Aug 12, 2011
There have been a cluster of earthquakes near Fukushima. Just today, there was another 6.0 earthquake.
There have been a cluster of meltdowns at Fukushima. For example, Asahi reportstoday:
A second meltdown likely occurred in the No. 3 reactor at the Fukushima No. 1 nuclear power plant, a scenario that could hinder the current strategy to end the crisis, a scientist said.
In that meltdown, 10 days after the March 11 Great East Japan Earthquake, the fuel may have leaked to the surrounding containment vessel, according to a report by Fumiya Tanabe, a former senior researcher at what was then the government-affiliated Japan Atomic Energy Research Institute.
Under Tokyo Electric Power Co.’s road map to deal with its crippled nuclear plant, reducing temperatures at the bottom of the core pressure vessel is one objective for bringing the accident under control. But if the fuel burned through the pressure vessel surrounding the No. 3 reactor and dropped into the containment vessel, that plan would be affected.
Around 11 a.m. on March 14, the reactor building was hit by a large hydrogen explosion that was likely caused by a core meltdown, which led to fuel falling to the bottom of the pressure vessel.
Tanabe also estimates that the second meltdown led to the release of large amounts of radioactive materials, and that much of the fuel fell through the pressure vessel to the surrounding containment vessel.
Kunihisa Soda, a former commissioner at the Nuclear Safety Commission of Japan who is a specialist on severe accidents at nuclear plants, said the possibility of a second meltdown could not be ruled out.