On april 29, the former head of the Japanese Institute of Nuclear Technology and currently its oldest supervisor, M. Ishikawa, stated on Asahi TV that the core had most certainly gone into meltdown and that the situation was much more serious than any public reports from either TEPCO or the government would acknowledge. Stunned by this admiission, the journalist running the talk show interrupted Ishikawa, "Wait a minute! We expect you to tell us that everything is okay!" To which Ishikawa, a long time proponent of nuclear power in Japan, replied, "only if I am authorized to lie." Experts in France have commented that by virtue of the design in the Fukushima plants, in the event of meltdown it would be impossible, unlike Chernobyl, to cordon off the core and prevent it from descending into the earth (the so-called "China syndrome"). So there is a high probability that some or all of the radioactive material has by now seeped into the aquifers below the plant, with potentially serious long term ramifications for waters in and around Japan, including the Pacific Ocean. Since it has been up to now impossible to enter the crippled reactor housing, it is impossible to verify the extent of the meltdown.
Ishikawa's televised interview has been widely circulated on Youtube, and I think there are translation/summaries in both English and French.
About one month prior to Ishikawa's statement, Reuters news service reported that Representative Edward Markey had been briefed by the NRC in the United States that the core of at least one of the reactors at Fukushima had gone into total meltdown. The story however was kept out of the mainstream press, and several weeks later became unavailable on Reuters' own web site. TEPCO's own estimation is that only 30% of the fuel rods in one reactor have gone into meltdown.
