Robots and the Japan nuclear crisis: Don't start a reactor you can't shut down.

Robots and the Japan nuclear crisis: Don't start a reactor you can't shut down.

Science, technology, and life.
March 22 2011 4:29 AM

The Robot Rule

Don't start a nuclear reactor unless you have robots to stop it from melting down.

William Saletan William Saletan

Will Saletan writes about politics, science, technology, and other stuff for Slate. He’s the author of Bearing Right.

Here's the first thing to learn: Get some robots that can help us in a serious nuclear accident.

Nuclear power plants are built with multiple layers of protection—automatic shutdowns, containment vessels, backup power generators—so that if one safeguard fails, another can avert disaster. After the March 11 earthquake and tsunami, these safeguards worked at every Japanese nuclear plant except one. The Fukushima Daiichi plant's reactors shut down, but its cooling systems failed. Pressure built up, and its reactor buildings exploded. The explosions didn't focus on the reactor cores, but they triggered radiation leaks that impeded workers from getting near the reactors.

This is the really scary thing about Fukushima: The cores were drifting toward meltdown, and we couldn't reach them. Helicopter missions to dump water on the reactors were called off due to radiation. More than 90 percent of the plant's workers had to evacuate. Catastrophe loomed because humans could do nothing.

But robots could. Robots can survive radiation. And if radiation kills them, robots are expendable.


Robots have been used at nuclear power plants for decades. They inspect pipes, check radiation levels, remove waste, dismantle reactors, and decontaminate sites. Normal robots can't endure radiation—it fries their cameras and circuits—but some robots built for nuclear plants are heavily shielded to manage it. Others rely on hydraulics, avoiding the need for vulnerable electronics.

For the most part, these robots are designed for routine tasks. Some robots have been sent to inspect and clean up accident sites such as Chernobyl and Three Mile Island. But in those cases, the robots took months to custom-build, and they weren't deployed until years later.

In 1999, Japan suffered an accident at its Tokaimura nuclear plant. The accident was caused by human error, and two of the humans, sickened by radiation, paid with their lives. Afterward, the government vowed to deploy robots that could handle such accidents. It enlisted Hitachi, Mitsubishi, and Toshiba to build the machines. One team produced RABOT, a "radiation-proof" two-armed robot that could open and close  valves. Another produced SWAN, a "Smart Working robot for Anti-Nuclear-disaster," which had a camera, a manipulator, and eight tools to perform "seven kinds of works for anti-nuclear-disaster."

But these prototypes never caught on. In 2006, U.S. evaluators reported that one such prototype, paid for by Japan, was "very expensive and hasn't sold well." Japan's leading researcher in disaster robotics says power plant owners felt "they did not need such robots because their nuclear plants never have accidents and are safe." A Korean expert in nuclear energy says plant operators like to buy robots for routine tasks, but they "don't like to think about serious situations that are beyond human control."

Financially, this makes sense. Power companies want cheap robots that can replace workers and are always useful. They don't want robots expensively equipped to handle unlikely nightmare scenarios. But nightmare scenarios are what we most need robots for. And in these situations, cheap robots won't cut it. Fukushima has suffered an earthquake and a tsunami. Its reactor buildings have exploded. It's full of debris and leaking radiation. For this, you need robots that can tolerate lots of radiation, navigate unfamiliar terrain, climb over irregular obstacles, drag hoses, and spray tons of water.

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