The inside of Fukushima's three busted reactor cores are a big mess. It's basically just hundreds of tonnes of very, very, very radioactive materials like uranium, plutonium, and caesium. Workers want to clean it up, but they have a problem. It's so dangerous, they can't peek inside, much less go inside.
Don't worry. Technology's coming to the rescue in the form of plentiful particles named muons and some obscure laws of physics. Because the steel and concrete walls of the reactors are several feet thick, traditional imaging technology like X-rays won't work.
Muons will, though. They're subatomic particles that are about 200 times heavier than electrons. Muons are constantly raining down on Earth—and even passing through Earth itself—because they're shaken loose from molecules in the atmosphere by cosmic radiation. How in the heck do the heck do these tiny things help us see inside impossible places? We just have to watch how they move.
The Los Alamos National Laboratory and Toshiba are putting the finishing touches on a muon-powered imaging device that they believe will let them see deep inside the reactors without putting any workers in danger or risking further radiation leaks. The technology basically spots muons when they go in one side of the reactor and checks to see if they bumped into any atoms inside and were diverted on the way through. Over time, this will help them map out the inside of the reactor.
It sounds a little confusing, but remember, this is some obscure physics here. The New York Times describes the device itself pretty clearly:
The accompanying apparatus, which has already been tried out on a small, intact reactor, consists of two billboard-size detectors, set up on opposite sides of the building. Each detector is like an array of pipes in a church organ, with each pipe filled with inert gases, including argon, that give an indication when a muon hits. The detectors keep track of which pipes were hit on the way in and on the way out, and at what angle.
Similar technology is currently used to check shipping containers for radioactive materials when they enter the US So-called muon tomography was also used to scan the insides of the Great Pyramids in Egypt back in the 1960s. Whether or not it will be Fukushima's saving grace remains to be seen. It's certainly better than the alternative because there are none that don't include certain death.