Second cover assembly underway at Fukushima
The installation of steel columns next to Fukushima Daiichi unit 4 marks the start of construction of a cover that will aid in the removal of fuel. This is the second cover to get underway at the site.
Columns being set into place next to unit 4 (Image: Tepco)Two columns that will support the cover’s first layer were set in place yesterday. When finished the cover will reach almost twice the height of the reactor building and help facilitate the removal of used fuel from the unit’s pool.Unit 4 was offline for maintenance with a full core load of fuel stored in the pool – as well as older stocks from previous operation – when the earthquake and tsunami struck on 11 March 2011. This status meant the unit’s reactor had no possibility of an accident, but risk lay instead in the possible overheating of the pool. The safety of the pool was then reduced by major structural damage to the building after the ignition of hydrogen that leaked through ventilation systems shared with unit 3.Plant operator Tokyo Electric Power Company (Tepco) put in place additional support structures last year, but clearing out fuel from the pool remains one of the highest decommissioning priorities for which the cover will provide ventilation, filtration and fuel handling gear.
How the cover will lie alongside and over the top of unit 4 (Image: Tepco)The cover for unit 1 was finished in 2011 and plans were unveiled for the unit 3 cover in November last year. However each cover is to be quite distinct in function and appearance, reflecting the different conditions at each unit.
Source: World Nuclear News