TOKYO -- Progress has been slow in decommissioning the wrecked Fukushima Daiichi nuclear power plant, four years after the devastating the March 2011 earthquake and tsunami led to a meltdown at the power station in northern Japan.
The government has drawn up a road map, published June 12, for mothballing the plant over the next 30-40 years. But the cleanup faces mounting challenges, particularly the removal of radioactive water from the site.
In late May, Tokyo Electric Power Company, operator of the Fukushima plant, said it had processed about 620,000 tons of highly-contaminated water stored in tanks. "We have been able to reduce risks significantly," said Naohiro Masuda, president of Tepco unit Fukushima Daiichi Decontamination & Decommissioning Engineering, at a news conference May 28.
The stored dirty water was a major stumbling block to Tepco's decommissioning effort, but the Advanced Liquid Processing System, or ALPS, and other devices have lowered the risk of environmental contamination and radiation exposure.
The battle to contain and purify the radioactive water is far from over -- and is just one step in a long cleanup and decommissioning process.
On the morning of May 29, workers at the plant discovered water leaking from a ruptured hose. The incident occurred as the workers were pumping highly radioactive water from a storage tank. In fact, Tepco's progress report refers to only a portion of the water used to cool the nuclear fuel in reactors 1 through 3, and groundwater that has seeped into the reactor buildings.
The power company continues to pour more water onto the still-hot fuel, and groundwater keeps flowing in. In other words, the radioactive soup is receding very slowly. The government road map calls for all the contaminated water to be removed from the reactor building and surrounding areas by 2020.
Even the figure 620,000 tons overstates how much water has been treated. Only 70% of the total, or 440,000 tons, has been run through the ALPS system. The remaining 180,000 tons has only had cesium and strontium filtered out; other contaminants remain. This water must be run through ALPS. That is the first step in the three-step plan for mopping up the contaminated water.
The second step is to halt the inflow of new water into the contaminated area. At the moment, about 300 tons flow into the area every day. A barrier of frozen soil will be created near reactor buildings 1 through 4 to cut the inflow to less than 100 tons a day by the end of March 2017.
Third, the roadmap discusses measures to prevent leaks.
The path ahead remains strewn with obstacles, including how to deal with the water that has been treated by ALPS. The system can remove 62 of the 63 radioactive materials found in the contaminated water, but it cannot strain out tritium, whose molecular structure is similar to water. The government is looking for new technologies that can separate out the tritium. If it fails, it will have to find some other way of dealing with the problem.
In February, an International Atomic Energy Agency team of experts led by IAEA Director of Nuclear Fuel Cycle and Waste Technology Juan Carlos Lentijo completed a review of Japan's decommissioning efforts. Lentijo's report said managing the contaminated water "would require considering all options, including the possible resumption of controlled discharges to the sea." But even a controlled release of radioactive water will raise concerns over harm to local fisheries already suffering from rumors of contamination.
The job of creating the frozen soil barrier is scheduled for completion by the end of March 2016. But observers note the project is technically very challenging. The government faces an uphill fight stemming the flood of dirty water around Fukushima Daiichi.