Chernobyl's exclusion zone was ~1000 mi^2, consisting of ~120,000 people. The Oroville dam evacuation zone is ~250mi^2 encompassing ~180,000 people. Floods are no laughing matters; the Chinese decision to break the levees of the Yellow River during the Second Sino-Japanese War is credited with killing 400,000 people or so and rendering millions homeless, and the land was unusable for the better part of a decade, not "a month."

> 2.) The area is unlivable (or even inaccessible) for a much smaller duration of month instead of millenia.

Millennia of uninhabitability is anti-nuclear propaganda. Most of the zone will be reinhabitable within a century of the accident, and much of it is already inhabitable again but still excluded out of safety margin concerns.