Meet the robots looking for fuel after Fukushima's Daiichi nuclear disaster

Seven years after a powerful earthquake and tsunami caused a massive nuclear meltdown in the Daiichi Power Plant, Lesley Stahl reports on the unprecedented cleanup effort. Sunday at 7:30 p.m. ET and 7 p.m. PT on CBS

Chernobyl remains the world's worst nuclear disaster in terms of lives lost, but the worst radioactive mess the world has ever dealt with is in Fukushima, Japan. Seven years after the most powerful earthquake ever recorded in Japan led to a massive meltdown in the Daiichi Power Plant, Lesley Stahl reports on a clean-up effort that looks like a science fiction film. Her story on how one-of-a-kind robots are being designed for the decades-long task will be broadcast on 60 Minutes, Sunday, Nov. 25 at 7:30 p.m. ET and 7 p.m. PT on CBS.

The earthquake struck March 11, 2011, causing several huge tsunami waves that swamped Daiichi, cutting power to the seaside facility's cooling pumps. Three reactors melted down, creating up to 3,000 tons of deadly radioactive fuel and debris that lays in the plant's ruins.  Finding it and containing it safely will be a historic task says nuclear engineer Lake Barrett. "This is a unique situation here. It's never happened in human history. It's a challenge we've never had before," he tells Stahl. Barrett oversaw the cleanup of the Three Mile Island partial meltdown in 1979, the worst nuclear accident at a power plant in the U.S. He is also a consultant on the Daiichi project.

Daiichi can't be encased in concrete, like Chernobyl, says Barrett, because the potential for another earthquake or tsunami that could compromise the structure is too high. Humans can't get near the material; it will remain deadly for thousands of years. Authorities hope specially designed robots will find, remove and secure the toxic material in special containment vessels.  But it could take 50 years and cost an estimated $200 billion.

There are four-legged robots, some that climb stairs and even robots that can swim into reactors flooded with water. They're equipped with 3-D scanners, sensors and cameras that map the terrain, measure radiation levels and look for the deadly material.

The Japanese government set up a research facility nearby to develop and test the robots. Some have been deployed in what amounts to experimentation at this early stage, says Barrett. One robot is called the Scorpion for its ability to raise its camera-carrying tail. It struck debris and became stuck only ten feet into its $100 million mission. Says Barrett, "You learn more from failure sometimes than you do from success."

Other early versions of robots died quick deaths, too, their cameras and operating systems fried by the intense radiation. It's a slow and steady project, says Barrett, that he is confident will get done, but not in his lifetime, nor those of many others involved. The task has been compared to putting a man on the Moon. "It's even a bigger project in my view. But there's a will here to clean this up as there was a will to put a man on the moon," says Barrett.