When in the last 70 years have we been building a reactor that we expect to generate net positive fusion power? I'm genuinely asking, I don't know if there is an answer.
In 1997, using this fuel, JET set the current world record for fusion output at 16 MW from an input of 24 MW of heating and a total input of 700-800 MW of electrical power. This is also the world record for Q, at 0.67. A Q of 1 is scientific breakeven, a point JET was not ultimately able to reach.
The Tokamak Fusion Test Reactor (TFTR) was an experimental tokamak built at Princeton Plasma Physics Laboratory (PPPL) circa 1980 and entering service in 1982. TFTR was designed with the explicit goal of reaching scientific breakeven, the point where the heat being released from the fusion reactions in the plasma is equal or greater than the heating being supplied to the plasma by external devices to warm it up.
The TFTR never achieved this goal, but it did produce major advances in confinement time and energy density.
JT-60 (short for Japan Torus-60) is a large research tokamak, the flagship of Japan's magnetic fusion program, previously run by the Japan Atomic Energy Research Institute (JAERI) and currently run by the Japan Atomic Energy Agency's (JAEA) Naka Fusion Institute in Ibaraki Prefecture. It is properly an advanced tokamak, including a D-shaped plasma cross-section and active feedback control.
First designed in the 1970s as the "Breakeven Plasma Test Facility" (BPTF), the goal of the system was to reach breakeven, a goal also set for the US's TFTR, the UK's JET and the Soviet T-15. JT-60 began operations in 1985, and like the TFTR and JET that began operations only shortly before it, JT-60 demonstrated performance far below predictions.
They did set the record. It doesn't sound like they were expecting to exceed breakeven, certainly not by a significant amount. It sounded like breakeven was a goal they thought possible. The wikipedia page calls it "successful".
Meanwhile ITER has this on their website:
"ITER is designed to produce a ten times return on invested energy: 500 MW of fusion power from 50 MW of input heating power (Q=10). It will be the first of all fusion experiments in history to produce net energy."
I don't think it will be considered successful if it doesn't break Q=1. The project is fully expecting to set this mark.
Did you see my edits? I made a few.
I didn't realize until today that ITER was planning on outputting a substantial amount of energy. 500 MW is about the capacity of a small fission reactor. That's more than I was expecting. If they actually achieve that figure, basically they're demonstrating a fission reactor capacity (for a very small amount of time). It's actually an even more ambitious project than I realized.
ITER began construction in 2007. First operation is set for 2025. That's a lead time of 18 years for the experimental reactor. Pricetag is $20B. Fission reactors probably cost 1/10th of that ($2B) or so for 500MW output. And they take about 5 years to build.
So price and time-wise it would not be prudent to build the exact same thing again for the purpose of producing power (unless they can blow way past 500MW). But it's actually not as far off as I would have expected.
The total electricity consumed by the reactor and facilities will range from 110 MW up to 620 MW peak for 30-second periods during plasma operation. Thermal-to-electric conversion is not included in the design because ITER will not produce sufficient power for net electrical production.
From what I understand, a ton of the electrical power consumed by a Tokamak is for cooling the superconducting magnets.