E Ireland wrote:
Its not really fair to use ITER to damn Tokamaks.
It is not built as a power plant - its built to show that ignition in a Tokamak is actually possible and very little else.
What basis do you have for this assertion? Do you think a power generator needs 1% the equipment of the test reactor? Do you think adding power generating machinery will reduce the cost to 1%?
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Plasma Physicists have been burned enough times by claims that they are building the most conservative machine they could possibly concieve. Its massively overengineered.
You and I have different definitions of massively overengineered. A pressure vessel that operates at 5% its rupture strength is massively overengineered. A powerplant that with state of the art technology that can't be expected to last for more than 10 minutes at this point in time, is not massively overengineered. Recent estimates for the carbon composite helium exhaust suggest it would between 3 weeks and 3 months.
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Also DEMO is only projected to have ~45% greater volume but also have a thermal output of ~2000MWt.
If the scaling rules work this time the reactors will get very big very rapidly.
Scaling rules don't seem to work for PWRs. Small ones were built for $200/kWe in the early days. Now big ones cost over $5000/kWe. Clearly other factors determine cost.
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And thanks to the low pressure differentials across the reactor walls we can build enormous vessels.
Enormous vessels and low plasma power density are part of the cost problem. You can't have a small vessel anyway because most of the energy is emanating through the reactor vessel. Its like trying to generate power with a PWR but in stead of a tube-and-shell steam generator you're only allowed to use the main pressure vessel as the steam generator!!
I'm willing to buy into a scaleup law of 2x cost reduction per Watt, and another 2x for improved efficiency and reduced self consumption. This still puts you at $125/Watt. Maybe you can cut it in half again by eliminating the experimental stuff that you don't need in a power generator. Still $62/Watt. See how hard it is to get within the realm of coal or LWRs even if you assume big improvements?