Can a Wall of Ice Save Fukushima?
By Jim Vess
No, I’m not talking about the giant ice wall to keep out marauding bands of wildlings in Game of Thrones or the plot of Frozen. Instead, I’m referring to Tokyo Electric Power Company’s (TEPCO) plan to use an underground wall of ice built around the damaged Fukushima-Daiichi reactors to help contain leakage of contaminated water into the Pacific Ocean.
The system is made up of 1,550 underground pipes designed to create a 0.9-mile barrier of frozen soil around the four reactor units that were damaged by the earthquake and tsunami of March 11, 2011. The pipes are set 100 feet deep and TEPCO says the coolant in the pipes will freeze the surrounding soil to minus 22 Fahrenheit, creating the wall over several months. The ice wall is expected to reduce by 75% the amount of groundwater flowing into the area and the amount of radioactive water from leaking out.
The installation of the ice wall system, at an estimated cost of $312 million, took two years, a year behind schedule. The project was funded by the Japanese government and built by Kajima Corporation, which has used similar technology in smaller projects, like subway construction.
On March 31st, TEPCO, with the approval of Japan’s Nuclear Regulation Authority (NRA), energized the first phase of the ice wall, which flanks the Fukushima-Daiichi No.1 plant, overlooking the ocean on the west. The second phase of the ice wall will extend to the north and southern parts of the plant area, covering about 95 percent of its total perimeter.
The amount of water flowing into and out of the plant site could be further reduced if the third phase of the underground barrier is completed, which would seal off the eastern side of the plant. This third phase is awaiting approval by the NRA.
There are some who doubt that the huge ice wall system can effectively freeze the soil while groundwater continues to flow in the area. TEPCO says that, while the results from a test of part of the wall last summer were mixed, the system has sufficient capability. Experts are also concerned that an ice wall cannot be adjusted quickly in an emergency situation, like a sudden increase in the flow of contaminated water, because it takes several weeks to freeze or melt. TEPCO says the wall, once formed, can remain frozen for up to two months in the event of a power failure.
Speaking of power, the electrical costs for running the ice wall refrigeration system will be steep.
Can a wall of ice save Fukushima? Well, it’s too late for the reactors – there is no repairing them. However, a wall of ice that can prevent further leakage of contaminated water will make decontamination and decommissioning of the plant safer and prevent contaminated water from reaching the Pacific Ocean. And all of those things are good for the future of the nuclear industry.