The disaster that struck four years ago may have abated for most of the Tohoku region, but the nightmare continues at Tokyo Electric Power Co.'s Fukushima No. 1 nuclear plant, which suffered three reactor core meltdowns and is plagued daily by increasing amounts of radioactive water.

Tepco hopes to improve the situation via two key measures: a 1.5-km-long sunken wall of frozen soil encircling stricken reactors 1, 2 and 3 and the damaged reactor 4 building to keep groundwater from entering and mixing with coolant water leaking in the reactor building basements, and "subdrain" wells around the buildings to pump up the tainted groundwater for treatment and ultimate discharge into the Pacific.

The utility hopes these steps will drastically reduce the amount of radioactive water, which is currently some 300 tons each day.