TEPCO officials plan to pump up contaminated groundwater through wells built around structures housing the plant's damaged reactors. The firm also plans to reduce the level of radioactive material in the water before releasing it into the nearby Pacific.
On Wednesday, the Nuclear Regulation Authority approved TEPCO's plan to install drainpipes and a pumping system and to reduce the level of radioactive cesium-137 to less than one becquerel per liter. It also agreed with the firm's policy of starting the drainage system gradually.
The regulator asked the utility to ensure that no wastewater leaks and to fully disclose measurements for radioactive material.
Tokyo Electric said it will not drain filtered wastewater until local residents agree to the plan.
The timing of such agreement is unclear, as local fishermen are worried that rumors of tainted seawater would affect their business.