Thirty months after the March 2011 earthquake and tsunami that touched off multiple meltdowns at the Fukushima Daiichi Nuclear Power Plant in northeastern Japan, the government has decided the crisis is too big a job for plant owner Tokyo Electric Power Co. to manage.
On Sept. 3, Prime Minister Shinzo Abe said that, instead of "ad hoc approaches," the government would formulate a fundamental solution. The government also announced it would appropriate $470 million to deal with immediate cleanup issues. That amount is considered a small down payment on what is likely to be a 40-year decommissioning process.
Frustration with TEPCO's handling of the cleanup had been growing even before Abe's announcement. TEPCO "has been responding with haphazard stopgap measures the last several years, but many things have been missing in terms of an overall plan," Shunichi Tanaka, chairman of Japan's Nuclear Regulation Authority, said at a Sept. 2 press conference.
The first priority is dealing with radioactive water leaks into the environment. Water being used to cool the melted and spent fuel rods becomes contaminated with radionuclides and collects in the basements of the reactor buildings. An estimated 400 tons of groundwater seeps into those basements daily and also becomes contaminated. TEPCO pumps the water out of the basements and through decontamination systems that remove cesium but not other radionuclides.
The utility has been storing this contaminated water, accumulating more than 300,000 tons in a thousand, hastily built tanks. Despite efforts to keep the contamination on-site, TEPCO confirmed in early August that, per day, up to 300 tons of radioactive water is leaking into the Pacific Ocean from the basements. Then, on Aug. 20, the company announced that water was leaking into the ground from one or more tanks.
The day after Abe announced the government would step in, the Ministry of Economy, Trade and Industry laid out a schedule for a three-pronged effort to manage the contaminated water. One aspect is to stop or at least reduce the flow of groundwater into the site.
As a first step, the ministry is calling for pumping water out of the ground on the landward side of the reactor buildings and diverting it directly to the sea. In a second phase, the ministry envisions creating a subsurface barrier by freezing a wall of earth by circulating a calcium-chloride solution chilled to -40° C through a piping system extending 30 meters down.
A spokesman for TEPCO said details were still being worked out by a ministry task force with input from Kajima Corp., which is expected to execute the plan. According to local press reports, a limited length of ice wall will be tested in the next several months before being extended around the reactors. The ministry schedule expects completion by spring 2015.
Ground freezing has been used as a temporary construction technique on excavations and tunneling projects around the world. "The basic engineering principles are quite well understood. However, this is a very energy-intensive process to maintain, so there will need to be careful design and trial work to produce an effective barrier that minimizes energy demand," says the University of Sheffield's Neil Hyatt, an expert in radioactive waste management.
The other government initiatives focus on minimizing leaks of contaminated water by monitoring the tanks and collecting spills and decontamination. TEPCO had been planning to start using the advanced liquid processing system (ALPS), developed by EnergySolutions, Salt Lake City, in cooperation with Toshiba Corp. ALPS can remove most nuclides, except tritium. Three systems have been built on-site but have suffered start-up problems. Tanaka says they expect the issues to be resolved by the middle of this month. When the ALPS plants are working, he said they expect the processed water to meet international standards for nuclear-facility wastewater.
For the time being, the treated water will be stored and eventually disposed, Tanaka says. Japan plans to explain its plans to the international community before releasing any contaminated water into the ocean.
"We will make every effort to ensure that the contamination levels are below accepted limits," he adds. Local press has reported that the fishing industry is fiercely opposed to dumping water with any contamination because of the impact on regional fishery products.