from TheAutomaticEarth Website
Co. After the Quake 1906
The pervasive consequences of station blackout began with a hydrogen explosion in unit 1, followed by a much larger explosion in unit 3, two explosions at unit 2 and one at unit 4.
Units 1-3 had been operational prior to the earthquake and tsunami, but were automatically shut down with the quake. Units 4-6 had not been operational for some months, but reactors require constant cooling whether or not they are operational.
It is likely that we will see all units
compromised due to the loss of power that has prevented cooling.
At nearby Fukushima Dai-Ni (Fukushima 2), where there are four units, outside power has apparently been restored and, although three units remain in a state of nuclear emergency.
Slightly radioactive steam is being
vented in order to reduce the internal pressure from overheating.
Similarly, steam venting is being undertaken at
the Onagawa plant,
where there are an additional three units. Fire was previously
reported at Onagawa.
There are seven spent fuel pools at Fukushima 1, many of them densely packed with some 20 years worth of spent fuel.
(All spent fuel world-wide is stored in this way, near the reactors which produce it, as no country has yet developed and implemented a long-term storage solution for waste that will remain radioactive for thousands of years.)
Explosion in reactor
no. 3 at Fukushima 1 Monday
The most seriously affected reactor so far is unit 2 at Fukushima 1, where an initial hydrogen explosion was followed by a second explosion in the suppression pool below the reactor.
A breach of containment in this unit seems to be the most likely source of the spike in radiation that has recently been noted.
Radiation levels of 400 millisieverts
per hour were observed at Fukushima, as compared to a normal yearly
background radiation level of 3 millisieverts.
Radiation levels have increased to levels harmful to human health, and all but 50 essential workers have been evacuated.
The Japanese Prime Minister is has called for evacuation of a 20km exclusion zone. People have been asked to remain indoors and not to bring in laundry drying outside that may now be contaminated. Thousands are being screened for contamination and those with high levels are being showered on site in insulated tents or sent to hospital.
Radiation levels are elevated as far away as Tokyo, following a change in wind direction.
People are trying to leave the city, but that is becoming more and more difficult as fuel line-ups begin and long distance trains are often not available. Stores are already running out of some supplies as people engage in panic buying. Fear of shortages can easily become a self-fulfilling prophecy under such circumstances.
As always, the human reaction to events can provide a major portion of the impact.
The health damage from exposure to radioactive isotopes comes from the energy they release as they decay from unstable forms to stable ones.
Each isotope has a specific decay path over a specific timeframe, defined by the half-life of the element. The half-life is the time it takes for quantity of material to be halved, halved again and so on. A short half life indicates a shorter term risk, as the material will release its decay energy over a short time.
In contrast, materials with a long half
life will be persistent in the environment.
Photo: Kim Kyung-Hoon
he health effects will depend on how the particular isotope is taken up in the body, what form the release of its decay energy takes, and what is the residence time of the isotope within the body.
Isotopes can decay by releasing alpha,
beta or gamma radiation. Alpha radiation is composed of helium
nuclei (2 protons and 2 neutrons). These are large and energetic and
therefore potentially very damaging), but do not penetrate far. Beta
radiation is composed of fast moving electrons, and gamma radiation
is composed of photons (light particles). Beta and gamma radiation
penetrate to a much greater extent.
Iodine 131 has a half life of only 8
days, so it is of most concern early on. It is taken up by the
thyroid gland where it can be retained (especially in young
children), greatly raising the risk of thyroid cancer. Taking
potassium iodide tablets can protect the thyroid from taking up the
radioactive isotope. People in the affected area should be given
this option as a preventative measure.
Cesium 137 is taken up by the body in
place of potassium, while strontium 90 is taken up in place of
calcium. Cesium accumulates primarily in muscles and organs, while
strontium accumulates in bones. The risk is organ damage, leukemia
and bone cancer, depending on the dose. At Chernobyl, cesium 137
appears to have represented a much larger health risk than strontium
Plutonium 239 is an alpha-emitter with a
half-life of some 24,000 years. If inhaled or ingested, alpha
particles can affect the lungs or digestive system at close range.
Explosions at sites where containment is impaired or destroyed are a
major risk factor for inhalation of radioactive particles.
suffered a nuclear explosion on an abrupt power surge aggravated by
a moderator fire.
The core could melt down into the groundwater, causing steam explosions.
Relatively local contamination could
eventually be considerable, depending on the final scope of this
rapidly developing situation, but I would not expect major
international contamination as happened following Chernobyl.
Even within Japan I would not expect widespread gross levels of contamination even under a worst case scenario.
Fear of radiation is likely to be widespread and extreme, however, as fear is a phenomenally 'catching' emotion, and that can have serious consequences of its own, especially under circumstances where social infrastructure is already overwhelmed. A perception of cover-up would add significantly to this fear.
It is therefore extremely important for
the Japanese authorities to be consistently and completely
forthcoming about the situation.
Those who live closest to Fukushima are the most concerned.
PS 1: Here is the latest
headline from Reuters: Tokyo Electric says may drop water by
helicopter onto Daiichi No.4 spent-fuel cooling pond. This is not
going well. This reeks of desperation.