Radiologically? Pretty much nothing. The regular industrial safety concerns will matter more.
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.
> What's the effect of this in a populated area in a certain radius?
I'd imagine this is, like with fission plants, deeply dependent on the specific design.
Radiologically? Pretty much nothing. The regular industrial safety concerns will matter more.
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.