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CTBTO.ORG
PUTTING AN END TO NUCLEAR EXPLOSIONS
Comparison of modelled atmospheric radionuclides from the
Fukushima Dai-ichi nuclear accident with CTBTO station measurements
Theodoros Christoudias
37
CTBTO.ORG
Disclaimer: The views expressed on this poster are those of the author and do not necessarily reflect the view of the CTBTO
Poster No.:
PUTTING AN END TO NUCLEAR EXPLOSIONS
P2.4-37
ABSTRACT
Comparison of modelled atmospheric radionuclides from the
Fukushima Dai-ichi nuclear accident with CTBTO station measurements
Theo Christoudias, Cyprus Institute (christoudias@cyi.ac.cy)
The global atmospheric dispersion and deposition of radionuclides released from the Fukushima Dai-ichi
nuclear power plant accident was modelled using the EMAC atmospheric chemistry –general circulation
model at different resolutions (equivalent to ∼50 km and ∼110 km Gaussian grid).
The model accounts for emissions and transport of the radioactive isotopes 131Iand 137Cs, and removal
processes through precipitation, particle sedimentation and dry deposition.
In addition, we simulated the release of 133Xe, anoble gas that can be regarded as apassive transport
tracer of contaminated air.
Modelled surface concentrations were compared to station observations by the Comprehensive Nuclear-
Test-Ban Treat y Organisation (CTBTO) global monitoring network for anumber of stations through the
CTBTO Virtual Data Exploitation Centre.
CTBTO.ORG
Disclaimer: The views expressed on this poster are those of the author and do not necessarily reflect the view of the CTBTO
Poster No.:
PUTTING AN END TO NUCLEAR EXPLOSIONS
P2.4-37
INTRODUCTION
Comparison of modelled atmospheric radionuclides from the
Fukushima Dai-ichi nuclear accident with CTBTO station measurements
Theo Christoudias, Cyprus Institute (christoudias@cyi.ac.cy)
Scientific application of the data used for test ban verification from CTBTO International
Monitoring System (IMS).
More than 35 radionuclide stations that are part of the IMS have provided information on the
spread of radioactive particles and noble gases from the Fukushima accident.
By comparing modelled surface concentrations to station observations by the CTBTO global
monitoring network after the Fukushima NPP accident, we can:
•Obtain observational constraint on aerosol lifetimes provided by radionuclide
measurements to evaluate model performance
•Evaluate impacts by estimating global deposited radioactivity:
In particular the isotopes of iodine and caesium adversely affect human health through the
large-scale contamination of air, water, soils and agricultural products
CTBTO.ORG
Disclaimer: The views expressed on this poster are those of the author and do not necessarily reflect the view of the CTBTO
Poster No.:
PUTTING AN END TO NUCLEAR EXPLOSIONS
ERA-Interim –EMAC Model Precipitation Comparison
11 March – 31 May 2011
11 – 18 March 2011
(first week after the
accident)
P2.4-37
METHODS
Comparison of modelled atmospheric radionuclides from the
Fukushima Dai-ichi nuclear accident with CTBTO station measurements
Theo Christoudias, Cyprus Institute (christoudias@cyi.ac.cy)
EMAC (ECHAM5/MESSy) Global Model
www.messy-interface.org
•Resolution: 50km (0.5°) and 110km (1.1°)
•31 vertical levels up to 10 hPa
•ECMWF ERA-Interim re-analysis nudging
•Period: 1st March –31st May 2011
•Scavenging by impaction (below-cloud) and
nucleation (in-cloud) by rain and snow/ice
•Dry deposition: removal by turbulent
transfer onto the earth’s surface.
•Sedimentation: based on mass of aerosol
CTBTO.ORG
Disclaimer: The views expressed on this poster are those of the author and do not necessarily reflect the view of the CTBTO
Poster No.:
PUTTING AN END TO NUCLEAR EXPLOSIONS
P2.4-37
RESULTS
Comparison of modelled atmospheric radionuclides from the
Fukushima Dai-ichi nuclear accident with CTBTO station measurements
Theo Christoudias, Cyprus Institute (christoudias@cyi.ac.cy)
Radionuclide Model Half-life Emissions
133Xe Passive transport tracer 5.25 days 15.3 EBq (Stohl et al., 2012)
137Cs Water-soluble aerosol
(dry & wet deposition)
13 PBq (Chino et al., 2011)
36.7 PBq (Stohl et al., 2012)
131IGas 8 days 150 PBq (Chino et al., 2011)
133Xe 137Cs 131I
CTBTO.ORG
Disclaimer: The views expressed on this poster are those of the author and do not necessarily reflect the view of the CTBTO
Poster No.:
PUTTING AN END TO NUCLEAR EXPLOSIONS
P2.4-37
RESULTS
Comparison of modelled atmospheric radionuclides from the
Fukushima Dai-ichi nuclear accident with CTBTO station measurements
Theo Christoudias, Cyprus Institute (christoudias@cyi.ac.cy)
CTBTO Global Station Network (IMS)
Model represents the Xe and Cs measurements well in the vicinity of the
source, but also in North and South America (stations USX75, PAX50, FRX31),
and even as far downwind as Germany (DEX33)
Model shows arrival of high aerosol concentrations in the Asia-Pacific region
(e.g. USP80 at Upi, Guam; PHP52 in Tanay, the Philippines) which are not
reflected in the station observations
Even though only 20–50 % of the 131I is captured on the filters, our model
underestimates concentrations → large uncertainty in 131Iinventory
CTBTO.ORG
Disclaimer: The views expressed on this poster are those of the author and do not necessarily reflect the view of the CTBTO
Poster No.:
PUTTING AN END TO NUCLEAR EXPLOSIONS
P2.4-37
RESULTS
Comparison of modelled atmospheric radionuclides from the
Fukushima Dai-ichi nuclear accident with CTBTO station measurements
Theo Christoudias, Cyprus Institute (christoudias@cyi.ac.cy)
80% of deposition over Pacific Ocean
CTBTO.ORG
Disclaimer: The views expressed on this poster are those of the author and do not necessarily reflect the view of the CTBTO
Poster No.:
PUTTING AN END TO NUCLEAR EXPLOSIONS
P2.4-37
CONCLUSIONS
Comparison of modelled atmospheric radionuclides from the
Fukushima Dai-ichi nuclear accident with CTBTO station measurements
Theo Christoudias, Cyprus Institute (christoudias@cyi.ac.cy)
Modelled the global atmospheric dispersion and deposition of radionuclides released from the
Fukushima Dai-ichi nuclear power plant accident.
The EMAC global atmospheric chemistry – general circulation model was used, with circulation
dynamics nudged towards ERA-Interim reanalysis at 50km resolution.
The calculated model concentrations have been compared to IMS station observations by CTBTO:
133Xe -Excellent model/observations agreement
137Cs -Good agreement within source and model transport, removal uncertainties
→ estimate 80% of radioactivity deposition over Pacific Ocean
131I -Model systematically underestimates observations (factor of 5 uncertainty in source)