By the way... I want to mention what I realize in this trip.
U.S.A. has a lot of nuclear power plants along rivers.
The Fukushima Nuclear Power Plant in Japan ejected an estimated 3,000,000,000,000,000 - 5,000,000,000,000,000 Bq of radioactive cesium into the ocean. And then it has spread in three-dimensional.
If some nuclear power plant along a river in U.S.A. is damaged in the same way as the Fukushima, around 5,000,000,000,000,000 Bq of radioactive cesium will be ejected into the river, which has a big cities, and then it will be spread in almost one-dimensional. We can easily imagine what will happen.