It's been six years since the terrible earthquake and tsunami that ravaged Japan, triggering the meltdowns at Fukushima. And six years later, some radiation still lingers in the surrounding area.
Radiation is composed of high-energy packets of light called gamma rays. These are produced all over the place in nature, from faraway supernovas to close-at-hand bananas. Radiation is colorless, odorless, and silent, which isn't a problem when you're dealing with bananas but makes radiation a formidable, invisible foe when there's a nuclear accident.
Geiger counters are probably the most well-known detectors of radiation, and they work by detecting when a gamma ray interacts with gas such as helium or neon in an enclosed chamber. This is helpful for monitoring radiation levels in, say, a nuclear power plant, but it isn't very helpful for determining where gamma rays are actually came from. To figure out where radiation is coming from with a Gieger counter, you physically have to move closer to the source, a perverse sort of game of Hot or Cold. Not exactly a safe or effective method for the cleanup crews at Fukushima.
Thankfully, scientists at Kyoto University have adapted a device that originally was created by astronomers to detect gamma rays emanating deep from the universe into a tool that can help speed up the cleanup of radiation fallout.
The device, called the Electron-Tracking Compton Camera (ETCC), can not only detect gamma rays, it can tell you where those gamma rays were coming from. ETCC does this by seeing how a gamma ray particle rebounds as it travels between two detectors. In principle, it is similar to the massive muon detector plates being used currently to pinpoint the melted fuel in the Fukushima reactors (which MOBProd covered in our most recent NOVA, The Nuclear Option, and in a NewsHour segment you can watch below).
There are, however, a few key improvements of the ETCC over those muon detectors. The ETCC is much faster than those muon detectors, gathering data in a few hours instead of a few months. And it's a real camera, so it can show the operator precisely where in front of them a bit of radioactive material might be so that it can be safely removed.
As you can see above, these fisheye-looking images show what spot of greenery or ground in front of the camera is likely to be emitting radioactive gamma rays.
Already, the scientists have been able to identify places in the Fukushima area that are still radioactive even though the cleanup crews had already passed through. The team hopes that this new device will be used more extensively at Fukushima and elsewhere in the future.
"Our ETCC will make it easier to respond to nuclear emergencies," said lead author Dai Tomono in a press release. "Using it, we can detect where and how radiation is being released. This will not only help decontamination, but also the eventual dismantling of nuclear reactors."
Banner image credit: original MOBProd footage from NOVA's The Nuclear Option.