Fukushima- the word alone is enough to inspire terror in any seafood aficionado in the wake
of the worst nuclear disaster in decades.
Going on eight years later, 50,000 households remain evacuated, and bans on fish and vegetables
from around the disaster area have been in effect for years to protect people from the
lingering radiation.
Today contaminated water from the plant is being stored to prevent it from spreading
radiation into the environment, and an ingenious refrigeration system keeps the soil around
the affected site frozen in an icy boundary meant to keep groundwater away.
But how did this modern nuclear disaster start, and how did things get so bad?
Let's take a look at the events of March 2011 minute by minute.
Monday, March 7th 2011: In a move that will prove to be eerily prophetic, the Tokyo Electric
Power Company submits a report to Japan's nuclear safety agency highlighting the vulnerability
of the plant to tsunami forces.
The plant's sea wall is nearly six meters high, and the report highlights a 1897 tsunami
with 10.2 meter waves which devastated the location the plant sits at today.
Officials take note and make plans to review the strengthening of the sea walls at a future
date.
Friday, March 11th
2:46 pm: A 9.1 magnitude earthquake tears through the seafloor off the coast of Honshu
Island at a depth of 15 miles (24 km) in the earth's crust.
At the Fukushima nuclear plant, emergency safety systems automatically kick on upon
being struck by the first tremor, and reactors 1, 2, and 3 are automatically shut down.
Reactors 4, 5, 6 are currently undergoing maintenance and not operational.
2:47 pm: The tremor is severe enough to have cut off the power plant from the national
electricity grid.
On site, backup diesel generators start up- their job is to continue circulating cooling
water into the nuclear reactors which while shut down, are still incredibly hot and will
take a long time to cool.
Without this cooling water circulating around the reactor core, the core will overheat just
like in Chernobyl, causing a massive steam explosion.
2:52 pm: Reactor 1's emergency cooling system, a safety relief valve, automatically opens
in response to rising pressure from inside the reactor vessel.
The valve is designed to vent dangerous buildups of steam in order to prevent an explosion.
For the next hour the valve will open and close automatically as it regulates the buildup
of pressure inside the reactor- this one safety system is likely responsible for averting
a catastrophic explosion.
3:27 pm: The first tsunami strikes the 19 foot (5.7 meter) high sea wall, but the wall
holds and protects the plant from major flooding.
3:30 pm: Steam continues building to dangerous levels inside reactor no.1.
The safety relief valve prevents an explosion but the temperature of the steam is steadily
climbing as the emergency condenser system meant to cool the steam fails.
Workers are extremely concerned, but as long as the safety relief valve remains operational
the reactor vessel should not explode.
Many believe that the worst is over, and that the first tsunami was the only one they would
have to deal with.
3:38 pm: One of the backup diesel generators stops running.
The rest continue running, but because all but one of the generators are located underground
there is concern of serious flooding from additional tsunami waves.
3:46 pm: A 46 foot (14 meter) tsunami crashes into the seawall and overtops it, flooding
the entire Fukushima facility.
The diesel generators are all flooded and shut down, and their fuel tanks are washed
away by the roaring waves.
Now all power has been lost in the facility, and all but the mechanical safety systems
meant to operate without power are offline.
Temperatures begin to rise inside the reactors, and only the remaining safety systems are
keeping any check on the temperature rise- though they alone will not be enough to prevent
a major disaster.
4:00 pm: The Nuclear and Industrial Safety Agency of Japan begins post-disaster emergency
procedures and convenes an emergency headquarters.
Personnel contact all nuclear power plants in Japan in an attempt to ascertain their
condition.
The news from Fukushima is grim, but so far the exterior plant sensors have not detected
any release of radioactivity into the surrounding environment.
6:00 pm: Inside reactor 1 water levels have fallen so low that the top of the nuclear
fuel rods are now exposed to dry air inside the reactor vessel.
Without water to radiate their heat onto, the temperature inside the reactor immediately
begins climbing again.
6:18 pm: Workers restore power to Reactor 1's emergency cooling system and water once
more begins circulating.
Workers however are unaware of the massive boil off of water inside the reactor.
7:02 pm: Prime Minister Naoto Kan declares a nuclear emergency.
The declaration is followed by announcements that no radiation leaks have been detected
and is merely a cautionary measure.
7:30 pm: Fuel rods inside reactor 1 are now fully exposed to air as water levels continue
to drop.
The incredible buildup of heat causes the rods to begin melting and pooling at the bottom
of the reactor vessel as a molten slag heap of highly radioactive metal.
9:00 pm: Workers fear that the dropping water levels inside Reactor 1 are inevitably going
to lead to a Chernobyl-like steam explosion.
The government issues an emergency evacuation order to all residents within two miles (3km)
of the plant.
Residents within 6.2 miles (10km) are told they can remain in their homes but they should
be prepared to evacuate nonetheless.
Inside Reactor no.
1 the pressure is at twice normal levels and climbing.
Older power plant workers offer to take the place of the younger men on-duty at the plant,
knowing that disaster may be inevitable and preferring to place themselves at risk to
radiation poisoning over the younger workers.
Saturday, March 12th
2:44 am: Emergency battery power for the high pressure core-flooder system, the main emergency
cooling method for reactor no.
3, runs out.
Water begins boiling off inside the reactor vessel.
4:15 am: Inside reactor 3, the dropping water levels expose the fuel rods and temperature
immediately skyrockets.
5:30 am: The situation inside reactor 1 is critical- extremely high pressure threatens
to explode the containment vessel at any moment.
Officials have been arguing all night over a proposed and extremely risky maneuver which
could cause a large explosion, and yet if not attempted the vessel is guaranteed to
explode.
At last it's agreed to vent steam from directly inside the reactor, and the workers hold their
breath as a large volume of steam is allowed to vent into the air above the plant.
Not only is the steam slightly radioactive, but there is a large possibility of hydrogen
having been formed inside the containment vessel due to the high pressure and temperatures,
and it's feared that it could ignite after combining with oxygen.
The venting is successful and there is no explosion.
5:50 am: More emergency power is restored, allowing plant workers to pump fresh water
into reactor 1 in an attempt to cool the fuel rods.
6:50 am: Although workers do not realize it, the entire core of reactor no.
1 has completely melted and fallen to the bottom of the pressure vessel.
With temperatures reaching over 2190 degrees (1200 C), the zirconium in the fuel rods splits
the hydrogen from the water vapor in the steam inside the vessels.
This causes a buildup in dangerous hydrogen gas.
10:58 am: Pressure inside Reactor no.
2 reaches critical levels, and once more workers gamble by venting off some of the radioactive
steam to avoid an explosion.
3:30 pm: Residents within 6 miles (10km) are now being evacuated.
All fear a Chernobyl-style explosion at the power plant.
3:36 pm: Hydrogen gas buildup inside the containment vessel of reactor no.1 reaches critical levels
and there is a massive explosion, cracking open the containment vessel but leaving the
reactor core intact.
Four workers are injured and the concrete building that surrounds the reactor vessel
collapses.
7 pm: Workers begin pumping seawater directly into reactor no.
1 in an attempt to keep the core cool.
7:25 pm: In a bid to limit how much water becomes contaminated, Tokyo Electric Power
Company orders that the seawater injection be halted.
Plant boss Masao Yoshida orders his workers to continue pumping in seawater though, ignoring
TEPCO- he fears a meltdown more than the release of contaminated water.
9:40 pm: The evacuation zone is extended to 12.4 miles (20 km).
Sunday, March 13th
2:42 am: the high pressure coolant injection system inside reactor no.
3 fails, and water levels immediately begin falling as the water is boiled off by the
intense heat of the fuel rods.
5:10 am: Fukushima Unit 1 is declared an International Nuclear and Radiological Event Scale level-4
event, signifying an accident with local consequences.
7:00 am: Water levels inside reactor no.
3 have dropped so low that the top of the fuel rods are now exposed.
9:00 am: Reactor no.
3's fuel rods begin to melt, causing a buildup in hydrogen gas.
1:00 pm: Workers believe that reactor no.
3 has suffered a partial meltdown, and reactors 1 and 3 are once more vented in order to relieve
the growing pressure.
The reactor containment vessels are refilled with water and boric acid, which absorbs neutrons
and helps prevent more nuclear reactions from the fuel inside the reactors.
Reactor no.
2 has low water levels and high pressure, but is believed to be stable.
Monday, March 14th 11:01 am: Hydrogen gas buildup inside the
containment vessel at reactor no.
3 leads to an explosion, collapsing the building housing the container and injuring six workers.
TEPCO announces no release of radioactive material but the blast damages the water supply
helping keep unit 2 cool.
1:15 pm: Reactor 2's cooling systems fail, and water levels immediately begin falling.
3:00 pm: A large chunk of molten fuel inside reactor no.
3 drops to the bottom of the pressure vessel and pools there.
6:00 pm: Water levels inside reactor no.
2 now reach the top of the fuel rods, and the temperature climbs as the exposed rods
overheat.
8:00 pm: Reactor 2 now also enters a meltdown state, as its fuel rods begin to melt from
the extreme heat.
Hydrogen gas once more builds as the zirconium strips hydrogen away from the water vapor.
Tuesday March 15th
11:00 am: A second explosion due to hydrogen gas buildup rocks reactor number 3, which
damages the cooling systems of reactor no.
2.
8:00 pm: Reactor no.
2 is now in worse condition than the other two reactors, and is in a full blown melt
down as most of the nuclear fuel drops to the bottom of the reactor pressure vessel.
An explosion causes damage to unit 2's containment system and radiation levels rise significantly
but quickly fall once more.
Workers would go on to bravely battle the rising temperatures inside the stricken reactors
and fuel rod storage pools.
Ultimately the Fukushima disaster would lead to a permanent quarantine zone around the
stricken power plant which lasts to this day, and to massive protests across the country
over nuclear power.
Yet the plant used reactors that were over forty years old, and lacked many of the safety
features of modern reactors.
Additionally, in the years since the disaster, workers have come forward to state that much
of the plant suffered from poor maintenance, and that many of the safety cooling systems
had not been tested since the reactors were first installed forty years ago!
Do you think nuclear power is a good thing or a bad thing?
Could a modern nuclear power plant have survived the Fukushima disaster?
Let us know in the comments!
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