[korantu]

The point is to be able to have way less exclusion radius, not 10 km but 500m, as nothing will fly out of there.

Chernobyl occured because of graphite/fuel configuration went wrong. In this fuel it just cannot go wrong as it never changes.

As for temperature being too hot, pebble reactors have a so called melt-plug, which will melt at temperatures much lower than would be threaten the pebbles

Once the plug melts, pebbles fall down via gravity into lower part of reactor where they are dispersed in a way that stops energy generation and they can be cooled by natural convection.

Walkaway-safe is huge deal. You can't overheat this reactor even if you set out to do so.