China has built what it claims is a melt-down-proof nuclear reactor that would remove one of the main objections to building more nuclear power stations to tackle the accelerating Climate Crisis.

Based on a “pebble technology”, Chinese successfully turned off the power at the High-Temperature Gas-Cooled Reactor Pebble-Bed Module (HTR-PM) in Shandong, China, and the reactor passively cooled itself as a result of the technology.

The technology was tested at a large-scale nuclear power station (NPP) and has become the first in the world to demonstrate complete imperviousness to a meltdown, even in the event of a total loss of external power.

Modern NPPs typically rely on powered cooling mechanisms to dissipate excess heat from reactors or require human intervention during emergencies to shut down the plant. Commonly used coolants, such as water or liquid carbon dioxide, depend on external power supplies to function. A catastrophic power cut that disabled the cooling system was what caused the meltdown during the Fukushima disaster in Japan in 2011.

The new reactor design, the pebble-bed reactor (PBR), uses low-energy-density “pebbles” containing small amounts of uranium encased in graphite rather than the larger fuel rods found in most reactors. The small size of the pebbles slows the nuclear reaction and can endure high temperatures. As the heat is spread over a much wider surface area and the pebbles themselves can be easily moved, it is easier to cool the system in an emergency using natural cooling processes like conduction and convection, The New Scientist reports.

China is rapidly catching up with Western nuclear technology and recently successfully tested the first nuclear fusion reactor that produces more power than it takes to create the fusion reaction.

Russia has also come on in leaps and bounds since the Soviet-era Chernobyl disaster. Those ill-fated RBMK-type reactors have long ago been ditched and replaced by the third-generation VVER 1200 (water-water energetic reactor) that are compliant with the IAEA’s International Nuclear Safety Group (INSAG) recommendations and are generally considered to be state of the art.

As an added safety precaution, Russian reactors are built over a deep pit with a heavy concrete roof. In the event of a meltdown, the reactor burns through the concrete floor, drops into the pit and pulls down the roof, which seals the reactor inside a sarcophagus, minimising the spread of radioactive debris. American reactors have not adopted this solution, which adds significantly to construction costs.

Russian nuclear exports are booming and its technology now accounts for some 70% of global installed nuclear capacity. Having lost most of its gas business due to clash with Europe, formerly its biggest customer, uranium is the new gas as the Kremlin uses nuclear power deals to bind countries from the Global South more closely to its orbit.

While small prototype PBRs have been operational in Germany and China before, this is the first time a full-scale PBR has been tested and shown to be safe. The “pebble technology” means there is no emergency core cooling system in the HTR-PM plant, unlike in conventional reactors.

Once the power to both modules of HTR-PM was turned off while they were operating at full power, the plant’s temperature naturally decreased to a stable level within 35 hours without the use of any external cooling mechanisms, the Chinese scientists reported.

More testing of the technology is needed before it can be rolled out commercially, but the Chinese scientists say they have passed a key milestone that paves the way for safer nuclear power generation globally.