As some of you have heard—and as was mentioned in a semi-recent Straight Dope column—Lockheed Martin is currently developing a “compact” fusion reactor, which, if it all goes according to plan, would result in a 300+ ton, 100 MW generator small enough to fit on a (large) truck.
Now, I have a technical question, but on a more mundane angle…the reactor is planned to generate electricity in the conventional way, heating a working fluid that would drive a turbine system. I’m wondering: how big would that system—the turbines, cooling system, etc.—to generate 50-100 MW of electrical power, need to be, in size and mass? Could it be made as easily transportable as the reactor itself?
The only thing I could think to compare it to would be similar systems for portablenuclear reactors, which were relatively compact/portable, but produced much less electrical power.
That’s…it, I guess. Can anyone enlighten me? Oh, and now I’ve got “I Am The Starlight” stuck in my head. Great.
The steam cycle for a 100MW CCGT [which I’ve worked at] isn’t all that huge; it would be about the same size with a 100MW nuke. The problem is the heat rejection system - the condensers and cooling towers, or cooling water system. You’d need an open-loop system, requiring access to a large amount of cool water you could circulate through the condenser (don’t even think about an ACC…good grief, they are huge). So I rather think you would need something about the area of a small house, maybe 1500 square feet or so, less the heat rejection system.
I’m certain with a lot more investment and design you could shrink the size of the system, stack some components vertically, etc. Maybe you cut down on feedwater heaters. I think there are a lot of possible options. I have great difficulty seeing the entire plant, nuke+TG system fitting on a single standard flatbed.
If the reactor really weighs 300+ tons, that’s 600,000+ lbs. The max payload of a typical US semi truck is about 70K lbs. Max gross weight including the tractor and trailer is typically 80K lbs.
So we’re looking at 7 or 8 semi trailer loads. I’m not sure what the absolute max sixe for special purpose roadable heavy haul trucks is, but those also have pretty severe restrictions on where and how they move. So even if there was a truck system able to carry 600K lbs you would have a system that was roadable only in a very limited way, and not really “portable”.
So sort of like a much scaled up mobile home. IOW it *is *moveable from factory to location of use. It isn’t easily moved from place to place as portable living quarters like an RV is.
There wouldn’t be any. The article from Lockheed is not written by their engineering team. Lockheed, like a number of other groups, actually wants aneutronic fusion. Most of the energy is in escaping positively charged helium atoms. There is a way to construct a series of wire mesh decelerator grids that decelerate the helium and in doing so induce electric currents into the decelerator. Direct electricity output. Some big transformers for voltage shifts and you have your electric power bus.
That’s why the article mentions a C-130 able to fly for years - the only feasible way to make that work would actually be to use electricity. Superconducting wiring and motors would be needed, of course, coupling the output of the fusion reactor to superconducting motors that turn the propellers. Now, one problem that is a nasty one is the problem of side reactions that *do *produce neutrons. You could stick the reactor in the back of the plane and use a shadow shield, but how do you maintain it…
I mean, you could drive the C-130 out to a runway in a deserted area. Fire up the fusion reactor. Taxi away, the lethal stream of side reaction neutrons escaping the back and side of the aircraft but not affecting anyone. After landing, you’d shut down the reactor and greatly reduce the radiation dose, but the materials in the back of the plan would still be radioactive.
Frankly, that’s just marketing bull then. If there’s no way to deal with the radiation that doesn’t make the aircraft too heavy to fly, then it’s never going to be feasible.