For about the same reason schools aren't located below water level: Building things underwater is a huge construction and maintenance problem.
With a nuclear reactor, you've got the additional potential problem that a breach could result in contaminating a large amount of water with radioactive material.
See the link below
Kewaunee and Point Beach. See NRC link below
I have put a link to the Wikipedia page, "List of nuclear reactors," below. It seems to be pretty good, and includes some reactors that are not in nuclear plants, such as research reactors.
See link below
There are 104 commercial nuclear power reactors in the US. See the related question below.
One unit, see link below
There are two reactors in Louisiana, see the NRC information linked below
The best source I know of is the NRC website which gives a map. See link below
Plutonium is very important for nuclear weapons and for nuclear fuels used in nuclear reactors. But plutonium is also toxic and radioactive. See the link below.
Two plants with four reactors total. See link below
Plutonium is very important for nuclear weapons and for nuclear fuels used in nuclear reactors. But plutonium is also toxic and radioactive. See the link below.
As of 2010, There are six nuclear power plants, comprising 20 reactors, in India. For further information, please consult the Related Links, below.