For years, scientists and environmentalists have worried about the long-term fallout of the Fukushima Dai-Ichi nuclear accident. And after a month of radioactive water leaking from the plant, the Japanese government has announced the construction of a giant, $470 million ice wall to stop it from filtering into the surrounding environment and the sea. This announcement was made shortly after another leak was discovered over the August long weekend.
This came only two weeks after Tokyo Electric Power Co. (TEPCO) revealed that some 300 tons of radioactive water had disappeared from a steel tank at the site. Shunichi Tanaka, chairman of the Japanese Nuclear Regulation Authority then announced at a press conference the following Monday that a small leak had sprung from a connecting pipe between some of the emergency storage tanks constructed in the wake of the tsunami.
TEPCO added that more radiation had been discovered near other storage tanks, pointing to the possibility of further leaks. Hence the decision to create a freeze wall, which would attempt to keep the leaks from getting into the groundwater and wreaking havoc all across the Pacific Ocean. According to the Associate Press:
The ice wall would freeze the ground to a depth of up to 30 meters (100 feet) through a system of pipes carrying a coolant as cold as minus 40 degrees Celsius (minus 40 Fahrenheit). That would block contaminated water from escaping from the facility’s immediate surroundings, as well as keep underground water from entering the reactor and turbine buildings, where much of the radioactive water has collected.
The project, which TEPCO and the government proposed in May, is being tested for feasibility by Japanese construction giant Kajima Corp. and is set for completion by March 2015.
Might sound a bit hokey, but this isn’t the first time that officials have tried using a giant frozen wall as a stopgap measure, or even the first time one was used to contain nuclear contaminants. In 1996, Tennessee’s Oak Ridge National Laboratory used an ice wall to keep radioactive waste from leaking into a creek.
In England and Wales, freeze walls have been used in mining operations for almost half century, and are being used to isolate arsenic trioxide leftover from an abandoned gold-mining operation in Canada’s Northwest Territories. And Moretrench, a company that worked on Oak Ridge, is creating a freeze wall pilot for containing contamination from the Albertan tar sands.
This latter project has served as a model for the current Fukushima freeze wall project. Earlier this year, TEPCO engineers also visited Hanford, Washington, to learn about nuclear containment techniques. There, engineers are still at work decommissioning the original nuclear reactors used to create plutonium for the atom bomb dropped on Nagasaki in 1945, and the government has spent $16 billion to clean up the leaks that have since resulted.
However, according to the Associated Press, the decision to put a freeze wall in place also appears to be motivated by the imminent deadline for the Olympic Committee to choose a city for the 2020 games. Since Japan is looking to host, any ongoing environmental issues could sully their chances. However, as far as long term containment goes, this option may prove effective at averting a long-term ecological disaster.
What’s more, if the cooling system to keep the barrier of insulated ice intact fails, any leaks or cracks will freeze to the wall, stopping the possibility of the further contamination. In addition, as demonstrated by the Oak Ridge Wall, an ice wall has incredible longevity. Years after it was decommissioned and remediated, the government was still hauling solid ice out of the ground.
So it would not be unreasonable to expect that it will hold long after the reactor leak is contained and worries about contamination are no longer an issue.