scholarly journals Modeling and sensitivity analysis of transport and deposition of radionuclides from the Fukushima Daiichi accident

2014 ◽  
Vol 14 (2) ◽  
pp. 2113-2173
Author(s):  
X. Hu ◽  
D. Li ◽  
H. Huang ◽  
S. Shen ◽  
E. Bou-Zeid
Keyword(s):  
Size Distribution ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Nuclear Power ◽  
Emission Rate ◽  
Radioactive Decay ◽  
Radioactive Isotopes ◽  
Horizontal Diffusion ◽  
Fukushima Daiichi ◽  
Ground Deposition

Abstract. The atmospheric transport and ground deposition of radioactive isotopes 131I and 137Cs during and after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident (March 2011) are investigated using the Weather Research and Forecasting/Chemistry (WRF/Chem) model. The aim is to assess the skill of WRF in simulating these processes and the sensitivity of the model's performance to various parameterizations of unresolved physics. The WRF/Chem model is first upgraded by implementing a radioactive decay term into the advection-diffusion solver and adding three parameterizations for dry deposition and two parameterizations for wet deposition. Different microphysics and horizontal turbulent diffusion schemes are then tested for their ability to reproduce observed meteorological conditions. Subsequently, the influence on the simulated transport and deposition of the characteristics of the emission source, including the emission rate, the gas partitioning of 131I and the size distribution of 137Cs, is examined. The results show that the model can predict the wind fields and rainfall realistically. The ground deposition of the radionuclides can also potentially be captured well but it is very sensitive to the emission characterization. It is found that the total deposition is most influenced by the emission rate for both 131I and 137Cs; while it is less sensitive to the dry deposition parameterizations. Moreover, for 131I, the deposition is also sensitive to the microphysics schemes, the horizontal diffusion schemes, gas partitioning and wet deposition parameterizations; while for 137Cs, the deposition is very sensitive to the microphysics schemes and wet deposition parameterizations, and it is also sensitive to the horizontal diffusion schemes and the size distribution.

scholarly journals Modeling and sensitivity analysis of transport and deposition of radionuclides from the Fukushima Dai-ichi accident

2014 ◽  
Vol 14 (20) ◽  
pp. 11065-11092 ◽  
Author(s):  
X. Hu ◽  
D. Li ◽  
H. Huang ◽  
S. Shen ◽  
E. Bou-Zeid
Keyword(s):  
Size Distribution ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Emission Rate ◽  
Radioactive Decay ◽  
Radioactive Isotopes ◽  
Wind Fields ◽  
Total Deposition ◽  
Horizontal Diffusion ◽  
Ground Deposition

Abstract. The atmospheric transport and ground deposition of radioactive isotopes 131I and 137Cs during and after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident (March 2011) are investigated using the Weather Research and Forecasting-Chemistry (WRF-Chem) model. The aim is to assess the skill of WRF in simulating these processes and the sensitivity of the model's performance to various parameterizations of unresolved physics. The WRF-Chem model is first upgraded by implementing a radioactive decay term into the advection–diffusion solver and adding three parameterizations for dry deposition and two parameterizations for wet deposition. Different microphysics and horizontal turbulent diffusion schemes are then tested for their ability to reproduce observed meteorological conditions. Subsequently, the influence of emission characteristics (including the emission rate, the gas partitioning of 131I and the size distribution of 137Cs) on the simulated transport and deposition is examined. The results show that the model can predict the wind fields and rainfall realistically and that the ground deposition of the radionuclides can also be captured reasonably well. The modeled precipitation is largely influenced by the microphysics schemes, while the influence of the horizontal diffusion schemes on the wind fields is subtle. However, the ground deposition of radionuclides is sensitive to both horizontal diffusion schemes and microphysical schemes. Wet deposition dominated over dry deposition at most of the observation stations, but not at all locations in the simulated domain. To assess the sensitivity of the total daily deposition to all of the model physics and inputs, the averaged absolute value of the difference (AAD) is proposed. Based on AAD, the total deposition is mainly influenced by the emission rate for both 131I and 137Cs; while it is not sensitive to the dry deposition parameterizations since the dry deposition is just a minor fraction of the total deposition. Moreover, for 131I, the deposition is moderately sensitive (AAD between 10 and 40% between different runs) to the microphysics schemes, the horizontal diffusion schemes, gas-partitioning and wet deposition parameterizations. For 137Cs, the deposition is very sensitive (AAD exceeding 40% between different runs) to the microphysics schemes and wet deposition parameterizations, but moderately sensitive to the horizontal diffusion schemes and the size distribution.

scholarly journals Atmospheric removal times of the aerosol-bound radionuclides <sup>137</sup>Cs and <sup>131</sup>I measured after the Fukushima Dai-ichi nuclear accident – a constraint for air quality and climate models

2012 ◽  
Vol 12 (22) ◽  
pp. 10759-10769 ◽  
Author(s):  
N. I. Kristiansen ◽  
A. Stohl ◽  
G. Wotawa
Keyword(s):  
Air Quality ◽  
Dry Deposition ◽  
Nuclear Power ◽  
Climate Models ◽  
Climate Model ◽  
Noble Gas ◽  
Measurement Data ◽  
Radioactive Decay ◽  
Data Set ◽  
Removal Time

Abstract. Caesium-137 (137Cs) and iodine-131 (131I) are radionuclides of particular concern during nuclear accidents, because they are emitted in large amounts and are of significant health impact. 137Cs and 131I attach to the ambient accumulation-mode (AM) aerosols and share their fate as the aerosols are removed from the atmosphere by scavenging within clouds, precipitation and dry deposition. Here, we estimate their removal times from the atmosphere using a unique high-precision global measurement data set collected over several months after the accident at the Fukushima Dai-ichi nuclear power plant in March 2011. The noble gas xenon-133 (133Xe), also released during the accident, served as a passive tracer of air mass transport for determining the removal times of 137Cs and 131I via the decrease in the measured ratios 137Cs/133Xe and 131I/133Xe over time. After correction for radioactive decay, the 137Cs/133Xe ratios reflect the removal of aerosols by wet and dry deposition, whereas the 131I/133Xe ratios are also influenced by aerosol production from gaseous 131I. We find removal times for 137Cs of 10.0–13.9 days and for 131I of 17.1–24.2 days during April and May 2011. The removal time of 131I is longer due to the aerosol production from gaseous 131I, thus the removal time for 137Cs serves as a better estimate for aerosol lifetime. The removal time of 131I is of interest for semi-volatile species. We discuss possible caveats (e.g. late emissions, resuspension) that can affect the results, and compare the 137Cs removal times with observation-based and modeled aerosol lifetimes. Our 137Cs removal time of 10.0–13.9 days should be representative of a "background" AM aerosol well mixed in the extratropical Northern Hemisphere troposphere. It is expected that the lifetime of this vertically mixed background aerosol is longer than the lifetime of fresh AM aerosols directly emitted from surface sources. However, the substantial difference to the mean lifetimes of AM aerosols obtained from aerosol models, typically in the range of 3–7 days, warrants further research on the cause of this discrepancy. Too short modeled AM aerosol lifetimes would have serious implications for air quality and climate model predictions.

scholarly journals Atmospheric removal times of the aerosol-bound radionuclides <sup>137</sup>Cs and <sup>131</sup>I during the months after the Fukushima Dai-ichi nuclear power plant accident – a constraint for air quality and climate models

2012 ◽  
Vol 12 (5) ◽  
pp. 12331-12356
Author(s):  
N. I. Kristiansen ◽  
A. Stohl ◽  
G. Wotawa
Keyword(s):  
Air Quality ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Dry Deposition ◽  
Nuclear Power ◽  
Climate Models ◽  
Climate Model ◽  
Measurement Data ◽  
Radioactive Decay ◽  
Data Set

Abstract. Caesium-137 (137Cs) and iodine-131 (131I) are radionuclides of particular concern during nuclear accidents, because they are emitted in large amounts and are of significant health impact. 137Cs and 131I attach to the ambient accumulation-mode (AM) aerosols and share their fate as the aerosols are removed from the atmosphere by scavenging within clouds, precipitation and dry deposition. Here, we estimate their removal times from the atmosphere using a unique high-precision global measurement data set collected over several months after the accident at the Fukushima Dai-ichi nuclear power plant in March 2011. The noble gas xenon-133 (133Xe), also released during the accident, served as a passive tracer of air mass transport for determining the removal times of 137Cs and 131I via the decrease in the measured ratios 137Cs/133Xe and 131I/133Xe over time. After correction for radioactive decay, the 137Cs/133Xe ratios reflect the removal of aerosols by wet and dry deposition, whereas the 131I/133Xe ratios are also influenced by aerosol production from gaseous 131I. We find removal times for 137Cs of 10.0–13.9 days and for 131I of 17.1–24.2 days during April and May 2011. We discuss possible caveats (e.g. late emissions, resuspension) that can affect the results, and compare the 137Cs removal times with observation-based and modeled aerosol lifetimes. Our 137Cs removal time of 10.0–13.9 days should be representative of a "background" AM aerosol well mixed in the extratropical Northern Hemisphere troposphere. It is expected that the lifetime of this vertically mixed background aerosol is longer than the lifetime of AM aerosols originating from surface sources. However, the substantial difference to the mean lifetimes of AM aerosols obtained from aerosol models, typically in the range of 3–7 days, warrants further research on the cause of this discrepancy. Too short modeled AM aerosol lifetimes would have serious implications for air quality and climate model predictions.

The Radionuclide Pollutant Dispersion Simulation in Nuclear Accident of Liaoning Hongyanhe Nuclear Power Plant

2015 ◽  
Vol 1092-1093 ◽  
pp. 722-729 ◽  
Author(s):  
Jian Wang ◽  
Ming Ming Xiao ◽  
He Ru Wang ◽  
Yong Wang ◽  
Yue Shen
Keyword(s):  
Power Plant ◽  
Point Source ◽  
Dry Deposition ◽  
Nuclear Power ◽  
Nuclear Proliferation ◽  
Radioactive Decay ◽  
Pollutant Dispersion ◽  
Nuclear Accident ◽  
Instantaneous Point ◽  
Continuous Point

In order to simulate the nuclear proliferation model of power plant accident, the objective factors of the nuclide dry deposition, wet deposition and radioactive decay are considered and studied based on Gauss diffusion model. With the model modified, the nuclear proliferation simulation of power plant accident is implemented. The simulation system of radionuclide nuclear proliferation is designed and realized with the application of information technology such as GIS and so on. In light of variations in such things as geography, climate and working, the nuclear proliferation of power plant accident emergency is simulated. The results showed that the system can effectively realize the simulation of radionuclide nuclear proliferation including the instantaneous point source, continuous point source, which provides decision support for nuclear accident emergency treatment.

scholarly journals A Remote-operated System to Map Radiation Dose in the Fukushima Daiichi Primary Containment Vessel

2018 ◽  
Vol 170 ◽  
pp. 06004
Author(s):  
M. Nancekievill ◽  
A. R. Jones ◽  
M. J. Joyce ◽  
B. Lennox ◽  
S. Watson ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Gamma Ray ◽  
Low Cost ◽  
Radiation Detectors ◽  
Radioactive Isotopes ◽  
Combined System ◽  
Dose Rates ◽  
Fukushima Daiichi ◽  
Small Form Factor ◽  
Cerium Bromide

This paper describes the development of a submersible system based on a remote-operated vehicle coupled with radiation detectors to map the interior of the reactors at the Fukushima Daiichi nuclear power station. It has the aim oflocating fuel debris. The AVEXIS submersible vehicle used in this study has been designed as a low-cost, potentially disposable, inspection platform that is the smallest of its class and is capable of being deployed through a 150 mm diameter access pipe. To map the gamma-ray environment, a cerium bromide scintillator detector with a small form factor has been incorporated into the AVEXIS to identify radioactive isotopes via gamma-ray spectroscopy. This provides the combined system with the potential to map gamma-ray spectra and particle locations throughout submerged, contaminated facilities, such as Units 1, 2 and 3 of the Fukushima Daiichi nuclear power plant. The hypothesis of this research is to determine the sensitivity of the combined system in a submerged environment that replicates the combination of gamma radiation and water submersion but at lower dose rates.

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