AmiMoJo writes: Today is five years since the Fukushima Daiichi nuclear plant was damaged by an earthquake and tsunami, leading to a series of meltdowns. Nearly half a million people were evacuated at the time, with 100,000 still unable to return to their homes. The government has set a goal of 20mSv/year before people are allowed to live in affected areas again, and while progress is being made hotspots are still a problem in many areas. Reconstruction has been largely waiting for decontamination to be completed, allowing homes and businesses to fall into ruin. Those who do wish to return find their communities gutted, with essential services and jobs gone. Meanwhile, engineers are still unable to determine exactly what happened at Daiichi, particularly what saved reactor 2's pressure vessel from exploding. The initial reports were scary even before the nuclear plant problems were evident. Engadget notes that even now, the worst part of the cleanup remains a grueling work in progress, tough even for robots. Reader the_newsbeagle writes, too, with a link to the New York Times' take on the 5-year mark, and notes that The state and location of the melted fuel inside the reactors is still a mystery. The meltdown zone is too dangerous for human workers to enter, and robots have had limited success navigating in the wreckage. So Japan is recruiting subatomic particles called muons to map the reactors' insides. These particles, born of cosmic rays, constantly stream down from the atmosphere, passing through most matter unimpeded. But their occasional interactions with the subatomic components of uranium allow physicists to locate the blobs of the deadly stuff.