Meanwhile, Tepco says it has achieved “stable cooling” of all of the reactors at the site. This might sound like good news until it is realized that Tepco does not mean the reactors are at cold shutdown. In fact, all 3 reactors with fuel in them remain above the boiling point of 100 degrees Centigrade, meaning that water continues to boil off and radiation continues to be released. Cold shutdown—bringing the temperatures below 100 degrees—is still not expected before What Tepco really means is that it has more or less successfully set up a system for water to be recirculated through the reactors, so that constant water from outside is no longer needed. However, the recirculation system has been plagued with problems from the beginning and continues to not work at desired capacity.

UPDATE, On November 30, Tepco released a document that acknowledged, for the first time, that fuel in Unit 1 of Fukushima Daiichi had likely melted through the reactor vessel onto the concrete basemat below.

UPDATE, Yesterday marked a milestone of sorts for the Fukushima Daiichi reactors: some six-and-a-half months after the onset of the accident, temperature levels at all of the reactors and fuel pools fell below the boiling point (100 degrees Celsius) for the first time since March 11.

UPDATE, Tepco reported today the highest radiation levels yet measured at Fukushima Daiichi—1,000 Rems/hour (10 Sieverts/hour)—a lethal dose. The measurements were taken at the base of the ventilation stack for Units 1 and 2 (the stack that did not work during the accident). The actual levels may have been more than measured, since the monitoring equipment could not measure more than 10 Sieverts/hour. Workers sent to the area to confirm the measurements, which were first picked up by a gamma measuring camera, received doses of about 400 millirems in just a few minutes.