The problems of the proliferation of nuclear power include the disposition of long-term radioactive waste ('long-term' being without precedent in recorded human history - the half-life of plutonium-239, a significant and inevitable by-product of nuclear reactors, is 24,000 years); the location of power reactors in regards to surrounding human populations and the preparation for emergencies associated with accidental radioactive releases; and the ecological impacts from the use of salt, clay, and hard rock geological formations.
As of 1981, there either existed, were in a state of construction, or were in advanced planning, 762 nuclear reactors spread throughout 42 countries. The most significant number of reactors include the USA with 174, USSR 73, France 70, Germany 53, UK 44, Japan 43, Canada 28, Spain 18 and Sweden 12.
2. The extensive use of nuclear power may prove to be the most effective way of diminishing the risk of global warming by reducing the use combustion of fossil fuels that release carbon dioxide.