Tokyo Electric Power Co. this week announced measures that bring it closer to preventing contaminated groundwater at its Fukushima Daiichi nuclear plant from reaching the sea.
Recent developments at the facility blacked out following Japan's 2011 earthquake and tsunami include:
Reactor Subdrains Restored
On Wednesday, TEPCO said it has repaired and expanded subdrains originally used to control groundwater levels near the reactors. A system now ready for government inspections will use a new network of 42 wells next to reactor and turbine buildings to pump the water and reduce flooding in plant basements by 200 metric tons daily. A treatment system is planned to remove radionuclides in the stream before releasing it into the ocean. TEPCO said in a release that it would seek an agreement with local fishermen and governments before taking that final step, noting that contamination levels would meet the same standards as groundwater pumped from behind another barrier uphill from the reactors. Test runs of subdrain pumping were scheduled to begin this week.
Seawall Nearing Completion
TEPCO also reported that an impermeable barrier between contaminated groundwater and the plant's man-made harbor could be complete as early as next month. The utility described its design as a steel pipe sheet pile wall. Driven 30 meters into the seabed, it will reach deeper than the adjacent aquifer and represents a long-awaited barrier between the ocean and contaminated groundwater flowing through the area immediately surrounding the damaged reactors. Additional wells will allow the water that accumulates behind the seawall to be pumped up and treated.