[maccam94]

IIRC, when ITER was conceived, it wasn't a waste of money. They just chose a conservative development path that was expensive but very likely achievable. Technology and theories have since advanced that might leapfrog it, but the project has still contributed a great deal to our understanding of fusion and the engineering required to produce it.

Relevant talk by one of the MIT professors working with Commonwealth Fusion Systems:

Breakthrough in Nuclear Fusion? - Prof. Dennis Whyte (2016) - https://www.youtube.com/watch?v=KkpqA8yG9T4

Timeline (in case you want to skip over some parts):

  00:01:00 - introducing Dennis Whyte, MIT department head for nuclear science
  00:04:24 - presentation starts
  00:06:00 - identifies breakthrough with REBCO magnets
  00:07:25 - explains deuterium-tritium fusion
  00:12:30 - basic metrics for reactor performance
  00:17:15 - energy output of other previous fusion experiments
  00:19:00 - examines ITER and the problems of its approach
  00:22:00 - problems solved by high energy magnetic fields
  00:28:15 - full scale reactor concept, teardown of REBCO magnets
  00:37:00 - design limits and margins
  00:39:00 - fixes plasma instabilities found in weaker magnetic chambers
  00:40:00 - maintainability, lifespan, component replacement
  00:45:00 - solution to neutron damage and energy capture
  00:50:30 - cost and profitability
  00:54:00 - full graph of field strength vs reactor scale (and thus funding requirements)
  01:01:50 - Q&A
  01:30:00 - question about the biggest risks

A more recent (2019) talk with more numbers and even more confidence: https://www.youtube.com/watch?v=rY6U4wB-oYM

[sgift]

> Technology and theories have since advanced that might leapfrog it

With "might" being the operative word. As long as none of these new approaches has achieved viable fusion (so, more power out than in) I think it's not a bad idea to just continue with the less radical plan that will probably work, even if it is slower.

[xorcist]

ITER is research. There are numerous engineering problems yet to be solved, plasma physics, materials science, you name it. Research projects are always a "waste of money" in some way so that particular criticism is neither surprising nor very helpful.