Nuclear power The main nuclear fuels are uranium and plutonium . In a nuclear power station, nuclear fuel undergoes a controlled chain reaction in the reactor to produce heat - nuclear energy is converted to heat energy: heat is used to change water into steam in the boiler the steam drives the turbine (heat to kinetic energy ) this drives the generator to produce electricity - kinetic to electrical energy Cross-section of a nuclear reactor Nuclear and geothermal energy are the only energy resources that do not come from the Sun. Advantages Unlike fossil fuels, nuclear fuels do not produce carbon dioxide or sulfur dioxide. 1 kg of nuclear fuel produces millions of times more energy than 1 kg of coal. Disadvantages Like fossil fuels, nuclear fuels are non-renewable energy resources . Although modern reactor designs are extremely safe, if there is an accident, large amounts of radioactive material could be released into the environment Nuclear waste remains radioactive and is hazardous to health for thousands of years, so it must be stored safely. This waste material can never be used to make a 'nuclear bomb'. It is the fission fragments from a nuclear chain reaction and not fissionable itself.