One week after the earthquake and tsunami, humanitatian relief efforts continue while workers at the Fukushima power plant strive to bring the situation under control. Overall, with possible exception of the spent fuel pool of reactor 3,
the status of all facilities is very similar to yesterday - which is a
bad thing.
Major uncertainty relates to: the amount of radiation already
being released to air and sea; risk of a violent fire in the cladding
of the fuel rods as the spent fuel pools are exposed for hours; as well
as to the behavior of the reactor cores as water levels remain low.
Good news is that the violent release of radioactivity, due to fire or
explosion, feared yesterday has not happened yet. Power is still not
restored to the facility, but some progress has made to bring off site
power and more equipment. This means more effective cooling could be
established in some days. But, at least until that happens, the situation
remains critical and unpredictable.
Our updates are based on the best
information we have been able to collect from various sources. There is
a lot of confusion in any crisis situation, and, in this case, several
governments and official bodies have already questioned whether all the
available information is being provided.
Summary: Status of facilities
Reactors 1-3: water level in reactors low (about
half of fuel rods exposed), no grid power, seawater injection apparently
ongoing. Fuel rods have certainly damaged and are releasing radioactive
substances.
Fire department has brought in 30 more trucks,
at least one reported to be a 'super bomber' able to shoot to a
distance of two kilometres. Yesterday, police trucks were unable to operate
close to plant because of high radiation levels, only SDF (Self Defense
Force) trucks that can be operated from inside the cabin were used.
Spent fuel pools of units 1 and 2: Water levels in unit 1 are decreasing. Steam was reported from unit 2, expected to be boiling.
Spent fuel pool of unit 3: Water in #3 almost depleted, but Tepco
hopes some water is left. Fuel rods have certainly damaged, releasing
radioactive substances. The reactor buildings are heavily damaged,
allowing releases directly to outside air.
Spent fuel pool of unit 4: Water level very unclear.
Spent fuel pools of units 5 and 6: Temperatures still rising, water left but level unclear.
Worst case scenarios
- The zirconium contained in the fuel rod cladding can react
violently with air if exposed for hours. This fire would release and
spread very large amounts of radioactivity high up in the air. There is however wide
disagreement on the probability of this happening.
- A large amount of molten fuel accumulates at the bottom and a
nuclear reaction starts. Very low probability and can be prevented if
there is any borated water in the pool.
- Reactor boils dry, molten core breaches reactor pressure vessel and
comes in contact with the water in the containment, which boils rapidly
causing a steam explosion.
- A major risk is an event (eg increased release of radioactivity
from a spent fuel pool due to overheating) that raises local radiation
levels to completely intolerable levels - preventing further work to
restore cooling.
Tepco seemed to suggest that encasing the plant in concrete is an
option if cooling efforts fail (according to Reuters live feed).
Wind
Local wind speed
slowed down considerably in the morning but direction remained towards
the sea. Winds towards Tokyo are still feared for Sunday.
See also
A day-by-day account of the nuclear accident from Reuters.
Our main Fukushima page and our Twitter updates.