Five years ago, powerful earthquake and tsunami struck, causing three reactors at Fukushima to melt down. Since then, the efforts to contain the radiation and the contaminated water has required an army of over 7,000 workers and robots with no end in sight.

There has been no precedent to help nuclear experts to figure out how to manage the clean up. The full cleanup of the site — including the extraction of melted uranium fuel from the damaged reactor cores — is expected to take another mind-boggling 40 years (at least!). And until then…Fukushima remains very vulnerable.

The effort at Fukushima has reached a few milestones. About 1,500 spent fuel rods were successfully removed from a damaged storage tank in late 2014, a delicate and risky operation. Much of the contaminated rubble left by the tsunami and hydrogen explosions has been cleared, and overall radiation levels are down. Workers will soon be able to enter some areas of the plant without full-body protective gear.


What would happen if there was another major earthquake or tsunami? No one knows.

Water is perhaps the biggest challenge at Fukushima. Engineers must keep it flowing through the damaged reactor cores to prevent the melted fuel from overheating, and then through miles of plastic pipes to recycle it inside the plant. But because the buildings are damaged, radioactive water leaks out and builds up in the basements. When it rains, more water seeps in.

To prevent it from spreading, Tokyo Electric pumps out about 720 tons of water from the basements every day, storing it in huge tanks that workers are building. About 1,000 of the tanks have already been filled. But because there are not enough tanks, the plant also releases 2,000 tons of the water into the ocean every week after a process that removes most, but not all, of the radioactive particles.

Tokyo Electric says the water poses no danger to people or marine life because radiation levels are low and further diluted in the ocean. But environmentalists are worried, nearby fishing grounds remain closed and it is a public-relations nightmare for the government.

The company says it may not be able to solve the water problem until 2020. Other goals, including the removal of spent fuel rods stored inside the reactors, are still further off.

Robots have recently begun mapping out areas around the cores, which are still too dangerous for workers to approach. Engineers are trying to determine if cracks in the containment vessels can be repaired, which would allow them to fill the cores with water to ensure the fuel remains submerged as it is extracted, minimizing the risk of releasing radiation. The process is expected to take decades and cost billions.