Jeremy L. Dillon
RW Monitor
6/6/2014
The Tokyo Electric Power Company this week began the construction of an ‘ice wall’ at the Fukushima Daiichi Nuclear Station in an effort to help divert groundwater from the contaminated site. The ice wall is part of TEPCO’s larger plan that also includes a well pumping system to prevent the further spread of groundwater contamination that has been plaguing the site’s cleanup. Close to 400 tons of water pours into the site every day, with some of that contamination flowing into the nearby ocean. “Beginning construction of the ‘ice wall’ represents another milestone in our overall effort to move forward in decontamination and decommissioning at Fukushima Daiichi,” TEPCO President Naomi Hirose said in a statement. “We appreciate the government’s cooperation, and the innovative work being performed by Kajima Corporation to make this important progress happen.”
The Kajima Corporation will provide its technology to the site under the Japenese government’s monetary support. Kajima’s ‘ice wall’ technology is actually a system that freezes the ground to a depth of 30 meters, preventing groundwater from flowing through the obstacle. The wall will surround the site at a circumference of approximately 1,500 meters, TEPCO said. Because of different pipes and necessary equipment in the ground, a frozen obstacle, compared to a more physical barrier made of concrete, helps avoid the problems associated with building an underground physical barrier. The system freezes around the obstacles in the ground, eliminating a more costly construction. TEPCO expects the ‘ice wall’ to be completed by early 2015.
The ‘ice wall’ is one of several planned strategies to deal with the groundwater contamination issue. Last month, TEPCO announced the launch of its by-pass system that diverts groundwater from the site. The bypass system is an attempt to reduce the accumulation of contaminated water by intercepting the clean groundwater before it reaches the plant by rerouting it around the plant into the sea. TEPCO said that once the system reaches its full operation capacity, it should reduce the amount flowing into the building’s basements by up to 100 tons per day, a reduction of 25 percent. TEPCO has placed 12 pump-up wells on the upstream side of the site’s buildings that will pump the groundwater to the surface. Once it has reached the surface, the groundwater is delivered to a special tank through a series of pipes. The water will then be monitored for quality, and when it meets the standard criteria, the water will be discharged.
