The largely government-owned Tokyo Electric Power Company (TEPCO) admitted that radiation levels had elevated to an estimated 8 millisieverts per year (mSv/y) outside of the Fukushima No. 1 nuclear plant in December.

This greatly eclipses the Japanese government-set limit of 1 mSv/y, put in place as part of the officially-sanctioned reactor decommissioning plan for the disaster-stricken nuclear plant as a safety measure to diminish the level of harmful effects on the surrounding areas so that the exclusion zone can eventually be lifted.