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THE Uranium Supply Thread pt 4 (merged)

Discussions of conventional and alternative energy production technologies.
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Re: Uranium Supply

Postby EnergyUnlimited » Tue 08 Jan 2008, 14:49:23

$this->bbcode_second_pass_quote('Dezakin', '')$this->bbcode_second_pass_quote('', 'B')ut in such situation you should also build reprocessing infrastructure, not only reactors.
If thorium cycle is to be used (and IMO it is about the only realistic option if one wants to ensure long term future of nuclear industry), then we must develop reprocessing infrastructure as well.

Reprocessing infrastructure is a silly, expensive waste of time given the price of uranium today. If we're going to go that route, we might as well just build molten salt reactors which dont require offsite infrastructure as the reprocessing is done online.

1. Today is a keyword here.
2. Reprocessing is about the best way to deal with issues related to waste storage.
3. What is a cost of molten salt reactor?
Is it proven civilian technology suitable for power production?

In any case all what we are going to be left with is enforced, hasty conversion of PWR-s to thorium cycle, once there is inadequate uranium supply.
So reprocessing will be essential, assuming that we will not abandon nuclear power altogether.
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Re: Uranium Supply

Postby sch_peakoiler » Tue 08 Jan 2008, 15:34:22

$this->bbcode_second_pass_quote('Starvid', 'T')he argument that we shouldn't build reactors now because we can't be sure of long term fuel supply is wrong on so many levels, but even if it was correct, it wouldn't matter as ordinary bog standard reactors can be converted to thorium breeders without much problems.


The assumption that you can convert whatever you like into a thorium breeder in any random time you'd like is wrong on many more levels, starvid. That is why it is just about stalemate:(
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Re: Uranium Supply

Postby sch_peakoiler » Tue 08 Jan 2008, 15:45:19

$this->bbcode_second_pass_quote('Dezakin', '
')You're looking in hindsight at a huge price collapse in uranium following the atrophy of new nuclear builds coupled with huge stockpiles of enriched uranium These aren't neverending short term problems except in the handbook of simple rhetoric.


the problem is that those short term problems are never addressed. In fact, only some people here assume that it could come to some short term problems with the supply.
If nuclear industry said: Well problems there are but we will solve them - would be nice. Instead they cough up numbers like 51000 ton for 2007. My only wish is to check them.


$this->bbcode_second_pass_quote('', '
')It doesn't matter. It looks like you've made up your mind what you want to believe. Whenever projected numbers are offered, you reject them as incorporeal paper proejections, and then demand real data.


nope, I do not believe anything. What I want is to take projected data and compare them to reality where it is possible. I was asking many times for any production forecasts but instead I get only the 35 million tons of estimated reserves, and the notice: "dont worry, be happy, we will mine as much uranium as we need in a timely manner.

you do not understand me again: what I do want to find are numbers, projected and real. For example production forecasts 2008-2010.

$this->bbcode_second_pass_quote('', '
')Cigar Lake is scheduled production thousands of tons in 2011, but somehow that isn't going to happen I suppose.


I quoted one article above where they say the schedule was 2008.

$this->bbcode_second_pass_quote('', '
')To say nothing of the routine capacity upgrades at the numerous smaller mines around the world.


this is exactly what the whole thing is all about. I wanted to find numbers. and instead you feed me with "many mines in many places expand capacity". I already got that. I know that. But if 100 mines expand capacity 100 tons each in 10 years - how much of growth would that be? That is exactly the reason I am asking for projected production numbers here, but I got only one number (3711 to 4000 expansion).
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Re: Uranium Supply

Postby Dezakin » Tue 08 Jan 2008, 15:54:29

$this->bbcode_second_pass_quote('EnergyUnlimited', '')$this->bbcode_second_pass_quote('Dezakin', '
')$this->bbcode_second_pass_quote('', 'A')gain, wide use of thorium cycle will guarantee proliferation of atomic weapons, so proponents must accept this.

No it doesn't. The thorium cycle breeds U233, and U233 is allways contaminated with U232 which has strong gamma emitters in the decay chain. While U233 is good for weaponization from a neutronic perspective, the gammas make such a weapon undeployable because of the handling issues around it. If you have the infrastructure to do this, you'll much more likely just rationalize having enrichment infrastructure for using U235 which doesn't have the problem of lots of gamma radiation.

1. U232 is not formed or only formed in irrelevant amounts, if your reactor is working in strictly thermal regime.


Thats just not true. It depends entirely on the fuel discipline.

http://www.princeton.edu/~globsec/publi ... _1kang.pdf

$this->bbcode_second_pass_quote('', '2'). Due to short life of U232 it is enough to leave recovered U233 for few hundred years in storage, and your material will self-enrich itself to weapon grade without doing anything.


Eh, thats not a worry that immediately concerns me.
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Re: Uranium Supply

Postby Dezakin » Tue 08 Jan 2008, 16:04:12

$this->bbcode_second_pass_quote('EnergyUnlimited', '')$this->bbcode_second_pass_quote('Dezakin', '')$this->bbcode_second_pass_quote('', 'B')ut in such situation you should also build reprocessing infrastructure, not only reactors.
If thorium cycle is to be used (and IMO it is about the only realistic option if one wants to ensure long term future of nuclear industry), then we must develop reprocessing infrastructure as well.

Reprocessing infrastructure is a silly, expensive waste of time given the price of uranium today. If we're going to go that route, we might as well just build molten salt reactors which dont require offsite infrastructure as the reprocessing is done online.

1. Today is a keyword here.
2. Reprocessing is about the best way to deal with issues related to waste storage.

No its not. Dry cask storage is.

$this->bbcode_second_pass_quote('', '3'). What is a cost of molten salt reactor?

The first one would be more expensive than a LWR (first to market costs and all), and future molten salt reactors would be less expensive because they're less capital intensive. Higher power densities, better thermodynamic efficiencies, no massive pressure vessels for a start.

$this->bbcode_second_pass_quote('', 'I')s it proven civilian technology suitable for power production?
Not sure what you mean by this, compared to PWR's running on thorium. Both of these require similar startup enrichments and deal with highly enriched uranium 233 after the whole process is started, so from a licensing standpoint they're similar. The liquid fluoride reactor is more proliferation resistant because the U233 never leaves the reactor.

$this->bbcode_second_pass_quote('', 'I')n any case all what we are going to be left with is enforced, hasty conversion of PWR-s to thorium cycle, once there is inadequate uranium supply.
So reprocessing will be essential, assuming that we will not abandon nuclear power altogether.
You're actually assuming that we're going to run short on our uranium supply? That seems incredibly unlikely to me, but in the longer run of a decade past the price spike, mines start delivering large quantities of uranium. In the meantime, enrichment capacity is much faster to scale in terms of simple build time and licensing, not to mention cheaper.
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Re: Uranium Supply

Postby Dezakin » Tue 08 Jan 2008, 16:46:19

$this->bbcode_second_pass_quote('sch_peakoiler', '')$this->bbcode_second_pass_quote('Starvid', 'T')he argument that we shouldn't build reactors now because we can't be sure of long term fuel supply is wrong on so many levels, but even if it was correct, it wouldn't matter as ordinary bog standard reactors can be converted to thorium breeders without much problems.


The assumption that you can convert whatever you like into a thorium breeder in any random time you'd like is wrong on many more levels, starvid. That is why it is just about stalemate:(

Sortof...

The breeding ratio of light water reactors is somewhere around .6 IIRC. When you use thorium it goes to .8 or so, and using thorium to U233 fuel is less problematic than using MOX, yet even MOX can be used in just about any light water reactor (paying attention to the fuel geometry.
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Re: Uranium Supply

Postby EnergyUnlimited » Wed 09 Jan 2008, 05:02:38

$this->bbcode_second_pass_quote('Dezakin', '
')Thats just not true. It depends entirely on the fuel discipline.

http://www.princeton.edu/~globsec/publi ... _1kang.pdf

Yes, it is true.
Please read page 15-17 of the reference, which you presented above.
Thermal neutrons cannot produce U232.
6 MeV is an optimum as per your reference.

Fuel discipline (means assuring low burn out before reprocessing) would allow you to produce reasonable quality U233, even if some fast neutrons *are* present.
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Re: Uranium Supply

Postby EnergyUnlimited » Wed 09 Jan 2008, 05:27:56

$this->bbcode_second_pass_quote('Dezakin', '')$this->bbcode_second_pass_quote('EnergyUnlimited', '')$this->bbcode_second_pass_quote('Dezakin', '')$this->bbcode_second_pass_quote('', 'B')ut in such situation you should also build reprocessing infrastructure, not only reactors.
If thorium cycle is to be used (and IMO it is about the only realistic option if one wants to ensure long term future of nuclear industry), then we must develop reprocessing infrastructure as well.

Reprocessing infrastructure is a silly, expensive waste of time given the price of uranium today. If we're going to go that route, we might as well just build molten salt reactors which dont require offsite infrastructure as the reprocessing is done online.

1. Today is a keyword here.
2. Reprocessing is about the best way to deal with issues related to waste storage.

No its not. Dry cask storage is.

As long as transuranides are left in your waste it will not be safe for hundreds thousands of years.
Dry cask storage does not remove these but reprocessing does.
Further, you can burn recovered transuranides in nuclear reactor to produce energy and get rid of them.

$this->bbcode_second_pass_quote('', '')$this->bbcode_second_pass_quote('', '3'). What is a cost of molten salt reactor?
The first one would be more expensive than a LWR (first to market costs and all), and future molten salt reactors would be less expensive because they're less capital intensive. Higher power densities, better thermodynamic efficiencies, no massive pressure vessels for a start.

$this->bbcode_second_pass_quote('', 'I')s it proven civilian technology suitable for power production?
Not sure what you mean by this, compared to PWR's running on thorium. Both of these require similar startup enrichments and deal with highly enriched uranium 233 after the whole process is started, so from a licensing standpoint they're similar. The liquid fluoride reactor is more proliferation resistant because the U233 never leaves the reactor.
My concerns are that molten salt reactors are only experimental installations and it is not certain, will they make into industry or not.
PWR run on thorium is a concept experimentally proven in US (Tanada was writing about that).
$this->bbcode_second_pass_quote('', 'Y')ou're actually assuming that we're going to run short on our uranium supply? That seems incredibly unlikely to me, but in the longer run of a decade past the price spike, mines start delivering large quantities of uranium. In the meantime, enrichment capacity is much faster to scale in terms of simple build time and licensing, not to mention cheaper.
At ~$400/lb of yellowcake thorium cycle would reach economical parity with LWR.
I have red article about it, but I cannot give online reference.
As a bonus we would not have much problems with long term waste storage (because all waste would be reprocessed), so overall economy would not be so bad.

As a drawback proliferation risk would be considerably increased.
This does not need to be a concern if installation is built in states which already possess atomic weapons or states like Brazil, Japan, Switzerland, Sweden, Germany or Ukraine, who officially do not possess such weapons, but could easily change this state of affairs within a month or two, if deemed necessary.
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Re: Uranium Supply

Postby sch_peakoiler » Wed 09 Jan 2008, 06:49:33

And how long would it take to convert one LWR to the thorium cycle?

Uranium price is very inflexible. Example: 2003 - seabed level, 2006 - stratosphere.
Lets say it stays at 100 till 2013 and then a part of secondary supplies dries out and say some projected mines are still not there, plus some new LWRs have been built: the price would be instantly at 1000-2000 USD/lb which would have no meaning because there will be physically no uranium to buy.

Then the question will be "how long it takes, how many years you need before thorium reactors run".
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Re: Uranium Supply

Postby EnergyUnlimited » Wed 09 Jan 2008, 08:12:01

$this->bbcode_second_pass_quote('sch_peakoiler', 'A')nd how long would it take to convert one LWR to the thorium cycle?

Uranium price is very inflexible. Example: 2003 - seabed level, 2006 - stratosphere.
Lets say it stays at 100 till 2013 and then a part of secondary supplies dries out and say some projected mines are still not there, plus some new LWRs have been built: the price would be instantly at 1000-2000 USD/lb which would have no meaning because there will be physically no uranium to buy.

Then the question will be "how long it takes, how many years you need before thorium reactors run".


I think, you should direct this particular question (in form of PM perhaps) to Tanada, who knows some details about experimental conversion run in one of US reactors.

My guess is that conversion of PWR into thorium cycle would take about 1 year of engineering work.
Breeding factor in thorium cycle was experimentally shown to be about 1.01.
It is reasonable to expect that we could increase it to 1.02 perhaps.

1% excess of fissile material over amount of used one would allow you to secure enough of U233 to set up additional reactor working after about 70 years of work of original one.

You could circumvent this difficulty to some extend by "igniting" additional thorium cycle reactors with HEU (weapon grade uranium 235) diluted to about 5% with thorium-232.
Such a fuel would have to be treated with care.
If stolen, it could be converted to weapon material with primitive measures only.

Perhaps better alternative here would be to ignite thorium cycle by mixing thorium with few% of reactor grade plutonium, which is more difficult (but still possible) to divert for weapon use.

I have red few articles suggesting diluting thorium with U238, just to prevent possibility of easy diversion of fissile materials to weapons use.
Anyone who might attempt diversion would end up with necessity of separation of uranium isotopes - difficult process which cannot be concealed easily and requiring reasonably developed technology.
However breeding factor in such a setup is always below 1, so this approach is a dead end in long run.
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Re: Uranium Supply

Postby sch_peakoiler » Wed 09 Jan 2008, 08:39:46

So effectively this means thorium is a no-runner in the next 20 years for sure, if we started yesterday (just because you can not breed enough of it).
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Re: Uranium Supply

Postby EnergyUnlimited » Wed 09 Jan 2008, 09:25:42

$this->bbcode_second_pass_quote('sch_peakoiler', 'S')o effectively this means thorium is a no-runner in the next 20 years for sure, if we started yesterday (just because you can not breed enough of it).

You are actually breeding U233, not thorium.

You could divert some high grade plutonium or HEU from atomic weapons, just to set up new thorium based reactors.

I am also suspecting that many PWR-s are going to be converted into thorium cycle once uranium is no longer available in required quantities.
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Re: Uranium Supply

Postby sch_peakoiler » Wed 09 Jan 2008, 10:14:19

$this->bbcode_second_pass_quote('EnergyUnlimited', '')$this->bbcode_second_pass_quote('sch_peakoiler', 'S')o effectively this means thorium is a no-runner in the next 20 years for sure, if we started yesterday (just because you can not breed enough of it).

You are actually breeding U233, not thorium.

You could divert some high grade plutonium or HEU from atomic weapons, just to set up new thorium based reactors.

I am also suspecting that many PWR-s are going to be converted into thorium cycle once uranium is no longer available in required quantities.



Yeah I know what you breed.
The question is how much HEU or Weapon-PU one needs convert say 100 PWR reactors? If at some time in the future we do not have enough LEU to run them normally where will we get enough HEU to "ignite" them in thorium cycle?
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Re: Uranium Supply

Postby EnergyUnlimited » Wed 09 Jan 2008, 12:28:15

$this->bbcode_second_pass_quote('sch_peakoiler', '')$this->bbcode_second_pass_quote('EnergyUnlimited', '')$this->bbcode_second_pass_quote('sch_peakoiler', 'S')o effectively this means thorium is a no-runner in the next 20 years for sure, if we started yesterday (just because you can not breed enough of it).

You are actually breeding U233, not thorium.

You could divert some high grade plutonium or HEU from atomic weapons, just to set up new thorium based reactors.

I am also suspecting that many PWR-s are going to be converted into thorium cycle once uranium is no longer available in required quantities.



Yeah I know what you breed.
The question is how much HEU or Weapon-PU one needs convert say 100 PWR reactors? If at some time in the future we do not have enough LEU to run them normally where will we get enough HEU to "ignite" them in thorium cycle?

Assuming that you need annual load 200 tons of 4% uranium 235 for running 1GW PWR, this makes 8 tons of fissile isotope.

My guess with error not exceeding 50% is that you would roughly need 4 tons of HEU, or reactor grade plutonium or weapon grade plutonium for ignition of single thorium breeder.
You could use anyone of these.
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Re: Uranium Supply

Postby sch_peakoiler » Wed 09 Jan 2008, 15:13:11

And how long should a thorium breeder run on HEU till it has bred enough U233 to start a normal cycle? about 10 years I guess? Lets take 10 years as a base.

so we take 100 PWRs, 400 tons of HEU, a bunch of thorium and start the cycle.
after 10 years we are able to refill them with Th+U233, and then they will breed at optimistic 1.02, so that we have another "fuel refill" after some 35 years. effectively 200 reactors after 35 years.

so we have

X years - conversion of 100 reactors
10 years - ignition of 100 reactors
35 years - 200 reactors
35 years - 400 reactors (close to what we have now)
35 years - 800 reactors...
etcetera

Tanada, Dezakin : where is the error?

you know what: this back of the envelope calculation tells us that we can forget breeders. we need more than 100 years to make them run "in an amount larger than what we have now.
We can only use breeders if the cycle were started as long as we use normal nuclear cycle. But as you say we will first wait for 400 USD/lb, which means another couple years....

Well: forget breeders completely and stick with SWU, old tails, MOX, Mining, PWR :):)
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Re: Uranium Supply

Postby EnergyUnlimited » Wed 09 Jan 2008, 16:36:18

$this->bbcode_second_pass_quote('sch_peakoiler', 'A')nd how long should a thorium breeder run on HEU till it has bred enough U233 to start a normal cycle? about 10 years I guess? Lets take 10 years as a base.

This I think is unimportant. After next and next round of reprocessing U233 will be greater and greater part of total fissile isotope at work.

$this->bbcode_second_pass_quote('', 's')o we take 100 PWRs, 400 tons of HEU, a bunch of thorium and start the cycle.
after 10 years we are able to refill them with Th+U233, and then they will breed at optimistic 1.02, so that we have another "fuel refill" after some 35 years. effectively 200 reactors after 35 years.

so we have

X years - conversion of 100 reactors
10 years - ignition of 100 reactors
35 years - 200 reactors
35 years - 400 reactors (close to what we have now)
35 years - 800 reactors...
etcetera

Tanada, Dezakin : where is the error?

you know what: this back of the envelope calculation tells us that we can forget breeders. we need more than 100 years to make them run "in an amount larger than what we have now.
We can only use breeders if the cycle were started as long as we use normal nuclear cycle. But as you say we will first wait for 400 USD/lb, which means another couple years....

Well: forget breeders completely and stick with SWU, old tails, MOX, Mining, PWR :):)

I think, you are still a victim of exponential growth paradigm.

Well, if you wish to plan for a long term future, you should forget about perpetual growth.
So you may have to accept perhaps 800 thorium breeder reactors within 100 or may be even 200 years from now on but yet keep this number working for ever, or close to that.

The only alternative is that you will end up with no reactors at all, once you cannot satisfy U235 demand.

Nuclear energy is not a magic bullet, which allows you to carry on with status quo for ever.
However, if developed in thoughtful fashion, it can provide reliable baseload of electricity supply amounting to about 20-30% of current consumption level for millennia perhaps.

However the sad truth is that we are likely to apply it in a silly, shortsighted fashion, building some more LWR-s and gradually running out of uranium supply within 60 or 100 years from now on.
First substantial shakes within industry are likely to be seen within decade from now on, when excess of HEU runs out.
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Re: Uranium Supply

Postby sch_peakoiler » Wed 09 Jan 2008, 17:52:42

$this->bbcode_second_pass_quote('EnergyUnlimited', '
')I think, you are still a victim of exponential growth paradigm.



I think you just do not understand what I am doing. But thats Ok. My questions just do not seem to make a system, do they? they do.
I want to quantify the basics of nuclear energy. thats it. Tanada started a FISSION FAQ here. But he explained isotope basics and then had enough of this - the FAQ is unfinished big time. So there are no numbers connecting WHEN with HOW MUCH on nuclear power. Only the assurance of Dezakin that we have enough uranium in the crust and can scale up the mining to any scale needed.
So if anybody says: then we will go thorium and this is an endless supply, I want to know WHEN and HOW MUCH. just for me. To understand the basics.
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Re: Uranium Supply

Postby Tanada » Wed 09 Jan 2008, 21:00:39

$this->bbcode_second_pass_quote('sch_peakoiler', 'A')nd how long should a thorium breeder run on HEU till it has bred enough U233 to start a normal cycle? about 10 years I guess? Lets take 10 years as a base.

so we take 100 PWRs, 400 tons of HEU, a bunch of thorium and start the cycle.
after 10 years we are able to refill them with Th+U233, and then they will breed at optimistic 1.02, so that we have another "fuel refill" after some 35 years. effectively 200 reactors after 35 years.

so we have

X years - conversion of 100 reactors
10 years - ignition of 100 reactors
35 years - 200 reactors
35 years - 400 reactors (close to what we have now)
35 years - 800 reactors...
etcetera

Tanada, Dezakin : where is the error?

you know what: this back of the envelope calculation tells us that we can forget breeders. we need more than 100 years to make them run "in an amount larger than what we have now.
We can only use breeders if the cycle were started as long as we use normal nuclear cycle. But as you say we will first wait for 400 USD/lb, which means another couple years....

Well: forget breeders completely and stick with SWU, old tails, MOX, Mining, PWR :):)


Seems how you asked I will answer. You can assemble a LWBR in roughly a year. This is done by rearranging the fuel elements and controll rods. A LWBR along the lines of the Shippingport project consists of positive controll rods as opposed to the regular negative controll rods used in a standard reactor. Where a negative controll rod works by absorbing neutrons and slowing or stopping the reaction a positive controll rod does the exact opposite by inserting moderatly higher enriched fuel (circa 6% fissionable) that add neutrons to the reaction and speed it up. The negative controll rods are still availible for emergency use, but under nearly all scenarioa extracting the positive controll rods causes the reaction to slow down and stop without them.

To convert any regular PWR to LWBR operation you need Thorium plus a fissionable material. The majority of the rods in the core would be 97% to 98.5% Thorium and 2.5% to 3% U-235 and the positive controll rods 94% Thorium and 6% U-235. Note that you can substitute U-233 or Pu-239 or Reactor Grade Plutonium for the U-235 in the first load.

Now once you have your first fuel load in the reactor you start out with the positive controll rods fully extracted. You then extract the negative controll rods. At this point the reactor is still off, there is not enough reactivity present to start and sustain a fission chain reaction. You then very slowly insert some of the positive controll rods until you acheive unity, where each fission of one atom leads to the fission of another atom and the reactor is critical.

For the next 10 years based on the shippingport experimental proof of concept the reactor continues to operate generating heat which is used to produce electricity without stopping to refuel.

After 10 years you withdraw all of the fuel and put it in a cooling pool, replacing it with a fresh load. For the next 10 years the second core will power the reactor without needing to be refueled.

9 years after you extract the first core it is cool enough that you can either reprocess it to recover the Thorium, Uranium and Plutonium or put it in dry cask storage for long term safe storage. If you choose to reprocess the fuel you remove the 7% to 10% of fission products, add 7% to 10% fresh Thorium to replace the fission products and reassemble the fuel into rods with 2.5% U-233/U-235/Plutonium and 97.5% Thorium for most of the core and 6% U-233/U-235/Plutonium and 94% Thorium for the positive controll rods. Because of the near unity breeding ratio all of the fissionable materials in the new fuel are captured during the reprocessing, the tiny amount left over can be used as additional fuel for other reactors or stored for later use.

With a LWBR you only ever need enough fissionable material to manufacture two cores up front, one to operate the reactor for 10 years and one to cool for 9 years before being reprocessed and remanufactured for use while the other core is in the cooling cycle.

LWBR do need Thorium feedstock to replace the fission fragments removed during reprocessing which amount to around 7% to 10% of the total fuel mass for the core. Because Thorium is three times as abundant as Uranium and about 50% better at capturing thermal neutrons than U-238 it will breed U-233 just fast enough in the LWBR configuration to replace used up fissionable materials.
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Re: Uranium Supply

Postby Tanada » Wed 09 Jan 2008, 21:26:02

$this->bbcode_second_pass_quote('sch_peakoiler', 'A')nd how long should a thorium breeder run on HEU till it has bred enough U233 to start a normal cycle? about 10 years I guess? Lets take 10 years as a base.

so we take 100 PWRs, 400 tons of HEU, a bunch of thorium and start the cycle.
after 10 years we are able to refill them with Th+U233, and then they will breed at optimistic 1.02, so that we have another "fuel refill" after some 35 years. effectively 200 reactors after 35 years.

so we have

X years - conversion of 100 reactors
10 years - ignition of 100 reactors
35 years - 200 reactors
35 years - 400 reactors (close to what we have now)
35 years - 800 reactors...
etcetera

Tanada, Dezakin : where is the error?

you know what: this back of the envelope calculation tells us that we can forget breeders. we need more than 100 years to make them run "in an amount larger than what we have now.
We can only use breeders if the cycle were started as long as we use normal nuclear cycle. But as you say we will first wait for 400 USD/lb, which means another couple years....

Well: forget breeders completely and stick with SWU, old tails, MOX, Mining, PWR :):)


Oh and one more thing, the initial fuel load of highly enriched U-235 uses up about as much natural Uranium as two regular PWR cores would use, but because of the fertility of Thorium it lasts three times as long in the reactor. It is also the last natural Uranium you need to consume once the LWBR is up and running on its first recycled core. Alternatley you can use reactor grade Plutonium for the first two cores and you can get that plutonium from reprocessing roughly six spent fuel cores for each load. The USA alone has about 700 spent cores in storage that would provide enough reactor grade plutonium to start up 120 LWBR. It would take about a year to convert a PWR to LWBR and the USA has about 68 PWR's in operation today so reprocessing the spent fuel currently in storage would provide the two initial cores of PU/TH for LWBR for 60 of them.

The BWR reactors are not well suited for conversion to LWBR due to the differences in their core design, they would need to keep operating on enriched Uranium or MOX. Alternatively the BWR's can be operated on TMOX-RG (Thorium Mixed Oxide Reactor Grade Plutonium fuel) or Thorium/Uranium fuel, however because of the core design they will not be able to acheive breeding, instead they would be high efficiency convertor reactors operating in the .9 region instead of 1.01 like the LWBR's would.
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Re: Uranium Supply

Postby Dezakin » Thu 10 Jan 2008, 16:13:57

$this->bbcode_second_pass_quote('EnergyUnlimited', '')$this->bbcode_second_pass_quote('sch_peakoiler', 'A')nd how long should a thorium breeder run on HEU till it has bred enough U233 to start a normal cycle? about 10 years I guess? Lets take 10 years as a base.

This I think is unimportant. After next and next round of reprocessing U233 will be greater and greater part of total fissile isotope at work.

$this->bbcode_second_pass_quote('', 's')o we take 100 PWRs, 400 tons of HEU, a bunch of thorium and start the cycle.
after 10 years we are able to refill them with Th+U233, and then they will breed at optimistic 1.02, so that we have another "fuel refill" after some 35 years. effectively 200 reactors after 35 years.

so we have

X years - conversion of 100 reactors
10 years - ignition of 100 reactors
35 years - 200 reactors
35 years - 400 reactors (close to what we have now)
35 years - 800 reactors...
etcetera

Tanada, Dezakin : where is the error?

you know what: this back of the envelope calculation tells us that we can forget breeders. we need more than 100 years to make them run "in an amount larger than what we have now.
We can only use breeders if the cycle were started as long as we use normal nuclear cycle. But as you say we will first wait for 400 USD/lb, which means another couple years....

Well: forget breeders completely and stick with SWU, old tails, MOX, Mining, PWR :):)

I think, you are still a victim of exponential growth paradigm.

Well, if you wish to plan for a long term future, you should forget about perpetual growth.
So you may have to accept perhaps 800 thorium breeder reactors within 100 or may be even 200 years from now on but yet keep this number working for ever, or close to that.

The only alternative is that you will end up with no reactors at all, once you cannot satisfy U235 demand.

Nuclear energy is not a magic bullet, which allows you to carry on with status quo for ever.

Well, it sort of is... just not growth forever. With thorium breeders you can utilize a fuel 3 times as plentiful 200 times more efficiently (in addition to uranium) multiplying your base reserves by 800 and opening up the lowest grade resources... basic crust has an energy density 30 times that of coal burned in thorium breeders.

Now the problem with burning the 160 trillion tons of uranium and thorium in the crust in growth isn't running out of fuel, with a 1GW reactor demanding some 1 ton per year... its running out of heat dissipation capacity of the earth. If you make as much energy as the sun (say 10^16 watts?) you become dangerously close to altering the global climate without doing anything to the atmosphere at all, and your fuel resource will only last 16 million years.

I dont think we're going to do that with nuclear reactors, partially because I expect solar will eventually become more economical and much of human industry will be space based, but its an interesting exercise.
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