I gather from this NYT report that the reactor at Daiichi that until today seemd to be doing okay has, within the span of 24 hours (maybe just 12 hours), become the most dangerously crippled of all the troubled reactors in Japan. For those keeping track, that is reactor No. 2 at the Fukushima Daiichi plant:
The extreme challenge of managing reactor No. 2 came as officials were still struggling to keep the cores of two other reactors, No. 1 and No. 3, covered with seawater. There was no immediate indication that either of those two reactors had experienced a crisis as serious as that at No. 2
The Times also quotes a senior nuclear industry executive as saying that “full-scale panic” has set in among Japanese power industry managers. “They’re in total disarray, they don’t know what to do,” the source told the Times.