Fukushima Marine Environment Monitoring (1 April 2011, 14.30 UTC)
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Transcript of Fukushima Marine Environment Monitoring (1 April 2011, 14.30 UTC)
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IAEAInternational Atomic Energy Agency
Marine Environment
Monitoring
Assessment of IAEA Environment
Laboratories on Data provided by
Japan
IAEA Environment Laboratories, Monaco
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IAEA
General comments
• The contamination of the marine environment has occurred both
through atmospheric fallout or washout with precipitation, and
through discharges of contaminated water into the sea
• Japanese institutes continue to perform measurements in seawater
at 30 m and 330 m off the discharge points of Dai-ichi NPP, as
well at 10 km and 20 km off-shore and along a North-South
transect situated 30 km off-shore
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IAEA
Seawater sampling offshore Fukushima carried out by
Japanese Authorities (23 - 30 March 2011)
Seawater sampling locations of
Japanese Authorities
• Transect about 30 km offshore,
sample locations separated by
10 kilometres, surface seawater
sampled
• Additional sampling stations at
10 and 20 km offshore, for
which both surface and bottom
seawater are sampled
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IAEA
General Comments
• Higher levels are measured 30 m, 330 m and 10 km near-shore
relative to those measured 30 km off-shore
• Concentration data off-shore reported for the past week show a
quite heterogeneous distribution, as expected, both on the surface
and deep layers, with general decreasing time trend
• It can be expected that, in the absence of additional releases, the
levels measured at the stations 30 km off-shore will continue to
decrease significantly by dilution into deeper layers and
dispersion by ocean currents
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IAEA
Bathymetry and main ocean currents
Credit: NOAA
Credit: SIROCCO
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IAEA
I-131 concentrations in seawater at 10 - 30 km off-shore FukushimaData submitted by Japanese authorities
0
10
20
30
40
50
60
70
80
90
1 2 3 4 5 6 7 8 9 10
I-131 concentration (Bq/l) in coastal waters (see map 1)
23 March Samples
24 March Samples
25 March Samples
26 March Samples
27 March Samples
28 March Samples
30 March Samples
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IAEA
Cs-137 concentrations in seawater at 10-30 km off-shoreData submitted by Japanese authorities
0
5
10
15
20
25
30
1 2 3 4 5 6 7 8 9 10
Co
nce
ntr
atio
n (B
q/l
)
Sampling Point
Cs-137 concentration (Bq/l) in coastal waters (see map 1)
23 March Samples
24 March Samples
25 March Samples
26 March Samples
27 March Samples
28 March Samples
30 March Samples
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1 103 104 105 106102101 107 108
April 200530 km
Bq.m-3
[1 – 101]
1 103 104 105 106102101 107 108
24, 27 March 2011
Bq.m-3
[103– 104]
[105– 107]
Monitoring of the Marine environment
• Comparison of Cs-137 seawater concentrations with historical data• 30 km offshore surface water concentrations were up to 3-4 orders of magnitude
higher than the values measured in 2005• 330 m East of Fukushima Dai-ichi concentrations were up to 3 orders of magnitude
higher than the values measured offshore, this showing the high dilution capacity of the marine environment
Cs-137 Bq.m-3
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IAEA
I-131 and Cs-137concentrations in seawater at the common
discharge point of Units 1-4Data submitted by Japanese authorities
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IAEA
I-131 and Cs-137concentrations in seawater at the common discharge point
of Units 5-6Data submitted by Japanese authorities
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IAEA
Conclusions
• Measurements of seawater are carried out by Japanese authorities since 23 March and data are reported to the IAEA for information and assessment.
• I-131 and Cs-137 were detected with highest activity concentrations of about 80 Bq/L and 25 Bq/L in surface water, respectively, on 23 March.
• Data reported for 30 March show generally lower values below 10 Bq/L for both I-131 and Cs-137. A higher value of 80 Bq/l was measured at the point situated 10 km offshore for I-131, while Cs-137 at this station remains low at 8 Bq/l.
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IAEA
Conclusions
• Levels at 30 m and 330 m from the discharge points showed increasing concentrations up to 130 000 Bq/L for I-131 and 32 000 Bq/L for Cs-137
• Modelling of the dispersion of radionuclides was initiated by the SIROCCO group of the Observatoire Midi-Pyrenees, University of Toulouse, and first results indicating the general pattern of dispersion are available. The results show an initial transport into north-east direction and fast dispersion along the Kuroshio curent.
• One marine expert from IAEA Environmental Laboratories, Monaco currently in Japan to review and advise on marine sampling and measurements