Is Rocketing Nuclear Waste into the Sun a Viable Solution?

[Astronuc]

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/Services/Expertise/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]

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

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]

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]

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_en/welcome/presentatie2/presentatie2.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]

...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]

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_en/welcome/presentatie2/presentatie2.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. I am 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]

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. I am 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.

 

[vanesch]

In sum the structural support materials cost for wind is going to be all in the steel, concrete relatively nil.

That's apparently the conclusion. I learned something: I always thought that the towers were in concrete...

 

[mheslep]

That's apparently the conclusion. I learned something: I always thought that the towers were in concrete...

To be clear the subsurface bases for these Belgium off shore towers, per the website you provided, are prefabricated concrete with a steel tower atop the waves. So in essence the slab mass of the typical land based buried concrete foundation is still present in the form of these conical subsurface bases. In general wind towers world wide are almost all steel.