Efforts to build an “ice wall” around units 1-4 at Japan’s Fukushima-Daiichi NPP are falling behind schedule. Work has proved more difficult than expected in areas where groundwater is fast-flowing, station owner and operator Tokyo Electric Power Company (Tepco) said on 4 August. The wall, based on technology similar to that used for ice skating rinks, is intended to keep groundwater from entering the reactor or turbine buildings where it becomes contaminated. The wall, which depends on cooling pipes driven into the ground, and surrounds the unit 1-4 reactor buildings. A cooling agent is pumped through the pipes, with the aim of freezing the soil and forming a barrier around the buildings to block groundwater inflow. In March Tepco said no firm timetable had been set for the gradual activation of the wall, but the process was expected to take months.