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dennisp wrote: Keep oil companies in business…

… why?

You’ve heard of the buggy whip makers?
http://en.wikipedia.org/wiki/Marketing_myopia

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JimmyT wrote: I read an interesting scheme for desalinating water a few years back which might play well with this technology. Rather than using distillation it uses fractional crystallization.

Basically you pump seawater up to the high Sierras during the winter and spray the water on the mountain slopes.

… hmmm… it seems that the cost of pipelines and pumping and spraying and recollecting the water would have to be greater than simply desalinating the water by the seaside and pumping fresh water to wherever it is needed. The free temperature difference offered by natural cooling would be more than offset by the added costs of manipulating the water to try to take advantage of the cooling.

The vicious circle again… the only reason someone would look into such a idea is the cost of energy. Make the cost of energy a non-issue and the idea becomes a non-issue.

And as climate change impacts the Sierras (and it will) the water shortages brought on by the decreasing snowpacks will be mitigated by the availability of fresh water from the seaside… and if it gets so bad that the Sierra ecology itself can’t take it any more then pump up [em]fresh[/em] water from the seaside and spray it on the slopes…

Aneutronic fusion would change a lot of perspectives.

JimmyT wrote: Relatively fresh water crystallizes as ice or snow and concentrated brine drains away (back to the ocean presumably).

As co-opted and as cowed as the Sierra Club has become I’d think even they would object to brining the Foothills vineyards 🙂

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? Neutrons behave exactly that way.

Oh, I see… I listed the occurrences in reverse order. What I meant was that only a small fraction of the neutrons interact with the core on the way out, and then they run into the shield.

And you seem to be assuming high cross-sections for some rather fast neutrons.

So, as I understand it…

1. Some neutrons are created… 0.1% of the reactions end up creating neutrons that carry less than 0.2% of the energy released… “the <0.2%" 🙂

2. Of the <0.2%, almost all would pass out of the core without hitting anything. At ~2.8 MeV and ~600 KeV these are not thermal neutrons and their absorption cross-sections are not very large.

3. Then they run into the shield. A meter of water, ~20 cm of B10 and a few cm of lead.

4. What’s left is supposed to be no greater than background radiation.

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delt0r wrote: I don’t think so. The side reactions that give off neutrons are indeed rare. But once you scale up to MW its still a lot. Also the true cool down time will depend on other materials used. Neutron activation over days, weeks and years will not be insignificant. It is of course something that is reasonably easy to deal with, given proper materiel choices. Remember that we are talking about moles of neutrons here, they all get absorbed somewhere.

Hmmm… I thought the few neutrons produced were mostly absorbed by the water and the B10, with only a fraction of those few interacting with the core on the way out.

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delt0r wrote: A 1MW plant would have the neutron power of 2kW @ .2% neutron power, even @ .02% its still 200W of neutrons. A *lot* more than “radiation output of a classroom of kindergarteners”.

Ah… as far as the kindergarten class is concerned I believe Lerner-hakase was speaking of the level of activation of the core when it is replaced after service… not the interior of the reactor during operation 🙂

So the proper comparison would be the used core sitting on the teacher’s desk … not… (beryllium, y’know) and the classroom full of kids.

delt0r wrote: E. Lerner has said this even in his first Google talk. There is a cool down time of hours/days after switch off before you can get your hands inside.

~9 hours, actually.

The culprit is C11… which is B11 that did not quite make to C12. It has a half-life of 20 minutes and decays back to B11 via positron emission. ~9 hours after shutdown you can open the reactor with no radiation hazard. Or you can open the reactor earlier if you need a free PET scan 🙂

It’s not that the C11 would be super-hazardous in and of itself… the ~9 hour wait is in order to adhere to Lerner’s apparent protocol of “less than background radiation.”

delt0r wrote: Rare side reactions matter.

Hmmm… as you seem to have misunderstood what I was trying to get at (my fault, very probably 🙂 ) perhaps we’re talking past each other?

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Indirectly related… with FF powering sewage reclamation plants in the big cities and churning out cheap organic fertilizer along with clean water a new type of techno-ecology might evolve between the cities and the farms…. maybe…

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nemmart wrote:

Extremely interesting. $25 to $30 million for a generator, within 5 years of a successful test, which may be 3 months away? That’s fascinating.

Er, I’d say 3 months away is a wee bit on the optimistic side.

My original, if ungrammatical, statement was “… and that test is hoped to happen early 2012.”

Will there be even more chapters added to the ever-growing epic titled “[em]Unexpected Adventures in Fusion Engineering[/em]” along the way? Probably 🙂

But they are now working with the desired voltage and even with o-ring concerns and what else they don’t seem to be all that far away from the next step. And the next step beyond 45kv is the smaller electrodes… and then boron.

There are no guarantees, of course, but I wouldn’t be surprised if they are trying to burn boron by March. Not that we’ll hear all that much about it at the time… LPP has made it very clear that after they start working with boron they’ll stay quiet until they have the results nailed down one way or another.

And if that happens then I wouldn’t be surprised if we get an announcement of acceptance for publication in the summer of 2012.

In other words we do seem to be looking at a time scale of months and not years… barring surprises 🙂

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tcg wrote: The figure of 233 tons per day times 2000 divided by 800 yields the number of houses which would have enough water, 580 in a community which has 7,500 houses. But wait! I have already calculated that it would take about a dozen 5MW plants to supply enough electricity for 7,500 houses, so 580 X 12 = 6960 homes.

… errr… I use metric tons…

… but keep forgetting to use the “tonnes” spelling… actually I just don’t like it… a decidedly provincial Hoosier, that’s me…

So, with the parameters you give above, a dozen FF units will desalt enough water for 7705 homes.

Beyond breakeven! Could this be called Net Water? 🙂

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vansig wrote: you might be able to do a lot using proton bombardment

… well, at least in current concepts, protons are what the accelerators are supposed to be accelerating. They are fired into a target just in front of the waste and the spray of neurons spalled off of the target are what actually do the transmuting.

But currently such plans are hobbled both by energy costs and by proposed fixes that try to recover some of the heat generated during the process as electricity to help power the accelerators.

And, again, FF shortcuts the vicious cycle: simply power the accelerators and be done with it.

It will be a big, big project and much engineering will need to be done but that is true of any plan that would actually reduce the waste.

What aneutronic fusion brings to the table is greatly reduced cost and greatly increased safety from the dual whammy of dirt-cheap power… and not having to make the waste a part of the power system.

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delt0r wrote: Desalination is much less energy intensive than boiling water. Because that steam can be used to heat the incoming water. ie recycle the heat.

Certainly, more efficient engineering will reduce water costs further. It’s just that a straightforward method makes for a nice upper limit on BOTE calculations… “The final product cost should be no more than $X” 🙂

delt0r wrote: Staged flash desalination needs a “lot” of power but its all low grade heat (less than 100C since it runs at partial vacuum) and it is *way* less than the latent heat requirement to vaporize the water processed.

But the cost of the water rises because of the costs of the vacuum chambers, associated gear and maintenance… and FF units would have power to spare.

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delt0r wrote: At 1% output power, activation is something that happens and that matters. It is not background. But it is manageable.

Ah, I was referring to pB11, boron fusion, which is estimated to have less than 0.2% of its energy in neutrons. My apologies… I was being pB11-centric 🙂

Less than 1% is just the cutoff point above which a particular reaction is not considered to be aneutronic… the actual percentage can be much lower than that and pB11 is the only aneutronic contender being researched at all.

BTW, “less than background” only refers to conditions outside the shield, which is a meter of water, some B10 and with a layer of lead as the final backstop.

delt0r wrote: Even much less than 1% (say kW or even 100W ) of neutron power over long term needs to be considered. aka Activation and corrosion modes of materials…

… and LPP has calculated that an end-of-life core (actually, a pre-recycling core) will have the the radiation output of a classroom of kindergarteners.

(I didn’t know that school lunch programs could still afford bananas…)

That’s not radioactive waste… that’s a paperweight 🙂

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Mike Weber Goodenow wrote: Extremely interesting. $25 to $30 million for a generator, within 5 years of a successful test, which may be 3 months away? That’s fascinating.

But is a generator different than an electric power plant?

With aneutronic fusion the generator would be tied closely to the structure of the reactor so all you’d need is the cooling gear, the electrical distribution gear, a weather housing and a fence to keep people away from the high voltage.

It wouldn’t be like a fission or neutronic fusion plant, which needs to have all the expensive turbine and accessory gear of a coal-fired plant adjacent to the reactor.

Theoretically you could stuff one or two 5 MWe FF units, cooling gear and transformers into a standard 40 foot shipping container for a complete portable genset.

Other aneutronic contenders such as Polywell would be intrinsically larger but would still be far smaller than any fossil, fission or neutronic fusion plant.

Mike Weber Goodenow wrote: If so, would a clean fusion (aneutronic) electric power plant still be $100 to $200 million?

Depends on the device… last estimate I remember for a Focus Fusion 5 MWe unit was $300,000 dollars. Add cooling, power distribution, land and fence and I can’t see it costing any more the $6-700,000. Add another FF unit or three and you’d get a nice equivalent of a self-powered suburban 20 MWe substation for maybe $1.6 million?

A Polywell was estimated to cost about $100 million but they are supposed to start out at 100 MWe and scale up rapidly from there.

Aneutronic means really cheap power plants 🙂

Mike Weber Goodenow wrote: What can you do with the generator?

… add cooling (air-cooled for FF), distribution gear, land and a fence… or a shipping container…

Attached find a rough outline of a 5 MWe FF unit such as you might find powering a neighborhood, a commercial complex or a manufacturing plant.

side note:
For the FF’s moderate heat output the cooling solution shown here is a bit overblown (literally 🙂 ) but it keeps people from freaking themselves out with the notion that heat from the plant is somehow going to turn nearby people into beef jerky…. elsewhere in the forum you’ll find schemes where I take the cooling to ridiculous heights just to show that it isn’t the problem that people can scare themselves into thinking it might be.

This design would have air from the stack carrying ~7 MWt from the plant at 600 degrees C… and the stack parameters are over and above those for a commercial portable 20 MWe gas turbine genset which has a stack exhaust temp of ~900 C. Cooling ain’t a problem for FF plants.

Attached files

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… late night thought…

… and wouldn’t that be an ironic sight? An iconic sight? A decommissioned fission plant at night dotted with a couple of dozen FF units and none of them contributing to the grid. Because they don’t have to, the grid’s taken care of by other FF units elsewhere. A few of the units would be keeping the waste cooled while the rest powered the transmuters, the particle accelerators that “age” the waste into something we and the planet can live with.

And it will have to go on for decades. At each plant. All that power just to hold the line and clean up the mess…. but aneutronic fusion would give us that power and buy us the time we need. The power and the time to clean up the mess safely and affordably.

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vansig wrote:

Before he died in 2007, Robert Bussard claimed that given 6 years and up to $200 million he and his team could build the world’s first real net-power clean fusion system electric power plant.

Is this true today of the ECM2 team or any other team? If not, what is the best guess?

as far as i know, scaling parameters for polywell have not changed

LPP said they think that it’ll take about 5 years to get a generator after feasibility is demonstrated… and that test is hoped to happen early 2012.

And I think I recall Lerner-hakase saying that the generator development should cost about $25-30 million.

Now can anyone figure out if Tri-alpha is just flirting with neutronic fusion om the way to aneutronic… or have they simply given up on getting to aneutronic with their device?

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Tulse wrote:

In fact anyone can generate neutrons. All you need is electricity.

Yes, but aneutronic fusion does not have some special advantage in radioactive waste transmutation [em]beyond[/em] producing cheap power. There is nothing [em]inherent[/em] in the aneutronic fusion process that makes it a good way to clean up radioactive waste.

While neutronic fusion… tritium and steam and turbines… makes a waste solution [em]possible[/em] it is not a particularly good solution and it integrates the waste problem into the power system.

It’s better than nothing, it’s even better than thorium and if neutronic is all we can get we’ll have to take it.

But if aneutronic fusion is achieved then it becomes the best waste solution hands down. As you say, the pB11 reaction itself can’t do anything about the waste. But as with so many other problems we face a source of really cheap and really safe power makes a better, safer solution not only possible but inevitable.

Just the savings and safety benefits from not having to integrate the waste into the power supply means that aneutronic would win this one hands down. Again 🙂

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