), which will use pressure tubes instead of a pressure vessel.

The Indian fuel cycle is going tobe crippled, in my opinion, by a reliance on reprocessing. PUREX plants have enough trouble, the problems from THOREX seem likely to push the price of the fuel reprocessing sky high to something like $1500/kg or even higher.
It appears we need economical once through cycles.

The Indian fuel cycle survived 34 yrs of restrictive trade, termed sanctions and a fast reactor is nearing completion. This is not covered by easing of sanctions.
Prices are flexible by laws of economics.
IFR concept, also developed in the USA but now followed in some countries with variations, is the way to extend the use of uranium for nuclear power. An interesting variation would be the use of fast MSR in the system.
The other methods for economy of uranium are
RMWR. http://en.wikipedia.org/wiki/Reduced_mo ... er_reactor
Use of thorium. http://dae.nic.in/writereaddata/.pdf_38
The ultimate focus of Indian fuel cycle is a thorium breeder, as with LFTR. The fissile material is to be collected through sodium cooled FBR.


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 Post subject: Re: Economising Uranium
PostPosted: Jun 12, 2014 9:15 pm 
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Reprocessing has been shown to be hopelessly uneconomic every time its been tried and the price for it just keeps on climbing.
As far as I know there is no operational industrial scale THOREX reprocessing plant at all.

Without cheap reprocessing fast reactors can't hope to beat a heavy water moderated thermal reactor - the fissile requirements in each fuel element are just too high. And we don't have any significant experience in operating a production-type fast reactor design, every design has been essentially experimental.


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 Post subject: Re: Economising Uranium
PostPosted: Jun 13, 2014 7:49 pm 
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E Ireland wrote:
macpacheco wrote:
If there were an immediate pickup in LWR/BWR nuclear projects today, by the time those are operational, the Thorium-Plutonium fuel would be fully tested and available to go (Halden-Sweden fuel qualification tests underway).
Any concerns surrounding reducing uranium usage should be satisfied by using 90% Th, 10% reactor grade plutonium solid fuel instead.

And where does the Plutonium come from?
There is only a finite supply, and even the UKs massive stockpile cannot provide enough to support a significant fleet of reactors for very long. And without reprocessing you will not get very much burnup from the material before the fission products poison it out of service.
Quote:
What are your thoughts on the thorium fuel cycle in India ? India will begin building the AHWR reactor in 2016. The AHWR is a PHWR like the Candu EC6, perhaps even more advanced. Some Canadian nuclear engineers are also busy a developing a supercritical water cooled reactor (SCWR), which will use pressure tubes instead of a pressure vessel.

The Indian fuel cycle is going tobe crippled, in my opinion, by a reliance on reprocessing. PUREX plants have enough trouble, the problems from THOREX seem likely to push the price of the fuel reprocessing sky high to something like $1500/kg or even higher.

It appears we need economical once through cycles.


As usual E Ireland is always criticizing anything that isn't current mainstream Nuclear tech...

I'll ask a question to the experts, and formulate my guess to try to answer your question. I have no nuclear degree, so I'm sure I'll be substantially off the exact numbers, but perhaps on the right ballpark. Main goal is to stir a good discussion.

Running 90% Th-232, 10% reactor grade Pu wouldn't produce lots of U-233 plus some U-234/U-235/U-232 ?
Wouldn't the spent nuclear fuel from 90% Th-232 + 10% reactor grade Pu produce at least something on the order of 80% fissile Uranium isotopes vs the fissions produced by the fuel ?
Even as low as 80% underbreeding would make this cycle extremely attractive !

Wouldn't this lead to a future (a little less than 90%) Th-232 + a mix of U-232/234/235/232 + Pu fuel, with increasingly ratio of Uranium vs Plutonium ?
As the cycle produces more and more U-233, the ratio of reactor grade plutonium needed would settle at a much lower number.

Finally, reprocessing 90% Th-232 + 10% reactor grade Pu has no U-238 to worry about, so it might be possible to do simple Pyro reprocessing, add just enough Th-232 and Pu to keep the 90% ratio of fertile to 10% fissile fuel and use the fuel again.

Considering the 2.3 neutron production ratio of the Th-232 -> U-233 -> fission and the 85% probability of thermal fission, except for the cost of reprocessing and making the fuel this cycle require much lower ratios of Pu for reprocessing ?

If that is true, than your concern about Pu stock piles isn't a big issue.

If the first batch of fuel needs 10% Pu, but after reprocessing just 2-3% Pu is needed, this would take a long time to deplete worldwide Plutonium stockpiles. And would make an excellent case to reprocess existing PWR/BWR spent nuclear fuel for its Pu content, wouldn't it perhaps enable 100% of the hot PWR/BWR spent nuclear fuel to be used (Uranium goes back into enrichment for making new low enriched Uranium fuel, Plutonium and all other transuranics go to Th-Pu fuel) ?

Just trying to show this type of fuel could help future MSR/LFTR reactors, the more U-233 gets made, the better.

Just thinking out loud. Please fire away the corrections/critics.

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 Post subject: Re: Economising Uranium
PostPosted: Jun 13, 2014 8:21 pm 
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Such a cycle might be technically possible, but the price of reprocessing just keeps climbing every time someone attempts it.
I have no confidence that pyroprocessing can actually deliver its claimed reductions in costs.
Thorium chemistry is problematic in terms that it is almost non-existent beyond the conversion of thorium metal into thoria.

Dissolution in the prototypical THOREX processes has been shown to be problematic without adding large quantities of HF as a catalyst which, as I am sure you are aware, has its own set of problems especially in terms of the extraction of the fissile material.
Unless you want to face even more horrendous radiological threats in the fuel fabrication stage than those already provided by 232U contamination you have to use an aqueous process - there is a reason pyrochemical fast reactor cycles make use of simple casting or vibropak fuel fabrication technologies.

You can't even use OREOX on Thorium fuels, removing the one technology that looks able to measurably reduce reprocessing costs - you could easily be looking at ~$2000/kgHM for fuel reprocessing.

While large quantities of fissile uranium isotopes will be produced by Pu-Th MOX, almost none of it will even make it out of the reactor since it is so easily fissioned that it will burn away, providing the neutrons required to attempt destruction of the parasitic non fissile Plutonium isotopes. This is why SEU fueled CANDUs can obtain ~2 atm% burnup in a fuel that was only 1.2% fissile to start with - and presumably has a nonzero fissile content at the end of the process.

Cycles which attempt bulk reprocessing of the entire fuel supply appear to be crippled by continuously escalating reprocessing costs - an extension of the above proposed thorium cycle that might just be viable is reprocessing of the expended thorium elements to generate new elements that already contain the equilibrium uranium content - which from a simplistic analysis could reduce uranium consumption by a further ten percent - while only having to reprocess ~5% of the fuel mass.


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 Post subject: Re: Economising Uranium
PostPosted: Jun 13, 2014 9:07 pm 
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E Ireland wrote:
Such a cycle might be technically possible, but the price of reprocessing just keeps climbing every time someone attempts it.
I have no confidence that pyroprocessing can actually deliver its claimed reductions in costs.
Thorium chemistry is problematic in terms that it is almost non-existent beyond the conversion of thorium metal into thoria.

Humm, isn't France, UK, Japan and a few other countries doing reprocessing, today ?
I believe that there are many anti nuclear interests inside the NRC and its equivalent in Germany (plus other countries).
Every time somebody tries to do nuclear reprocessing (I assume you are talking about doing it in countries that don't do it already), it gets more expensive, because the goalpost is constantly being moved to make it more expensive.
Either you are making the case of LFTR reactors being a fool's errands, or Dr. Sorensen should step in and set the record straight.
Honestly, if somebody that understands this stuff orders of magnitudes better than I do can't reply to the opposing post, I'm afraid I just lost the will to fight for Thorium reactors.

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 Post subject: Re: Economising Uranium
PostPosted: Jun 13, 2014 9:48 pm 
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macpacheco wrote:
Humm, isn't France, UK, Japan and a few other countries doing reprocessing, today ?

The French and British plants continue to soldier on and were built decades ago - as far as I know EDF is trying to get out of having to pay for a new reprocessing plant so it looks like that will eventually come to the end, additionally only a relatively small fraction of the spent UOX fuel reproduced in EDF's reactors is actually reprocessed.
The only reason the British ever did reprocessing was because Magnox fuel has to be reprocessed as it reacts with water - later attempts with AGR fuel have been problematic in the extreme and THORP has been an endless source of trouble, and is coming to the end of its life, it will be out of service in 2018.
Then there is the disaster that is the British MOX production plant that has turned out almost no actual fuel.
The Japanese plant at Rokkasho is several times over budget and as far as I know has not actually reprocessed any operational fuel yet - the previous unit ceased several years ago so they are not currently reprocessing.
macpacheco wrote:
I believe that there are many anti nuclear interests inside the NRC and its equivalent in Germany (plus other countries).
Every time somebody tries to do nuclear reprocessing (I assume you are talking about doing it in countries that don't do it already), it gets more expensive, because the goalpost is constantly being moved to make it more expensive.

This might be the case - but it appears that reprocessing has never really been economic and seems unlikely to become so in the near future - and if seawater uranium extraction continues to get cheaper even that far future requirement may be taken away.

It seems unlikely you will get the cost down to the $200-300/kg required for general use to become economic, and while the cost may be a smaller additional to the cost of the nuclear energy we have to search for every last economic advantage we can get to enable complete rollout.

This is one of the reasons I support the EC6, its a reactor that can be built in large numbers today and can handle any number of possible fuel cycle scenarios, allowing us to make changes to the fuel cycle over the life of the reactor and avoiding lock-in.
macpacheco wrote:
Either you are making the case of LFTR reactors being a fool's errands, or Dr. Sorensen should step in and set the record straight.
Honestly, if somebody that understands this stuff orders of magnitudes better than I do can't reply to the opposing post, I'm afraid I just lost the will to fight for Thorium reactors.


I am not talking about liquid reactors, if the technical challenges can be solved they have an interesting economic case - however they are nowhere near ready for the sort of rapid rollout we are going to need to avoid the disaster that awaits us by the mid 21st century.


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 Post subject: Re: Economising Uranium
PostPosted: Jun 14, 2014 3:33 am 
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Russia, India and China, the main builders of reactors, also continue to reprocess and recycle uranium in fast reactors. Power producing fast reactors are likely to be commissioned in Russia and India this year. (Russians already have a fast reactor producing power) Russians are helping to build fast reactors in China. Some processing similar to IFR reprocessing or one further simplified may be developed once these reactors come online.
Thorium and uranium tetra-chlorides boil below 1000C and in case of thorium fuel, the reprocessing shall most probably consist of fractional distillation of chlorides. This will have synergy with fast chloride reactors.
As a historical precedent of reducing costs, aluminium was more valuable than gold in Napoleon's time. Now it is the stuff of disposable cans, beside other uses.


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