Eh, a core-containment failure (in any magnetically-contained system) would involve superheated hydrogen getting friendly with oxygen. That, in turn, would give neutron-impregnated barrier materials a free ride on propellant. It's not strictly a melt down. But it's in the same practical category of failure.
The truly concerning failure modes would be related to release of radiation or activated materials. But that would require damaging the reactor in ways that the reactor is incapable of imparting on itself.
Overall, the technology is remarkably safe.
Thanks for the correction. If you're breeding lithium in the walls, might that be an incendiary concern?
With all that said, it seems to be way less 'dangerous' material than would be in your average nuclear reactor, making it more of an industrial accident versus a planet contaminating mess.
What does this even mean?
> You are also ignoring what happens when several hundred MW of energy (at about 1,000,000C) under pressure is released instantly.
If you have a gram of hydrogen at a million degrees, it can continue putting out several hundred MW for about a fiftieth of a second.
Even if it somehow gets outside the machine with no heat loss to the structure, by the time it mixes with a few cubic meters of air it'll be down to 1000C or less.
The proliferation risk of someone using the neutron flux to produce an atomic or dirty bomb are real but that exists no matter where it is.
Hybrid nuclear fusion–fission power plants have been already proposed and studied in theory.
"In general terms, the hybrid is very similar in concept to the fast breeder reactor, which uses a compact high-energy fission core in place of the hybrid's fusion core. Another similar concept is the accelerator-driven subcritical reactor, which uses a particle accelerator to provide the neutrons instead of nuclear reactions."
I have a hand-wavy hard sci-fi universe I've been rolling around my head for years and I eventually came to the conclusion that fission-fusion drives would be really handy for spacecraft, since it would be much easier to start a fission reaction in a cold/dark ship than fusion because of the power requirements. Otherwise you need some other way to generate 10s or 100s of MW to start the fusion reaction.
Modern fission power plants are designed with a reactor vessel to last a century and to withstand high pressures and temperatures. It's built and emplaced permanently in a large concrete shielding structure.
In a hybrid design this just won't work. Fuel will need to be right next to a high-vacuum chamber that will need periodic maintenance.
The plant will have some tritium, and the material in reactor walls will get activated by the neutron flux. Some of the activated materials can disperse in case of a catastrophic explosion (e.g. a couple of large airplanes being flown the reactor building).
But the material of the walls is not volatile, so it'll stay on the site. And tritium is very volatile, so it'll quickly disperse to safe levels. You'll be able to detect them with sensitive equipment, but it won't be dangerous.
I'd imagine this is, like with fission plants, deeply dependent on the specific design.
