South Korea’s KSTAR reactor has rewritten the limits of what is possible

Three of the experimental reactors nuclear fusion most promising on the planet reside in Asia. He JT-60SAin which Europe participates, is hosted in Naka (Japan). Not too far from there, in Hefei (China), it is being built the CFETR reactor (Chinese Fusion Engineering Testing Reactor), a name that we can translate as Chinese Fusion Engineering Test Reactor. However, the real protagonist of this article is the KSTAR fusion reactor (Korea Superconducting Tokamak Advanced Research), a machine located in Daejeon (South Korea).

This latest genius It is being operated by the KFE (Korea Institute of Fusion Energy or Korean Fusion Energy Institute) and aims to demonstrate that fusion energy on a commercial scale is viable. Neither more nor less. And it’s on the right track. In fact, it has just signed the most important milestone in the field of nuclear fusion so far this year: it has managed to sustain stable plasma at fusion temperatures for 102 seconds. It is a true feat if we keep in mind that stabilizing plasma under these conditions is not easy at all.

However, it is worth taking a closer look at what the researchers operating the KSTAR reactor have achieved. What they have achieved is exactly this: they have sustained the plasma in high confinement mode (H-mode) for 102 seconds while simultaneously maintaining the plasma temperature at 100 million degrees Celsius for 48 seconds. These are record numbers. Be that as it may, not only what they have achieved is important; It is also crucial to know how they have done it.

A key piece in fusion energy

Maintaining a plasma temperature of 100 million degrees Celsius or more over time is essential in nuclear fusion. And it is because under these conditions the ionized nuclei of deuterium and tritium acquire the kinetic energy necessary to overcome their natural electrical repulsion and fuse. However, dealing with plasma at such a high temperature is very complex. In magnetic confinement reactors, such as KSTAR, a sophisticated system of high-power magnets is responsible for confining this ionized fuel at very high temperatures.

The problem is that the plasma is subject to turbulence that originates naturally and is especially intense in the outermost layer of this gas. Understand how plasma behaves when nuclear fusion processes begin is essential on the path to a solution that allows us to control it precisely, and, therefore, stabilize it.

One of the determining factors in KSTAR’s recent success is the use of the new divertor tungsten. This component is made of stainless steel, although it incorporates tungsten shields that are responsible for withstanding the bombardment of high-energy neutrons from the plasma, transforming its kinetic energy into heat. To release this thermal energy and cool the divertor The water that circulates inside is in charge.

Tungsten has been chosen to tune the shields exposed to plasma because this is the metal that has the highest melting point: no less than 3,422 degrees Celsius. Furthermore, the divertor is responsible for purifying the plasmaallowing the extraction of ash and impurities resulting from the nuclear fusion reaction and the interaction of the plasma with the most exposed layer of the mantle.

According to the Korean Fusion Energy Institute, the divertor previously installed carbon had reached its limit as experiments intensified and temperatures increased. The next step he wants to take is ambitious: operate the reactor for 300 seconds at temperatures above 100 million degrees Celsius.

This achievement invites us to be optimistic, but we must not overlook the fact that keeping the plasma stable for minutes, or even hours, and ensuring that the reactor generate more energy than you consume It is undoubtedly one of the greatest engineering challenges facing science.

Image | Michael Maccagnan

More information | KFE | The Times of India

In Xataka | Spain’s milestone in nuclear fusion: the first plasma produced by the SMART reactor invites us to optimism