There would be no alpha sources left in the plant, as they are confined in the fuel rods, that would be taken away from the plant. (And be managed like spent fuel, which is a totally different problem than decommissioning).

> A halflife of 5 years means 10% of the radioactivity is still there 16 years later.

But it's very likely that 10% is irrelevant.

Radioactivity is not a all or nothing thing. It exists all around you right now.

Camping out at a old abandoned nuclear power plant 20 years after it's decommissioned probably gives you less radiation exposure then you would get from a flight from California to Hong Kong.

Iz’s not about camping. It’s about water. France is timy compared to the US.

Ever heard about RO water? You can get a RO water filter for 150€ if you're concerned about contamination.

That won’t solve water table contamination. Are you going to RO plants? The soil?

It's not confusing at all, or maybe only to people with irrational fears. Just leave the building sit for 50 years and you've got 1/2^10 Co60 left.

Also dispose the vitrified spent fuel in a repository after reprocessing it.