"The Real 'Dream Energy' Is Me"…How Far Has Nuclear Fusion Power Come? [Reading Science]

-Korea achieves world record by maintaining 100 million Celsius for 30 seconds
-Securing technology for long-term maintenance and development of ultra-high temperature plasma is crucial
-No concerns about environmental pollution, accident risks, or radioactive waste; abundant cheap raw materials

[Asia Economy Reporter Kim Bong-su] 'Nuclear fusion'?a term that might have seemed even more unfamiliar during school days, especially if you were a 'Munsong' (a newly coined term meaning 'sorry for being in the liberal arts'). It's important to remember this word well. It is a promising next-generation energy source that can help prevent global warming and leave a livable environment for future generations. It is safe with no risk of accidents, low-cost, eco-friendly, and highly efficient. If the technology is properly developed, future generations will be able to use abundant energy without worrying about the environment or resources. Moreover, Korea is exceptionally leading in this research and development field, with KSTAR?the nuclear fusion reactor installed as a pilot project?recently setting a world-first record by maintaining 100 million degrees Celsius for 30 seconds. Korea also bears a great responsibility to pioneer this uncharted territory. Let's delve into the world of nuclear fusion.

◇What is Nuclear Fusion Energy?

It is well known that nuclear energy utilizes heat generated from the process of nuclear fission. Uranium nuclei break apart upon meeting neutrons, transforming into lighter nuclei, and energy is released corresponding to the lost mass. Nuclear fusion energy is the exact opposite. It is energy generated from the process where atomic nuclei combine, a technology that heats water to produce electricity. For example, in the sun’s core, hydrogen nuclei forcibly fuse into helium nuclei due to temperatures of 15 million degrees Celsius and immense pressure, releasing energy equivalent to the lost mass. This process produces light and heat with a surface temperature reaching about 5778 degrees Celsius. The light and heat energy generated by the sun is the source of all life on Earth. It is expected to continue nuclear fusion reactions for about 5 billion more years, supplying light and energy. The sun releases energy equivalent to 200 billion hydrogen bombs exploding every second.

The technology of nuclear fusion energy literally started from the idea of creating a small 'artificial sun' on Earth. But how can nuclear fusion reactions be generated on Earth, where the environment is completely different from the sun? Scientists studied the conditions required to fuse hydrogen nuclei, which repel each other, and discovered that it is possible by heating them to over 100 million degrees Celsius on Earth. This led to the development of nuclear fusion reactor technologies currently being developed by Korea, the United States, China, Japan, Russia, and others.

◇Creating an Artificial Sun on Earth

A nuclear fusion reactor uses deuterium and tritium as fuel to create ultra-high-temperature plasma exceeding 100 million degrees Celsius, and the heat generated is used to heat water and produce electricity. How do we heat hydrogen nuclei to 100 million degrees Celsius? Countries around the world, including Korea, have succeeded in heating to 100 million degrees Celsius by creating nuclear fusion reactors using the fully superconducting tokamak method (a sealed container that confines ultra-high-temperature plasma with superconducting magnets). Of course, as seen in France’s 20-year failure case, this technology is not simple. In Korea’s case, a neutral beam heating device is used to accelerate ion particles to high energy to generate heat, which is then transferred into the plasma. In some countries like the U.S., methods focusing ultra-powerful lasers on a single point to raise the temperature are also being researched. The ultra-high-temperature plasma at 100 million degrees Celsius is ‘managed’ using magnetic fields. Although it is a powerful ‘flame’ that can melt and destroy anything it touches, it is influenced by magnetic fields. The plasma is suspended in the air by magnetic fields generated by superconducting magnets.

Accordingly, the temperature touching the reactor’s internal materials is at the level of several thousand degrees Celsius, which can be withstood by elements found on Earth. Currently, carbon, which has the highest melting point on Earth (about 3642 degrees Celsius), is used as the internal lining (diverter) of nuclear fusion reactors. However, with accumulated use, it combines with deuterium to convert into methane impurities, reducing durability. Therefore, tungsten, the most durable metal element (melting point 3422 degrees Celsius), is increasingly used as an alternative. It has the advantage of almost no damage from neutrons at ultra-high temperatures and low radioactivity. The international nuclear fusion reactor (ITER), being constructed by seven countries including Korea, has adopted tungsten for some parts, and tungsten diverters are currently being installed in Germany, China, and Korea’s KSTAR as well.

◇Why Nuclear Fusion Energy?

The fuels deuterium and tritium are abundant on Earth. Deuterium can be obtained by decomposing seawater, and tritium can be produced by nuclear transmutation of lithium inside the fusion reactor. Lithium reserves in the Earth’s crust alone can supply energy for 600 years, and if seawater is decomposed, it is a plentiful resource that can be used for 15 million years. This is incomparable to other fuel energy sources such as oil, which has only 40 years left, natural gas with 60 years, and uranium with 65 years of supply. It also boasts an enormous calorific value. The 0.03g of deuterium contained in 1 liter of seawater produces heat equivalent to 300 liters of gasoline. For a 1 million kW-class power plant, the annual fuel consumption is 10 tons, which is much less than 2.2 million tons of coal or 1.5 million tons of oil. There is no worry about handling high-level radioactive waste like nuclear power plants. Although low- and intermediate-level radioactive waste is generated, it becomes naturalized after several decades of storage, significantly reducing the burden. There are no greenhouse gases. Especially, the risk of accidents, which is the fundamental reason for opposition to nuclear power plants, is almost nonexistent. Because it generates high heat, it can produce high output electricity at once. The amount of electricity produced compared to the energy input to heat the plasma is designed to be about 10 times more efficient with current technology.

Han Hyun-seon, head of the KSTAR research division at the Korea Institute of Fusion Energy, explained, "Electricity is input to maintain the plasma state through the magnetic field generated by superconducting magnets, but if the power supply is cut off due to an accident, the plasma immediately disappears," adding, "There is absolutely no risk of explosions like those in nuclear power plants."

However, there are still high hurdles to overcome. The ultra-high-temperature plasma above 100 million degrees Celsius must be continuously maintained using magnetic fields generated by superconducting magnets, and countries worldwide are struggling with this. Korea set a world record this year by maintaining plasma for 30 seconds, but the U.S., China, and Russia are struggling even to reach 10 seconds. The goal is to achieve a 300-second maintenance record by 2026 and commercialize the technology by the 2050s, but no one can guarantee its feasibility. Han said, "The most important technology is the control technology to maintain plasma for a long time using magnetic fields generated by charging and discharging electromagnets," adding, "So far, success has only been for a short time. To become an alternative energy source in the carbon-neutral era of the 2050s, more groundbreaking technological advances are needed."