The nuclear reactor has been in the works since 2016 and was only began operations in December 2023.
In a global first, researchers at Tsinghua University in China have successfully demonstrated a meltdown-proof nuclear fission reactor. The twin reactor design can generate 105 MW of power each and has been in the works since 2016. The technology is a welcome step for the nuclear energy industry after the meltdown at Fukushima in Japan more than a decade ago.
During nuclear fission, large amounts of heat energy are generated, which is useful in generating electricity but is also a risk for the reaction. Nuclear reactors are designed with in-built cooling mechanisms that take the heat away from the reaction, failing which the reactor can overheat or even explode.
Typically, the cooling mechanisms use water or carbon as cooling agents and are backed by external power supplies to ensure that the reactor temperature stays within control. In 2011, the Fukushima nuclear reactor experienced a rare event in which the standard and emergency power supply to the cooling mechanism failed, leading to a meltdown.
Researchers have since pushed to build a nuclear reactor that is passively cooled and uses natural cooling methods. One such design is a high-temperature reactor with a pebble-bed module (HTR—PM).
What is a Pebble-bed Module nuclear reactor?
Conventional nuclear reactors use fuel rods that are energy-dense, containing large amounts of uranium with smaller amounts of graphite. In the HTR-PM reactor design, the fuel rod is inverted, and a large amount of graphite is used within which uranium is encased. This makes the energy density of the fuel much lower, almost like pebbles in a larger body of water.
The approach has two major advantages. The first is that the nuclear fission reaction occurs much slower than a conventional reactor and can withstand a higher temperature for much longer. The second advantage is that the excess heat generated through the process is dispersed over a larger fuel area and can be cooled using passive or non-energy-consuming methods such as conduction and convection.
The approach has previously been demonstrated in prototype reactors built in Germany and China but a full-scale HTR-PM reactor had yet to be attempted.
China’s ambitious attempt
Interesting Engineering has previously reported China’s ambitious push for nuclear power to reduce its dependence on fossil fuels. The Asian country has been building nuclear reactors at an unprecedented scale, but attempting a commercial-scale nuclear reactor for a new technology is a first for China, too.
Success did not come easily either. The Institute of Nuclear and New Energy Technology began constructing the commercial-scale HTR-PM at a facility in Shandong in 2016, with expectations that the site would be ready for testing a year later.
The reactor began commercial operation only in December 2023. To demonstrate that it could cool itself down without an external source, the team shut down both modules when it was running at full power and began tracking temperature movements inside the reactor.
As expected, the reactors cooled down naturally and reached a stable temperature 35 hours after they were shut down.
The technology’s drawback is that it cannot be retrofitted onto existing nuclear reactors. To build a future where nuclear reactors are meltdown-proof, the nuclear energy industry will have to build HTR-PM reactors first.
Luckily, the reactors do not have to be built on-site and can be rapidly deployed worldwide.
The research findings were published in the journal Joule.
Source: Interesting Engineering
