Situation looks like it's still getting worse
Battered by a terrifying earthquake, exhausted from days of battling a spiralling nuclear crisis, and aware that their loved ones were only miles from the crippled facility, the exhausted workers at the Fukushima No 1 plant must have hoped a new day would finally bring respite.
Instead, Tuesday dawned with the outbreak of fire at a fourth unit  the start of a chain of events in which their worst fears appeared to be coming true.
More than 90 hours after the earthquake and tsunami battered Japan's north-east, shutting off the Fukushima plant and halting its cooling systems, workers learned that radiation at the facility had hit a level harmful to human health.
Hundreds of non-essential personnel were shipped off-site after the blaze, knowing that they were leaving behind dozens of colleagues risking permanent damage to their health. The gravity of the situation emerged a few hours later when Naoto Kan, the Japanese prime minister, addressed the nation.
Radiation in the reactor complex has reached the point that the crew had to be pulled out except for a small emergency operations staff. The fire at the 4th unit was put out, but damage at the other three reactors continues to spread. Open air exposure of the nuclear rods or spent fuel rods seems to have occurred, and it's just a question of how far the radiation will spread. Melt down remains possible, but becomes less likely with time as the reactors cool down.
On the scale of disaster, this is still between TMI and Chernobyl, but getting closer to Chernobyl. It is still unlikely to be worse then Chernobyl, but it remains possible if one of the reactors containment units fail.
Jay