Chinese State news agency Xinhua reported that the Experimental Advanced Superconducting Tokamak (EAST), in a facility in the eastern city of Hefei, registered a plasma temperature of 120 million degrees Celsius for 101 seconds on Friday. It also maintained a temperature of 160 million degrees Celsius for 20 seconds, the report said.
China has thus reached another milestone in its quest for a fusion reactor, with one of its “artificial suns” sustaining extreme temperatures for several times longer than its previous benchmark, according to state media. A study now points out to the use of ceramics 3D printing in nuclear fusion energy generation and how it could play a key role in the development of future commercial nuclear fusion power plants.
According to a study conducted by Professor Chen Zhangwei and Lao Changshi of Shenzhen University, in cooperation with the Southwest Institute of Physics of the Nuclear Industry of China National Nuclear Corporation, ceramic 3D printed parts could be used to produce the necessary tritium fuel.
The scientists proposed and realized the design and formation of complex porous lithium orthosilicate ceramic parts based on a photopolymerization 3D printing process. The microsphere bed structure could introduce a new generation of tritium devices, showing important application prospects.
Nuclear fusion uses deuterium and tritium as fuel. While deuterium is abundant, tritium is almost non-existent in nature and needs to be produced by the continuous catalytic reaction of helium and lithium ceramics. As an important component of the magnetic confinement fusion reactor, solid-state tritium-producing cladding is one of the core problems that need to be solved before the commercial application of fusion energy.
At present, the preferred tritium multiplier material for scientists in various countries is lithium orthosilicate (Li4SiO4). The prevailing method is to react lithium orthosilicate ceramics with helium to produce tritium. Scientists refer to the ceramic components that achieve this function as a tritium production unit.
In order for the lithium orthosilicate powder slurry to be cured quickly after 3D printing, a suitable curing method must be selected.
“Ceramic 3D printing has two main curing and forming methods, one is light curing, and the other is powder bed-based sintering or melting.” Chen Zhangwei said that powder sintering uses high-energy lasers to directly sinter ceramic powder at high temperatures, which is required for firing. Shape, but because the temperature is relatively high, it is prone to cracking, and the accuracy and controllability are poor. The light-curing not only has fewer cracking defects and higher printing accuracy but also has a strong ability to control the details of the porous structure.
Therefore, the scientific research team chose the light-curing method and developed a high-phase-purity lithium orthosilicate powder slurry for light-curing 3D printing.
Chen Zhangwei said: “We have mixed optimized organic chemical additive components in the lithium orthosilicate powder slurry, as well as a small dose of photosensitive additives, which are sensitive to specific wavelengths of light, and use 405 nanometer ultraviolet light on the slurry. The material is irradiated to realize the photopolymerization and curing of the slurry.”
The 3D printed structural parts are sintered at a high temperature and fired in an environment of 1050 degrees Celsius for 8-10 hours to achieve porcelainization. Various additives in the solidified structure can be removed, and the water and carbon dioxide in the environment will no longer be generated. The reaction, “These chemical additives are physically added and will not cause damage to lithium orthosilicate.” Chen Zhangwei explained.
The tritium production unit printed by this method is an integrated and defect-free structure. After testing, it overcomes the reliability problems caused by the limited pebble bed filling rate and stress concentration. Its stability and mechanical properties are twice as high as the traditional microsphere structure. .
The tritium production efficiency of the 3D-printed tritium production unit is also expected to be greatly improved. The duty ratio of the traditional microsphere structure is up to 65%, while 3D printing can be flexibly adjusted between 60% and 90% as needed. The specific surface area of lithium orthosilicate is also greatly increased compared with the microsphere structure.
3D printing technology has been internationally recognized as extremely innovative in the manufacture and application of core ceramic components for nuclear fusion. This research has great prospects in the application of fusion reactors, which will provide more possibilities to replace the traditional pebble-bed ceramic production structure of tritium and promote the commercialization of Tokamak nuclear fusion reaction technology.