It will take several decades to decommission reactors at the Fukushima No. 1 nuclear power plant, where meltdowns occurred in three reactors, according to a draft plan compiled by Tokyo Electric Power Co. and reactor manufacturers.
It will take several decades to decommission reactors at the Fukushima No. 1 nuclear power plant, where meltdowns occurred in three reactors, according to a draft plan compiled by Tokyo Electric Power Co. and reactor manufacturers.
TEPCO will begin removing 3,108 spent nuclear fuel assemblies in storage pools for the No. 1 to No. 4 reactors in the early part of fiscal 2014, according to the plan obtained by The Asahi Shimbun.
The company intends to begin removing damaged fuel from the No. 1 to No. 3 reactors, where meltdowns occurred, in fiscal 2021. Originally, 1,496 fuel assemblies were in the reactors.
TEPCO and reactor manufacturers drafted the mid- to long-term road map toward decommissioning based on the 1979 Three Mile Island accident and other cases.
In a meeting at the Democratic Party of Japan headquarters on July 9, Prime Minister Naoto Kan reaffirmed that it could take up to several decades to bring the Fukushima accident to a close.
"To deal with the accident, it is expected to take three, five to 10 years, or eventually several decades," Kan told senior officials from the ruling party's local chapters.
Kan did not elaborate what types of work will have to be completed within that time frame.
At Three Mile Island, fuel melted and dropped to the bottom of the pressure vessel of only one reactor. But it took more than 10 years to remove the fuel from the reactor.
Junichi Matsumoto, acting general manager of TEPCO's Nuclear Power and Plant Siting Division, said July 9 it is premature to say whether it will require fewer or more years to deal with the Fukushima accident than was needed for Three Mile Island.
The accident at the Fukushima No. 1 nuclear power plant was the world's first in which meltdowns occurred in three reactors and hydrogen exploded.
TEPCO first set the 10-year target for the start of removing damaged fuel from reactors and then decided on schedules for other work.
TEPCO and the government will develop a detailed road map, but target years could be pushed back depending on reactor conditions and technological developments.
TEPCO must lower radiation levels in reactor buildings and research the inner conditions of containment vessels before removing melted fuel from reactors.
A key task is how to keep melted fuel cooled while removing it from the reactors.
At Three Mile Island, the pressure vessel was filled with water to cool the fuel.
TEPCO plans to keep melted fuel inside water, without exposing it to the atmosphere.
But cooling water is leaking from damaged parts of the pressure vessels of the No. 1 to No. 3 reactors, and part of the melted fuel has apparently fallen into the outer containment vessels.
TEPCO must find the damaged parts and seal them. If the breaches cannot be closed completely, the company must at least find ways to control water leaks.
Another challenge is where melted fuel will be stored.
The U.S. Department of Energy took over the storage of melted fuel from the Three Mile Island plant.
Japan Nuclear Fuel Ltd.'s nuclear fuel reprocessing plant, under construction in Rokkasho, Aomori Prefecture, will accept spent fuel from ordinary nuclear power plants.
But it has not been decided where the damaged fuel from the Fukushima plant will be taken to.
Meanwhile, TEPCO plans to move spent nuclear fuel from storage pools for individual reactors to a pool for common use on the plant premises.
But the equipment to remove fuel at the buildings that house the No. 1, No. 3 and No. 4 reactors needs to be repaired because it was damaged by the explosions.
Special containers to transport fuel also need to be manufactured.
Reactor manufacturers such as Toshiba Corp. and Hitachi Ltd., as well as the Japan Atomic Energy Agency, will help develop technologies. But TEPCO may need to ask for help from foreign companies and organizations.