Advanced Nuclear Energy Technologies: Towards greater safety and reliability

Nuclear fission energy technology: squeeze nuclear waste, enrich nuclear fuel

In 2016, Zhan Wenlong, an academician of the Chinese Academy of Sciences, visited Hanford, a town on the Columbia River in Washington State. It's the largest radioactive waste disposal site since the United States developed nuclear weapons. There are large, rusted tanks containing enhanced chemical corrosion, highly radioactive nuclear waste.

Zhan remembers the shock: "The United States now spends $2 billion a year to maintain security there." That made him more determined to develop a technology in our country that could dispose of nuclear waste more safely and economically.

In the eyes of scientists, nuclear waste is not "waste", but "spent fuel" that can continue to be used. As early as 2011, the Chinese Academy of Sciences launched the "Future Advanced Nuclear fission energy - ADS Transmutation system" strategic pilot science and technology project (referred to as ADS pilot project), the goal is to use the accelerator to produce high-energy protons, drive spent fuel to continue to "burn". Because the fuel stops "burning" when the accelerator stops running, this technology is internationally recognized as the most promising way to safely dispose of long-lived nuclear waste using transmutation.

By the time Zhan Wenlong visited the United States in 2016, scientists had broken through some of the key core technologies of ADS and completed the design of a new program, a more cost-effective "accelerator Driven Advanced Nuclear Energy System" (ADANES) that can "eat and squeeze" spent fuel.

The new program consists of two parts, one is to industrialize the existing ADS technology, and the other is to develop the spent fuel recycling system (ADRUF). The former is equivalent to "making a furnace", the latter is equivalent to "making fuel".

Zhan Wenlong introduced that according to this program, the utilization rate of uranium resources will be increased from the current less than 1% to more than 95%, and ultimately only need to dispose of less than 5% of nuclear waste, its radioactive life will be shortened from hundreds of thousands of years to 500 years, and 30% of thorium resources can be burned, which will support the development of nuclear power for thousands of years. While achieving the goal of carbon neutrality, it also generates valuable isotopes that can be used for precision targeted radiotherapy and nuclear mobile power.

When the ADANES program is in full swing, the pilot project of "Future Advanced Nuclear fission energy - Thorium-based molten salt Reactor Nuclear Energy System" (TMSR) launched at the same time as the ADS pilot project has also achieved initial results.

"Before the launch of the 'future advanced nuclear fission energy' pilot project in 2011, it has been clear that the Chinese Academy of Sciences will do scientific and technological innovation in the field of nuclear energy." After analyzing the situation, we believe that there are two starting points. One is to develop nuclear waste safe treatment and disposal technology to minimize the nuclear waste that needs geological disposal, aiming at the problems of nuclear waste safety and environmental impact. In response to the shortage of uranium-235 nuclear fuel, we will develop technology to use thorium-232 as nuclear fuel to diversify nuclear fuel sources." Peng Zilong, then director of the Material and Energy Department of the Major Task Bureau of the Chinese Academy of Sciences and secretary of the Discipline Inspection committee of the Ganjiang Innovation Research Institute of the Chinese Academy of Sciences, told the Chinese Science Journal when recalling the pilot project.

TMSR pilot special plan with about 20 years, the first in the world to achieve the application of thorium-based molten salt reactor, while the establishment of thorium-based molten salt reactor industry chain and the corresponding scientific and technological team. In November 2017, the Chinese Academy of Sciences and Gansu Province signed a strategic cooperation framework agreement for fourth-generation advanced nuclear thorium-based molten salt reactors. By May 2021, the main project of TMSR has been basically completed.

Nuclear fusion energy technology: Eastern Hyperring and Divine Light

In the development of nuclear fission energy at the same time, the Chinese Academy of Sciences has a group of researchers to explore another type of future advanced nuclear energy technology - controlled nuclear fusion energy technology.

"Fusion energy is the ultimate goal of nuclear energy development, and fusion energy can make a significant contribution to achieving carbon neutrality." Said Song Yuntao, vice president of the Hefei Institute of Material Sciences and director of the Institute of Plasma Physics.

Nuclear fusion is the equivalent of squeezing a bunch of atoms together and releasing energy. Nuclear fusion reaction conditions are harsh, not only need to reach tens of millions or even hundreds of millions of degrees Celsius of high temperature, but also need enormous pressure. Therefore, how to trigger the reaction is a major difficulty in nuclear fusion energy technology.