I work at a nuclear power plant that utilizes the Susquehanna River for cooling water. One of the questions that is always asked is about the gigantic COOLING TOWERS.
Yep, these babies are about 500 feet tall, and can cost up to a billion dollars to construct. The vapor that comes out of the top, is just that, plain, old water vapor. The radioactive constituents from the reactor plant do not end up in this plume.
For those of you in hotter climates, you may be familiar with the phrase, "swamp cooler". That is the same principle that the COOLING TOWERS are based upon. These are an added protection for the environment, because technically, the design of the plant really would not require them.
To keep everything "on the square" we have a contracted company of biologists, that routinely sample the environment. My colleagues get to review their information, and if anything is untoward, then it has to be remedied. This it very rare.
But when it all said and done, they are billion dollar swamp coolers.