In the mid-1960s, U.S. nuclear scientists introduced the term “China syndrome”, which referred to a severe accident involving core destruction. This nuclear meltdown scenario was named so for the fanciful idea that there would be nothing to stop a meltdown tunneling its way to the other side of the world (colloquially referred to as China).
Despite the very low probability of such an event, additional measures to improve nuclear facility safety have recently been taken throughout the world. For instance, Russian nuclear scientists invented a special device, the so-called “core catcher”, which is installed under the reactor as early as during the construction stage. During operation, this device allows to prevent the release of radioactivity beyond the containment even in the event of a worst-case accident.
The core catcher is a container installed under the bottom of the reactor vessel. In the event of an anticipated accident, the core catcher holds molten core mixed with reactor structural materials, thus precluding any possible containment damage and preventing the spread of radioactive substances into the environment. When molten core contacts the cassettes with special material located in the core catcher, it loses cumulative heat; also, a number of chemical processes occur that cumulatively solidify the molten core while preventing release of radioactive substances into the atmosphere within the containment, and create conditions for long-term corium containment and cooling.
The world’s first core catchers was installed at Tianwan NPP (China). The first Russian nuclear power stations equipped with core catchers are Novovoronezh NPP II and Leningrad NPP II.
This technical solution is recognized all around the world and is applied at all Russian-made nuclear power plants currently under construction.