Wonder why anyone would build a nuclear power site in an area where it could be flooded, and would have to be sandbagged?
For the same reason people built in the Missouri River floodplain all manner of other buildings.
In the case of nuke plants, they want access to large quantities of cooling water. In the case of others, they like the nice fertile soil, level ground, etc.
You should check out the state of the Missouri River these days:
http://www.crh.noaa.gov/mbrfc/?n=fop
We’ve had so much snow and rain in the upper Missouri River Basin that it isn’t remotely funny. Here in Wyoming, our snowpacks are 200 to 300% of normal. Our spring has been wet beyond belief. All of this means that the Missouri will be high or flooded in places for weeks to come.