After a month of alarming leaks at Fukushima’s Dai-Ichi nuclear power plant, the Japanese government has announced the construction of a giant, $470 million ice wall to stop radioactive water from filtering into the surrounding environment and the sea.
The news, which the Associated Press connected to the imminent deadline for the Olympic Committee to choose a city for the 2020 games, followed the discovery of yet another leak over the weekend at the ill-fated plant. Two weeks after Tokyo Electric Power Co. (TEPCO) revealed that 300 tons of radioactive water had disappeared from a steel tank at the site, Japanese Nuclear Regulation Authority Chairman Shunichi Tanaka announced at a Tokyo press conference on 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.
You're asking yourself: an ice wall is a real thing? The Associated Press reports:
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.
This isn’t the first time that officials have tried using a giant frozen wall as a stopgap. In 1996, Tennessee’s Oak Ridge National Laboratory used an ice wall to keep radioactive waste from leaking into a creek. Though freeze walls had been used in mining operations throughout Wales and England as early as a century and a half ago, it was the first time that a frozen barrier had been used to contain nuclear contaminants, remembers Edward Yarmak Jr., who at the time served as chief engineer (and is now president) of Arctic Foundations, Inc., one of the two companies that collaborated on the Oak Ridge wall. Today, freeze walls are being used to isolate arsenic trioxide leftover from an abandoned gold-mining operation in Canada's Northwest Territories, and Moretrench, the other company that worked on Oak Ridge, is creating a freeze wall pilot for containing contamination from the Albertan tar sands, Yarmak says.
"I think the key thing here is that the technology’s not new--it’s not hard to do," Yarmak told Co.Exist. "It’s not going to be a really difficult job to engineer the ground freezing system. The real big project here is getting the system installed. And keeping the people that are doing the installation safe at Fukushima."
Specifically, Yarmak worries about the amount of contaminated dust from explosions at the Fukushima site that engineers were lucky to avoid at Oak Ridge. "We were on a fairly clean pad--even though there were radioactive trees, you could blow away the leaves with a leaf blower in the fall," he said. "At Oak Ridge, when we were digging we had fairly high contamination levels of the soils, but they were wet, so you didn’t have stuff becoming airborne so you could breathe it," Yarmak noted. By contrast, nearly all photos of workers at or around Fukushima show that they wear air-purifying respirators--a sign that contaminants are loose and airborne.
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. More than 100 tanks of radioactive waste are buried underground at Hanford, some of which are still currently leaking. The reactors have been dormant since 1987, but the U.S. has spent more than $16 billion on clean-up, according to the Japan Times.
It may be better that TEPCO decided to go with the Oak Ridge option--in late June, the DOE launched an investigation into the possibility that one of Hanford’s double-walled tanks had contaminated a leak detection pit nearby. It turns out that the radiation detection may have in fact been human error, but the full report has yet to be released.
Yarmak, however, points to the fact that each site has a different set of geological circumstances--what worked or didn't work at Hanford might not have bearing on Fukushima. However, he does believe that the ice wall could prove to be an effective strategy in Japan, and points out that if the cooling system to keep the barrier of insulated ice intact fails, "it's not the end of the world." With ice, for example, if a leak somehow springs and flows through a crack, it'll freeze to the wall, stopping the possibility of the further contamination.
As another example, Yarmak points to what happened at Oak Ridge when the Department of Energy decided to decommission the wall and fully remediate the site after seven years--hauling all contaminated soils, and the ice wall, out. "A year after they had begun remediating the site, they were still taking out huge chunks of ice," Yarmak said, adding that it takes a significant amount of time for the ice wall to thaw once the system is in place.
[Image: Ice via Shutterstock]