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Safe Storage of Nuclear Waste

by baywax
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vanesch
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May13-08, 11:10 AM
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Quote Quote by mheslep View Post
Well I'm suspicious that recent world price spike in materials, esp. steel, is making cost comparisons unreliable unless they are exact contemporaries. I suspect this imminent C-power wind project is reflecting these price hikes and thus only an imminent nuclear project (ala the $14B/2GW Florida plan) would be truly comparable.
Well, the Finnish EPR has just started construction, so that is the closest I can come up with (3.3 B Euro and estimated 50% cost overrun).

Actually, a related question is: how does the material bill (steel and concrete) compare between wind and nuclear ? I would think nuclear consumes more material, but is it gigantically more so ?

For the EPR reactor, the pressure vessel contains about 500 tons of steel, and I don't have the numbers for the steam generators, but compared to the N4 French plants, the steam generators are of the same order of magnitude as the pressure vessel (about 20% less, and there are 4 of them), so an estimate would be 2000 tons of steel for an EPR of 1.6 GW electric.

The double containment building, about 55 m high, 2 x 1.3 m thick, and diameter 48 m, must contain about:
3.14 x 48 x 55 x 2.6 = 22 000 m^3 of concrete for the wall, and
2 x 3.14 x 48^2 x 2.6 = 37 000 m^3 of concrete for roof and bottom, so total of 60 000 m^3 concrete.

Now how does that compare to about 1000 5 MW wind turbines (equal average power),
http://www.c-power.be/applet_mernu_en/index01_en.htm
each 120 m high (the tower), with wings 63 meter long each (total height 184 m, 2/3 of the Eiffel tower) ?

Do you do with so much less for one windmill than 2 tons of steel and 60 m^3 of concrete (half a m^3 per meter height) ?

It is my opinion - I can be wrong - that the material investment in steel and concrete of one EPR unit is comparable to the amount of steel and concrete needed for these 1000 turbines.

If that's the case, then material cost is going to have a null-effect on comparisons.
baywax
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May13-08, 11:42 AM
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What is the attraction about CANDU reactors? As a Canadian I should know but I don't! Are they cheaper, produce less waste or what?
vanesch
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May13-08, 12:08 PM
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What is the attraction about CANDU reactors? As a Canadian I should know but I don't! Are they cheaper, produce less waste or what?
CANDU reactors are heavy-water moderated and cooled natural uranium reactors.

The main advantage is that they can use natural uranium. As such, they are comparable to the Gen I graphite reactors, but they are a lot safer. They can be loaded and unloaded continuously (that can be seen as an advantage, or a disadvantage, because as such, they are ideal tools to make weapon grade plutonium, or do the thorium - U-233 conversion).

The disadvantage is that they need heavy water, which is expensive to produce (by distillation of ammoniak, I think), and there's another disadvantage connected to the heavy water: they produce loads of tritium (well, that too can be considered an advantage).

Another disadvantage is that they can only moderately "use up" the U-235 in the natural uranium (which can be compensated for by using slightly enriched U, so that the burn-up can be much higher, but then this undoes the main advantage of a CANDU).
mheslep
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May13-08, 12:13 PM
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What is the attraction about CANDU reactors? As a Canadian I should know but I don't! Are they cheaper, produce less waste or what?
No enrichment required, they work (can) on natural uranium. Either CANDU or NRX reactors (Im not sure which, perhaps both) can then be used to make Pu and give one a path to a bomb and bypass a technologically difficult enrichment program.
baywax
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May13-08, 01:10 PM
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Quote Quote by vanesch View Post
CANDU reactors are heavy-water moderated and cooled natural uranium reactors.

The main advantage is that they can use natural uranium. As such, they are comparable to the Gen I graphite reactors, but they are a lot safer. They can be loaded and unloaded continuously (that can be seen as an advantage, or a disadvantage, because as such, they are ideal tools to make weapon grade plutonium, or do the thorium - U-233 conversion).

The disadvantage is that they need heavy water, which is expensive to produce (by distillation of ammoniak, I think), and there's another disadvantage connected to the heavy water: they produce loads of tritium (well, that too can be considered an advantage).

Another disadvantage is that they can only moderately "use up" the U-235 in the natural uranium (which can be compensated for by using slightly enriched U, so that the burn-up can be much higher, but then this undoes the main advantage of a CANDU).
Thank you. Theres another reactor in Ontario that was shut down for some reason to do with safety but then a global outcry because it was one of the only reactors that could produce medical grade imaging or treatment grade material. Then the watchdog that shut it down was fired by the Conservative Govt... (like Republicans) and the plant has been re-started... safety issues aside. (?)
baywax
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May13-08, 01:11 PM
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Quote Quote by mheslep View Post
No enrichment required, they work (can) on natural uranium. Either CANDU or NRX reactors (Im not sure which, perhaps both) can then be used to make Pu and give one a path to a bomb and bypass a technologically difficult enrichment program.
I think we've sold CANDUs to many different countries. Oops.
mheslep
#241
May13-08, 03:36 PM
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Quote Quote by vanesch View Post
...If the point is that "in an extended region, the wind always blows *somewhere*", then you need to install the FULL capacity of an entire country several times over:...

I don't believe that any fuel cell station that has a significant fraction of the capacity of a country will come online in the next few decades....
Here's the basic idea at an NREL test facility.
http://www.nrel.gov/hydrogen/proj_wi...animation.html
Wind runs straight to the grid when needed, when its peaking over load it generates H via electrolysis, is pressurized and stored. Fixed plant storage is not that problematic, unlike vehicle storage. Then when needed the H2 drives either and H2 ICE (in low production now) generators or fuel cells.
mheslep
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May13-08, 05:20 PM
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Quote Quote by vanesch View Post
Well, the Finnish EPR has just started construction, so that is the closest I can come up with (3.3 B Euro and estimated 50% cost overrun).
Yes those are the costs I see, however Olkiluoto started in 2005, they've long since contracted for all their materials.

Actually, a related question is: how does the material bill (steel and concrete) compare between wind and nuclear ? I would think nuclear consumes more material, but is it gigantically more so ?

For the EPR reactor, the pressure vessel contains about 500 tons of steel, and I don't have the numbers for the steam generators, but compared to the N4 French plants, the steam generators are of the same order of magnitude as the pressure vessel (about 20% less, and there are 4 of them), so an estimate would be 2000 tons of steel for an EPR of 1.6 GW electric.

The double containment building, about 55 m high, 2 x 1.3 m thick, and diameter 48 m, must contain about:
3.14 x 48 x 55 x 2.6 = 22 000 m^3 of concrete for the wall, and
2 x 3.14 x 48^2 x 2.6 = 37 000 m^3 of concrete for roof and bottom, so total of 60 000 m^3 concrete.
Plus rebar steel. Strong reinforced concrete about 5% steel by cross section: 60000m^3*0.05=3500m^3; 3500m^3 * 7900kg/m^3 * 907kg/ton = 26000tons rebar steel.

Is the cooling tower significant? Schmehausen, for example: average diameter ~120M, height 180M, 0.1M thick average(?)= 3.14*120*180*0.1 = 6800 m^3 walls
base = 3.15*60^2* 0.2(?) = 2300m^3, total 9000m^3 for the tower. Say 1000tons rebar steel. Not so much compared to that containment bldg. Call it 70,000M^3 concrete, 29000 tons steel, total project.

Now how does that compare to about 1000 5 MW wind turbines (equal average power),
http://www.c-power.be/applet_mernu_en/index01_en.htm
each 120 m high (the tower), with wings 63 meter long each (total height 184 m, 2/3 of the Eiffel tower) ?
The blades are fiber glass composite now. The tower is almost always steel, though concrete has some inroads. Weight? 11m steel sections w/ 55mm walls weigh 60tons, so lets say 700tons/tower. So 700,000 tons for a 5GW 1000 tower field. The concrete I think is small in comparison.

Do you do with so much less for one windmill than 2 tons of steel and 60 m^3 of concrete (half a m^3 per meter height) ?

It is my opinion - I can be wrong - that the material investment in steel and concrete of one EPR unit is comparable to the amount of steel and concrete needed for these 1000 turbines.

If that's the case, then material cost is going to have a null-effect on comparisons.
Apparently Wind requires a lot of steel; I doubt very much concrete.
vanesch
#243
May13-08, 11:25 PM
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Quote Quote by mheslep View Post
Plus rebar steel. Strong reinforced concrete about 5% steel by cross section: 60000m^3*0.05=3500m^3; 3500m^3 * 7900kg/m^3 * 907kg/ton = 26000tons rebar steel.
Hey, that's funny, there's 10 times more steel in the building than in the actual reactor part.
One should make then out of fibre glass...

Is the cooling tower significant? Schmehausen, for example: average diameter ~120M, height 180M, 0.1M thick average(?)= 3.14*120*180*0.1 = 6800 m^3 walls
base = 3.15*60^2* 0.2(?) = 2300m^3, total 9000m^3 for the tower. Say 1000tons rebar steel. Not so much compared to that containment bldg. Call it 70,000M^3 concrete, 29000 tons steel, total project.
Right, which gives us an equivalent budget of 29 tons of steel and 70 m^3 of concrete per turbine, or essentially 70 m^3 of reenforced concrete.

The blades are fiber glass composite now. The tower is almost always steel, though concrete has some inroads. Weight? 11m steel sections w/ 55mm walls weigh 60tons, so lets say 700tons/tower. So 700,000 tons for a 5GW 1000 tower field. The concrete I think is small in comparison.

Apparently Wind requires a lot of steel; I doubt very much concrete.
For these offshore applications, I'm pretty sure that the base on the seafloor requires quite some concrete, but I don't know how it compares to 70 m^3 which would make a base plate of 10 m x 10 m x 70 cm.
baywax
#244
May13-08, 11:48 PM
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Quote Quote by mheslep View Post
Here's the basic idea at an NREL test facility.
http://www.nrel.gov/hydrogen/proj_wi...animation.html
Wind runs straight to the grid when needed, when its peaking over load it generates H via electrolysis, is pressurized and stored. Fixed plant storage is not that problematic, unlike vehicle storage. Then when needed the H2 drives either and H2 ICE (in low production now) generators or fuel cells.
Another source of presently wasted H2 is at electrolysis plants around the world. They just burn off the excess H2 instead of storing it. What does it take to collect the H2 rather than burn it off? Probably the same amount of equipment. There must be many other chemical processes going on in industry today that discharge hydrogen rather than store it for re-sale. This represents work that has been done anyway so the efficiency goes up 100%... and you get two or more outcomes for the price of one.
vanesch
#245
May14-08, 02:23 AM
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Quote Quote by mheslep View Post
Here's the basic idea at an NREL test facility.
http://www.nrel.gov/hydrogen/proj_wi...animation.html
Wind runs straight to the grid when needed, when its peaking over load it generates H via electrolysis, is pressurized and stored. Fixed plant storage is not that problematic, unlike vehicle storage. Then when needed the H2 drives either and H2 ICE (in low production now) generators or fuel cells.
Sure, all this is nice. This test facility (that's why it is a test facility) is on the 10 KW scale. IN the US we need to go to a 10 million times bigger scale. This is not going to happen in the next few decades, that's the point.
Also, I wonder what the efficiency is of "generated electricity" - "generated hydrogen" - "re-generated electricity". I wonder if you get overall over 30% (especially if the hydrogen is used in a combustion engine), which means that you need 3 times the capacity to account for the variability.

Again, I'm not against this, on the contrary. But these are experiments on a scale where nuclear power was in the 40ies. It took at least 4 decades before this became a major player in the world energy provision.
Astronuc
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May14-08, 06:44 AM
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Quote Quote by mheslep View Post
No enrichment required, they work (can) on natural uranium. Either CANDU or NRX reactors (Im not sure which, perhaps both) can then be used to make Pu and give one a path to a bomb and bypass a technologically difficult enrichment program.
With respect to CANDU fuel, AECL has been offering slightly enriched fuel (CANFLEX) for some time.

http://www.aecl.ca/Commercial/Servic...CANDU-Fuel.htm

NRX was a research reactor and not appropriate for power reactor, although certainly one could breed fissile isotopes. It is now being decommissioned.

Production of fissile materials requires processing of the converted material, which requires chemical processing.
vanesch
#247
May14-08, 06:59 AM
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Quote Quote by Astronuc View Post
NRX was a research reactor and not appropriate for power reactor, although certainly one could breed fissile isotopes. It is now being decommissioned.

Production of fissile materials requires processing of the converted material, which requires chemical processing.
Well, there's a link of course. When you look at the Wiki entry (I don't know if it is correct), India got his nuclear weapons (in 1974 already) from a CANDU-style reactor:

http://en.wikipedia.org/wiki/Nuclear_proliferation

Quote Quote by wiki
It is widely believed that the nuclear programs of India and Pakistan used CANDU reactors to produce fissionable materials for their weapons; however, this is not accurate. Both Canada (by supplying the 40 MW research reactor) and the United States (by supplying 21 tons of heavy water) supplied India with the technology necessary to create a nuclear weapons program, dubbed CIRUS (Canada-India Reactor, United States). Canada sold India the reactor on the condition that the reactor and any by-products would be "employed for peaceful purposes only.". Similarly, the U.S. sold New Delhi heavy water for use in the reactor "only... in connection with research into and the use of atomic energy for peaceful purposes". India, in violation of these agreements, used the Canadian-supplied reactor and American-supplied heavy water to produce plutonium for their first nuclear explosion, Smiling Buddha.[16] The Indian government controversially justified this, however, by claiming that Smiling Buddha was a "peaceful nuclear explosion."
mheslep
#248
May14-08, 10:05 AM
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Quote Quote by vanesch View Post
Sure, all this is nice. This test facility (that's why it is a test facility) is on the 10 KW scale. IN the US we need to go to a 10 million times bigger scale. This is not going to happen in the next few decades, that's the point.
Also, I wonder what the efficiency is of "generated electricity" - "generated hydrogen" - "re-generated electricity". I wonder if you get overall over 30% (especially if the hydrogen is used in a combustion engine), which means that you need 3 times the capacity to account for the variability.
Yes there are some significant losses. Electrolysis requires 1.4 electric joules to make 1 joule of H2 (71%), and the fuel cell is 50% unless the FC heat is reused in a combined cycle, absent that about 35% total as you guessed. Is this a problem? It depends on the outage ratio (not the turbine average capacity). If it is 1 week a year as posited some threads ago, then the wind system needs to be plus rated (1/51)/.3 = 6.5% to supply the needed storage energy over it's on time, so producing the back up H2 is no problem. A more complicated problem is that the FC or H2 ICE has to have the same power capability as the downed percentage of wind. That also gets back to the transmission and weather scenario guess work which I don't enough about.

Again, I'm not against this, on the contrary. But these are experiments on a scale where nuclear power was in the 40ies. It took at least 4 decades before this became a major player in the world energy provision.
A big part of that time must be credited to safety concerns, political games, major development of reactor technology, complexities of plant operation, and the development of very evolved government regulatory bodies (e.g. NRC, necessary IMO); the nuclear history doesn't make the argument that any new technology must take 40 years to roll out. The internet? 5-10 years. Cell telephones? 5-10 years. I don't believe nuclear development parallels must necessarily be drawn to Wind; solar perhaps needs a couple more generations (ala reactors) but not wind.
vanesch
#249
May14-08, 10:17 AM
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Quote Quote by mheslep View Post
Yes there are some significant losses. Electrolysis requires 1.4 electric joules to make 1 joule of H2 (71%), and the fuel cell is 50% unless the FC heat is reused in a combined cycle, absent that about 35% total as you guessed. Is this a problem? It depends on the outage ratio (not the turbine average capacity). If it is 1 week a year as posited some threads ago, then the wind system needs to be plus rated (1/51)/.3 = 6.5% to supply the needed storage energy over it's on time, so producing the back up H2 is no problem. A more complicated problem is that the FC or H2 ICE has to have the same power capability as the downed percentage of wind. That also gets back to the transmission and weather scenario guess work which I don't enough about.
The Belgian project I referred to earlier (and is placed on one of the better spots in the world) http://www.c-power.be/applet_mernu_e...sentatie2.html
tells me that about 46% of the time, the unit is below half of its installed power, and 20% of the time below 1/5 of its installed power (which means it is below its average of 1/3 of installed power - so at that point, one needs an intervention from the backup - 4% of the time, it is totally dead).
The problem is that this simulation doesn't give us a distribution of the consecutive times when this happens, but as I said, typical anti-cyclone situations take 4-5 days.
mheslep
#250
May14-08, 01:57 PM
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Quote Quote by vanesch View Post
...Right, which gives us an equivalent budget of 29 tons of steel and 70 m^3 of concrete per turbine, or essentially 70 m^3 of reenforced concrete.

For these offshore applications, I'm pretty sure that the base on the seafloor requires quite some concrete, but I don't know how it compares to 70 m^3 which would make a base plate of 10 m x 10 m x 70 cm.
Hmm apparently at least three foundation techniques in use/planned. One for onshore and two for off shore. Looks like a 6.8M^3 concrete base for the onshore. Offshore: phase one, zero concrete, 'monopole' towers are just pile driven (more steel); phase two uses flared prefab concrete bases w/ excavation and then the base is filled, probably <10M^3 for the base.
http://www.c-power.be/applet_mernu_en/index01_en.htm

In sum the structural support materials cost for wind is going to be all in the steel, concrete relatively nil.
mheslep
#251
May14-08, 03:39 PM
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Quote Quote by vanesch View Post
The Belgian project I referred to earlier (and is placed on one of the better spots in the world) http://www.c-power.be/applet_mernu_e...sentatie2.html
tells me that about 46% of the time, the unit is below half of its installed power, and 20% of the time below 1/5 of its installed power (which means it is below its average of 1/3 of installed power - so at that point, one needs an intervention from the backup - 4% of the time, it is totally dead).
The problem is that this simulation doesn't give us a distribution of the consecutive times when this happens, but as I said, typical anti-cyclone situations take 4-5 days.
If Belgium was to plan for some dependence on this system one would target the Capacity rating of ~115MW (35%) and not the name plate rating of 300MW (=60*5MW). The wind dips below that as you say 20% of the time, and is at no power 4% of the time. Im guessing there's a trade off in wind farm design: max energy collection vs max availability, and the Belgians, already having plenty of nuclear backup , swung for the fence.
vanesch
#252
May14-08, 11:30 PM
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Quote Quote by mheslep View Post
If Belgium was to plan for some dependence on this system one would target the Capacity rating of ~115MW (35%) and not the name plate rating of 300MW (=60*5MW). The wind dips below that as you say 20% of the time, and is at no power 4% of the time. Im guessing there's a trade off in wind farm design: max energy collection vs max availability, and the Belgians, already having plenty of nuclear backup , swung for the fence.
You have to know that this project is a pilot project in a program to phase out nuclear (of which Belgium has about 5.6 GW installed, which accounts for 56% of its production) and replace it by wind and gas: at least that was the proposition back 5 years ago when socialists and green party which were in the gov. then voted for that law. I would have preferred seeing this kind of wind farm in addition to nuclear (which is existing) to reduce coal-fired plants... I have a hard time imagining they are going to multiply this with a factor of 56. I think they will end up replacing nuclear by a lot of gas and a few windmills.

I'm not against such kind of wind farm, on the contrary. My view is that each KW hour produced in the current situation is a KW hour less produced by coal. But given the situation, I find it stupid to use that to try to phase out partially nuclear, while one is rather well placed to use it to diminish coal consumption.
I have the serious impression that it is oversold and the "300 MW" label is part of that.


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