standpoint of the french institute for radioprotection and nuclear safety (irsn) on the impact of...
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Standpoint of the French Institute for Radioprotection and Nuclear Safety (IRSN) on the impact of radioactive releases from the Fukushima-Daiichi nuclear accident on the marine environment
Bruxelles, EU meeting, 03 Oct 2011
(http://www.irsn.fr/EN/news/Pages/201103_seism-in-japan.aspx)Paper sumitted to JER “Estimation of marine source-term following Fukushima Dai-ichi accident” by Bailly du Bois et al.
Bruxelles, EU meeting, 16 May 2011
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IRSN estimation of the source-term of releases into seawater
137Cs quantities were estimated on the basis of sample measurements in a 50 x 100 km area around the plant (issues: depth, mixing layer, atmospheric fallout, rain water washout, …)
140.8 141 141.2 141.4 141.6
37
37.2
37.4
37.6
37.8
02468101215192329364556698610013016020025031039048060074092011001400170021002700
Bq.L -1
April 11 - 18
Fukushima Dai-ichi
140.8 141 141.2 141.4 141.6
Fukushima Dai-ichi
April 18 - 25140.8 141 141.2 141.4 141.6
April 25 - May 02
Fukushima Dai-ichi
140.8 141 141.2 141.4 141.6
May 02 - 16
Fukushima Dai-ichi
a b c d
140.8 141 141.2 141.4 141.6
37
37.2
37.4
37.6
37.8
02468101215192329364556698610013016020025031039048060074092011001400170021002700
Bq.L -1
Fukushima Dai-ichi
140.8 141 141.2 141.4 141.6
Fukushima Dai-ichi
140.8 141 141.2 141.4 141.6
Fukushima Dai-ichi
140.8 141 141.2 141.4 141.6
Fukushima Dai-ichi
Blue frame: area for integration of 137Cs quantities : Sam pling locations
e f g hMay 16 - 30 May 30 - June 13 June 13 - 27 June 27 - July 11
0 km 20 km 40 km 60 km
1E+12
1E+13
1E+14
1E+15
1E+16
1E+17
08/04/11 22/04/11 06/05/11 20/05/11 03/06/11 17/06/11 01/07/11 15/07/11
137
Cs a
ctivit
y (Bq
)
Exponential decay back extrapolated to April 8 -> 22E+15 Bq(depth of mixing layer ?)
Total until July 18 -> 27E+15 Bq
Bruxelles, EU meeting, 16 May 2011
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IRSN estimation of the rate of seawater renewal
1E+12
1E+13
1E+14
1E+15
1E+16
1E+17
08/04/11 22/04/11 06/05/11 20/05/11 03/06/11 17/06/11 01/07/11 15/07/11
137
Cs a
ctivit
y (Bq
)
Exponential decay t1/2 = 6.9 d
• Dilution by clean water through
marine currents (remarkably
constant)
• Convergence of Kuroshio and
Oyashio Seasonal changes in the
ocean circulation ? Return of contaminated
water back in the area ?
• If no more releases occur and
dilution remains constant, back
to prior situation is expected in
Nov 2011
Bruxelles, EU meeting, 16 May 2011
IRSN/Ifremer dispersion modelling(based on IRSN estimated source-term)
Short distance
1E0
1E1
1E2
1E3
1E4
1E5
Bq/L
28/03 04/04 11/04 18/04 25/04 02/05 09/05 16/05 23/05 30/05 06/06 13/06 20/06 27/06 04/07
Mesures Simulation Mars
Cs137
matching calculations/measurements
less than 1 km off the facility
Bruxelles, EU meeting, 16 May 2011
IRSN/Ifremer dispersion modeling(based on IRSN estimated source-term)
Mid distance
• (color-scale changed by a factor
10)
• Long distance dispersion is not
yet validated by measurements
• as of July 1st, calculated values
are below actual DL (5 Bq.L-1, but
DLs below 0.001 Bq.L-1 are
routinely achieved in
radioecology)
Bruxelles, EU meeting, 16 May 2011
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Inventory of main 137Cs releases in the oceans
Source PBq (1E+15Bq)
Fallout from nuclear weapon tests 704*
Nuclear fuel reprocessing1951 - 2010
BNFL Sellafield 41.21
Areva-NC La Hague
1.04
Tchernobyl accident 16*
Solid waste dumping 41.4 (beta + gamma)
Fukushimaaccident
Direct liquid release
27
Atmospheric fallout 0.076 (80 km radius
circle)
* Aarkrog, 2003. Input of anthropogenic radionuclides into the World Ocean. Deep Sea Research Part II: Topical Studies in Oceanography Volume 50, Issues 17-21, Pages 2597-2606
Bruxelles, EU meeting, 16 May 2011
Measurements in sediments
average [137Cs]until Aug 30
• Cs, I, Te, Sr, Pu, Ba
• The map is a draft document with
over- estimated values along the
shore (this biais will be fixed)
• As regards Kd’s, amounts of 137Cs in
sediments are relatively low
• 137Cs seems to increase with time (kinetics
of transfer to particles and deposition) but
is expected to level off in the forthcoming
months.
• Because of remobilisation processes,
sediments will behave as a secondary
sources of contamination (postponed,
remote and diffuse)140.6 140.8 141 141.2 141.4 141.6 141.8 14235.6
35.8
36
36.2
36.4
36.6
36.8
37
37.2
37.4
37.6
37.8
38
38.2
38.4
38.6
38.8
39
0
25
75
150
250
350
450
567
700
867
1083
1333
1667
2067
2550
3167
3933
4883
6050
7517
9333
11500
14333
17833
22000
27333
34000
42167
52333
64833
80333
100000
Bq.kg -1
April 11 - August 30
Fukushima Dai-ichi
Bruxelles, EU meeting, 16 May 2011
FURTHER WORK PLANNED BY IRSN WITH COLLABORATIONS
• to compare the results of dispersion modeling by IRSN/Ifremer,
Sirocco and Japan Atomic Energy Agency
• to estimate the transfers of radionuclides from seawater to biota by
modeling in collaboration with Collecte Localisation Satellite (CLS)
radionuclides bioaccumulation in the different marine trophic
levels will be dynamically predicted on the basis of dispersion
modeling outcomes
maps of radioactive quality index to support monitoring survey
for commercial fish species
• fish survey in the Pacific (IRSN and IFREMER)
• post-doc IRSN fellowship
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