BEIJING – Professor Xu Hongjie, the 70-year-old visionary nuclear physicist who was the chief architect of China's revolutionary thorium reactor program, died while working at his home, just weeks before his life's work achieved a world-first milestone.
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| The father of China's thorium reactor, Xu Hongjie, passed away on September 14. |
The former director of the Shanghai Institute of Applied Physics (SINAP) passed away in Shanghai on September 14, according to an official obituary. However, the poignant details of his death—a scene of quiet devotion to his work were only revealed this week in a memorial article by the Science and Technology Daily.
According to the newspaper, the official media outlet of China's Ministry of Science and Technology, Xu died after midnight while working at his home computer.
"The books were still open on his desk, the computer mouse had fallen to the floor," the memorial article wrote, painting a solemn picture. "On the screen, his lecture, 'An Introduction to Nuclear Science and Technology,' remained unfinished."
The next day, Xu had been scheduled to teach the first class of the new semester to students at ShanghaiTech University.
The official obituary stated he died of an unspecified illness at 8:15 a.m.
The tragic timing of his death was underscored just weeks later when China announced a major breakthrough at the very project he led. The experimental Thorium-based Molten Salt Reactor (TMSR) had, for the first time in a running reactor, successfully converted thorium into uranium fuel.
A Strategic Scientist and His Life's Work
Xu was the chief engineer of the TMSR project at SINAP, a division of the Chinese Academy of Sciences (CAS), and was widely regarded as the program's leading scientist.
His colleagues described him as a visionary who dedicated his final moments to the cause.
"He was the type of strategic scientist who always looked to the frontiers of global science and technology and responded to the country's major needs," Zhu Chong, director of SINAP's reactor physics department, told the Science and Technology Daily.
"The guidance he provided in the last six months alone gave us a clear view of the development roadmap for molten salt reactor fluid mechanics for the next 10 to 15 years," Zhu said.
The Thorium "Holy Grail"
The project Xu championed, located in the Gobi Desert in Gansu province, is the world's only operating molten salt reactor (MSR) that uses thorium as its primary fuel.
MSRs are a "Generation IV" nuclear energy system, which are considered potentially safer and more efficient.
Safety: They use molten salt instead of water as a coolant. This allows them to operate at much higher temperatures but at very low pressure, significantly reducing the risk of a pressure-related accident or meltdown.
Fuel: Thorium, a radioactive element, is seen as a potential "holy grail" for nuclear fuel. It is far more abundant in the Earth's crust than uranium, produces less long-lived radioactive waste, and is inherently proliferation-resistant, making it difficult to weaponize.
In an internal CAS meeting on April 8, Xu himself stated that China "is leading the world" in this specific field, according to the Guangming Daily.
The US was the original pioneer of MSR technology, building a small test reactor in the 1960s. However, the program was famously shut down in the 1970s to prioritize uranium-based systems, and its research was declassified.
A Career of Scientific Leadership
Born in 1955, Xu Hongjie earned his PhD in nuclear physics from Fudan University in 1989 and joined SINAP as a postdoctoral researcher that same year. He rose quickly, becoming deputy director in 1995 and serving as the institute's Director from 2001 to 2009.
He was not only a nuclear expert. In 1995, he was tapped to lead the massive Shanghai Synchrotron Radiation Facility project, successfully building a "third-generation" high-brightness light source for advanced research.
In 2009, after that facility was operational, he was assigned his next great task: to lead the thorium reactor project, paving the way for the official launch of the TMSR program in 2011.
Under his leadership, the 2-megawatt Gobi Desert reactor achieved criticality a stable, self-sustaining nuclear chain reaction in October 2023, and reached its full operational power in June 2024.
His work will live on. China is already building a larger 10 MW thorium reactor, slated to achieve criticality by 2030, with a 100 MW demonstration reactor planned for 2035.