Wouldn't the major differentiator be the safety standards?
You can't have a runaway reaction, because you need energy input to the magnet field to get more energy out. Instead of creating the right environment to get a chain reaction started if your control rods end up in the wrong place. Drop the magnet field and it all collapses.
Even if you lose control of it with the magnet field on the quantity is limited, tokamaks can only sustain bursts before going unstable. Wendelstein like designs would also be limited by the quantity contained.
If everything goes completely wrong you simply end up with a dirty bomb from the neutron bombarded core material and an initial burst of radiation. Sure not amazing but not a meltdown releasing vast quantities of heavy radioactive decay materials which can leach into the environment. Remember, fission is messy, it's not a chemical reaction where A+B = C. You get a spread of materials and energies, as seen by the Z number here. [0]
Essentially, you can at any point do an unsafe abort which might damage something or if everything aligns it's no more than a dirty bomb, but you will never lose control. Your Swiss cheese model needs to have far fewer and simpler layers compared to fission, vastly bringing at least those costs down.
I'm still betting on renewables for the near future, but my guess is at least harnessing fusion will have a place for projects with extremely specific goals in the 50-100 year timescale.
We can make fission plants that are also immune to run away reactions. Even with old designs, you have to do something really stupid like have nightshift take out all your control rods to get a run away reaction.
While the fusion reaction itself isn't very dangerous, the magnetic coils in a fusion reactor can potentially quench, causing them to explode, which because of their position will throw radioactive debris from the irradiated reactor vessel all over the place, as well as your tritium breeding blanket which will be highly flammable, toxic, and a bit radioactive. Worse, you can't make the magnets passively-safe.
Then there are the standard issues like tritium release. And you have nuclear proliferation concerns as a fusion reactor is great at making plutonium by just doping the tritium breeding blanket with some natural uranium. In fact, the first "fusion" reactors will probably do this anyways as they need to produce more tritium to get more reactors online and because this dramatically increases power output - so you get all the fun of dealing with fission products too.
I would be willing to bet complying with the safety standards for fusion will in fact be more expensive than for fission. Yes the general population doesn't have the same irrational fear of fusion that it has of fission, but once people start seriously proposing to put these in people's backyards that will likely change.
Fusion will still require a containment building because of tritium and because of the pressure from volatilized cryogenic coolants. The building will also require very strict control of tritium escape in normal operation. Remember, a 1 DW(e) DT reactor will burn enough tritium in one year to contaminate 2 months total flow of the Mississippi river above the legal limit for drinking water.
Fusion will also require highly reliable equipement, just like fission. Not because of safety, but because the fusion reactor will be complicated and very difficult to repair. The reactor itself, even the magnets, will be irradiated and activated beyond the point where hands on maintenance could be performed.
You can't have a runaway reaction, because you need energy input to the magnet field to get more energy out. Instead of creating the right environment to get a chain reaction started if your control rods end up in the wrong place. Drop the magnet field and it all collapses.
Even if you lose control of it with the magnet field on the quantity is limited, tokamaks can only sustain bursts before going unstable. Wendelstein like designs would also be limited by the quantity contained.
If everything goes completely wrong you simply end up with a dirty bomb from the neutron bombarded core material and an initial burst of radiation. Sure not amazing but not a meltdown releasing vast quantities of heavy radioactive decay materials which can leach into the environment. Remember, fission is messy, it's not a chemical reaction where A+B = C. You get a spread of materials and energies, as seen by the Z number here. [0]
Essentially, you can at any point do an unsafe abort which might damage something or if everything aligns it's no more than a dirty bomb, but you will never lose control. Your Swiss cheese model needs to have far fewer and simpler layers compared to fission, vastly bringing at least those costs down.
I'm still betting on renewables for the near future, but my guess is at least harnessing fusion will have a place for projects with extremely specific goals in the 50-100 year timescale.
[0]: https://upload.wikimedia.org/wikipedia/commons/thumb/6/68/Th...