Key facilities in Fukushima plant could have collapsed before tsunami: report, Xinhua, May 15, 2011:
Key facilities at the Fukushima No. 1 nuclear power may have been damaged by the quake itself that day rather than tsunami-caused power loss that failed the reactor’s cooling function, Kyodo News quoted a utility source said Saturday.
Data taken by workers entering the No. 1 reactor building at the crippled plant on the night of March 11 showing the radiation level was as high as 300 millisieverts per hour suggest a large amount of radioactive materials from nuclear fuel in the reactor was already released. [...]
Kyodo said a source at TEPCO admitted the possibility of key facilities having been compromised before the tsunami waves, saying, “The quake’s trembling may have caused damage to the pressure vessel or pipes.”
Two Other Reactors Suffer Serious Damage, Wall Street Journal by Mitsuru Obe, May 15, 2011:
Tepco separately released its analysis on the timeline of the meltdown at unit No. 1. According to the analysis, the reactor core, or the nuclear fuel, was exposed to the air within five hours after the plant was struck by the earthquake. The temperature inside the core reached 2,800 degrees Celsius in six hours, causing the fuel pellets to melt away rapidly.
Within 16 hours, the reactor core melted, dropped to the bottom of the pressure vessel and created a hole there.
Published: May 15th, 2011 at 3:35 pm ET