Most of the world's electricity is generated by either thermal or hydroelectric power plants. Thermal power plants use fuel to boil water which makes steam. The steam turns turbines that generate electricity. Hydroelectric power plants use the great force of rushing water from a dam or a waterfall to turn the turbines. The majority of thermal power plants burn fossil fuels because thermal power plants are cheaper to maintain and have to meet less of the governments requirements compared to nuclear power plants. Fossil fuels are coal and oil. The downfall of using fossil fuels is that they are limited. Fossil fuels are developed from the remains of plants and animals that died millions of years ago. Burning fossil fuels has other downfalls, too. All the burning that is required to turn the turbines releases much sulfur, nitrogen gases, and other pollutants into the atmosphere.
The cleanest, cheapest, and least polluting power plant of the two types is the hydroelectric power plant. The main reason most countries use thermal versus the hydroelectric is because their countries don't have enough concentrated water to create enough energy to generate electricity. (World Book vol. 14, 586)
Nuclear power plants generate only about eleven percent of the world's electricity. There are around 316 nuclear power plants in the world that create 213,000 megawatts of electricity. (INFOPEDIA)
Radioactive, or nuclear, waste is the by-product of nuclear fission. Fission occurs when atoms' nucleus' split and cause a nuclear reaction. (General Information) When a free neutron splits a nucleus, energy is released along with free neutrons, fission fragments that give off beta rays, and gamma rays. A free neutron from the nucleus that just split splits another nucleus. This process continues on and is called a chain reaction. (World Book vol.
14,588) The fission process is used to create heat, which boils water inside the nuclear reactor.
The steam that boiling the water makes is used to turn turbines, which in turn, generate electricity. Fission happens inside a carefully monitored nuclear reactor, when being used in a nuclear power plant. The fission process that nuclear power plants use spends approximately 30,000 tons of highly radioactive waste a year. (General Information)
In a nuclear power plant, Uranium is used as fuel to boil the water for the steam that makes the turbines turn. So, uranium is, in a sense, the coal of a coal-fired power plant. When fueling nuclear power plants, the uranium arrives as uranium-enriched pellets. These pellets are an equivalent to one ton of coal. The pellets are sealed in tubes that are made of a strong heat- and corrosion-resistant metal alloy. This metal alloy will protect people and the environment from the high levels of radiation that the uranium is giving off. The tubes are bundled together to make a fuel assembly. The assemblies are put inside the reactor to create heat that will boil the water. The fuel assemblies are used until they are depleted. A fuel assembly is depleted when it no longer gives off enough energy to turn the turbines. Once every year, one third of the nuclear fuel in a reactor is replaced with fresh fuel. The used-up fuel is called spent fuel. Spent fuel is highly radioactive and is the primary form of high-level nuclear waste. (General Information)
High-level radioactive waste is the by-product of commercial nuclear power plants generating electricity, and from nuclear materials production at defense facilities. This high level waste must be isolated in a safe place for thousands of years so its radioactivity can die down and not be harmful to people and the environment. The name of the safe place that the Department of Energy is trying to make is called a repository. But until a repository is made, spent fuel and high-level waste is being stored in.