May 25, 2011
The operator of the troubled Fukushima Daiichi nuclear plant says data analyses suggest damage to its reactors may have caused cracks and openings in the reactor containment vessels equivalent to a 10-centimeter hole.
Reactors 1 through 3 at the plant suffered nuclear fuel meltdowns after the March 11th earthquake and tsunami. This is likely to have created holes and cracks at the bottom of the pressure vessels protecting the reactor cores and damaged the containment vessels.
Massive amounts of highly radioactive water also leaked from the structures.
Tokyo Electric Power Company analyzed the changes in pressure levels inside the pressure and containment vessels to gauge the scope of the damage.
TEPCO said the analyses show that holes in the Number 1 reactor containment vessel amounting to 3 centimeters in total may have formed 18 hours after the quake. It said that may have expanded to 7 centimeters at least 50 hours after the quake.
The utility said holes and cracks equivalent to 10 centimeters in diameter may have formed in the Number 2 reactor's containment vessel about 21 hours after the quake. It said a similar amount of holes could have been created in the suppression pool chamber by an explosion heard coming from there on March 15th.
TEPCO said these results were obtained through data calculations, and that it has yet to confirm whether such holes actually exist.