By Satoshi Takamatsu
March 17, 2011
In Japanese: http://amba.to/fn9kLX
Due to the subject matter, this entry may seem a bit more formal than usual. It is quite a long
entry, but if you have time, please read it. It may help shed some light on what is happening in Fukushima.
The Fukushima Nuclear Power Plant was hit by an earthquake of a magnitude that far
surpassed any expectations. The intensity of the earthquake and tsunami (tidal wave) that
followed was a hundred times greater than what Japan had been preparing and bracing for,
so it is not surprising that the nuclear power plant in Fukushima also suffered damage. (A 0.2
difference in magnitude produces 2 times the energy).
Despite being struck by a natural disaster of such magnitude, the reactors that were in
operation automatically shut down when the earthquake struck. The situation will not
become catastrophic as long as the temperatures of the reactors can be maintained
low. Having said that, I completely understand why some people are expressing
concerns. Through conversations or emails exchanged with friends, I have discovered that
many people are scared and worried. Some people are over-reacting, it seems, to the nuclear
issue; they are barricading themselves indoors. I felt that the best way I could help people
under the current situation was to accurately and in simple layman's terms explain what is
happening in Fukushima, so that is why I am writing this entry.
I studied radiation in college and conducted experiments at the Tokai Village Nuclear Plant
in Ibaragi prefecture. Before I began my experiments I studied radiation at length and also
acquired the Radiation Protection Supervisor certification. So I have some knowledge about
radiation. What I am about to write is my personal opinion, which I have carefully formed
based on the analysis of experts around the world. I am writing this with the hope that it will
help clarify what is going on amidst a confusing mass of information.
Those of you who may be more directly impacted by issues in Fukushima may find this entry
offensive as I will be focusing on the situation in Tokyo and reiterating, "Tokyo is safe." I do
sincerely apologize in advance for any offense this entry may cause you. Please note that I am
writing this for my friends and family living in Tokyo. I felt that this would be the best way for
me to help people who are close to me, living in Tokyo, and to give them some peace of mind,
so please bear with me.
I have tried to summarize the information I have collected over the last three days as
accurately and as straightforward as I could (as of the night of March 17th). Although I had
initially written this summary for my friends and family, I have decided to post it on my blog.
I am neither a journalist nor an expert, so please do not expect my synopsis to be perfect.
Sorting through the superabundance of information may help you "understand" what you may
have thought was "confusing" before; that was true for myself. I believe often we are "afraid"
of the "unknown." I hope that my entry will help you understand what is going on and
alleviate fears.
I will be introducing information I thought was essential, that would help give us reassurance.
1. It is impossible to get accurate real-time updates about "what is happening" and "what
measures are being implemented" at the Fukushima nuclear plant from the government.
The government does not want to provide real-time information for a number of reasons. And
there are also things even the "government doesn't know in real-time."
This is true even with a "good government" or an "ideal government." (Although there
may be a difference in the way they communicate or in the capabilities of the nation) what
governments are first and foremost concerned with is the safety of their people and about
the preservation of the nations' economic capacity (with the desire to minimize primary and
secondary damages). Faced with a crisis of such unparalleled scale, governments neither
can take responsibility nor evade taking responsibility for what has happened. Governments
(in most cases) only have one thing on their minds – to do the best they possibly can for the
people.
Some have criticized Tokyo Electric Power Company Inc. (TEPCO) saying that it has only
provided vague answers to date, but this can't be helped either. There are frequent explosions
at the nuclear plant, and even if the workers are wearing hazmat suits, they are only able
to work up to 15 or 30 minutes a day near the facility before they reach the daily limit of
radiation exposure. It is difficult enough just to "go look" at what is happening to the reactors.
What is more, many of the radiation measuring instruments are broken. So it is very difficult
for TEPCO to acquire a great deal of accurate information. Of course since the people working
on site are professionals, they are able to make an "intelligent guess" of what may happen.
But "estimations" and "possible scenarios" would only cause confusion among the public.
Without a doubt, as a private enterprise, TEPCO wants to minimize the damages. And it is
also indisputable that as a public utility company, it would like to contain and limit radioactive
contamination as much as possible. Moreover, they have had no training or experience
speaking to the public about such a matter of great importance. And as they are trying
to stick to the facts and refrain from making speculations as much as they possibly can,
this makes their press conferences seem rather awkward. And if an extremely important
announcement needs to be made, the "government" would want to be the one to make such
an announcement. TEPCO and other institutions are employing their best efforts and acting
as professionally as they can. I believe that for the moment, we should stop being suspicious
of "what TEPCO is doing right now." The fact that they tried to use the same facility for over
40 years or other policy errors are another matter. What I am talking about are the measures
they are implementing to handle the current issue. Japan's Self Defense Force, the police, and
the fire department are also working as hard as they can to help.
I have also heard some people say, "Can the government be trusted? Can we really leave it up
to our head of state?" But one cannot interject one's opinion in announcements regarding an
issue of such gravity and scale as radiation. So, there is no room for the head of state to reflect
his personal opinion in the measures being taken. When sophisticated technical problems
are putting people's lives at risk, it is the experts in the field that decide what the appropriate
measures are.
When Apollo 13 was facing a crisis, was the U.S. president able to do anything? He could not.
It was NASA's intelligence and the astronauts that tackled the issue. The experts at the nuclear
plant, the police, the Self Defense Force, and the firefighters are, as sleep deprived as they
are, working around the clock trying to think of and implement the best possible solution.
With all eyes on Japan, the Japanese government cannot cover up what is going on like the
Russian government did in Chernobyl. Therefore, we have no reason to be "suspicious of our
government."
We can trust our government. Having said that, there are many areas where they can improve
– "are they communicating well?"; "have they been able to provide accurate directions
quickly?"; "is the government implementing preemptive measures in preparation for the
worst?" These are questions we are all asking ourselves. Although the experts are developing
strategies to handle the technological issues, there may come a time, in the near future, where
the government will have to make a difficult political decision. I hope that when that time
comes, the government will make the right "decision" and exhibit strong leadership. If we
begin criticizing the government, there will be no end, and I am sure you have all become tired
of reading such articles. Here, I would like to refrain from critiquing the government; rather I
would like to focus on shedding light on the current situation.
2. I believe that the government is refraining from sharing information about "what is
happening now" and "what measures are being implemented" for the following reasons
(although they have begun to give details recently):
A. The media may over publicize or provide erroneous information without sufficient literacy
about nuclear power generation or radiation (for example, "what does it really mean when a
nuclear reactor melts down?" and if "a meltdown does occur," "within what walls," "within
what container" does it occur?" "Can the radiation be contained in the container?"
Making comments such as "meltdown has begun" or a "meltdown is inevitable" without
understanding these issues in depth will only cause unnecessary confusion.
B. In addition to the mass media, social networks such as twitter, which was a well functioning
lifeline immediately after the earthquake, may suddenly transform into a device used to
widely disperse the general public's mistaken notions. In the mid term, the information
available will converge on a large social network to become the "truth" or "recognized fact."
But in the meantime, although people's "anxieties" may be "incorrect," they can spread
instantaneously and be perceived as being "factual" until people realize that such information
is actually a misconception.
C.
There is a possibility that people will begin to panic in response to the media coverage.
D. As a result, people may begin to hoard goods, thereby create a shortage in supply of
essential commodities.
E. Unnecessary evacuation will wreak havoc to the transportation system such as trains.
F. Collective fear and stress, especially during blackouts, may lead to localized riots resulting in
criminal activities such as looting and rape.
G. When economic and manufacturing activities significantly decrease due to perceived fears
about the current situation, this will have an astronomic effect on the economy in the short
term.
From the broader perspective, the above should be avoided. In the mid term, although the
freedom of the press should be respected, unless the media can take responsibility for the
possible confusion and chaos its coverage on the nuclear plant may cause, providing more
information than "what has been released by the government" "about what is happening
now" based on "speculations" is not necessarily the right thing to do.
If information about "what is happening now" and "what measures are being taken" is
released in real-time, there will be a lot of commotion, a lot of "criticism" and "suggestions."
"Inject sea water!" "Secure electrical power!" "Use helicopters pour water on the reactors!"
– The government and TEPCO have taken all of this into account and are implementing the
best measures possible. But on site, even a delay of a single second in decision making may
result in a catastrophe. There is no time to be listening to "criticism" and "suggestions" or
for "rebuttals."
The only thing that can be done is to implement the plan experts believe is the right one, the
best one, step by step. Each phase and method should be formulated based on a manual
comprised over an extended period of time and decided flexibly by taking various conditions
on site into consideration.
For the above reasons It is impossible for the government to accurately know "what is
happening now" and "what measures are being implemented" in real-time. There may be
things happening that the "government doesn't even know about." But even if we "knew what
was happening, there is nothing we can do."
3. The government may "intentionally delay" providing information to the public.
But I am sure we can be safe in believing that they would not "fabricate" information or "play
down" the situation. This is because the truth cannot be withheld from the public in the long
term. (As long as you have a device) anyone can measure the level of radiation. And there
are too many people involved, which makes it impossible to hide what is going on with the
reactors.
4. Therefore, at the moment there is no need to escape from Tokyo (at least in Tokyo or
anywhere west of Tokyo), refrain from going outdoors, or to panic because you think "the
government can't be trusted" (albeit it is understandable to feel that way about the current
administration).
5. On the International Nuclear and Radiological Event Scale, the incident at Fukushima
nuclear plant has been rated level 5. The incident at Three Mile Island, US, which was also
a level 5, required pregnant women and children living within 16km of the nuclear plant to
evacuate after the accident, but (so far) the evacuation zone has not been enlarged. So the
20km radius at Fukushima seems like it is a more than sufficient margin.
In response to the incident at Fukushima, the US government advised its citizens within an
80km radius to evacuate, but this is not because the "US government knows something we
don’t." The "US government doesn't know any more than the Japanese government," so
that may be one of the reasons why it has set a wider, more cautious buffer zone. And if you
think about it, it is quite normal for foreigners to evacuate faster, when "faced with a crisis in
a foreign country." It is very difficult for people who do not speak the local language to go to
hospitals to get care or to go to evacuation centers.
When there is a coup d'etat or natural disasters overseas, Japan is the first country to evacuate
its citizens. If a natural disaster of a similar scale occurred in another country, the Japanese
government wouldn't stop at an 80km radius evacuation zone; it would advise its citizens to
refrain from traveling overseas, and also brings its citizens home. So there is no need to be
frightened by the US government's 80km evacuation zone.
6. The intensity of radiation is inversely proportional to the square of the distance from the
point source. This means the following. The evacuation zone is set at 20km. If you are in a
location that is double the distance of 40km from the source, the radiation level would be 1/
4 what it is at the source; at 80km, 4 times the distance, the level would be 1/16; at 160km,
8 times the distance, the level would be 1/64, and at 320km, 16 times the distance, the level
would be 1/256. Tokyo is about 300km away from the source.
Even if the radiation levels within the 20km evacuation zone gets as high as 200 times the level
considered harmful to human health, (by the time the radiation reaches Tokyo, the level will
be 1/256 of the level at the source, that is 0.7 times the level considered harmful to human
health. I will talk about radiation in more detail later), people in Tokyo have no reason to
worry about adverse effects to their health.
7. What is most important and what is also misunderstood, it seems, by many people
about "what actually happened" at Fukushima is this: immediately after the earthquake, the
reactors successfully, automatically shut down, and the "nuclear fission chain reaction of
uranium" had ceased. This is a very important fact. Without a doubt, the "nuclear reactors
have shut down." If they had not, in about 45 hours the reactors would have started to melt
down, and we would not have been able to stop the process.
In other words, if a "meltdown" had actually occurred immediately after the earthquake,
by Sunday the situation would have become a catastrophe of cosmic scale. But this has not
happened, so the "reactors have indeed stopped." This fact is scientifically indisputable.
People seem to be mistaken that "uranium is on fire" or "nuclear fuel is continuing to melt
and spewing radiation." But this is not at all the case. We should first understand that
the "nuclear reaction of uranium" has already stopped.
The fact that there was a hydrogen explosion that took down the exterior building (just in case
you may be wondering, a hydrogen explosion has nothing to do with hydrogen-bombs), is also
not a very serious problem. (The explosion was within expectations and) the external building
does not serve any purpose when it comes to preventing radiation. There "actual walls" – all 3
layers - of the containment vessel remain in tact.
8. So, "what is happening," and "what are they doing?"
Although the "nuclear fission chain reaction of uranium has stopped," in other words,
the "nuclear reactors have shut down," what people on the ground are doing now is "cooling
the residual heat with water." The No.4 reactor was not in operation when the earthquake
struck, but spent fuel rods were being cooled in a pool of water. This is because fuel rods
continue to give off heat even after "nuclear fission chain reaction of uranium stops." The
heat given off by the spent fuel rods gradually dissipates, and in due course they will be safely
transported and processed.
This may be a little confusing, but when the nuclear reactors are in operation (while uranium
undergoes nuclear fission), there ar e"byproducts" such as radioactive caesium and iodine.
They have much less "power" and shorter "half-lives" than uranium. These "byproducts" emit
heat even after the nuclear reactors shut down. (Compared to the nuclear fission reaction of
uranium, the amount of heat byproducts give off may be far smaller, but) the "byproducts"
naturally decay over time (decay refers to the process through which these radioactive
isotopes become no longer radioactive). And the heat these "byproducts" emit rapidly
decreases over time.
What is needed is a good way to keep cooling the fuel rods, and as time passes, less water will
be needed each day to cool the fuel rods.
If the heat can be managed and cooled with water, the nuclear reactors will not melt down.
According to the most recent information, there may be a possibility that a part of the reactor
has begun to melt down. But even if the reactor partially melts down, if the fuel rods can be
cooled before the 3 layers of the containment vessel are destroyed, the damages will not be
extensive.
The last defense line, the third wall of the containment vessel "has been designed from the
start to stop a meltdown should it occur," to contain the melted fuel to ensure that it does not
come in contact with the outside world. As of today, there is no news that the third wall has
been penetrated.
9. Having said that, to cool "residual heat," you need "water" and a "pump," as well
as "electricity" to power the pump.
Ordinarily, "pure water" (such as distilled water without any impurities) is used, otherwise the
reactors might end up rusting or there may be a build up of grime. After the earthquake struck
(more precisely after the tsunami) TEPCO could not secure enough "pure water" and lost the
ability to generate "electricity."
Due to the lack of "pure water," "sea water" has been injected into the reactors. This means
that the reactors will no longer be viable, but the government and TEPCO decided to throw the
idea of getting the reactions back in operation out the window, and injected "seawater." But
this also means that there is an infinite supply of water.
The problem is securing electricity. Immediately after the earthquake hit and the reactors
shut down, emergency diesel generators supplied electricity for a while. So a possible power
failure was foreseen and there was a contingency plan. However, the diesel generators were
damaged in the tsunami, so they can no longer generate power. Then, backup batteries were
used to supply power for around 8 hours. These are batteries, so once they run out, there is
nothing to be done.
What will be done today and tomorrow will be to secure electricity somehow to operate the
pumps, and to continue to cool the reactors. Or they may douse the reactors with water from
helicopters or use water trucks to hose them down. In any case, it will require quite a lot of
manpower. On March 16th, they had to stop dousing the reactors from helicopters because
the radiation levels were too high, but they were successful on the 17th. And from the 17th
they will also supply water from water trucks.
We can't take our eyes off reactors No.1 through No.6, but there is no immediate threat (as of
March 17th).
Reactor No.1 is being cooled smoothly. I don't know "how it is progressing" or "exactly what
they are using to supply water." But the important thing is that the temperatures are coming
down.
Reactor No.3 requires additional measures. They will begin extensive hosing operations on the
18th, but it is not in a critical condition.
The building containing reactor No.2 is still in tact, but there is potential damage to the
suppression chamber, so measures need to be implemented. Because it still has a roof,
reactor No.2 is the most difficult to cool from the outside, but if the electricity can be
resupplied, they will try to get the pumps up and running.
Reactor No.4 was not in operation when the earthquake hit, but there were spent fuel rods
cooling in the pool, which ended up causing a fire. As I explained before, that was a result of
the "heat emitted by byproducts" even after shut down. As long as water can be supplied,
reactor No.4 is safer than reactors No.1, No.2, and No.3, but because the "building hasn't
exploded and remains in tact," it is harder to supply water to it. They plan to supply water
through "one of the large holes" the fire made.
Reactors No.5 and No.6 are fine for the moment, but that does not rule out the possibility of
something happening to them.
In any case, what is important is getting electricity back and water trucks.
With respect to electricity, General Electric, the manufacturer of the No.1 and No.2 reactors,
have announced that it will deliver 10 gas turbine generators. However, hopefully TEPCO will
be able to successfully supply power to the Fukushima nuclear power plant from the Tohoku
Electric Power Company's power lines before these generators arrive and start working. There
are high expectations that significant progress will be made by the 19th. (If these efforts
are successful, the situation will dramatically improve; that is, if the pump isn't broken.)
Moreover, special water trucks are on the way from the US base, Yokota, and those of Japan's
Self Defense Forces are also going to be put into operation.
Due to the maximum dose of exposure and the amount of water that can be transported
each time, this cannot go on for a very long time, nevertheless, the efforts up to date seem
to be working. If we can get the power supplied from Tohoku Electric and if the pump and
emergency cooling system kick in, we will be able to constantly cool the fuel rods.
If we can prevent the meltdown of the nuclear core through all these efforts, there will be no
major catastrophe. And what is another important point is that even if the cooling efforts are
insufficient and the "nuclear core melts down," as long as the radioactive materials "remain
within the third layer of the containment vessel" there will be no major catastrophe. I will
touch upon this again below.
10. The radiation being detected at the moment - what is the nature of it and what effect will
it have on Tokyo?
So, why are radioactive isotopes being released into the air and how serious (or not serious) is
it?
As I have explained a few times already, currently, the nuclear reactors are shut down. So the
uranium is not undergoing nuclear fission. However, byproducts are emitting heat. Because
water is being used to cool it, the water vapor causes the pressure within the containment
vessel to rise. If this pressure is not relieved, the containment vessel (and not the building) will
explode. This must be avoided at all costs. That is why pressure is being released. (Imagine
a pressure cooker. When the pressure builds up to a certain level, the valve pops up and
relieves pressure.)
Most of the radioactive materials that are being released into the air with the vapor are
substances known as rare gases, such as xenon-137 (this may not sound familiar, but it is not
dangerous). Xenon-137's ability to emit radiation "halves in a few minutes" so as long as you
are far away, "this radioactive substance is not dangerous." Even if the substance is carried in
the wind, it won't reach Tokyo in a few minutes.
The half-life of iodine-131, which is most likely the radioactive material being detected by
people who have been exposed and evacuated, is said to be 8 days. So even if you came in
contact with it, in 8 days time (this is if you don't wash it off) its effect would be halved. But in
reality, there aren't that many people who don't wash their hands or take a shower for over a
week, so the substance would be washed off before the 8-day period. Let's take a close look
at 2 of the worst cases of "exposure" to radiation reported in Fukushima so far.
At the moment, the worst case of exposure to radiation reported (levels taken from shoes
of an evacuee in Futaba) recorded an absorbed dose of 0.53mGy/h (I have decided to skip
over the complicated equations and just give you the end result) (source: National Institute of
Radiological Sciences). Your skin starts to become affected from 2-3Gy. So 0.53Gy/h is not a
problem at all. And even if it stays in contact with your skin for 8 days, the total effect would
only amount to 0.1Gy (0.52Gy/h x 24 hours x 8 days x 1/1000 = 0.102).
On March 12th, the highest radiation levels of 1015 mSv (micro sievert) were detected. This
means that even if you stood there in a daze for about an hour, the amount of radiation
you would be exposed to would be approximately 1 mSv. Those of us who live in Japan are
exposed to 2.4 mSv of radiation in any given year. If you live in high altitudes, you would be
exposed to 10 mSv. Each time you get an x-ray mass examination, you are exposed to 4 mSv.
Pilots and cabin attendants are also exposed to 2-3 mSv annually. So we are "exposed to
radiation" every day. You can see how "there is no reason to be overly scared" since even the
highest case reported at the gates of the Fukushima Nuclear Power Plant is 1 mSv .
In addition, the strengths of radioactive materials are, as I mentioned before, inversely
proportional to the square of the distance from the source. And the half-lives of many of the
radioactive isotopes range from a few minutes to around 8 days.
There are some are people in Tokyo who are afraid when they hear reports about how the
radiation levels in the neighboring prefecture, Chiba, spiked (momentarily) to "twice normal
levels." Even if the levels were 5 times the usual, we would only be exposed to the same level
of radiation as people living in high altitudes, and these people live up there year round. So it
is completely safe even if we are exposed to a higher level of radiation for a few hours or few
days. If you are worried about this, you wouldn't be able to get any x-rays or CT scans.
In comparison to getting a CT scan or getting on a plane to go to New York, for example, the
increase in the radiation levels in Tokyo is miniscule.
There is no need to be "scared of radiation" in Tokyo. You don't have to stay indoors, wear
a mask when you do go outdoors, keep the windows closed, or refrain from using the air
conditioning (except to save energy).
Similarly, even if you get rained on it is completely safe at the moment (but it's still cold
outside, so it is better if you don't get wet). Unlike the atomic bomb, there will be no nuclear
fallout. And Fukushima Nuclear Power Plant is fundamentally built different from the
Chernobyl, so even in the worst-case scenario, damages of calamitous scale will not occur.
A nuclear reactor will "never" be a nuclear weapon. Although people seem to believe the
myth that what is happening in Fukushima may end up causing the same scale of damages as
Hiroshima, even if the world turned upside down and sideways, this will not be the case. If a
nuclear reactor could become a nuclear weapon, countries like Iran or North Korea wouldn't
have to go through all the trouble. These 2 are completely different things.
Moreover, the word "meltdown" is being used quite vaguely, and this is probably contributing
to the fear. This word is not a scientific term. It seems like people use the word with the
following image in their minds: as a result of the "reactor core melting down," the nuclear
fuel within the containment vessel "melts," releasing the radioactive materials outside, which
results in extensive radioactive damage. If this is what is referred to as a meltdown, then a
meltdown didn't occur at the incident at Three Mile Island in the US either even though it was ,
described as being catastrophic. What happened at Three Mile is that the nuclear core began
to melt beyond control, which dissolved through later 1 and 2 of the containment vessel, but
pooled at the bottom of layer 3 and stabilized within the walls of layer 3.
Even in this case, although people living in the 16km radius were evacuated, there was hardly
any impact on the environment, and no one has died from radiation exposure.
The Three Mile incident occurred 12 days after the movie, "China Syndrome" was released.
The movie told a story about a nuclear reactor in the US melting down, nuclear fuel melting
through the containment vessel, the earth, and reaching all the way down to China on the
other side of the planet. Perhaps this movie helped create this fear or overreaction to the
word, "meltdown."
Even if a meltdown occurs, and even if they could not cool the fuel rods successfully, nuclear
reactors in Japan and the US have been designed in a way to contain the fuel within the third
wall of the containment vessel.
Lastly, let me talk about the "worst-case scenario." The possibilities of this happening are very
low, but it's now zero. And as I mentioned in the beginning "not knowing" is "scary." So let's
see what would happen in the "worst-case scenario."
"The worst-case scenario"
If the reactors cannot be sufficiently cooled even with the efforts of Tokyo Electric, the fire
department, Self Defense Forces, the US Army, GE's generators, and the supply of electricity
from Tohoku Electric, then "meltdown" in one or some of the reactors from No.1 through No.6
will be unpreventable.
If layer 1 and layer 2 of the containment vessel melt, then the nuclear fuel will start to pool at
the bottom of layer 3. With this possible scenario in mind, the third layer of the containment
vessel has been designed to absorb, diffuse, and solidify the substances. Radioactive
substances solidifying at the bottom of layer 3 is what happened at Three Mile. If this
happens, it will require a lot of time and staggering costs to clean up.
But what I would like for you to remember is that even at Three Mile, the radioactive
substances remained within the third layer, and the fuel did not come in contact with the
outside world. As a result, the damage wasn't too serious.
What this all means is that even in the "worst-case scenario," the damage radiation will have
on the surrounding region is slight. And there is no possibility that Tokyo will incur damages.
I would like to end here, but let me talk briefly about the "ultimate worst-case scenario."
If the melted nuclear fuel does not remain pooled at the bottom of the third layer, in other
words, if the third layer of the containment vessel is breached, the melted fuel and radioactive
substances would be released and the radioactive leakage would be devastating. This is the
ultimate worst-case scenario. This will have a significant effect on the surrounding region. The
extent of the damage will depend on the amount of radioactive materials that leaks. Should
this happen, there will be mid to long-term adverse effect on human health, crops grown in
the area, and the sea.
(For the moment, crops grown in and near Fukushima do not contain enough radiation to
be "harmful to human health." There is talk about spinach being contaminated, but this is not
harmful to human health either, except if you could consume a truly crazy amount of spinach
in one sitting. The half-life of iodine is said to be 8 days. The half-life of caesium is said to be
30 years but if you take metabolism into consideration, the internal exposure to radiation is
about 200 days. (Even if you ate the detectable amount of spinach after you've washed it)
and multiply it by 200 days, and 24 hours the amount of radiation would not be harmful to
human health. Of course the result would be higher than the baseline, so it is probably better
to temporarily stop distributing such produce. However, if the levels fall below the baseline
in the future, there is no reason to worry about eating produce from Fukushima or Ibaragi
prefectures. We need to be careful not to completely devastate the farming and fishing
industries in Fukushima and Ibaragi by believing unfounded rumors in the mid to long term.
Even in the "ultimate worst case scenario," the radiation (enough to be harmful to human
health) will not reach Tokyo immediately (and if you remember, the intensity of radiation is
inversely proportional to the square of the distance from the point source.)
Of course there is a possibility that the wind and rain may carry radioactive substances. If
that happens, we would hear about it on the news. Governments and media from around
the world all have their eyes on Japan. And now IAEA and the US army are also offering their
cooperation to get the situation in the Fukushima Nuclear Power Plant under control. Google
Earth continues to take photographs regularly and is sharing the information. So even if
the "ultimate worst case scenario" does occur, you will have enough time to act.
I say act, but there is no reason to evacuate Tokyo. Just listen to the government and the
media coverage, and avoid walking in the rain or stain indoors if necessary.
Understanding what the "ultimate worst scenario" would be, I am sure you see that it
is "unnecessary to live in fear in Tokyo" under the current situation.
So let's stop worrying, hoarding, and sending emails that may cultivate fear; let's spend each
day with a positive attitude. And let's appreciate the efforts of those who are putting their
lives on the line to cool the reactors in Fukushima, and calmly wait and see how things pan
out.
I truly believe that with Japan's world-class technology and the efforts of those who are risking
their lives, we will be able to avoid the worst.
Satoshi Takamatsu
March 17th, 2011
23:20
Revised with additional information
March 21st, 2011
18:55
I reorganized the links I would like for you to reference.
I corrected some grammatical errors.
I added comments to clarify certain points and also added a section on farm produce.
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