Tokyo Electric Power Co. and the government said Monday they will attempt to remove all 1,533 fuel assemblies in the spent-fuel pool perched atop reactor 4 at the crippled Fukushima No. 1 plant by the end of 2014.
The schedule was moved up by a year amid lingering concerns about the condition of the unit, where hundreds of fuel assemblies had been stored before last year’s quake and tsunami triggered three core meltdowns at the Fukushima plant and damaged four of its six reactors.
The upper part of the building housing reactor 4 was severely damaged by a hydrogen explosion caused by the meltdowns, sparking concern the remaining structure might collapse in another big quake and dump the pool and its rods onto the ground.
The fuel rods, exposed to the air, might then burn up and release massive amounts of radiation into the atmosphere. Some experts dispute this possibility.
Nevertheless, the issue at unit 4 caused enough concern to have the structure holding up the pool reinforced and a lid put on it.
Tepco plans to start extracting the fuel assemblies in November 2013, a month earlier than scheduled, because debris clearance in the upper part of the building went well enough that it can skip some of the preparatory work that was deemed necessary earlier.
To hasten the process, the utility plans to use two containers instead of one as earlier planned to transport the assemblies to a so-called common pool in a different building at the site. This is expected to provide more stable conditions for keeping the fuel cool.
The operation is part of the process of dismantling units 1 to 4.
When the plant was rocked by the offshore earthquake and its tsunami on March 11, 2011, unit 4 was offline for maintenance and its fresh fuel had been stored in the spent-fuel pool.
The pool contains 1,331 spent fuel assemblies and 202 fresh ones. The utility has already succeeded in taking out two unused assemblies in a trial.