Are nuclear power plants really safe, or are there risks we don’t know about?

Nuclear power plants don’t explode like nuclear bombs, and there are many safeguards that make them safe to operate. The Fukushima and Chernobyl accidents were caused by factors other than explosions, and safer reactors are being developed as a result of the lessons learned.

 

The Fukushima nuclear disaster has sparked debate about the safety of nuclear power plants. In South Korea, there was a recent broadcast that suggested that nuclear power plants were unsafe due to corruption in the nuclear industry. After watching this, South Koreans were worried that their nuclear power plant would explode like the one in Fukushima, Japan. The bottom line is that nuclear power plants never explode. Sure, the heat transfer system inside can explode, but a nuclear power plant doesn’t explode like a nuclear bomb. Now let’s look at why.
In nature, uranium exists in two main forms: uranium-235 and uranium-238. Of the two, uranium-235 is the most unstable, fissioning itself, releasing the energy needed to generate electricity and breaking down into other particles. This is called radioactive decay. Because of this natural decay, uranium-235 makes up only 0.7% of all uranium. However, this property makes it possible for uranium-235 to be used in nuclear power generation.
In nuclear power generation using uranium-235, a process called the “chain reaction” is very important. This means that the decay of one atom causes the decay of another, similar to the principle of dominoes. When a domino is unstable and one domino falls, it causes the other dominoes to fall. If the distance between dominoes is too great for the fallen domino to touch the next domino, the chain reaction stops. The nuclear fission reaction is similar. When uranium-235 splits, it causes other uranium-235 to split, but if the concentration of uranium-235 is low, the splitting of one uranium does not lead to the splitting of the other.
This principle means that uranium fuel must be enriched to a concentration higher than the concentration of uranium-235 in nature in order to generate nuclear power. The concentration of uranium-235 is increased through a process called “enrichment” to produce nuclear power. For stable nuclear power generation, uranium-235 enrichment of about 3-5% is required. At a concentration of 3-5%, fission is active, but if excessive fission occurs, measures are taken to contain it so that the chain reaction can occur properly.
Now consider the what-if situation. What happens if a power plant loses electricity, causing excessive fission, and there are no artificial measures in place to contain it? People who don’t understand nuclear engineering might think that the plant would explode. However, when the temperature of the uranium rises due to active fission, a phenomenon called Doppler broadening occurs, which naturally slows down the fission rate. In simple terms, Doppler broadening prevents the effects of the decay of one uranium-235 atom from reaching other uranium atoms. This kills the chain reaction, and the overheated reactor slowly cools down. Doppler broadening has the effect of helping the reactor operate safely.
Now, with this knowledge, let’s look at the Fukushima nuclear disaster. The reason why the Fukushima nuclear disaster was so devastating is that the seawater that was used to cool the reactors leaked into the contaminated water, which contained radioactive material. These radioactive substances spread into the air, contaminating large areas of Japan, and entered the ocean, rendering fish in the area inedible. But this is not the kind of explosion we’re concerned about.
The Chernobyl nuclear accident is similar to the Fukushima nuclear accident. The Chernobyl explosion occurred when plant operators tried to increase the power of the reactor, and the rapidly rising temperatures caused the coolant to vaporize and destroy the reactor structure. While these accidents caused unimaginable damage, it’s important to note that these two nuclear power plant accidents did not occur in the same way that an atomic bomb exploded. Nuclear researchers have learned from these two accidents and have developed a number of safer reactors, including separating the reactor from the heat transfer system.
Nuclear power is dangerous, but it’s been studied for a long time, and there are many ways to design it safely. Many people have a negative image of the nuclear industry due to events related to nuclear power generation. In order to change these people’s attitudes in favor of the industry, all power plants in South Korea must be free of corruption and operate safely. In addition, in order to prevent incidents such as Fukushima and Chernobyl from happening, nuclear power plants should be designed to be earthquake-resistant, designed to be able to operate normally even if seawater penetrates, and safety should be emphasized repeatedly so that if an accident does occur, it will not lead to something terrible.