Although nuclear explosions and nuclear power utilize the same principle, they are entirely different concepts. In the wake of the Fukushima accident, we are reexamining the safety and necessity of nuclear power.
It has already been 15 years since the Fukushima nuclear power plant accident occurred. Nevertheless, even today, it is common to see numerous reports related to this incident in the news. What is evident among many people who encounter such news is that they do not distinguish between “nuclear explosions” and “nuclear power generation”; furthermore, one can see worried expressions on their faces, fearing that a nuclear explosion might occur at the nuclear power plants around us. Therefore, this article aims to explain how nuclear power generation—which produces electricity in our communities—differs from a nuclear explosion.
First, the basic principle behind harnessing nuclear energy is as follows: When a neutron collides with the nucleus of a heavy element with a high atomic number, such as uranium (U), the nucleus becomes unstable, triggering a fission reaction. As this fission occurs, the atomic nucleus emits heat along with two or three additional neutrons. These newly generated neutrons then collide with nearby uranium nuclei, triggering the same reaction, and thus a chain reaction of nuclear fission takes place. The vast amount of heat—that is, the immense energy—generated during this process is what we commonly refer to as nuclear energy.
The key distinction between a nuclear explosion and nuclear power generation lies in whether this released energy can be controlled. A “nuclear explosion,” used for military purposes, involves harnessing the vast thermal energy released without control; in contrast, “nuclear power generation” involves regulating the rate of the chain reaction to produce an appropriate amount of energy.
So, how is this energy controlled? The two main types of uranium found in nature are U-235 and U-238, which account for 0.7% and 99.3% of the total, respectively. Of these, U-235 is the isotope that absorbs neutrons and undergoes fission. This is why nuclear explosions do not occur spontaneously in nature. Therefore, when it comes to energy control, the amount of energy released can be regulated based on the degree to which U-235—the isotope that undergoes fission—is enriched. In the case of a nuclear bomb, U-235 is enriched to a purity of 90% or higher, so that once the reaction begins, an enormous amount of energy is released all at once without any hindrance. In contrast, the nuclear fuel used in nuclear power plants to generate electricity is enriched to only 3–5% U-235. Furthermore, these plants are equipped with safety systems that regulate the number of neutrons released during the reaction. Therefore, the terrifying nuclear explosions with billowing mushroom clouds that we might imagine occurring at the nuclear power plants around us are fundamentally impossible.
Even though a nuclear explosion cannot occur, it is unlikely that we can completely shake off our anxiety about accidents at nuclear power plants. However, the point this article aims to make is that, at the very least, the lethal nuclear bombs dropped on Japan during World War II and the nuclear power generation that supplies electricity in our communities are fundamentally different concepts. We must evaluate nuclear power—a source of energy for humanity—based on cool, rational thinking, but we must not fall into the error of assuming that it inevitably leads to a nuclear explosion.
In recent years, there has been active global discussion regarding the safety and necessity of nuclear power. In particular, nuclear power is being re-examined in light of climate change and carbon emissions issues. Nuclear power is gaining attention as an eco-friendly energy source capable of replacing fossil fuels. This is because nuclear power emits almost no carbon dioxide during the electricity generation process.
However, concerns about the safety of nuclear power still persist. Major accidents, such as the Fukushima and Chernobyl disasters, clearly demonstrate the risks associated with nuclear power. These accidents caused immense damage to humanity and the environment, and their repercussions continue to this day. Therefore, advocates for expanding nuclear power emphasize the need to further strengthen safety measures.
The future of nuclear power depends on technological advancements and ensuring safety. Recently, development is underway on new types of reactors that are safer and more efficient than existing ones. Furthermore, the issue of spent nuclear fuel disposal is a major challenge, and active research is underway to address it.
In conclusion, nuclear power is one of the key energy sources capable of addressing climate change and carbon emissions. However, ensuring its safety is essential, and this requires continuous technological development and rigorous safety management. It is important to formulate future energy policies by carefully balancing the advantages and disadvantages of nuclear power.
