mdsolar sends this report from Symmetry Magazine: Cosmic rays can help scientists do something no one else can: safely image the interior of the nuclear reactors at the Fukushima Daiichi plant. ... [M]uon tomography is similar to taking an X-ray, only it uses naturally produced muons. These particles don't damage the imaged materials and, because they already stream through everything on Earth, they can be used to image even the most sensitive objects. Better yet, a huge amount of shielding is needed to stop muons from passing through an object, making it nearly impossible to hide from muon tomography. ... By determining how muons scatter as they interact with electrons and nuclei within the item, the team's software creates a three-dimensional picture of what's inside. ... To prove the technology, the Los Alamos team shipped a demo detector system to a small, working nuclear reactor in a Toshiba facility in Kawasaki, Japan. There, they placed one detector on either side of the reactor core. "When we analyzed our data we discovered that in addition to the fuel in the reactor core, they had put a few fuel bundles off to the side that we didn't know about," says Morris. "They were really impressed that not only could we image the core, but that we also found those bundles."