U.S. to Rejoin the ITER Fusion Project

spiro_killglance writes: "BBC news is reporting here, that the USA may be about the rejoin the International Thermonuclear Experiment Reactor project. The USA left the ITER consortinum in 1999 when it bulked at the 10 Billion dollar price tag. Canada, Europe and Japan continued in the project, downscaling it to a cheaper 4.5 Billion dollars. The project claims to be the final step before commcercial reactors are possible, although the price tags might still be daunting to utility companies. ITER is designed to generate bursts of fusion energy, producing over 10 times the ammount of energy used to generate the fusion reaction (a Q factor >10), will not quite reach ignition (a self sustaining fusion reaction, or Q=infinity), but should pave the way for devices that will."

Comments

Fusion reactor

[bofh31337]

A common misconception about fusion reactor is that there are no negative byproducts of its use. this is simply not true. The tokamak fusion reactor would have extremely dangerous core due to neutron and proton radiation. You would have to have one heck of a system of shielding for this to be useful. Any thoughts on what would work best in the fuel?

Over-simplification

[Spamalamadingdong]

A common misconception about fusion reactor is that there are no negative byproducts of its use. this is simply not true.

Is there any technology which has no negative byproducts?

The tokamak fusion reactor would have extremely dangerous core due to neutron and proton radiation. You would have to have one heck of a system of shielding for this to be useful.

You could say the same thing about a solar furnace; the focus would be extremely dangerous due to thermal radiation. It doesn't mean that it isn't trivial to keep yourself safe from it. Direct neutron and proton radiation is simply not a problem. Indirect exposure, say from leakage of tritium or corrosion of used reactor parts, is another issue. Lots of chemical processes have nasty intermediate products, so it's not like industry doesn't have plenty of experience managing such things.

Any thoughts on what would work best in the fuel?

The easiest fuel to ignite is deuterium-tritium. If you are concerned about radioactive byproducts and you don't mind building a much bigger and more expensive reactor, you could use boron-11 and protium; B-11 + p -> 3 He-4 + . This would give you a neutron-free reaction, at the cost of very high temperatures required to ignite the plasma and very rapid heat loss due to X-rays from the multiply-ionized boron nuclei.

Plasmas almost can't get out of control

[TheBoquaz]

Work was done on this question at General Atomics last year. I believe it was found that adding a very small amount of neon to the plasma will stop the reaction in a matter of nanoseconds. With no harmfull effects at all. It effectively turns the reactor into one big neon light. It was quite a thing to see (via CCTV cameras in the reactor of course). With the cost of these reactors, they don't want the plasma to even touch the wall, let alone have the chance to eat through it. It's far easier to just add a little neon to the vessel, than to try to control any sort of energy surge. It took less than 5 minutes to have the reactor ready to go again, and it worked fine.