Tokyo Electric Power Co. on Oct. 9 cut a pipe to install equipment to reduce radioactive leaks after confirming hydrogen levels posed no risk of exploding at the Fukushima No. 1 nuclear plant.
The hydrogen levels were 1 percent or lower, enabling TEPCO to use spark-free tools to cut parts of the pipe, which is connected to the containment vessel of the No. 1 reactor, the utility said.
The work was initially scheduled for on Oct. 8, but a hydrogen concentration level of nearly 4 percent was found in part of the pipe.
A hydrogen concentration level of 4 percent or higher mixed with an oxygen concentration level of 5 percent or more could lead to an explosion.
TEPCO injected nitrogen into the pipe to drive out the hydrogen.
"We will make sure that sufficient nitrogen is injected into the pipe, even after cutting off the pipe, to prevent air from coming in and causing a fire," Susumu Kawamata, a TEPCO official, said.
On Sept. 28, the hydrogen concentration in the pipe was 63 percent.
- « Prev
- Next »