[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.