[CuriousCosmic]

It's really not. Inertial Confinement Fusion tests have already produced energy positive results quite a few times. The most recent ICF tests that made the rounds were notable because they were consistently repeatable.

i.e. we know a well defined lower bound on the conditions required for energy positive fusion.

These bounds are more or less what we expected so sustainable energy positive fusion is essentially guaranteed to be feasible, it's just ungodly expensive until we can learn how to reduce the lower bounds for fusion or improve our ability to achieve those conditions.

So ITER will work. There really isn't a discussion on whether ITER will work or not. Like technically there's a small fraction of a percent chance it won't work for a number or reasons but even then it's less likely to be "it will never work" and more "we need to make changes and it'll work eventually".

This is actually part of the reason for the updated baseline schedule. It's apparently going to be far more aggressive now that there are better assurances that the existing model is in line with experimental evidence.

[BirAdam]

So, there’s cost, sure. But from what I understand, ITER was only energy positive when one discounts everything involved in building and running it. That is, the energy positive result was essentially just containment and reaction, and not everything else needed. It’s a big jump from that to viable.

[CuriousCosmic]

That was the case for the ICF project at LLNL as the lasers used for confinement are grossly inefficient and it's a research facility but that's not the case for ITER to my understanding.

ITER won't be a power plant of course. It's a research facility first and foremost but it will produce power at a 10 to 1 ratio relative to the input which should be a net 450GW of power before you factor in the secondary equipment.

Containment and chilling will require quite a bit of energy of course but all together the energy usage for the reactor facilities should still be less than the produced power.

But yes ITER isn't designed to produce power out to the grid. It's just designed to work sustainably and any power it does produce will almost certainly just be sunk into a resistive load on site. It's a research project to build a viable nuclear power plant first and foremost.

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Then provided ITER doesn't outright fail, the DEMO reactor will be built and that facility will be optimized for power generation and will be built to the requirements to efficiently produce energy (vs ITER which is significantly overbuilt "to produce power at Q=10 so help me god"). The DEMO project will of course actually hook up to the grid with the intent of being a sustained base load power generator.