An economical viable tokamak fusion reactor based on the ITER experience

This is my personal vision and outlook towards a fusion reactor based on my extensive experience from being part of the ITER design, and now construction, as well as leading the largest fusion technology program worldwide (KIT—Karlsruhe Institute of Technology) for 7 years. In particular, I want to discuss how a fusion reactor can be economically viable without employing too advanced physics and technology. It certainly will be a pulsed machine (approx. 20 000 s pulses) with thermal energy storage (turbine is steady state). I also want to discuss the optimum machine size and toroidal field for such a machine and why I think that high field and smaller plasmas may not necessarily make a fusion reactor more competitive. When one extrapolates from today's knowledge on ITER construction, even considering that ITER can be built much cheaper, it is clear that a fusion power plant will cost more than 10 or more likely more than 15 billion Euros/Dollars (the first of a kind even approx. 30 billion). Therefore, in order to have an economically attractive fusion reactor, it needs to produce a large amount of power (on the order of 2.5 GW electric). The possible size (R ∼ 10 m) and reasonably conservative physics basis of such a machine will be briefly described in the presentation. If we are successful in achieving advanced physics in a burning plasma, e.g. in ITER, then we can make the machine slightly smaller but the principal arguments for a large machine will not change significantly. Key technologies and their status will be discussed with particular emphasis on a realistic blanket and divertor design and the size and issues of a tritium-plant (T-plant) for such a machine as well as the challenges which have to be overcome beyond what is needed for ITER. Finally, a simple economic consideration will be discussed to show that a large machine could be economically viable, even in today's environment, in particular, in competition with renewables. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.