"The biggest danger during the Chornobyl disaster was that the molten mass from the reactor could go downwards. The same danger is now present at Fukushima. It can form a drop that can heat up, burn the bottom, go under the ground and reach the groundwater," Voznyak told a press conference at the Interfax head office on April 25.
Once under the ground, radiation is most likely to stop spreading, but underground waters could take the drop over a vast area, he said. "And there seemed to be no possibility to stop this radiation," Voznyak said.
At the time, Chornobyl clean-up workers took urgent steps to solidify the bottom of the reactor, he added. "We decided to make a large slab under the reactor with an area of 900 square meters and more than 2 meters thick, insert pipes into this lab and fill the pipes with liquid nitrogen that gives a temperature as low as minus 200 degrees," he said.