TOKYO, Dec. 2 (UPI) -- Fuel rods in one Fukushima nuclear power plant reactor in Japan may have melted and bored most of the way through a concrete floor, the plant's operator said.
Tokyo Electric Power Co. said fuel inside reactor No. 1 appeared to have dropped through its inner pressure vessel and into the outer containment vessel, whose steel outer casing is the reactor's last line of defense.
Tepco revised its estimate of the damage inside the reactor, one of three damaged in the March 11 earthquake and tsunami disaster, after running a new simulation of the accident, the British newspaper The Guardian reported Friday.
The fact that the fuel rods may have melted most of the way through the reactor's concrete floor indicated the accident was more severe than first thought.
"Almost no fuel remains at its original position," Tepco said.
The simulation showed the fuel may have penetrated the concrete floor by up to 26 inches, just 15 inches from the reactor's outer steel wall, Tepco said.