TEPCO to start water-freezing work at Fukushima plant in Dec

JAPAN - Tokyo Electric Power Co. will begin implementing a plan early next month to freeze water in tunnel pipes where they connect with turbine buildings as part of a battle to remove highly radioactive water accumulated in the pipes at its Fukushima No. 1 nuclear power plant, according to sources.

As the pipes are connected to turbine buildings where massive amounts of contaminated water are located, the utility plans to first freeze the connective sections to prevent the water from escaping from the buildings. Work to remove the water from the pipes is expected to start in April, the sources said.

The freezing operation is intended to block the flow of the water into underground water and into the ocean, so TEPCO can speed up efforts to decommission its reactors.

An estimated 10,000 tons of contaminated water has accumulated inside the tunnel pipes that link the Nos. 2 and 3 turbine buildings and the sea. The highly radioactive water in the pipes leaked out of the buildings shortly after the 2011 Great East Japan Earthquake triggered a nuclear crisis at the plant. TEPCO believes the water continues to escape from the buildings and make its way into the harbour adjacent to the plant after mixing with underground water. It therefore has accelerated efforts to develop a method to freeze the sections of the pipes that connect to the buildings.

Under the plan, ducts enclosed in nylon bags will be placed at the connections to the buildings to block the entrance of water into the tunnel pipes. Cement and soil will then be injected into the bags, and minus 40 C coolants will be put into the ducts. This is expected to freeze the bags and the contaminated water around them. The frozen soil and water eventually will block the tunnel pipes completely, according the plan.

TEPCO said it has tested this method since August and confirmed that the use of the ducts will block the water. After pumping the contaminated water from the pipes, the utility plans to inject cement and other materials into the full length of the pipes to block them.

Hiroyuki Ishikawa, general manager in charge of TEPCO's crisis team, said, "The work will take several months, so we'd like to position the ducts appropriately and minimize the workload for workers to prevent excessive exposure to radiation."