Radia%on
Exposure
to
the
Popula%on
in
Japan
A6er
the
Earthquake
Marco
Kaltofen,
MS,
PE
(Civil,
MA)
Department
of
Civil
and
Environmental
Engineering
Worcester
Polytechnic
Ins%tute
Worcester,
MA
kaltofen@wpi.edu
Presented
October
31,
2011,
at
the
139th
annual
mee%ng
of
the
American
Public
Health
Associa%on,
Washington,
DC
Radia%on
Exposure
to
the
Popula%on
in
1
Japan
A6er
the
Earthquake
Presenter
disclosures
The
following
personal
financial
rela%onships
with
commercial
interests
relevant
to
this
presenta%on
existed
during
the
past
12
months:
No
rela%onships
to
disclose
Radiation Exposure to the Population in
2
Japan After the Earthquake
Acknowledgments
• Fairewinds
Energy
Founda%on
• Dept.
of
Physics,
WPI
• Dept.
of
Civil
and
Environmental
Engineering,
WPI
• Hanford
Challenge
• Safecast
Radia%on
Exposure
to
the
Popula%on
in
3
Japan
A6er
the
Earthquake
Hypothesis
• Dust
contaminated
with
fallout
from
the
Fukushima
accidents
is
a
source
of
human
exposure
to
radia%on.
Radia%on
Exposure
to
the
Popula%on
in
4
Japan
A6er
the
Earthquake
Radioisotopes
in
dusts
released
by
Fukushima
Daiichi
units
• Radioiodine
• Cesium-‐134
and-‐137
• Cobalt-‐60
• Fission
wastes
and
neutron
ac%va%on
products
• Uranium
and
plutonium
fuels
and
transuranics
such
as
americium
and
neptunium
Radiation Exposure to the Population in
5
Japan After the Earthquake
How
are
people
exposed
to
radioac%ve
par%culates?
• Inhala%on
of
airborne
par%cles
• Inhala%on
of
resuspended
dusts
• Inges%on
of
contaminated
food
(seaweed,
shellfish,
beef,
milk,
spinach,
eggs,
tea
and
finfish
including
pollock
and
cod)
• Inges%on
of
soils
and
dusts
(pica)
• Dermal
contact
Radia%on
Exposure
to
the
Popula%on
in
6
Japan
A6er
the
Earthquake
Common
materials
that
retain
radioac%ve
par%culate
ma`er
• Car
air
filters,
~
650
M3air
/mo.,
qualita%ve
• 37
mm
air
filters,
30
M3air
/
d.,
quan%ta%ve
• Home
air
filters
• Shoes
• Se`led
dusts
• Surface
soils
• Food
and
plants
Radia%on
Exposure
to
the
Popula%on
in
7
Japan
A6er
the
Earthquake
Air
sampling
sta%ons
Radiation Exposure to the Population in
8
Japan After the Earthquake
Primary
radioisotopes
detected
• Cesium-‐134
and
cesium-‐137
• Iodine-‐131
(short
lived)
• Cobalt-‐60
• Fission
products
Detected
as
elements
by
SEM/EDS
and
as
isotopes
by
gamma
spectrometry,
with
total
α
&
β
counts.
Radiation Exposure to the Population in
9
Japan After the Earthquake
Cs-‐137
Distribu%on
–
Fukushima
Prefecture
NMEXT
and
US
DOE
Data
Radia%on
Exposure
to
the
Popula%on
in
10
Japan
A6er
the
Earthquake
Permissible
doses
in
Fukushima
Prefecture,
2011
• Raised
from
1
mSv
yr-‐1
to
20
mSv
yr-‐1
(100
mRem
yr-‐1
to
2000
mRem
yr-‐1
)
• US
general
public
limits:
10
mRem
yr-‐1
EPA
and
100
mRem
yr-‐1
NRC
Radiation Exposure to the Population in
11
Japan After the Earthquake
Collec%ng
samples
from
Japan
• Sampling
team
includes
university
scien%sts,
bloggers
and
farmers,
all
with
varied
technical
training
• Requires
educa%on
on
safety
and
sample
care
• Must
be
cognizant
of
cultural
issues
• Requires
safe
and
legal
shipping
methods,
despite
involving
common
everyday
items,
especially
for
biologically
ac%ve
soils
Radiation Exposure to the Population in
Japan After the Earthquake
12
Autoradiographs
–
car
air
filters
April
2011,
X-‐ray
film
image
and
uR/hr.
Sea`le
m=11.7
Tokyo
m=18.9
Fukushima
City
m=199
Radia%on
Exposure
to
the
Popula%on
in
13
Japan
A6er
the
Earthquake
Examining
individual
radioac%ve
par%cles
Ibaraki
dust
sample,
collected
4/4/2011,
High
z
par%cles,
(Eu,
Y,
Zr,
Th,
Ce,
Sr,
Ce),
in
1
to
15
um
size
range
Analyzed
by
SEM/EDS
and
gamma
spectrometry
Radiation Exposure to the Population in
14
Japan After the Earthquake
Radia%on
on
children s
shoes
Fukushima
48.8
uR/hr.
σ
=
15.4,
USA
mean
10.6
uR/hr.
σ
=
0.68
Elementary
schools
soils,
Fukushima
Pref.,
mean,
(vs.
12.7
uR/hr.
US)
260
to
359
uR/hr.
2.6-‐3.5
uSv/hr.
I131+
Cs137+
Cs134
MEXT
data
Radiation Exposure to the Population in
15
Japan After the Earthquake
Cs134
+
Cs
137
on
children s
shoes
Radiation Exposure to the Population in
16
Japan After the Earthquake
Environmental
fate
of
radioac%ve
dust
• Airborne
levels
have
dropped,
soil
levels
remain
high,
while
food
chain
radia%on
can
increase.
• Radia%on
is
not
uniform.
Some
areas
are
much
higher
than
average,
forming
hot
spots
with
up
to
2.92
nCi/62
radiocesium
in
surface
dust.
• Cleaned
areas
can
become
recontaminated
by
dusts
from
hot
spots.
Sept.
2011
Noda
City
house
filters:
0.23
nCi
radiocesium
despite
generally
lower
air
levels.
Radiation Exposure to the Population in
17
Japan After the Earthquake
Long
distance
dust
transport
Boston
air
filters
had
60
slightly
elevated
total
50
α
and
β
counts
during
April
and
May
2011.
40
Sea`le
and
Boston
30
air
filters
had
posi%ve
autoradiographic
20
results
during
April
2011.
All
other
USA
10
filters
were
nega%ve.
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Radiation Exposure to the Population in
18
Japan After the Earthquake
Conclusion
• Circular
evacua%on
zones
were
not
protec%ve;
some
evacuees
moved
to
greater
contamina%on.
• Air
now
cleaner,
but
dusts
remobilize
cesium.
• Cs-‐134
and
Cs-‐137
nearly
ubiquitous
in
Fukushima
Prefecture
and
detectable
throughout
Tokyo;
Co-‐60
found
in
dusts
from
northern
Japan.
• US
samples
had
only
two
isolated
Cs-‐134
and
Cs-‐137
detec%ons
in
soil;
Am-‐241
found
offsite
only
in
one
Tokyo-‐area
dust
sample;
I-‐131
has
decayed.
Radiation Exposure to the Population in
19
Japan After the Earthquake
The
12
mile
Japanese
evacua2on
zone
appears
inadequate
to
protect
the
public
health.
Is
it
2me
to
reexamine
the
US
Nuclear
Regulatory
Commission
10
mile
planning
zone
for
airborne
accidental
nuclear
releases?
Radiation Exposure to the Population in
20
Japan After the Earthquake