11 Juin 2013
June 11, 2013
The extraction of melted nuclear fuel rod debris at the Fukushima No. 1 nuclear power plant could begin in 2020, or 18 months earlier than originally anticipated, the central government and Tokyo Electric Power Co. said June 10.
In releasing a draft amendment to the current decommissioning road map, however, the government and TEPCO said they are not expecting the entire decommissioning process to end earlier than they had initially planned, which is 30 to 40 years after the nuclear disaster that was set off by the March 2011 Great East Japan Earthquake.
The latest draft document is the first to have presented the timeline of fuel debris removal separately for the three reactors that went into meltdowns.
It said the extraction process could begin during the first half of fiscal 2020 at the No. 1 and No. 2 reactors, and during the second half of fiscal 2021 at the No. 3 reactor, if circumstances enable workers to follow the least time-consuming methods that involve basic equipment.
But the No. 1, No. 2 and No. 3 reactors will have to wait until the second half of fiscal 2022, the first half of fiscal 2024 and the second half of fiscal 2023, respectively, for the extraction process to begin if the most time-consuming methods have to be followed, the draft said.
The workers have yet to gain a grasp of the locations and condition of the fuel debris. They have yet to develop extraction equipment and determine removal methods.
The government and TEPCO are expected to meet by the end of June to revise their decommissioning road map on the basis of the latest draft amendment.
TOKYO (Kyodo) -- The government and Tokyo Electric Power Co. said Monday they may be able to start removing the melted fuel inside the crippled nuclear reactors at the Fukushima Daiichi complex within the first half of fiscal 2020 by improving work efficiency, around 18 months earlier than initially planned.
The schedule was included in a draft version of a revised road map toward decommissioning the Nos. 1 to 4 reactors at the plant, but prospects are unclear because technology must be developed to perform the work.
The fuel inside the Nos. 1 to 3 units is believed to have melted through the reactor pressure vessels and been accumulating in the outer primary containers, making the task of defueling more challenging than in the case of the 1979 Three Mile Island accident in the United States.
Apparently taking into consideration the uncertainties ahead, the government and plant operator TEPCO maintained the overall timeline for completing the decommissioning process within 30 to 40 years from the point the plant achieved a stable state of cold shutdown in December 2011.
"How much time we need to take out the fuel debris hinges on the situation of the fuel. Our basic policy is to accelerate such work as much as possible, but we are not moving up the goal of spending 30-40 years," an Economy, Trade and Industry Ministry official said.
The revised road map is expected to be compiled later this month after listening to the opinions of local governments and experts, he added.
According to the draft road map, workers may be able to start removing the melted fuel from the Nos. 1 and 2 reactors within the first half of fiscal 2020 at the earliest by installing new structures for fuel removal and restoring existing fuel handling equipment.
As for the No. 3 reactor, fuel removal could start within the latter half of fiscal 2021.
But the time schedules could be delayed depending on how resistant reactor buildings are to earthquakes, or how much the buildings are contaminated with radioactive substances.
The draft showed that fuel removal could start from fiscal 2022 for the No. 1 reactor, fiscal 2024 for the No. 2 reactor, and fiscal 2023 for the No. 3 reactor at the latest.
According to the official, it will be the first time that the specific timing of fuel removal for respective reactors will be included in the decommissioning road map. The current plan has only said that defueling will start in December 2021 without specifying which reactor will be the first.
Prior to removing the melted fuel, TEPCO plans to start taking out fuel assemblies from spent fuel pools located atop the Nos. 1 to 4 reactor buildings.
The work will start from the No. 4 unit later this year. The No. 4 reactor was offline for maintenance work with fuel stored in the spent fuel pool when the huge earthquake and tsunami ravaged the plant on March 11, 2011.
TEPCO preparing to remove melted fuel
Tokyo Electric Power Company is continuing preparations to permanently shut down the reactors at the damaged Fukushima Daiichi nuclear plant.
On Tuesday, the utility invited reporters to see the installation of a crane on a 54-meter tall structure that covers the Number 4 reactor building. The crane will be used from November to remove nuclear fuel rods from a storage pool of the reactor.
Media people also saw a tank near a building that houses the Number 1 reactor. The tank will be used to store contaminated water starting later this month.
Until now, contaminated water has been stored in a temporary tank on the north side of the same building.
The tank is at the end of a pipeline through which contaminated water circulates to cool melted down nuclear fuel in the Number 1 to Number 3 reactors.
The utility says the new tank will shorten the length of the pipeline from the current 4 kilometers to 3 kilometers.
It says the change in the pipeline route is meant to reduce the possibility of leaks.
The company says it will study ways to further shorten the pipeline route to reduce the risk of leakage.