There are several objections to this new plan :
- Senior Scientist: Fukushima giant ‘ice wall’ to make crisis worse — Radioactive release into ocean from saltwater intrusion
- An alternative material could do better
A construction project is being launched at Japan’s imploded Fukushima nuclear power plant, which melted down after an offshore undersea earthquake and the resulting tsunami three years ago, to try to limit the release of immense amounts of radiation.
Officials already had announced plans for a $300 million project to build an almost mile-long subterranean ice wall around the complex, which is hoped to have the effect of halting the drainage of contaminated water from the plant site.
Construction is scheduled by Tokyo Electric Power Company, the Japanese utility that owns the failed site, to begin on the complicated system within days.
It was September of last year when the Japanese government released plans for an underground wall based on technology first tested in the 1990s at Oak Ridge National Laboratory with encouraging results.
Joe Sopko, executive vice president of Moretrench, a Rockaway, N.J., based contractor specializing in frozen-earth projects, is convinced it’s certainly possible. As he told The Atlantic, “This is not a complicated freeze job. It really isn’t. However, the installation, because of the radiation, is.”
“It’s just sometimes it’s the only scenario that will really work,” said Sopko. “When nothing else will work, it just jumps out at you and says, ‘Wow, it’s a freeze job.’”
To build the wall, 1,073 pipes will be sunk about three feet apart into the ground to a waterproof rock layer (a depth of about 90 feet). The pipes will then be filled with brine (concentrated salt water) and circulated through the pipes. Using 14 400 kW refrigerating units, the brine will be cooled to -40 degrees Fahrenheit, which will freeze the ground around the pipes.
This ground-freezing technology has been successfully applied before on projects such as the construction of building foundations on unstable ground, the construction of underground storage tanks and escalator tunnels on subways. With hundreds of ground-freezing projects having been implemented, it is hoped that the use of a proven technology will work in this application.
To make this technology work, the pipes must be set in a precise vertical position and spacing. If these dimensions are off, then pockets of unfrozen earth would develop, allowing the contaminated water to escape. Making sure the placement of the pipes is precise in a lethal radioactive environment is a huge engineering challenge.
Assuming that the pipes will be able to be placed correctly, the frozen ground around the pipe will spread and eventually connect, forming a wall of frozen subterranean earth around the complex that, it is hoped, will stop the contaminated water from going any farther. The ice wall will form a barrier surrounding 25 acres of the contaminated site.
If the project is successful, once the pipes are all put in place and coolant circulating through the pipes, it is estimated that it will take six months for the ground to freeze, completing the ice wall.
While the ice wall may stem the flow of radioactive water, it is at best, a temporary solution. It is also assuming several things to be true:
- The pipes will be able to be placed in a dangerous environment within the precise tolerances needed to freeze the ground; people involved in the construction risk exposure to contaminated dust, as well as radioactive leaks.
- The refrigerating units will be sufficient to provide the cooling to freeze the ground completely;
- The waterproof rack layer underneath the complex is level enough that the water will not just flow under the wall.
Analysts suggest to provide a long-term solution, the radiation situation at the plant site needs to be stabilized. The heat being generated by the atomic fuel needs to be brought under control. (Plans call for work to begin removing the melted fuel from the No. 1 and No. 2 reactors in fiscal 2020.)