Tokyo Electric Power Company has begun transferring radioactive water from a leaking storage tank at its Fukushima Daiichi nuclear plant.
The company says radioactive strontium and other substances were detected on the ground around a storage tank from Wednesday to Friday.
TEPCO estimates that 120 tons leaked so far based on the change in the level of water in the tank.
The work began on Saturday morning.
Workers are using 4 pumps to transfer radioactive water in the tank to an adjacent tank.
The utility says the leaked water has not flowed into the ocean because there is no ditch around the tank, and the sea is some 800 meters away.
TEPCO says it will take at least 5 days to finish the transfer of water.