23.6 Responding to a nuclear accident is difficult and dangerous work.

By March 14th, three days after the earthquake and tsunami, all but a handful of workers had evacuated. The world media would dub the cohort that stayed behind “The Fukushima 50.” The radiation levels in the main control room of reactor No. 2 had climbed so high that those remaining workers had to rotate out at regular intervals to avoid being poisoned with radiation.

Around the world, nuclear experts worried aloud over what might happen next: would there be another explosion? Would the spent-fuel pools run completely dry? Would fuel that had already melted into a heap at the bottom of some reactors now melt through their steel vessels and react with the concrete below? And how far would the wind carry all the radioactive vapours that were escaping into the atmosphere? Experts in the United States said it was at least possible that the vapours could reach the edges of Tokyo—the world’s largest city, with a population of 35 million.

Meanwhile, helicopters were scooping up buckets of water from the sea and trying to dump them on the reactors. First, they were deterred by high radiation levels. They bolted lead plates to the choppers’ bottoms and tried again, but strong winds blew most of the water askew of the Daiichi plant. Eventually, fire engines made their way through. Using hoses designed for jet-fuel fires, they were able to get some water to the places where it was most needed.

The saving move, however, was already in the works by then. “Even as buildings exploded,” the New Yorker reported, “some of the workers had hooked up a train of fire trucks capable of generating enough pressure to inject water directly into the fuel cores. The drenching continued around the clock, and it went on for months. The process was ungainly, and it produced millions of litres of radioactive waste that will be dangerous to store, but it probably did more than any other measure to avert a far worse disaster.”