Yomiuri Shimbun, Aug 06, 2014: In its latest findings, TEPCO also said that most of the nuclear fuel in the No. 3 reactor at the plant in Fukushima Prefecture melted through the pressure vessel and continued down to the bottom of the outer containment vessel. The finding may make it even more difficult to decommission the plant. […] a record made by a worker […] suggests it is possible that the coolant apparatus had already ceased functioning nearly seven hours before TEPCO stopped the coolant-injection device. […] A new analysis of conditions inside the reactor, made on the basis of the uncovered record, led to the latest finding that the temperature in the reactor core reached the fuel’s melting point of 2,200 C at around 5:30 a.m. on [March 13]. […] the amount of melted nuclear fuel that passed into the containment vessel through the pressure vessel is considered to have been greater, making it technically more difficult to extract the melted fuel and dispose of it.
NHK Transcript, Aug. 6, 2014: [TEPCO has] learned some of their challenges may be more difficult than they thought. They’re looking into unresolved problems at the nuclear plant. What they found has changed their understanding of what’s happening inside.
NHK, Aug. 6, 2014: Meltdown at Fukushima reactor 3 worse than thought –The operator of the crippled Fukushima Daiichi nuclear plant says the damage to nuclear fuel in one of its reactors may be worse than previously thought. […] Officials with the utility now say most of the nuclear fuel in the No. 3 reactor melted through the reactor core […] They had previously said some of the fuel was still inside the reactor […] It says most of the fuel melted through the reactor core and had dropped into the containment vessel by the following morning.
Kyodo News, Aug. 6, 2014: Fukushima No. 3 reactor meltdown worse than previously believed: TEPCO — Fuel inside the No.3 reactor at the Fukushima Daiichi nuclear plant began melting earlier than thought, and more fuel than previously estimated fell into the outer primary container after the cooling function failed […] [TEPCO] initially estimated that around 60 percent of the fuel melted through the base of the pressure vessel and dropped into the outer primary containment vessel. But a company official told a press conference now most of the fuel “is believed to have dropped,” and the utility is still studying ways to remove it.