[cyberax]

They are not "inherently safe". Reactors that produce power (in large quantities) are dangerous because fission products are radioactive, and they produce energy even after the chain reaction stops. So once cooling is lost, these fission products can melt through the reactor vessel and escape the confinement.

Also, accelerator-driven reactors are just bonkers. They make no freaking sense for power generation. They are being investigated because they can produce very energetic neutrons, in quantities that are large enough to transmute some long-lived nuclear waste.

[kwhitefoot]

Are you implying that they do not produce more energy than they consume? Conventional commercial reactors release only a tiny fraction of the energy available in the fuel. Accelerator driven reactors make it possible to release more of it. They can also make effective use of thorium.

[cyberax]

No. I'm implying that they are completely impractical.

You need to have a system with cryogenic superconducting magnets and high vacuum within centimeters from a reactor producing at least hundreds of megawatts of power (if not gigawatts) within a volume of several cubic meters. You're basically constructing a fusion reactor at this point.

Oh, and parts of your accelerator close to the reactor will become activated, so you won't be able to do maintenance. ITER (the fusion reactor project) is planning to solve this problem using robots.

Fission reactors solve this by using VERY THICK pipes made of special steel, with careful inspection of every single weld. So once the vessel and its connections are placed, they stay inside the shielded area until it's time to decommission the reactor.