Something happened at the Fukushima Daiichi that's only happened once before in the history of nuclear power -- a full meltdown occurred.  Only this time, unlike the previous incident at Chernobyl in Soviet Ukraine, a natural disaster was to blame.

I. TEPCO Gives Disaster Timeline

In the wake of the disaster Tokyo Electric Power Company (TEPCO) (9501), the operator of the damaged plant, is still working to clean up the contaminated water now that the rods have been cooled.  

And it's facing tough questions from the Japanese government, both at a provincial and national level.  The governor of Fukushima recently admonished the head of TEPCO and ordered that the Fukushima I (Daiichi) Power Plant be permanently shut down.

TEPCO has released a new report, trying to sate the Japanese government's demands.  The analysis provides a fascinating timeline of the events that are believed, based on evidence, to have occurred in the early hours of the disaster.

According to the timeline, within 5 hours of the quake, which occurred on March 11, the fuel rods were exposed and rapidly melting.  By the next morning, 16 hours later, the uranium rods in Reactor No. 1 had melted down and dropped to the bottom of the core's cylindrical steel containment vessel, which holds the nuclear fuel during reactions.

Reactors No. 2 and 3 also melted down, following a similar frame of events. 

As the Japanese pumped in water to cool the damaged reactor, it leaked out of the containment vessel, creating a large pool of radioactive water.  This water contains longer-lived isotopes like Caesium-137, which has a half-life of 30 years, approximately.

Authorities fear that the water could leak, contaminating ground and seawater.

II. Chance to Advert Meltdown May Have Been Lost Due to Inaction

On the morning after the quake TEPCO finally decided to vent steam from the reactors in an effort to reduce them from heating.  One thing the Japanese government is upset about is that TEPCO didn't vent them sooner.  It was instructed to vent them on March 11, but failed to act until the next morning.

Nuclear Safety Commission Chairman Haruki Madarame told Japan's Parliament, "We can certainly say that if the venting took place a little earlier, we could have prevented the situation from worsening."

Prime Minister Naoto Kan and Trade Minister Banri Kaieda also criticized TEPCO, stating that they had ordered the company to act, but that it did not immediately do so.  Stated Mr. Kaieda, "We had instructed them to go ahead with the vent and I think Tokyo Electric was trying to do this. Even though we asked them repeatedly to vent, it did not happen and so we decided to issue an order. All of us there, including the prime minister and myself had said it should be done as soon as possible."

It is thought if the steam was vented sooner the rods could have been cooled faster, preventing the full meltdown that occurred.

III. Did the Quake Damage the Plant?

TEPCO, under government orders, is now conducting a study examining the events immediately after the record-setting magnitude 9.0 quake that struck Japan.  The question being raised is whether the quake itself could have damaged the reactor building or backup generators.

It is widely believed that the plant escaped the quake intact, with all reactors properly terminating nuclear reactions.  It is thought that the subsequent tsunami flooding was what knocked out the backup generator, preventing the rods from being properly cooled down.

The possibility that the quake itself damaged the backup generators hasn't been ruled out, though.  Junichi Matsumoto, a spokesman for Tokyo Electric Power Co on nuclear issues, told reporters, "We want to review the data from the 40 to 50 minutes between the time of the earthquake and when the tsunami struck."

Japan's Kyodo news agency cited an unnamed source as claiming that the reactor building at Reactor No. 1 is though to have sustained structural damage from the quake.  This is troublesome as it raises the possibility that radioactive water may have leaked from the building after it seeped out of the containment vessel housed inside.

IV. Conclusions

The Fukushima nuclear disaster shows the dangers of using ancient reactor designs in flood-prone regions without proper precautions.  TEPCO likely skipped on flood proofing the backup generators for expense reasons, but in the end paid a far greater cost for their negligence.

The disgraced firm has been working hard to try to minimize the damage resulting from accident.  In that regard, it is perhaps handling the incident better than authorities did Chernobyl.

However, the familiar themes of outdated technology and gross negligence were central to both the Chernobyl and Fukushima stories.

The impact of the disaster remains to be seen, but one thing is for the sure -- the accident stands as a stirring cry to decommission older reactors and move to modern designs, and as damning condemnation on engineering negligence.