The nuclear fuel in three of the reactors at the Fukushima Dai-Ichi nuclear plant has melted through the base of the pressure vessels and is pooling in the outer containment vessels, according to a report by the Japanese government.
The radiation will also have contaminated the soil and plant and animal life around the facility, making the task of cleaning up more difficult and expensive, as well as taking longer.
The experts have also yet to come up with a plan for decommissioning the ruined plant. Studies have estimated that the cost of the accident at Fukushima may rise as high as $250 billion over the next 10 years.