Electrical power
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Accessed 19 Mar. 2024.
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Technology, Electrical power, s.v. "Nuclear power," accessed March 19, 2024.
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Nuclear power
Nuclear energy is the energy contained by an atom, due to the strong force that holds together the protons and neutrons in its nucleus. There are two ways of releasing nuclear energy: nuclear fission and nuclear fusion. They are both forms of nuclear reaction. A nuclear power station produces energy by nuclear fission. A reaction is created in the nuclei (cores) of uranium atoms. Inside the reactor, neutrons are made to collide with other nuclei, causing them to split (nuclear fission) and release more neutrons. This repeated process, called a chain reaction, produces immense amounts of heat energy. The energy heats water, making steam that drives turbines.
Nuclear fission
Matter can be converted into energy and energy can be changed into matter. This conversion is used in nuclear power stations. A nuclear particle called a neutron smashes into the nucleus of a uranium atom (1). The nucleus breaks into two parts (2). This releases large amounts of heat and other energy and also two more fast-moving neutrons (3). These smash into more uranium nuclei and so on in what is called a chain reaction (4). Splitting of nuclei is known as nuclear fission. During the process bits of matter cease to exist and become vast quantities of energy instead.
Inside a reactor
Splitting the atoms that make up a substance like uranium produces a very intense heat for creating steam, which is in turn used to drive a turbine and generate electricity. Uranium is the fuel used in a nuclear power station because it is the only naturally-occurring substance in which the process of nuclear fission can take place.
Water pumped around the reactor is heated by the nuclear chain reaction. The heated water is then pumped through pipes to the heat exchanger. There, its heat is used to boil water, making steam to drive a turbine. This is connected to the generator, which consists of a huge magnet surrounded by copper wire. The turbine makes the magnet spin, thus producing an electric current in the wire. Coolant turns the steam back to water.
The future of nuclear power
Renewable energy sources such as wind and solar power rely on suitable weather conditions. Hydrogen power has not yet been developed to run electrical power stations. This means that nuclear power, a zero-carbon energy source, remains essential to many governments' plans in their drive to reduce carbon emissions to net zero by 2050.
Large nuclear power stations are expensive and take a long time to build, so small modular reactors (SMRs) may be a cheaper and quicker solution for the future. Scaled-down versions of existing nuclear reactors, SMRs can be assembled on site from components ("modules") manufactured in factories. SMR cores are less hot than those of large reactors, meaning they do not need so much water for cooling and so can be located both at the coast (where most nuclear power stations are situated) and inland.
However, apart from an experimental station in Pevek, in Russia’s Far East, no SMRs are yet in service—so it is uncertain how useful they will be. There is also the problem of public distrust of nuclear energy in general. This includes how and where used-up uranium or plutonium, which remains radioactive for thousands of years, can be safely stored. There is also the threat of nuclear weapons proliferation (spread), because the technology and materials used for creating nuclear power can also be used to make weapons. There are also grave concerns about the risk of accidents, such as those at Chernobyl (1986) and Fukushima (2011).
The Fukushima nuclear disaster
On 11th March 2011, a powerful earthquake, followed by a tsunami, took place off the coast of Tohoku, northeastern Japan. Immediately after the earthquake, the reactors inside the Fukushima Nuclear Power Plant shut down automatically, and emergency generators came on to power the reactor's coolant system. However the tsunami following the earthquake flooded the rooms in which the emergency generators were housed, causing the emergency generators to fail.
As the coolant pumps stopped working, the reactors, still extremely hot, started to overheat. The reactors could still have been saved had seawater been allowed to flood the rest of the plant, but this was delayed because it would destroy the reactors permanently. By the time flooding with seawater finally began, it was already too late to prevent the fuel rods in the reactor from becoming intensely hot, and they began to melt. This is what is known as "meltdown". Several explosions then took place.
Consequences
of meltdown
A meltdown is highly dangerous, because it could result in radioactive substances being released into the environment, leading to radiation poisoning. Following the meltdown at the Chernobyl plant in Ukraine in 1986, a radioactive cloud spread across large areas of Europe. While the region around the Fukushima plant was contaminated, the amount of radioactivity released was low and there will be no long-term effects of radiation exposure to the local people.
Consultant: Chris Oxlade