TEPCO has also reported that following their recovery procedure, the background radiation levels have dropped from an earlier reported 1000+ mSv, to approx 800 mSv shortly after 6pm (local time), and to approximately 70 mSv currently.
Sorry, but after reading your last posts I have to say this is not correct.
The measured levels of radiation from all sources speak of 1015 (max) to 70
microsieverts per hour (µSv/h), not millisieverts (mSv). Further, these increased levels of radiation were measured within the building, not outside and definitely not within "10-km radius". The levels outside, but within the site were said to be "8 times as normal", which suggests 1.5-2 µSv/h. The average background radiation is ~2300 µSv per year or ~0.25µSv/h.
Currently, there is no chain reaction going on in the reactors, the cooling needs to be done to remove the heat generated by the short-lived fission products, that may constitute up to 5-10% of the total power output during normal operation. This means, even after the reaction has been terminated by introduction of neutron absorbers, the fuel rods still generate some 50-150 MW of heat.
Cs-137 is a fission product normally generated in uranium-based reactors, and during the operation. The presence of this isotope in the exhaust is not a direct indication of a meltdown. It doesn't exclude the possibility of rods partially damaged, but the real "meltdown" is a situation where the reactor is damaged so much it's no longer possible to pump coolant into it or the pressure vessel or containment breach. This situation certainly did not occur, since the containment still maintains high pressure.
The fuel rods that are not cooled by water do not go critical - it's exactly the opposite - the water is necessary as moderator to maintain the criticality, and all water-moderated reactors actually have so-called "negative void coefficient", meaning that if water starts evaporating/boiling due to high thermal output, the efficiency of the reaction falls, automatically reducing the thermal output. By contrast, the Chernobyl-type reactor ("RBMK") is graphit-moderated and has a positive void coefficient, where increase of temperature actually leads to increase of fission rate, at some point starting a run-away effect.
Looks to me like cnic.jp is deliberately reporting bullshit.