Work has begun to prepare ground for a structure to remove the spent fuel from Fukushima Daiichi unit 4.
The new unit 4 fuel removal building would tower over the unit 4 reactor building, modified by removing the damaged top level and having received a weatherproof cover.
A steel girder structure will be erected to support a fuel handling machine and an overhead travelling crane above the unit 4 building, which will also receive a cover to protect it from rainwater. The new crane structure, 69m long by 31m wide by 53m high, will take about a year to install, depending on debris removal operations. The fuel handling system will start to be installed in late 2012 and take about four months.
Elevation cutaway view of unit 4 fuel removal structure
To prepare for the new structure, a foundation area to the south of the unit 4 reactor building is being prepared. In addition, damaged reinforced concrete girders above the operating floor of unit 4 are being removed with long-boom demolition machinery based on the ground and also smaller machines that have been lifted on to the building. Debris removal is expected to last until perhaps October 2012.
Also, a crane-hung camera has taken photographs and video of the Fukushima Daiichi unit 3 spent fuel pool. The camera shows scenes of twisted metal and other debris near the surface, and deeper it found part of the fuel transfer machine. Dust and pebbles of concrete appear to cover the tops of empty fuel racks.
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