Chinese Pebble-Bed Reactor Passes “Meltdown” Test
30th November 2024
New testing done at China’s Shidaowan nuclear power plant has confirmed its ability to be naturally cooled down, an industry-first milestone for achieving commercial-scale inherent safety, according to researchers.
The Shidaowan plant, a demonstration high-temperature, gas-cooled reactor with a pebble-bed module (HTR-PM), went into commercial operation last December.
Shidaowan’s twin 100-MW units house tiny uranium capsules encased in graphite shells about the size of billiard balls (dubbed “pebbles”), which make the energy density of the fuel much lower than in a traditional nuclear reactor with fuel rods. In the pebble design, the nuclear fission reaction occurs more slowly than in conventional reactors, but the fuel can withstand higher temperatures for longer and the heat resulting from the fission reaction is dispersed, enabling a passive cooling process.
The reactor doesn’t rely on large volumes of water in the cooling process—instead, a small amount of helium gas, which can withstand much higher temperatures than water, is piped through the system to naturally cool it down. If the reactor starts to get too hot, its components automatically slow down the nuclear reaction and the system cools. This setup makes such a reactor “meltdown proof,” in concept.