TEPCO completes wall at Fukushima plant to block contaminated groundwater

27 October 2015

Tokyo Electric Power Co. announced on Oct. 26 that it has completed construction of a seaside underground wall at the crippled Fukushima Daiichi nuclear power plant, a major part of the utility's strategy to minimize the flow of contaminated groundwater into the ocean. The barrier is expected to significantly reduce the amount of radioactively tainted water flowing into a local port from 400 tons to 10 tons per day.

It was a major milestone in TEPCO's plan to manage contaminated water from the plant, more than four years and seven months since the triple reactor meltdowns at the plant following the 2011 Great East Japan Earthquake. Attention is now focused on operations to create a frozen soil barrier to prevent groundwater from flowing into reactor buildings.

According to TEPCO, the seaside impermeable wall is formed by driving into the soil 594 cylindrical steel sheet piles side by side across over a stretch of 780 meters. Construction of the wall wrapped up at around 9:40 a.m. on Oct. 26 when work was completed to fill gaps between the pipes with mortar to shield water.

By blocking the flow of contaminated groundwater, TEPCO estimates that the amount of groundwater flowing into the ocean will be reduced sharply, with radioactive cesium and strontium down to one-40th and tritium to one-15th of their current levels.

To prevent the rise of groundwater, it will be pumped up through subdrains dug around the reactor buildings and groundwater drains near the new wall for processing at a purification facility before being cleaned and released into the ocean. TEPCO said it will analyze the concentration of radioactive substances in seawater at the port for about a month to check on the effectiveness of the impermeable wall.

(Translated by Kyodo News)