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Modeling the Dispersion of Radioelements from the Fukushima Power Plant into the Sea: Methodology for an Emergency Answer, Estimation of Sources, Residence time in the Water Column and Sediment. Claude Estournel for the SIROCCO group, CNRS, Univ.Toulouse, France - PowerPoint PPT Presentation
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Modeling the Dispersion of Radioelements from the Fukushima Power Plant into the
Sea: Methodology for an Emergency Answer, Estimation of Sources, Residence time in the Water Column and Sediment
Claude Estournel for the SIROCCO group, CNRS, Univ.Toulouse, FranceEmmanuel Bosc and Iolanda Osvath, IAEA, MonacoMarc Boquet, Victor Winiarek, CEREA, Paris Tech
presented by Patrick Marsaleix
Motivation•Request from IAEA on March 14: dispersion into the sea of radionuclides from the atmosphere and from direct release•Daily conferences with IAEA: data availability, last news…•March 24: (10 days later) first bulletin on the Sirocco website•Regular improvement of the system and the results
Material• Sirocco Ocean Model (Marsaleix et al., JAOT 2006, Ocean Modelling 2008, 2009a,b, 2011): free surface, sigma coordinate, curvilinear grid (resolution 600m to 5km)• Bathymetry : Japan Oceanographic Data Center merged with GEBCO-08 30" database• Tidal forcing :
• Sirocco Ocean Model (Marsaleix et al., JAOT 2006, Ocean Modelling 2008, 2009a,b, 2011): free surface, sigma coordinate, curvilinear grid (resolution 600m to 5km)• Bathymetry : Japan Oceanographic Data Center merged with GEBCO-08 30" database• Tidal forcing: T-UGOm (Lyard et al., 2006)
Material
• Air-Sea Fluxes: Bulk formulae (ECMWF air parameters and radiative fluxes) resolution: 3hrs, 0.25°
Motivation•Request from IAEA on March 14: dispersion into the sea of radionuclides from the atmosphere and from direct release•Daily conferences with IAEA: data availability, last news…•March 24: (10 days later) first bulletin on the Sirocco website•Regular improvement of the system and the results
Mean tidal transport (a few cm/s)
after one year of integration
MERCATORSST
NCOMSST
Material (continued)
Lateral open boundary conditions and initial state: comparison of two operational models
•MERCATOR (French operational model) used for the Sirocco bulletin•NCOM (US Navy operational model) now being tested
A higher resolution in MERCATORSimilitudes: the Kuroshyo currentDifferences: Eddies, alongshore circulation
MERCATORsurf. current
NCOMsurf. current
RADIONUCLIDES INPUT
1. Atmospheric deposit
Cumulated depositionon the sea:
2.6 1015 Bq
Outputs of the atmosph transport model Polyphemus/Polair3D (1hr, 0.25° resolution) pers. comm. M. Bocquet & V. Winiarek, Ecole des Ponts ParisTech/CEREA
Source term (on our domain)
137Cs
RADIONUCLIDES INPUT
NPP
Unknown, an a priori Cesium 137 flux is thus introduced at the coast. Following a simple inverse method (prediction/correction runs), the input flux is deduced from the nearest monitoring stations T1 and T2 (30m & 300m of NPP).
Bq/l
2. Direct liquid release
simulation
obs. at 30 and 300mof the NPP
ALONGSHORE VALIDATION
NPP
detection limit
At 10 and 16 km south of the NPP2 long series of dataGood agreement model/observation
100k
m
simulationobservation
Bq/lDaini
Iwasawa
Independent observations e.g. not involved in the calibration of the source term
Independent observations
Bq/l
NPP
VALIDATION at 3km offshoreover a ~80km north-south segment
100k
m
simulationobservation
Bq/l
No observation during the peak of release
No observation during the peak of release
No observation during the peak of release
Independent observations
Independent observations
Independent observations
VALIDATIONat 15 km offshore
NPP
100k
m
simulationobservation
Bq/l Underestimation of the simulated atmospheric deposit in the northern region ?
Independent observations
Independent observations
Source term
Cumulated release into the sea:
5.6 1015 Bq
A major result of this study: the source term of the direct liquid release137
Cs A correct agreement observation/simulation=
Confidence in the liquid source term
RESIDENCE TIME IN THE COASTAL REGION
March 20 – April 20 May 1 – May 31 June 1 – June 30
one-month averages
high inputs &strong confinement due to rather calm
wind conditions
more wind events causing dispersion
Bq/l
RESIDENCE TIME IN THE COASTAL REGION
March 20 – April 20 May 1 – May 31 June 1 – June 30
one-month averages
Stock of Cesiumin the coastal box
Songda Typhoon
ESTIMATION OF DEPOSITION OF CESIUM ON THE SEDIMENT
Based on KD=4000liter/kg (IAEA,2004), a concentration of suspended matter of 5mg/land a sedimentation velocity of ~ 1m/day (very fine suspended matter)
0.2
1
2
10
20
2.102
1.103
1.102
2.103
1.104
2.104
1.105
0.2
1
2
10
20
2.102
1.103
1.102
2.103
1.104
2.104
1.105
Bq/m2 Bq/m2
from the atmosphere from the direct release
end of June
PERSPECTIVE AT LOCAL SCALE in collaboration with Institut de Radioprotection et de Sûreté Nucléaire (IRSN)
through a PhD fellowship (We a looking for a candidate!)
Wave height calculated with the Wavewatch3 model
Songda Typhoon
take into account secondary sources •Input by rivers•Resuspension of contaminated sediments
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