Naturally occurring nuclear reactor

Dr. David Ruzik, PhD describes the geological conditions necessary for a natural nuclear fission reactor to form underground. The example he talks about ran about two billion years ago in present-day Oklo, Gabon. I thought this was super interesting! I'd never considered that it was possible.

One of the doctor's takeaways: even though the reaction took place in an underground river, its radioactive byproducts didn't travel a long distance after the reaction. He suggests that this lack of dispersion by natural processes also applies to modern facilities. Anthropological nuclear waste is kept in solid, impermeable casks within small geographical areas—the implication is that it poses less risk of wide-area contamination than we might expect.

I was curious and looked up more literature. François Gauthier-Lafaye writes in the Comptes Rendus Physique that "the [natural] reactors are similar to spent commercial reactor fuel," so it's a useful analogue for waste management analysis. If I understand the paper correctly, scientific observations of surrounding geology apparently indicate that the more dangerous radioactive elements like uranium, plutonium, and thorium migrated distances on the "metric scale" (highly local, as opposed to the "kilometric scale" or higher), remaining mostly in the core area. The elements that dispersed tended to be less harmful ones.

Perhaps it's a reassurance for engineers that nature accidentally created an effective long-term nuclear waste containment vessel; their intentional solution of "borosilicate glass as an immobilization material" sealed in seismically inactive caverns with low host rock permeability ought to be similarly or more effective. Perhaps it's an increasingly moot point if we're only a few key breakthroughs away from nuclear fusion, although we've all been hearing that for a long time.