Space Particles Are Helping Map the Inside of Fukushima

A worker looks up at welding storage tanks for radioactive water at the Tokyo Electric Power Co's (TEPCO) tsunami-crippled Fukushima Daiichi nuclear power plant, March 10, 2014. Toru Hanai/Reuters/Corbis

In just about every industrial factory you’ll see them: huge lead pipes. These move fluid—often super hot, or even steamed water. Over time, the fluids wear the pipes down. Or maybe they get dinged by a passing forklift. Or maybe changes in temperature cause tiny cracks to appear. Then the pipe bursts, and people get hurt.

Inspecting pipes is a pain in the tochus. Usually these pipes are covered in insulation and pumping hot, high pressure steam. To inspect them, you have to shut down the pipe, take it out of service, remove the insulation, then apply X-rays or ultrasound—both of which require special certification to use because of the radiation involved.

But the days of butt-achey industrial inspection could be numbered, because a group of scientists at Los Alamos National Lab (you know, the atomic bomb place?) have figured out how to see through just about anything—including the radioactive disaster zone inside the Fukushima reactor core—using subatomic particles from outer space.

“Any industrial process is subject to flow-accelerated corrosion,” says Matt Durham, lead author of a new paper detailing the process, called muon tomography. Inside a pipe, whichever side that’s in contact with a fluid tends to get eaten up. The difficulty of disassembling a pipe for inspection means that comprehensive checks rarely happen. But using muons, “you don’t have to tear it apart,” says Durham. “You just have to zap it from the outside.”

Except Durham’s method doesn’t really do any zapping. The muon detector doesn’t emit anything. Instead, it just logs naturally-occurring muons as they enter and exit the pipe in question. Radioactive particles like these are everywhere in the universe. These ones start as particles called pions, which fly around in outer space until they enter the Earth’s atmosphere and decay into muons.

The detector works like this: Durham and his co-investigators sandwich the pipe in question between two four-by-four-foot aluminum slabs. When an errant muon passes through one of the slabs, it sends a message to a computer, which logs the particle’s trajectory. The muon continues through the pipe, then passes through the slab on the other side—which again measures the particle’s angle. By calculating the difference between angles, researchers can get an idea of the path the muon took through the pipe’s molecules. And with enough muons, they can draw a pretty good picture of what’s going on inside the pipe.

Or inside anything, really. Muon detectors were invented after the 9/11 attacks, as a way of looking for smuggled nukes. It’s no problem to sneak a bomb past an X-ray detector. But muons can see through cars, can see through boats, can see through shipping containers. “At Freeport, in the Bahamas, they have a detector big enough to drive an 18-wheeler through,” says Durham. The detector can find a lump of uranium in about a minute. “A lot of stuff goes through the Bahamas on its way to the East coast,” says Durham.

But finding a glowing hunk of uranium is a lot easier than detecting the structure of a faulty pipe—hence the Los Alamos breakthrough. Compared to the Bahaman detector, the Los Alamos model moves pretty slow. This is because muons are rare. “We only get one muon per square centimeter per minute,” says Durham, so it can take about 4 to 6 hours to survey a single section of pipe. Increase the area of the detector, and you can get a faster picture.

The time problem doesn’t faze Durham. “Four, six, eight hours; that’s about the length of a single shift,” he says. “You could have a guy come in, set up a scanning machine, go off to his other duties, then at the end come back and can make a judgement call.” Depending on the readout, the worker would recommend a finer-grained inspection, or if everything was good the relief worker could just move along to the next section of pipe.

Some projects require a bit more speed, though. Working with Los Alamos, Toshiba has built a giant version of the muon detector. The technology company plans to put one 27-square-foot slab on either side of the Fukushima plant in order to find the melted fuel within the damaged reactor cores—a job that so far has stymied robots.

Muon detectors could be useful for tons of industries—the biggest holdup is scaling the product to fit the needs of each use. “We need to talk to industry people and see what their exact needs are,” says Durham. “Then we can design an instrument that’s focused to scan what they have the most concerns about.” In addition to cutting down size, Los Alamos is also working on new machines made out of carbon fiber—carbon interferes with muons less than aluminum, so it creates prettier pictures. Safe factories never looked so cool.