HARMFUL TO MAN AND MACHINE

It’s been more than five years since the disastrous Fukushima Daiichi nuclear power station’s multiple reactor meltdowns. The event occurred in the of wake of a 40 meter high tsunami that hit the northeastern shores of Japan in 2011. The tsunami left thousands of casualties, and the subsequent meltdown created a 20-kilometer radius of highly radioactive territory. The Fukushima meltdown has been classified as a Level 7 on the International Nuclear Events Scale (INES) — second only to the Chernobyl disaster in 1986.

An effort to assess the current conditions in Fukushima is underway, with hopes of completely cleaning up the area. The Japanese government, in tandem with the Tokyo Electric Power Company (TEPCO), launched a project to send robots into the site. The robots, called “scorpions,” were designed and developed by Toshiba to examine the remains of the unit and find the melted uranium fuel inside.

Unfortunately, the “scorpions” didn’t get very far. Earlier this month, a “scorpion” robot that was sent inside the meltdown site malfunctioned after just two hours because of high radiation levels. A second “scorpion” was sent in just last week, only to meet a similar fate as its predecessor: the machine’s left crawler belt malfunctioned and the robot stopped working altogether.

WHY RADIATION IS HARD TO CLEAN UP

The Japanese government has already cleaned up more than 9 million cubic meters of contaminated soil and other materials in the area surrounding the Fukushima power plant. The target is to bring down outdoor radiation exposure to 0.23 microsieverts per hour so that people can safely live there again. Radiation levels of just 1 sievert (1,ooo microsieverts) would cause immediate radiation sickness, but most exposures are in smaller doses which is why scientists use microsieverts as a more precise measurement for assessing risk.

Despite these risks, some people have already started relocating back into the areas surrounding Fukushima. The radiation inside the power plant itself remains at harmful levels, too. This isn’t surprising to scientists, because radiation usually sticks around due to the long half-life of radioactive material — about 30 years in Fukushima’s case. The scorpion robots that got stuck inside the power plant measured radiation levels of 210 sievert per hour — enough to kill a human being in just two minutes. According to an earlier robot survey, the levels could potentially reach up to 1,000 sievert per hour.

While humans are clearly unequipped to make the assessment of Fukushima safely, it turns out we may need tougher robots to do the job.