The frame of a structure to cover Fukushima Daiichi 4 has reached the third level and is now higher than the reactor building. When complete it will enable the removal of used reactor fuel from the storage pool.
|The framework rises in front of the damaged reactor building, as pictured yesterday
It took about a week in early January to assemble the frame's first level and yesterday Tokyo Eelctric Power Company (Tepco) announced it had completed the third level. Two more levels are to come, but these will extend across the top of the reactor building and enclose the area of the used fuel pool.
When complete the new structure will feature ventilation, filtration and handling gear to remove highly radioactive fuel assemblies from water storage and place them in canisters for transfer to the plant's shared storage facility. This is one of the highest priorities at the site.
Unit 4 was off line for maintenance when the earthquake and tsunami struck on 11 March 2011. Its full core load of fuel, plus used fuel from previous operation, was being stored in a pool at the top of the reactor building. Although this meant there was no possibility of a reactor accident at unit 4, there was a risk of the pool overheating. The stability of the pool was then threatened by major structural damage to the building after the ignition of hydrogen that leaked through ventilation systems shared with unit 3.
Researched and written
by World Nuclear News