China has announced a breakthrough in nuclear fusion technology by using an innovative new alloy, CHSN01 (China High-Strength Low-Temperature Steel No. 1). The material is a high-tech fabric that has been specially designed to withstand the harsh conditions of nuclear fusion reactors, where the high-strength superconducting magnets have to run in magnetic fields of over 20 Tesla and at temperatures close to absolute zero.
Fusion energy, the so-called holy grail of clean energy, needs materials that are able to withstand higher than ever before seen thermal and mechanical stresses. CHSN01 provides exactly that. The alloy is the product of many years of research, and it has to satisfy very strict requirements: a yield strength of 1,300 MPa and a large elongation capacity at cryogenic temperatures. In 2023, it was confirmed to be able to contain twice the magnetic fields of ITER, aka the International Thermonuclear Experimental Reactor in France, a new benchmark.
According to the Chinese media, CHSN01 is currently used in the first fusion nuclear power generation reactor in the world, which is the BEST reactor. Construction started in May 2023 and was scheduled to be completed in 2027. The 500 tonnes of conductor jackets are also constructed of this homegrown steel out of the 6,000 tonnes of components being assembled.
The path to CHSN01 started more than ten years ago. Chinese scientists broke the global standards in 2011 when they introduced substitutes to the ITER 316LN stainless steel. Skeptical of the international community, Chinese scientists led by cryogenics pioneer Zhao Zhongxian and materials scientist Li Laifeng carried on. As of 2021, China established a national research alliance to research the alloy, including institutes, companies, and welding experts.
The breakthrough does not only enhance Chinese leadership in fusion technology but also marks a larger strategic goal to achieve self-sufficiency in next-generation energy materials. The success of CHSN01 demonstrates the importance of advanced materials science in the development of fusion power as a source of energy. And its uses are soon to be beyond fusion reactors to other advanced areas where ultra-tough, cryogenic-grade steel is needed.