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
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
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
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
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.
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.
quote: Based on that history, Sakai, a senior safety manager at Tokyo Electric, and his research team applied new science to a simple question: What was the chance that an earthquake-generated wave would hit Fukushima? More pressing, what were the odds that it would be larger than the roughly 6-metre (20 feet) wall of water the plant had been designed to handle? The tsunami that crashed through the Fukushima plant on March 11 was 14 meters high.Sakai's team determined the Fukushima plant was dead certain to be hit by a tsunami of one or two meters in a 50-year period. They put the risk of a wave of 6 metres or more at around 10 percent over the same time span. In other words, Tokyo Electric scientists realised as early as 2007 that it was quite possible a giant wave would overwhelm the sea walls and other defences at Fukushima by surpassing engineering assumptions behind the plant's design that date back to the 1960s.
quote: In that case, then yes there seems to be evidence to support the accusation. If they determined that there was a significant chance (and I would call a 10% chance significant) of a wave topping the breakwall and swamping the emergency generators, then they should've modified their equipment to account for it.I'll be interested in seeing how this is handled in the inevitable lawsuit(s) that will come from this disaster.