After two and a half years, two leaks have been found in the containment vessel of the Unit 1 reactor at the Fukushima Daiichi nuclear power plant.
Workers used a robotic boat equipped with cameras and radiation detectors to investigate the suppression chamber of the Unit 1 reactor. The suppression chamber is filled with contaminated water, which was injected to cool the melted reactor fuel. Extremely high radiation levels have prevented workers from investigating these critical areas of the reactor buildings.
Tokyo Electric engineers were not able to locate the actual location of the leaks, or to measure the amount of water which is leaking, but described the flow as gushing out into the basement of the reactor building.
“Part of the containment vessel is damaged, and water leaking from there is likely to be flowing down into the ground via the pipe,” one TEPCO official said.
One leak was discovered near a rupture in a sand-cushioned drain pipe which was used to direct condensation which formed on the surface of the vessel.
The other leak was located just above the suppression chamber, in a vent pipe which connects to the suppression chamber.
TEPCO engineers assume that there is similar damage to the bottom of the Reactor 2 and Reactor 3 containment vessels which are also allowing the leakage of highly contaminated water.
Hiroshi Miyano, a professor at Hosei University, said the volume of leaking water suggests a significantly large amount of damage to critical connections between the containment vessel and suppression chamber. Miyano suggested that the damage could have been due to the impact from the hydrogen explosion in March of 2011.
Source: JiJi Press