At the Fukushima No. 1 nuclear power plant, holes that connect underground tunnels, where radioactive water has been found, and radiation controlled areas were not sealed up, the plant’s operator said Tuesday.
The operator, Tokyo Electric Power Co. <9501>, said Monday that radiation levels of over 1,000 millisieverts per hour were detected from the surface of water inside an underground tunnel that is connected to the turbine building of the No. 2 reactor.
Radioactive water has also flown into such tunnels from the basements of the turbine buildings of the No. 1 and 3 reactors at the plant in Fukushima Prefecture, northeastern Japan, that was damaged by the March 11 earthquake and tsunami.
Tokyo Electric Power said rubber sealant is applied to fill the holes where pipes and cables pass through, the holes are not completely sealed.
The company suggested that water with radioactive substances possibly leaked from the reactor cores through a valve or pipe and piled up at the reactor turbine buildings’ basements and flew into the underground tunnels.