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ISIS Report 11/06/12
Fukushima Fallout Rivals Chernobyl
State-of-the-art analysis based on the most inclusive
datasets available reveals that radioactive fallout from the Fukushima meltdown
is at least as big as Chernobyl and more global in reach Dr. Mae-Wan Ho
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14 000 Americans already died from Fukushima fallout?
A paper published online December 2011 in a peer-reviewed
journal estimated that nearly 14 000 have died in the United States in 14 weeks
following the arrival of the radioactive fallout from the Fukushima meltdown .
It noted that the estimate is comparable to the 16 500 excess deaths in the 17
weeks after the Chernobyl disaster. The rise in reported deaths after Fukushima
was greatest among infants less than one year of age.
The authors’ credentials appeared impeccable
. Joseph Mangano is a public health administrator and researcher who studies
low-dose radiation exposure and subsequent risk of diseases such as cancer and
damage to the newborn. He has published numerous articles and letters in
medical and other journals as well as books, including Low Level Radiation
and Immune system Disorders: an Atomic Era Legacy. Janette Sherman worked
for the Atomic Energy Commission (precursor of the Nuclear Regulatory
Commission) at University of California Berkeley, and for the US Navy Radiation
Defense Laboratory in San Francisco. She specializes in internal medicine and
toxicology, with an emphasis on chemicals and nuclear radiation, was an advisor
to the National Cancer Institute, and served on the advisory board of the
Environment Protection Agency for 6 years.
major criticism of their work is that the authors claimed Fukushima fallout
arrived just six days after the earthquake, tsunami, and meltdowns, but they
provided no evidence for this assertion . Another is the paucity of
radioactive measurement data; but that is the responsibility of the US
Environment Protection Agency (EPA), and is hardly the authors’ fault. Indeed,
the authors are themselves critical : “The paucity of data from the U.S. EPA
is unfortunate and will hamper future studies.” The same paucity of data has
indeed hampered studies that might have prevented the humanitarian health
disaster still unfolding more than 25 years after the Chernobyl disaster (see
Deaths Top a Million Based on Real Evidence, SiS 55).
Ban Treaty Measurements
Withholding data, or not
bothering collecting appropriate data, appear endemic to the nuclear industry
and governments in general; and Fukushima is no exception ( Truth about Fukushima, SiS 55). But a surprising source of observations
is coming from radioactivity measuring stations set up under the
Comprehensive Test Ban Treaty (CTBT), which foresees a global ban of all
nuclear explosions. To verify compliance with the Treaty, a global monitoring
system is being built, which includes measurements of radionuclides.
Measurements of atmospheric concentrations of both Xe-133 and Cs-137 were
available from CTBT stations to a high degree of sensitivity. Sixty monitoring
stations are currently delivering data on Cs-137, and 25 stations delivering
data on Xe-133 to the International Data Centre of the Preparatory Commission
for the CTBT Organisation in Vienna. Cs-137, with a half-life of 30.17 years, comprises approximately half of the total radioactive
caesium released, the other half being Cs-134 . Xe-133, with a half-life of
5.25 days is the most abundant Xe isotope, comprising >97.3 % of xenon in
State of the art analysis on the most inclusive available
After the earthquake and Tsunami struck, elevated levels of
radioactive emissions were measured in Japan and all over the Northern
Hemisphere including the CTBT monitoring stations. But the point measurements
are too sparse to determine the three-dimensional distribution of radionuclides
in the atmosphere and their deposition on land and sea. Given accurate
emissions data, dispersion models can simulate the atmospheric distribution and
deposition of radionuclides and provide a more complete picture than the
measurements alone. The simulations must be compared, and fit the measurement
data. However, the single largest source of error in prediction is the source
term, the rate of emissions into the atmosphere from the accident site. To
this day, the time variation of emissions from Chernobyl is still uncertain.
comprehensive information on the events in the Fukushima disaster is a report
released by the Japanese Government in June 2011 to the International Atomic
Energy Agency (IAEA) , and its subsequent updates. Although the report
contains estimates of the amounts of radioactivity released into the atmosphere
for certain key radionuclides, the data are not reliable; as the
releases did not take place through defined pathways and were not metered.
To make the best use of the
available information and data, an international team led by Andreas Stohl at
the Norwegian Institute for Air Research (NILU) applied state-of-the-art atmospheric
dispersion models to optimise the fit between the model calculations (simulations)
and the observed measurements, thereby to obtain the most reliable source term.
This top-down approach, called inverse modelling, was earlier used to make
estimates of the Chernobyl source term. And members of the team have previously
developed an inverse modelling method for volcanic eruptions and greenhouse gas
A first guess of release rates were
based on fuel inventories and documented accident events at the site based on
information provided by the Japanese government’s report . The first guess
was subsequently improved by inverse modelling, which combined the results of
an atmospheric transport model, FLEXPART, and measurement data from several
dozen stations in Japan, North America and other regions.
The simulation was driven with
three-hourly operational meteorological data from two different sources: The
European Centre for Medium-Range Weather Forecasts (ECMWF) analyses, and the
National Centers for Environmental Prediction (NCEP) Global Forecast System
Total releases greater than Chernobyl
The results obtained for the total release of Xe-133 was
15.3 EBq (uncertainty range 12.2-18.3, EBq – 1018 Bq), more than 2 x
total release from Chernobyl (Chernobyl total was 5.2 EBq) and “likely the
largest radioactive noble gas release in history”. This took place between 11
and 15 March 2011. In fact, the release is greater than the entire estimated
Xe-133 inventory of the Fukushima Dai-ichi nuclear plant, and is explained by
the decay of I-133 (half-life 20.8h) into Xe-133. There is strong evidence that
Xe-133 release started before the first active venting was made, possibly from
structural damage to reactor components and/or leaks due to excessive pressure
inside the reactor.
For Cs-137, the inversion
modelling results gave a total emission of 36.6 PBq (20.1-53.2, PBq = 1015
Bq); 70 % more than first guess, and about 43 % of estimated Chernobyl
emission. The results showed that Cs-137 emission peaked on 14-15 March but
were generally high from 12 until 19 March, when they suddenly dropped by
orders of magnitude at the time when spraying of water on the spent-fuel pool
of unit 4 started. This indicates the emission may not have originated only
from the damaged reactor cores, but also from the spent fuel pool of unit 4.
Altogether, an estimated 6.4 PBq
of Cs-137, or 18 % of the total fallout until 20 April were deposited over
Japanese land areas, while most of the rest fell over the North Pacific Ocean.
Only 0.7 PBq or 1.9 % of the total fallout was deposited on land areas other
Correspondence between simulated and observed results
improved by inverse modelling
A scatter plot of all available Xe-137 observations versus
simulation results, both a prior (from guess estimate of source) and a
posteriori (source values optimised to fit the data) is given in Figure 1.
Figure 1 Scatter
log/log plot of all Xe-133 data both a priori and a posteriori (see text)
The straight line in the middle is where the
correspondence is 1:1 between measured and simulated values, the lines above
and below represent respectively overestimates and underestimates by a factor
of 5. There is a background emission of Xe-133 from nuclear facilities, which
is highly variable, and this is allowed for by adding a value of 1 x 10-4
Bq /m3 to every simulated concentration; consequently, one cannot
expect correlation between measured and simulated values at the low end (lower
left quadrant). Many of the data points there represent enhanced background
observed. Data point in the upper right quadrant all reflect emissions from the
Fukushima fallout, and for those data points, the modelled and observed values
show a tight correlation, with most simulated points falling within a factor of
5 of the observed values. While the model results using the first guess
emissions are already well correlated with the measurements, applying the
inversion simulation clearly improves the correspondence, with most of the data
points falling closer to the 1:1 line.
The scatter plot of the measured
and simulated Cs-137 concentrations is given in Figure 2, where again, a
background of normally distributed random concentration was added to every
simulated concentration value.
The fit between simulated and observed data
are not as good for Cs-137 as it is for Xe-133. One reason is the added
complexity of modelling wet and dry removal of the particles carrying Cs-137
from the atmosphere. Nevertheless, there is still a clear correlation between
simulated and observed concentrations.
Time series of simulated and observed
measurements made at key stations in Japan, Oahu (Hawaii), Richland (Washington
State), and Stockholm were also produced, as well as the amount of
radioactivity deposited on the ground. The fit between simulated and observed
tend to be better outside Japan, possibly due to contamination of monitoring
stations in Japan.
Deposition of radioactivity on land
It may have seemed fortunate that westerly winds prevailed
during most of the accident to carry the radioactive plume offshore. But
exactly during and following the period of the strongest Cs-137 releases on 14
and 15 March, as well as after another period with strong emissions on 19
March, the radioactive plume was carried over Eastern Honshu Island, where rain
deposited a large fraction of Cs-137 on the land.
Radioactive clouds reached North
America on 15 March and Europe on 22 March. By mid-April, Xe-133 was fairly
uniformly distributed in the mid-latitudes of the entire Northern Hemisphere
and was for the first time also measured in the Southern Hemisphere (Darwin
Station, Australia). In general, simulated and observed concentrations of
Xe-133 and Cs-137 both at Japanese as well as distant sites were in good
The dispersion of radionuclides from the
Fukushima fallout was simulated based on GFS meteorological analyses. The first
releases associated with the venting and explosion of Fukushima Daichi Nuclear
Power Plant unit 1 reactor on 11 and 12 March 2011 was blown mainly offshore
and transported eastsoutheast over the North Pacific Ocean, though a change in
wind direction on 12 March blew the plume over the coastal areas north of the
power plant. There was no precipitation, and the magnitude of the release was
an order of magnitude lower than on 13 and 14 March, associated with the
venting and explosions in the other units. On 14 March, a cyclone developed
over southern Japan, and this coincided with a period of very high emissions from
ventings and explosions of unit 2, unit 3 and in the spent-fuel pool of unit 4.
(Details of the release events are given in an Appendix of the paper .)
the accident events, Xe-133 and Cs-137 from the Fukushima fallout dispersed
throughout the Northern Hemisphere and eventually also reached the Southern
Hemisphere. A first radionuclide cloud ahead of the main plume containing only
Xe-133 was transported rapidly across the North Pacific at low altitudes and
arrived in western North America on 15 March (Figure 3). The first radioactive
cloud skimmed along the North American seaboard because a large cyclone over
the Eastern Pacific produced a southerly flow along the coastline. It was
nevertheless detected at Richland, Washington State in USA. The main part of
the radioactive cloud entered western North America on 17-18 March and could be
detected by monitoring sites there (see Figure 4). A comparison of the top left
panels in Figure 3 and 4 shows that the lead part of the Xe-133 plume is much
stronger than the Cs-137 plume, resulting mainly from the earlier start of
Xe-133 emissions. On 18 March, high levels of both Xe-133 and Cs-137 can be
found over the eastern Pacific Ocean and western North America. This part of
the cloud was still close to the surface south of 50º. The high altitude head
of the cloud with lower levels of Cs-137 had already arrived over the North
Atlantic. At the same time, the radioactive cloud penetrated the subtropics and
arrived at Hawaii on 19 March.
Figure 3 Simulated total atmospheric columns of Xe-133 (colour
shading) in kBq/ m2 and geopotential (height adjusted for pressure,
blue isolines) at four different time points from 12 March (upper left) to 22
March 2011 (lower right); Fukushima Dai-ichi Power plant, yellow circle; air
sampling site at Tokai-mura, green square; deposition monitoring site in Tokyo,
green diamond; air sampling station on Oahu (Hawaii), green triangle;
Stockholm, green circle.
the Xe-133 maps (Figure 3), it can be seen that already, by 18 March, the
highly radioactive plume had engulfed much of western and central North America
from Canada to the USA, with radioactivity ranging well over 1 000 to 100 000
Bq or more. Some of this could be easily have been inhaled by the inhabitants.
22 March, contaminated air from Fukushima had circled the Northern Hemisphere
and reached both the tropics as well as the polar regions (Figs. 3 and 4). Even
though enhanced surface concentrations were still limited to small parts of the
Northern Hemisphere, this changed quickly. In April, all measurement stations
recorded an enhanced background of Xe-133. Even the Australian station Darwin
started registering enhanced Xe-133 in April.
Figure 4 Simulated total atmospheric columns of Cs-137 (colour
shading) in Bq/m2 and geopotential (height adjusted for pressure,
blue isolines); other details as in Figure 3
maps of total deposition of Cs-137 in Japan and globally are shown in Figure 5.
Note that the scale is in kBq/m2. The orientation of the simulated
plume is exactly as found by aerial surveys of Cs-137 between 6 April and 26
May by MEXT. The airborne measurements show that along the main plume axis,
Cs-137 deposition values greater than 1 000 kBq/m2 extends about 50
km from the Fukushima plant (well outside the evacuation zone) .
Figure 5 Maps of total deposition of Cs-137 until 20 April 2011 for
Japan (upper panel) and globally (lower panel). The colour scale is in kBq/m2;
other details as in Figure 3
In the Chernobyl disaster, Cs-137 deposition values exceeding 1 000
kBq/m2 were observed in two areas: in the exclusion zone around
Chernobyl Nuclear Power Plant and Prypjat, and north of the city of Gomel in
Belarus. For the Fukushima accident, the land areas receiving such high
deposition values are smaller, but still extensive. In the extratropical North
Hemisphere, Cs-137 deposited from past nuclear testing is still present,
raising the background to about 1-2 kBq/m2. That value is exceeded
by deposition from Fukushima over large parts of Honshu Island and the western
Pacific Ocean. However, deposition of Cs-137 over other parts of Asia, North
America and Europe is minor compared to this pre-existing background.
analysis accounts for more than 90 % of the Cs-137 emissions until 20 April, with
the rest still residing in the atmosphere and small amounts lost by radioactive
decay. Japan received 6.4 PBq or 18 % of total Cs-137 deposition until 20
April. This is quite similar to a previous estimate of 22 % reported, although
their absolute values are smaller because of lower source emissions used. Only
0.7 PBq or 1.9 % of total Cs-137 deposition occurred over land areas other than
Japan, while the remaining 80 % (29.28 PBq) were deposited in the oceans. This
is in addition to the deliberate releases of radioactivity that constituted
“the largest radioactivity releases into the ocean in history” ).
Central data repository and increased monitoring urgently
These results for only two of the main radionuclides already
added up to nearly 15 times the total radioactivity in the latest TEPCO
estimates  of just over 1 EBq. If we take the amount of Cs-134 as equal to 36.6
PBq (same as for Cs-137 when measured ), and add the value of 500 PBq for
I-131 given by TEPCO for releases into the atmosphere, as well as the rest
released into the ocean (18.1 PBq), we arrive at a total of 16.0532 EBq. This
is certainly more than the estimated total of 14 EBq released in Chernobyl
according to the World Nuclear Association .
The estimates are the best
available based on still very incomplete information. In their
closing remarks, the authors pointed out that the data collected for the
analysis come from various sources, none of which is available to the public
. They speculated that more useful data sets were not even accessible to the
research team; stating: “Institutions having produced relevant measurement data
should make them freely available,” and calling for a central data repository
to be created. The analysis has only derived the source terms for two important
radionuclides, and work needs to be done on others, notably I-131. This is
absolutely necessary to address and mitigate the health impacts of the Fukushima
catastrophe already unfolding.
of officials to disclose information in the early days of the disaster has
meant that iodine tablets were not distributed to people in the most highly
contaminated areas, with the result that 44.5 % of the children showed
radioactive contamination of up to 35 mSv in their thyroid gland; and an
examination of more than 38 000 children in Fukushima prefecture found cysts in
35 % of the children’s thyroid gland (see ).
deaths in the US observed by Mangano
and Sherman in the 14 weeks following the accident do coincide with the arrival
of high levels of radioactivity (in X-133) by day 5 (Figure 3), and by day 10 engulfed
the whole of North America in both X-133 and Cs-137 (Figures 3 and 4). They wrote
in the conclusion of their report : “It is critical that research
should proceed with all due haste, as answers are essential to early diagnosis
and treatment for exposed people, particularly the children and the very
need for systematic monitoring, data-sharing, and research applies across the
globe; as the available data already demonstrate, the disease burden will not
be restricted to Japan.
and Sherman JD. An unexpected mortality increase in the United States
follows arrival of the radioactive plume from Fukushima: Is there a
correlation? Internation Jour al of Health Services 2012, 42, 47-64.
trumpet another flawed Fukushima death study”, Micheal Moyer, Scientific
American, 20 December 2011, http://blogs.scientificamerican.com/observations/2011/12/20/researchers-trumpet-another-flawed-fukushima-death-study/
Stohl A, Seibert P, Wotawa G, Arnold D, Burkhart JF,
Eckhardt S, Tapia C, Varga and Yasunari TJ. Xenon-133 and caesium-137
releases into the atmosphere from the Fukushima Dai-ichi nuclear power
plant: determination of the source term, atmospheric dispersion, and
deposition. Atmos Chem Phy 2012, 12, 2313-43. Led by A. Stohl at Norwegian
Institute for Air Research, Kjeller.
Ho MW. Truth about Fukushima. Science in Society 55 (to
Assessment on the 66th day of projected
external doses for populations living in the north-west fallout zone of
the Fukushima nuclear accident, outcome of population evacuation measures,
Report DRPH/2011-10, Directorate of Radiological Protection and Human
Health, Institut de Radioprotection et de Sûreté Nucléaire, October 2011.
harvey wasserman Comment left 12th June 2012 07:07:32 i would like to publish the link to this material at www.nukefree.org. please let me know.
could you also send me a paragraph bio of the author.
thanks! harvey wasserman