LFTR fission reactions are self-regulating in many ways due to the liquid fuel and thermal expansion abilities, and even if something goes wrong, there is a melt plug that will automatically stop a runaway reaction.

That seems like a faulty explanation. Uncontained fusion is massively energetic and destructive. The device in this article is analogous to an H-bomb weapon with a pneumatic rather than fissile primary.

Fusion bombs are when you put fusible materials next to fission explosions.

Yes, they are massively energetic, (we wouldn't be harvesting power from it if they weren't.) However, they require a very high input energy to trigger the release of the output energy.

With a fission reactor meltdown, the way you get there is by pulling out dampening rods or boiling off all the water, but otherwise leaving the fission rods in the same place.

With a fusion reaction, you have to be constantly providing both the energy to keep the fusion going AND the input material to be fused. Interrupt one or the other and fusion stops.

I know it seems weird that the bigger energy release is safer, but that's how it is. It's the difference between requiring constant input into the system to produce power vs an idle system with no input producing power.

Their explanation is not really faulty. FYI hydrogen bombs are mainly destructive due to fission, not fusion. The fusion step is primarily for bombarding the dangerous fissile fuel with neutrons.

That a fusion bomb has significant energy from fission doesn't seem germane. It still has a great deal of energy from fusion alone.

I'm not trying to scaremonger fusion energy, but I think it's intellectually dishonest to portray is as fundamentally sound, with a binary outcome of either inertia or safe energy. This design relies on spherical compression to both initiate and confine the fusion. We should not discount the possibility that if it instead creates a cylindrical or elliptical confinement due to malfunction, it will just explode, at a minimum destroying the device. We know it is possible to initiate fusion with radial compression in a cylinder, because that's how an H-bomb secondary works.

The main safety factor in these things comes from the fact that a fusion weapon needs hundreds of kilos of hydrogen, and they are experimenting with much smaller masses. That limits the destructive potential.

> but I think it's intellectually dishonest to portray is as fundamentally sound

No offense but I think this sentiment is a huge problem with Hacker News. I have a minimal understanding of fusion energy production from an engineering perspective but I know more than the vast majority of the world due to my background.

You are smart but not a subject matter expert in this topic. Fusion is not a sustainable a reaction while fission is. Fission happens on its own, fusion requires something else to happen first (on Earth). Please don't insult the people in this thread who are subject matter experts in the field by implying they are intellectually dishonest. I am not a subject matter expert but recognize that a few of them are commenting in this thread with details that I have learned from other experts.

It's not dishonest to portray it as fundamentally sound, because it is. Your argument is that 'If scaled up several orders of magnitude this device could cause dangerous explosions.' This ignores two very important realities:

1) There isn't a reality in which these devices get scaled up to that size. 2) The real danger with fission is radiation, not explosions, which fusion reactors will produce in smaller quantities than a banana farm.

Pure fusion power, even in its largest, most powerful, Elon Musk fever-dream incarnation, is safer than even the safest fission reactor, because there is no way for it to create a boom larger than it's vessel was designed to produce.

It is more intellectually dishonest to bemoan the danger of "uncontained fusion" by citing the hydrogen bomb.