On Thursday, officials from the Tokyo Electric Power Company admitted that the suppression pool of the Fukushima Daiichi Unit 2 reactor may have a 3-centimeter hole in it, allowing the highly radioactive water used to cool the melted nuclear fuel rods to leak out.
TEPCO confirmed the whole by studying data gathered by a robot sent into the suppression pool at the bottom of the primary containment vessel earlier this month.
On March 14th, 2011, the pressure in the suppression chamber of the Unit 2 reactor gradually decreased between 13:30 and 18:00. The next day, around 6:14 am, an explosion was heard near the Unit 2 suppression chamber, and the pressure inside of the chamber again decreased afterwards.
Water is being constantly injected into the Unit 1, Unit 2, and Unit 3 reactors, but TEPCO has been unable to identify the source of the leakage in the reactors.
TEPCO will be forced to attempt to plug the hole, in order to continue remove melted nuclear fuel from inside of the reactor containment vessel.