Jeremy L. Dillon
RW Monitor
8/1/2014
Tokyo Electric Power Company’s (TEPCO) strategy to freeze contaminated water in trenches surrounding Fukushima’s Units 2 and 3 reactors is proving more difficult than initially thought, the company announced late last week. TEPCO had planned to freeze the contaminated water in the trenches in an effort to avoid spreading the flow of the water from the buildings to the trenches. The problem, though, is that the water is proving difficult to freeze due to the pumping of water in and out of the building and trenches, TEPCO said. The company is actively looking for new approaches for the trench water, including upgrading the cooling capacity of the freezing system, suppressing the flow of the water, and exploring other methods of lowering the water’s temperature.
According to TEPCO, the company has already increased the flow of coolant in the freezing technology, and it may add ice or dry ice to the water to lower its temperature. “If none of these approaches work, the company may install additional pipes to carry coolant, and insulate the pipes in the trenches with additional nylon bags filled with cement. Still other strategies may include filling spaces with grout or other materials,” TEPCO said in a release.
‘Ice Wall’ on Track, TEPCO Says
TEPCO’s troubles with the trench water are separate from its ‘ice wall’ project. The ‘ice wall’ is one of several planned strategies to deal with the groundwater contamination issue plaguing the site. While the ‘ice wall’ itself was having problems getting started, TEPCO indicated that the project is well underway to meetings its 2015 completion date. The “ice wall’ freezes the surrounding soil in an effort to block the flow of groundwater, compared to the attempted freezing of water in the trenches for removal. “We are committed to these efforts and will continue to pursue these alternatives until we have successfully removed the water from the trenches,” Site Superintendent Akira Ono said in a statement.
Both strategies are part of TEPCO’s larger multi-faceted approach to addressing water contamination at the Fukushima site. Earlier this year, 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.
