In this blog post, we take an in-depth look at whether nuclear power plants are a safe choice, examining their structure and the role of water in areas prone to earthquakes.
On March 11, 2011, a tsunami near Fukushima sent shockwaves around the world. There was a nuclear power plant consisting of six reactors in the area, and the tsunami caused the Fukushima nuclear accident. This accident brought the dangers of nuclear energy back into focus and sparked a lively debate on nuclear safety around the world. Japan is a country prone to earthquakes, so when selecting sites for nuclear power plants, the risk factors associated with natural disasters such as tsunamis would have been thoroughly considered. Nevertheless, there may be special reasons for building nuclear power plants near the sea. This is closely related to the nature of nuclear power plants, which require water.
Like Japan, South Korea is also exposed to natural disasters such as earthquakes. Most of South Korea’s nuclear power plants are located on the coast and have a similar structure to the Fukushima nuclear power plants. This layout raises the question of why nuclear power plants must be located near the sea. Nuclear power generation is achieved through the fission of uranium, a process that requires enormous amounts of water. A single 1,000-megawatt nuclear power plant in South Korea requires 60 to 70 tons of water per second. Assuming that there are four nuclear power plants on one site, a tremendous amount of water is consumed in just two days.
Such a large amount of water is essential for the normal operation of nuclear power plants. Without water, the reactor cannot be cooled, which greatly increases the risk of safety accidents. For this reason, all nuclear power plants around the world are located on the coast to ensure a stable supply of sufficient water from the sea.
Water plays two important roles in nuclear power plants. First, water is used as a moderator in the primary system. A moderator is a substance used to regulate nuclear reactions by reducing the energy of neutrons that promote nuclear fission. Second, water is used as a coolant in the secondary system to absorb and release heat energy generated by the power plant, turning the turbine and generating electrical energy in the process. Water is an essential element in both of these roles and is indispensable to the operation of nuclear power plants.
The reason water is used as a moderator and coolant in nuclear power plants is because it is a stable and reliable substance. Water can effectively slow down neutrons as a moderator and efficiently absorb and release heat energy as a coolant. There are other substances that can be used as moderators and coolants besides water, but water is the most suitable when considering safety and efficiency.
For example, carbon and heavy water can be used as moderators instead of water. However, water has been studied more extensively than carbon and heavy water, so its properties are well understood, and appropriate responses can be taken in the event of an accident. On the other hand, carbon burns easily, which can cause danger in the event of a fire, and heavy water is restricted in its use due to nuclear proliferation issues. Therefore, water is the safest and most reliable choice as a moderator.
In addition to water, liquid metals, carbon dioxide, and helium are also used as coolants. However, liquid metals pose an explosion hazard when in contact with water, and gaseous coolants have low energy efficiency, requiring higher reactor output, which can lead to the risk of exceeding the melting point of the reactor. For these reasons, water is the best choice as a coolant in terms of safety and efficiency.
Nuclear power plants have very high operating rates, so they must be continuously supplied with materials used as moderators and coolants in the primary and secondary systems. Water is the most stable and reliable moderator and coolant, which is why most nuclear power plants in South Korea use water. The use of water as a moderator and coolant is essential for ensuring the safety of nuclear power plants, which explains why nuclear power plants must be located near the sea.
By understanding why water is essential for nuclear power plants and its role, we can gain a deeper understanding of the location selection and importance of nuclear power plants. Furthermore, it is necessary to continue researching and improving the safety and efficiency of nuclear energy. Thorough preparations for the operation and management of nuclear power plants are required to prevent tragedies such as the Fukushima accident from ever happening again. Through these efforts, we will be able to secure safer and more sustainable energy.
