Gaps in cement-filled tunnels

December 26, 2014

New method for contaminated water may be failing

http://www3.nhk.or.jp/nhkworld/english/news/20141226_37.html

Dec. 26, 2014 - Updated 12:32 UTC+1

Tokyo Electric Power Company has indicated that a new method aimed at tackling a large volume of highly radioactive wastewater at the Fukushima Daiichi nuclear power plant has not been entirely successful.

TEPCO gave a progress report on its work to a panel of experts at the Nuclear Regulation Authority on Friday.

The utility last month began pouring cement into underground tunnels filled with the contaminated water from the reactor buildings to stop the water inflow. The water is believed to be leaking into the sea.

TEPCO officials told the panel that workers have completely filled the U-shaped tunnels except for 4 vertical pits that connect the tunnels to the ground surface. They removed 2,500 tons of radioactive water.

But the officials said that when they pumped water up from one of the pits, the water level at another pit changed. That suggests that gaps exist in the concrete-filled tunnels.

The officials argued that they can stop the water from flowing into the tunnels once the 4 vertical pits are filled. But panel members and authority commissioners said more thorough inspections are needed.

TEPCO plans to monitor water levels for a month, look for gaps, and study more effective ways to block the water.

The utility initially planned to freeze wastewater at the end of the tunnel to stop inflow from the reactor buildings and remove the water. But the plan did not work.