Japan has given its consent to revised plans for decommissioning Tokyo Electric Power’s Fukushima Daiichi nuclear facility, which suffered a severe meltdown following the 2011 earthquake and tsunami.
The roadmap extends over a 30 to 40 year period, and delays removal of spent fuel in storage pools at the melted reactors by nearly three years, reports the Associated Press.
As per the revised plan, the spent fuel rod assemblies must be removed from the pools above reactor Nos. 1, 2 and 3 before the fuel is extracted, which melts inside the reactors during the disaster.
The fuel assembly removal process from the No. 3 cooling pool will not start until 2017 while the process on units 1 and 2 will start in 2020, reported Japan Times.
The 2011 disaster had resulted in the meltdown of three of the plant’s six reactors, and caused damage to the structure of the fourth unit, which was offline at the time.
Fuel storage pool at the fourth reactor was emptied in 2014.
Within six years, locating and studying melted fuel inside the reactors is expected to start, following which the experts intend to remove the debris with robots, despite the delay caused by the revised plan.
Tokyo Electric Power has carried out limited surveys at the reactors using remote-controlled robots.
However, melted fuel is expected to have breached the cores of the reactor cores, most of which is likely to subside at the bottom of the containment chambers, according to experts.
Portions of the melted fuels are likely to have sunk into the concrete foundation.
Radiation levels are still high at the plant, which is filled with contaminated water.
The revised roadmap acknowledges that damage repair for the containment chambers and refilling them with water to turn debris removal easy is more technically challenging than thought of.
As such, alternative policies and methods need to be identified.
Earlier this week, Atkins had secured a contract from Tokyo Electric Power Company (TEPCO) to provide fire hazard analysis services at the Fukushima Daiichi nuclear plant.
Image: Fukushima I nuclear power plant. Photo: courtesy of KEI / Wikipedia.