* The safety is massively different than fission because there is no 'run away' reaction. If you turn off the power, fusion will stop. Fission will keep going once started, and can be very dangerous if the cooling system fails.

* I do believe the fusion paths Helios is using emit neutrons, which is a big safety concern. Not only is neutron radiation directly deadly to humans, it's also a challenge to maintain containment. Neutrons are not magnetic, so matter must be used as a shield. Most materials that absorb a neutron will itself become radioactive. I'm unsure about the number of neutrons Helios is emitting, or will emit as they scale up.

In fact, even for D-T fusion the NRC recently decided to regulate reactors like accelerators instead of like fission reactors.

Also, we never mass-produced fission reactors. Helion wants to build a factory making twenty 50MW reactors per day, shippable by rail.

When it becomes clear that fusion can displace coal those safety, activist and political concerns will immediately pop up again

I wonder if there's already a paper, or a fictional book, about what happens if someone invents something that makes fossil fuels obsolete within, say, a year. The OPEC countries would suddenly be faced with losing one of their biggest income streams. It would be interesting to speculate...

Of course there are different levels of obsolence, all the petrol cars won't disappear, unless someone invents a magic liquid to replace petrol/diesel with something that works identically but without the pollution.