It was truly a trial by fire - one that has now become part of Russia's nuclear marketing message. Cynical as that might seem.

In April 1986, as workers and engineers scrambled to keep the Chernobyl nuclear power plant's molten radioactive uranium from burrowing into the earth - the so-called China syndrome - a Soviet physicist on the scene devised a makeshift solution for containing remnants of the liquefied core.

Teams of coal miners working in shifts tunneled underneath the smoldering reactor and built a platform of steel and concrete, cooled by water piped in from outside the plant's perimeter.

In the end the improvised core-catcher was not needed. The melted fuel burned through three stories of the reactor's basement but stopped at the foundation - where the mass remains so highly radioactive that scientists still cannot approach it.

Although 25 years later Chernobyl remains the radiation calamity by which all subsequent nuclear accidents will be measured, core-catchers are now a design feature of the newest reactors that Russia's state-owned nuclear power company, Rosatom, is selling around the world. That includes a contract the company signed with Belarus just last week, even as radioactive steam was rising from the Fukushima Daiichi plant in Japan.