Aug 8, 2014

Fukushima Reactor No. 3 meltdown occurred 4 hours earlier than thought

....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.

....record 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 that day.

TEPCO has come to assume that the core meltdown was highly likely to have started in the early morning of March 13.

As the core meltdown is now believed to have started earlier than was previously thought, 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.