Scientific American: Seven years after one of the largest earthquakes on record unleashed a massive tsunami and triggered a meltdown at Japan’s Fukushima Daiichi nuclear power plant, officials say they are at last getting a handle on the mammoth task of cleaning the site before it is ultimately dismantled. But the process is still expected to be a long, expensive slog, requiring as-yet untried feats of engineering—and not all the details have yet been worked out.
When the disaster knocked out off- and on-site power supplies on March 11, 2011, three of the cooling systems for the plant’s four reactor units were disabled. This caused the nuclear fuel inside to overheat, leading to a meltdown and hydrogen explosions that spewed out radiation. The plant’s operator, Tokyo Electric Power Co. (TEPCO), responded by cooling the reactors with water, which continues today. Meanwhile thousands of people living in the surrounding area were evacuated and Japan’s other nuclear plants were temporarily shut down.