Americium is extracted from spent nuclear fuels where is formed by nuclear reactions.
Well...I cannot say about how much has been the money spent on nuclear arms worldwide but nuclear weapons have cost the United States at least $5.48 trillion since 1940....!!
spent nuclear fuel
Irradiation of uranium in nuclear reactors, separation from the spent nuclear fuel, refining
After the nuclear fuel is spent the fuel is radioactive. This radiation causes decay heat. The result of the radiation causes movement of atoms, converting it into thermal energy.
Thousands of years at least
It is highly radioactive (that is the waste contained in the spent fuel)
No, they are stored in pools of water.
It will have very little effect. Any power station whether fossil fuel or nuclear rejects low quality heat to a cooling water source, lake, river, ocean, or the atmosphere via cooling towers, so nuclear can't be blamed for that. Other than that there is the question of nuclear waste, primarily the spent fuel. The problem here is finding a place to store it in perpetuity, or at least thousands of years. It should be possible to solve this problem with a depository at Yucca Mountain Nevada or some other place. In the meantime it is being safely stored on the power station sites.
Heat, radiation, and spent fuel.
16 trillion dollars
Yes there certainly is, both in the fission process and in the spent fuel when it is unloaded.