edit: I got confused about which forum I was posting in, this probably should be in theory, or maybe general, instead of news. If a moderator wants to move it, that might be appropriate. Sorry.
I notice that many of the posters on this forum view ITER as a large black hole, and view it as never being economically viable. I believe that Bussard expressed a similar view in the Google Video.
My question is, I know that there are physics reasons why the reactor chamber has to be physically large, but as for the costs of building Tokamak reactors (if Polywell doesn't work as well as hoped), is there some reason they won't scale down over time?
What I mean is, I've heard the argument for large research projects like the ITER (and I've probably heard this argument specifically about ITER, but not sure), that the first reactor is extremely expensive because you need to do a lot of basic science, materials science, engineering work, etc, but that once the first one is built, you can leverage the investments you made in the first one to build additional ones cheaper.
If every Tokamak would cost nearly as much as ITER (what's it up to now? 15bn Euro and counting?), then Tokamak definitely can't compete with Coal and Gas plants which can be built for, what, less than $100M? But is there any reason the costs of a Tokamak can't soon come down to more competitive costs, after you've built and proved the first one?
Does a commercial power plant need to be as physically large as ITER? I'm not asking about the reactor itself, I'm assuming the reactor in a commercial plant will likely be as large or larger than the ITER reactor to get a large enough amount of net power, but instead, what I'm asking is that the reactor itself is, I suppose, only a relatively small amount of the physical space allocated for the ITER campus (I assume there is a lot of scientific labs, measurement instruments, maybe office buildings, etc in ITER which a commercial power plant would not have)?
Cost scale-down on Tokamak?
My understanding of ITER: not only will the construction of a powerplant be high compared to nuclear/coal, but neutron degradation of the reactor means you have to replace it every several months. This is the D-T reaction which produces lots of energetic neutrons. An ITER-style reactor will produce gold-plated electricity at very high cost. Many other, far more economical, alternatives exist.
Well from what I understand (note: not a nuclear physicist), there are several issues with the Tokamaks:
1. They can never work with aneutronic fuels. That means that the materials will suffer from the neutron bombardement. They have to be replaced often and be treated as nuclear waste (all expensive).
2. You need to breed Tritium. That is complicated, needs Lithium and makes the reactor more complicated (more parts that have to be replaced and maintained frequently which costs money).
3. As you mentioned, they are also quite big. I am not sure that they can get much smaller.
1. They can never work with aneutronic fuels. That means that the materials will suffer from the neutron bombardement. They have to be replaced often and be treated as nuclear waste (all expensive).
2. You need to breed Tritium. That is complicated, needs Lithium and makes the reactor more complicated (more parts that have to be replaced and maintained frequently which costs money).
3. As you mentioned, they are also quite big. I am not sure that they can get much smaller.
Re: Cost scale-down on Tokamak?
[quote="jsbiff"]
Does a commercial power plant need to be as physically large as ITER? ....
My understanding is that yes, a commercial plant needs to be a little large than ITER. I believe DEMO is only supposed to be ~ 20% larger (in volume?), so a commercial plant would probably be a little larger than that. Certainly a commercial plant could benefit from all that had been learned before and there might be significant savings in the ancillary equipment and reduced capital costs with assembly line techniques. But, remember ITER does not incorporate any effort to generate tritium insitu. This will be a difficult, and probably very expensive process.
Also, keep in mind that due to scaling issues, by the time the machines reach breakeven they are huge and to justify the capital costs, each plant will need to produce a lot of power. I have heard that this may be in the range of 7-10 GW. This introduces a lot of problems for utilities in distributing the power as long power lines eats into the power delivered and thus the cost. So, if Tokamaks are ever successful from an economic standpoint, the significantly increased costs will have to be acceptable. Even renewables like solar and wind, even with storage considerations may end up being considerably cheaper than tokamak sourced electricity.
Smaller and thus cheaper fusion approaches (if any ever work) have many advantages, in terms of redundancy, grid considerations, capital and probably maintenance costs/KwH delivered, etc.
Take Dense Plasma Focus for example. They are projected to produce only limited power past breakeven, but they are very small, cheap, easy to replace and to build in large numbers, depending on needs. Polywells are larger (but still much smaller than Tokamaks), but probably have significantly less maintainance costs compared to DPF, and both could hopefully avoid the extreme complications of needing to generate tritium from neutron bombardment. I would guess that FRC plants would be less economical than Polywells, mostly because they probably will have smaller net power gains than Polywells, perhaps similar to DPF (but not the cheapness of DPF). Even if they only work with deuterium- deuterium fuel, that is a large advantage. Add the benefits of aneutronic fuels and direct conversion, and, at least potentially, the costs per KwH are much less than the cost of coal plants.
Even if succesful, tokamaks have a lot of economical hurdles to overcome. That doesn't necessarily mean that some other modified tokamak or stellorator like solution might not win out in the end.
Dan Tibbets
Does a commercial power plant need to be as physically large as ITER? ....
My understanding is that yes, a commercial plant needs to be a little large than ITER. I believe DEMO is only supposed to be ~ 20% larger (in volume?), so a commercial plant would probably be a little larger than that. Certainly a commercial plant could benefit from all that had been learned before and there might be significant savings in the ancillary equipment and reduced capital costs with assembly line techniques. But, remember ITER does not incorporate any effort to generate tritium insitu. This will be a difficult, and probably very expensive process.
Also, keep in mind that due to scaling issues, by the time the machines reach breakeven they are huge and to justify the capital costs, each plant will need to produce a lot of power. I have heard that this may be in the range of 7-10 GW. This introduces a lot of problems for utilities in distributing the power as long power lines eats into the power delivered and thus the cost. So, if Tokamaks are ever successful from an economic standpoint, the significantly increased costs will have to be acceptable. Even renewables like solar and wind, even with storage considerations may end up being considerably cheaper than tokamak sourced electricity.
Smaller and thus cheaper fusion approaches (if any ever work) have many advantages, in terms of redundancy, grid considerations, capital and probably maintenance costs/KwH delivered, etc.
Take Dense Plasma Focus for example. They are projected to produce only limited power past breakeven, but they are very small, cheap, easy to replace and to build in large numbers, depending on needs. Polywells are larger (but still much smaller than Tokamaks), but probably have significantly less maintainance costs compared to DPF, and both could hopefully avoid the extreme complications of needing to generate tritium from neutron bombardment. I would guess that FRC plants would be less economical than Polywells, mostly because they probably will have smaller net power gains than Polywells, perhaps similar to DPF (but not the cheapness of DPF). Even if they only work with deuterium- deuterium fuel, that is a large advantage. Add the benefits of aneutronic fuels and direct conversion, and, at least potentially, the costs per KwH are much less than the cost of coal plants.
Even if succesful, tokamaks have a lot of economical hurdles to overcome. That doesn't necessarily mean that some other modified tokamak or stellorator like solution might not win out in the end.
Dan Tibbets
To error is human... and I'm very human.
Re: Cost scale-down on Tokamak?
I just want to ask for a clarification - are you talking about the entire size of the plant/campus, or *just* the reactor. A statement like ~20% larger (in volume) sounds like you are talking about just the reactor.D Tibbets wrote:My understanding is that yes, a commercial plant needs to be a little large than ITER. I believe DEMO is only supposed to be ~ 20% larger (in volume?), so a commercial plant would probably be a little larger than that.jsbiff wrote: Does a commercial power plant need to be as physically large as ITER? ....
I was asking about the total footprint on the ground of the buildings. The reactor, of course, takes space inside a reactor building of some sort, but the size of a power plant is more than just the size of the reactor. I don't know what all would be part of a power plant, but at the very least, you have the reactor itself, plus steam piping, plus steam turbines (at least for a thermal plant, which I believe tokamaks are[?]), plus things like large tranformers for interfacing with the grid), possibly a security building, maintenance building, fuel storage tanks, etc.
So, the question was, basically, are there a lot of non-power-generating related buildings (science labs, office buidings, etc) that are part of ITER? I've seen pictures of the cleared 'slab' that has been constructed as stage one of ITER and it is absolutely massive - like a very large football stadium or convention center, or a small airport. It got me to wondering if all Tokamaks would have such a huge footprint, or if ITER, because it is a *research* project, might have a lot of buildings/space in the design that a commercial plant wouldn't?
I just can't imagine finding sites for hundreds or thousands of power plants that huge in/near urbanized areas of the U.S. or Europe. Especially since most folks will probably have a NIMBY view of these things (even though they are significantly safer than fission plants, since they *do* produce radioactivity, people *will* be afraid of these things).
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CaptainBeowulf
- Posts: 498
- Joined: Sat Nov 07, 2009 12:35 am
I have less to say than the others, but:
1. I don't think ITER will even be a useful science experiment if its funding is cut back greatly. If you're going to do it, at least spend all the money and get as much data as you can. The more we know about how to handle plasmas, the better.
1a. This doesn't mean that Tokamak supporters should try to get funding for other lines of research quashed. They should just try to get what they asked for originally and then do their science project without playing politics.
2. Once all the problems are understood, the design is tweaked, and is then put into "mass production" ("mass production" is relative - in the case of an ITER/DEMO follow-on it would be maybe dozens of units) economies of scale to come into effect, to some extent. A mature design should become cheaper over its lifetime, unless so few are built that everyone stops making the required parts after the initial production run. Once the parts are no longer made it becomes very expensive to restart production (the problem with, say, resurrecting a Saturn V).
3. I doubt tokamaks will become cost-effective unless a smaller design like a stellarator is achieved.
1. I don't think ITER will even be a useful science experiment if its funding is cut back greatly. If you're going to do it, at least spend all the money and get as much data as you can. The more we know about how to handle plasmas, the better.
1a. This doesn't mean that Tokamak supporters should try to get funding for other lines of research quashed. They should just try to get what they asked for originally and then do their science project without playing politics.
2. Once all the problems are understood, the design is tweaked, and is then put into "mass production" ("mass production" is relative - in the case of an ITER/DEMO follow-on it would be maybe dozens of units) economies of scale to come into effect, to some extent. A mature design should become cheaper over its lifetime, unless so few are built that everyone stops making the required parts after the initial production run. Once the parts are no longer made it becomes very expensive to restart production (the problem with, say, resurrecting a Saturn V).
3. I doubt tokamaks will become cost-effective unless a smaller design like a stellarator is achieved.
Tokamaks, Spheromaks, etc. are subject to the same types of breakthroughs in magnetics that polywells are. If inexpensive, high flux SCs are developed, it may be that a commercial plant would become economical. Indeed, it is even plausible that sufficient advances may be made to make p11B a possibility even with a Tokamak. Maybe. It could happen. With some real breakthroughs.
I was referring to the size of the reactor (and presumably the magnet arrays).
In a production machine some scientific equipment may be deleted. But, not included in ITER is any concideration of what is nessisary for tritium breeding. This may require additional layers of complexity, size, and cost. Also, I believe that diverter technology will not be addressed untill DEMO. This will also require Herculean efforts to make it work, though if it ever reaches a production machine this may not require enormous costs past that of the prototype stage.
Dan Tibbets
In a production machine some scientific equipment may be deleted. But, not included in ITER is any concideration of what is nessisary for tritium breeding. This may require additional layers of complexity, size, and cost. Also, I believe that diverter technology will not be addressed untill DEMO. This will also require Herculean efforts to make it work, though if it ever reaches a production machine this may not require enormous costs past that of the prototype stage.
Dan Tibbets
To error is human... and I'm very human.
jsbiff,
If they expect this to happen, the folks at ARES (beyond ITER/DEMO) haven't told us. Their most advanced PowerPoint slides are still an order of magnitude below LWRs in plant power density. I'd have to check just how optimistic their assumptions were.
I think it's a low beta problem (i.e. they don't scale as well), but someone else can chime in if they're more toknowledgable.
If they expect this to happen, the folks at ARES (beyond ITER/DEMO) haven't told us. Their most advanced PowerPoint slides are still an order of magnitude below LWRs in plant power density. I'd have to check just how optimistic their assumptions were.
I think it's a low beta problem (i.e. they don't scale as well), but someone else can chime in if they're more toknowledgable.
n*kBolt*Te = B**2/(2*mu0) and B^.25 loss scaling? Or not so much? Hopefully we'll know soon...
a. This doesn't mean that Tokamak supporters should try to get funding for other lines of research quashed. They should just try to get what they asked for originally and then do their science project without playing politics.
With the amount of funds needed and the long horizon for economic payback they HAVE to play politics.
Engineering is the art of making what you want from what you can get at a profit.