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.)
Also, the thousands of gallons of cooling water brought into the site every day needs to be stopped. The stored contaminated water needs to be filtered and evaporated with the radioactive material left behind and safely disposed of.
Critics say Fukushima is a stark reminder that there are safety issues still outstanding for the nuclear industry and the consequences of these disasters have not been properly addressed.
In the U.S., politicians are starting to turn up the heat on regulatory agencies to submit plans to prevent a Fukushima-like incident from occurring in the United States.
One year after calling on regulators to issue a progress report on their efforts to implement a range of safety measures identified in the aftermath of 2011 calamity, Sen. Barbara Boxer, D-Calif., renewed her call for the Nuclear Regulatory Commission, or NRC, to speed up its review of nuclear plant vulnerabilities to seismic activity both in her home state and across the western part of the United States.
To date, the NRC has taken nearly three years to assess the risks and has stated that it may take an additional three years to complete the process.
“This is an unacceptable delay – earthquakes will not wait until after the paperwork has been completed,” she said during opening remarks at a hearing on the issue.
Boxer is the chair of the Senate Committee on Environment and Public Works.
She warned that it will be another three years at least before some 60,000 Fukushima-area residents can return to their homes.
There are other complications.
The Russian news outlet RT.com recently reported that TEPCO fears that a three centimeter (one and one-quarter-inch) hole has developed in retaining basin that holds highly radioactive water. Data gathered remotely by a submersible robot revealed a damaged area in the bottom of the pool. This area may be among the pathways for irradiated water to migrate into the soil, and eventually the ocean.
Since the Fukushima incident, the leakage of contaminated water has been an issue. It caused an immediate danger to the residents near the plant complex, and that danger has now spread with possibly global implications.
TEPCO is pouring tons of water into damaged reactors to try to keep the reactor fuel cool. But the damaged buildings are allowing this now radioactive water to seep into groundwater and find its way into the nearby sea.
Several methods have been tried to stop the water from migrating into the ocean. Most have had mixed results.
The contaminated water first started to accumulate in the basements of buildings in the complex when crews began injecting tons of water into the reactors after the earthquake and tsunami on March 11, 2011, which knocked out power to cooling systems.
Groundwater then started leaking into the basements, adding to the problem. Then the irradiated water migrated into groundwater, causing radiation at nearby monitoring wells to spike.
Adding to the problem is the direct runoff of water from the surrounding area coursing over the ground and through the complex. The Fukushima nuclear facility is located on a slope. This means groundwater running down from the Abukuma plateau east of the plant flows through the site.
Approximately 96,000 gallons of groundwater runoff water reach the plant every day and mix with water used to cool the reactors. That’s roughly 96,000 gallons of radioactive water. About 76,000 gallons of this water makes it out to sea daily, according to Japan’s National Resources and Energy Agency.
Earthen dams were constructed to retain the water, but did not hold all the water back.
Storage tanks were used to hold the water that was circulated through the containment buildings, but these tanks developed leaks.
Later, it was discovered that the water was leaking straight down from the complex into the underground water aquifers.
Water leaking from one tank into the ocean is heavily contaminated with strontium-90, cesium-137. The radiation was so high that a person standing less than two feet away would receive, in one hour, five times the acceptable annual dosage for nuclear workers. After 10 hours, the exposed person would develop radiation sickness, with symptoms ranging from nausea and vomiting to hair loss and fatigue.
When the tank leaks were first reported, Ken Buesseler, senior scientist of marine chemistry and geochemistry at the Woods Hole Oceanographic Institution, shared his concern.
“It is not over yet by a long shot, Chernobyl was in many ways a one-week, fire-explosive event, nothing with the potential of this right on the ocean.”
“We’ve been saying since 2011 that the reactor site is still leaking whether that’s the buildings and the ground water or these new tank releases. There’s no way to really contain all of this radioactive water on site,” Buesseler said. “Once it gets into the ground water, like a river flowing to the sea, you can’t really stop a ground water flow. You can pump out water, but how many tanks can you keep putting on site?”