3 ms·

>> How much extra energy is needed to keep the lead-lithium melted You misunderstand. The energy from the fusion is taken up by the molten lead -- which is the

>> How much extra energy is needed to keep the lead-lithium melted You misunderstand. The energy from the fusion is taken up by the molten lead -- which is then used in a heat exchanger, like the present fission reactors etc. (The steam pistons also get their energy from the created heat. It seems unlikely that accelerating all those steam pistons won't be the major energy cost in the system, but sure -- pumping lead is hardly easy. But five times more than the pistons?) So the thing missing from an experimental power plant is a heat exchanger, like fission etc power plants. (And sure, lead is less fun than water!) I assume THAT is what you missed and assumed was a major problem? From what I've read, the proposed experimental system will (if it works) not be built to last for long, it is experimental. But again -- the energy system needed for this to be an experimental power plant is very similar to most other power plants that work by heating a medium. Work has been done on much worse than lead (see liquid sodium!). (About not being built to last: There are lots of moving parts, but those should probably not be a show stopper; boat engine pistons work for quite a while.)

dalke 12y ago
I don't misunderstand. There's heat flow loss out of the body of the reactor. How much is this loss, compared to the amount generated? What I'm missing are numbers: how much power do they expect to generate from fusion, how much power do they think it will take to run the full prototype system, and what's the operating temperature; ideally as part of a Sankey diagram. I think this isn't available because they simply don't know. Again I ask, was Chicago Pile #1 a nuclear power plant? If not, what was the first nuclear power plant, and what distinguishes a power plant from other sorts of nuclear reactors? I think it must generate at least enough power to be be self-sustaining to qualify as a power plant. I therefore believe this General Fusion system, when built, will be an experimental fusion reactor used to develop the principles leading to a fusion power plant, but will not itself be a fusion power plant, experimental or otherwise. BTW, the Wikipedia page says "They hope to have a working reactor by 2020", which is of course 6 years after Asimov's prediction. The WP does not give a source for that information.
- BugBrother 12y ago
  First I'll note that the remaining problems seems to be engineering more than plasma physics -- and most of the show stoppers seems to be solved. If that don't make you go "wow", well... >>what distinguishes a power plant from other sorts of nuclear reactors? Again: I argued the main difference here is connecting a heat exchanger, you had nothing to say? >>What I'm missing are numbers: how much power do they expect to generate from fusion Again: The target is 6X the used energy for the pistons, according to the presentation. (It is a private company, details for investors.) (You know the number of pistons, their size/speed. That should be enough to make a good guess on the target energy from fusion. You can also guess quite well the volume of the lead and hence wuite a bit of the pumping needs.) There are other GF sources on the internet over the last few years, but since you ignore what I write please check them yourself.
  - dalke 12y ago
    My apologies. I did overlook your mention of a heat exchanger as being the requirement for a power reactor. To me a heat exchanger is something which moves heat from one medium to the other, and is not necessarily part of power production. The radiator in a car is a heat exchanger, and not a power generator. Thus, I did not understand your viewpoint. Quoting from the first link you gave: "Pumped through a heat exchanger, that hot lead will help generate steam just like a conventional thermal power plant". Thus, I consider it as not a power plant, because it only produces steam. While I see that you consider the production of steam to be sufficient, likely because it reduces the issue to a previously solved problem. I am satisfied that the General Fusion design, which hasn't even started, is not a nuclear fusion power plant of the sort that Asimov predicted would be available by 2014. That is my primary interest in this discussion. FWIW, after more looking around, I found this quote from http://www.technologyreview.com/news/414559/a-new-approach-to-fusion/page/2/ http://www.technologyreview.com/news/414559/a-new-approach-t... : > However, if the company can pull off its test reactor, it hopes to attract enough attention to easily raise the $500 million for a demonstration power plant. Note how that magazine author also distinguishes between "test reactor" and "demonstration power plant"? The information I found are not sufficient to make the estimates that you mentioned. For example, while I found pictures of the small sphere experimental setup, and a mention that the final velocity is 50 m/s, I did not find learn the mass of the piston, or equivalently the amount of power used to drive it. Nor did I find out how much power goes into the plasma injectors. There are images of some pretty hefty capacitor banks, but I couldn't tell if they are discharged at once, or if they are rotated through in order to lengthen the charge time for any one bank of capacitors. Estimating the pumping needs is very complicated. I found no reference of what the internal surface of the sphere looks like. If liquid extends into each piston then there well be turbulence at each interface, causing power loss. Even if it's laminar, I still need to know the rotational speed. The depictions I've seen show that the lead surface is a near cylinder, which means a very high speed, as the natural shape of a rotating fluid is a parabola. Assuming 0.25 meter radius for the upper part of the cylinder and a height of 3 meters gives 400-500 Hz. That seems rather a lot, given that they're talking about some 50 cubic meters of lead, or 500 tons, moving at some 2,000 m/s. (I used the equation for a liquid mirror telescope: h = 1/(2g) * (omega * r) ^ 2. Hopefully I didn't calculate it incorrectly.) Since the information I've found doesn't make sense, either my math is wrong, or the information I've found is incomplete. Since you are the one who believes that this is a near-term power plant, then surely you must have worked out these details already, or read them some place. That is, how fast is the molten lead mixture supposed to rotate, and how much energy is needed to keep it at that speed?

dalke 12y ago

I don't misunderstand. There's heat flow loss out of the body of the reactor. How much is this loss, compared to the amount generated? What I'm missing are numbers: how much power do they expect to generate from fusion, how much power do they think it will take to run the full prototype system, and what's the operating temperature; ideally as part of a Sankey diagram. I think this isn't available because they simply don't know. Again I ask, was Chicago Pile #1 a nuclear power plant? If not, what was the first nuclear power plant, and what distinguishes a power plant from other sorts of nuclear reactors? I think it must generate at least enough power to be be self-sustaining to qualify as a power plant. I therefore believe this General Fusion system, when built, will be an experimental fusion reactor used to develop the principles leading to a fusion power plant, but will not itself be a fusion power plant, experimental or otherwise. BTW, the Wikipedia page says "They hope to have a working reactor by 2020", which is of course 6 years after Asimov's prediction. The WP does not give a source for that information.

BugBrother 12y ago
First I'll note that the remaining problems seems to be engineering more than plasma physics -- and most of the show stoppers seems to be solved. If that don't make you go "wow", well... >>what distinguishes a power plant from other sorts of nuclear reactors? Again: I argued the main difference here is connecting a heat exchanger, you had nothing to say? >>What I'm missing are numbers: how much power do they expect to generate from fusion Again: The target is 6X the used energy for the pistons, according to the presentation. (It is a private company, details for investors.) (You know the number of pistons, their size/speed. That should be enough to make a good guess on the target energy from fusion. You can also guess quite well the volume of the lead and hence wuite a bit of the pumping needs.) There are other GF sources on the internet over the last few years, but since you ignore what I write please check them yourself.
- dalke 12y ago
  My apologies. I did overlook your mention of a heat exchanger as being the requirement for a power reactor. To me a heat exchanger is something which moves heat from one medium to the other, and is not necessarily part of power production. The radiator in a car is a heat exchanger, and not a power generator. Thus, I did not understand your viewpoint. Quoting from the first link you gave: "Pumped through a heat exchanger, that hot lead will help generate steam just like a conventional thermal power plant". Thus, I consider it as not a power plant, because it only produces steam. While I see that you consider the production of steam to be sufficient, likely because it reduces the issue to a previously solved problem. I am satisfied that the General Fusion design, which hasn't even started, is not a nuclear fusion power plant of the sort that Asimov predicted would be available by 2014. That is my primary interest in this discussion. FWIW, after more looking around, I found this quote from http://www.technologyreview.com/news/414559/a-new-approach-to-fusion/page/2/ http://www.technologyreview.com/news/414559/a-new-approach-t... : > However, if the company can pull off its test reactor, it hopes to attract enough attention to easily raise the $500 million for a demonstration power plant. Note how that magazine author also distinguishes between "test reactor" and "demonstration power plant"? The information I found are not sufficient to make the estimates that you mentioned. For example, while I found pictures of the small sphere experimental setup, and a mention that the final velocity is 50 m/s, I did not find learn the mass of the piston, or equivalently the amount of power used to drive it. Nor did I find out how much power goes into the plasma injectors. There are images of some pretty hefty capacitor banks, but I couldn't tell if they are discharged at once, or if they are rotated through in order to lengthen the charge time for any one bank of capacitors. Estimating the pumping needs is very complicated. I found no reference of what the internal surface of the sphere looks like. If liquid extends into each piston then there well be turbulence at each interface, causing power loss. Even if it's laminar, I still need to know the rotational speed. The depictions I've seen show that the lead surface is a near cylinder, which means a very high speed, as the natural shape of a rotating fluid is a parabola. Assuming 0.25 meter radius for the upper part of the cylinder and a height of 3 meters gives 400-500 Hz. That seems rather a lot, given that they're talking about some 50 cubic meters of lead, or 500 tons, moving at some 2,000 m/s. (I used the equation for a liquid mirror telescope: h = 1/(2g) * (omega * r) ^ 2. Hopefully I didn't calculate it incorrectly.) Since the information I've found doesn't make sense, either my math is wrong, or the information I've found is incomplete. Since you are the one who believes that this is a near-term power plant, then surely you must have worked out these details already, or read them some place. That is, how fast is the molten lead mixture supposed to rotate, and how much energy is needed to keep it at that speed?