Areas are declared suitable for habitation if residents are exposed to a maximum of 20 millisieverts of radiation per year . 350 people from the central district of the city will be allowed to head home . 20-kilometer ( km ) exclusion zone declared around crippled nuclear plants since 2011 . Devastating earthquake and tsunami wiped out the Fukushima nuclear plant . Many residents remain concerned about radiation levels despite evacuation efforts .
350 people from the central district of the city will be allowed to head home . 20-kilometer ( km ) exclusion zone declared around crippled nuclear plants since 2011 . Devastating earthquake and tsunami wiped out the Fukushima nuclear plant . Many residents remain concerned about radiation levels despite evacuation efforts .