TOKYO - Japan’s government said yesterday that it could take 40 years to clean up and fully decommission a nuclear plant that went into meltdown after it was struck by a huge tsunami.
Nuclear crisis minister Goshi Hosono suggested that the timetable was ambitious, acknowledging that decommissioning three reactors with severely melted fuel plus spent fuel rods at the Fukushima Daiichi plant was an “unprecedented project,’’ and that the process was not “totally foreseeable.’’
“But we must do it even though we may face difficulties along the way,’’ Hosono told a news conference.
Under a detailed roadmap approved earlier yesterday following consultation with experts and nuclear regulators, plant operator Tokyo Electric Power Co. will start removing spent fuel rods within two to three years from their pools located on the top floor of each of their reactor buildings.
After that is completed, Tokyo Electric will start removing the melted fuel, most of which is believed to have fallen to the bottom of the core or even down to the bottom of the larger, beaker-shaped containment vessel, a process that is expected to begin in 10 years and be completed 25 years from now. The location and conditions of the melted fuel is not exactly known.
That timetable is more than twice as long as it took to remove the fuel from the Unit 2 reactor at Three Mile Island in Pennsylvania that suffered a partial meltdown in 1979.
Trade Minister Yukio Edano said authorities would ensure safety at the plant. He also vowed to pay attention to the concerns of tens of thousands of residents displaced when the plant was knocked out by Japan’s March 11 earthquake and tsunami, spawning the world’s worst nuclear crisis since the Chernobyl accident in 1986. “We must not allow the work toward decommissioning to cause any new risks or delay the return of the residents to their homes,’’ he said.
Completely decommissioning the plant would require 5 to 10 more years after the fuel debris removal, making the entire process up to 40 years, according to the roadmap.
The process still requires the development of robots and technology that can do much of the work remotely because of extremely high radiation levels inside the reactor buildings. Officials say they are aiming to have such robots by 2013 and to start decontaminating the reactor buildings in 2014.
The operator and the government would also have to ensure a stable supply of workers and save them from exceeding exposure limits while keeping the long process going. They also have to figure out ways to access each containment vessel and assess the extent of damage, as well as locate holes and cracks through which cooling water is leaking and flooding the area.
The decades-long process also would place an enormous financial burden on Tokyo Electric. The ministers said that the total cost estimate cannot be provided immediately but promised that there will be no delay because of financial reasons. Prime Minister Yoshihiko Noda announced last Friday that the plant has achieved “cold shutdown conditions,’’ meaning the plant had been brought to stability in the nine months since the accident.