scholarly journals One-year, regional-scale simulation of <sup>137</sup>Cs radioactivity in the ocean following the Fukushima Daiichi Nuclear Power Plant accident

2013 ◽  
Vol 10 (4) ◽  
pp. 6259-6314 ◽  
Author(s):  
D. Tsumune ◽  
T. Tsubono ◽  
M. Aoyama ◽  
M. Uematsu ◽  
K. Misumi ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Atmospheric Deposition ◽  
Nuclear Power ◽  
Regional Scale ◽  
137Cs Activity ◽  
Deposition Rates ◽  
One Year ◽  
Accident Site ◽  
Good Agreement

Abstract. A series of accidents at the Fukushima Dai-ichi Nuclear Power Plant following the earthquake and tsunami of 11 March 2011 resulted in the release of radioactive materials to the ocean by two major pathways, direct release from the accident site and atmospheric deposition. A 1 yr, regional-scale simulation of 137Cs activity in the ocean offshore of Fukushima was carried out, the sources of radioactivity being direct release, atmospheric deposition, and the inflow of 137Cs deposited on the ocean by atmospheric deposition outside the domain of the model. Direct releases of 131I, 134Cs, and 137Cs were estimated for 1 yr after the accident by comparing simulated results and measured activities. The estimated total amounts of directly released 131I, 134Cs, and 137Cs were 11.1 ± 2.2 PBq, 3.5 ± 0.7 PBq, and 3.6 ± 0.7 PBq, respectively. The contributions of each source were estimated by analysis of 131I/137Cs and 134Cs/137Cs activity ratios and comparisons between simulated results and measured activities of 137Cs. Simulated 137Cs activities attributable to direct release were in good agreement with measured activities close to the accident site, a result that implies that the estimated direct release rate was reasonable, while simulated 137Cs activities attributable to atmospheric deposition were low compared to measured activities. The rate of atmospheric deposition onto the ocean was underestimated because of a~lack of measurements of deposition onto the ocean when atmospheric deposition rates were being estimated. Measured 137Cs activities attributable to atmospheric deposition helped to improve the accuracy of simulated atmospheric deposition rates. Simulated 137Cs activities attributable to the inflow of 137Cs deposited onto the ocean outside the domain of the model were in good agreement with measured activities in the open ocean within the model domain after June 2012. The contribution of inflow increased with time and was dominant (more than 99%) by the end of February 2012. The activity of directly released 137Cs, however, decreased exponentially with time and was detectable only in the coastal zone by the end of February 2012.

scholarly journals One-year, regional-scale simulation of <sup>137</sup>Cs radioactivity in the ocean following the Fukushima Dai-ichi Nuclear Power Plant accident

2013 ◽  
Vol 10 (8) ◽  
pp. 5601-5617 ◽  
Author(s):  
D. Tsumune ◽  
T. Tsubono ◽  
M. Aoyama ◽  
M. Uematsu ◽  
K. Misumi ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Atmospheric Deposition ◽  
Nuclear Power ◽  
Regional Scale ◽  
137Cs Activity ◽  
Model Domain ◽  
Model Region ◽  
Accident Site ◽  
Good Agreement

Abstract. A series of accidents at the Fukushima Dai-ichi Nuclear Power Plant following the Great East Japan Earthquake and tsunami of 11 March 2011 resulted in the release of radioactive materials to the ocean by two major pathways: direct release from the accident site and atmospheric deposition. A 1 yr, regional-scale simulation of 137Cs activity in the ocean offshore of Fukushima was carried out, the sources of radioactivity being direct release, atmospheric deposition, and the inflow of 137Cs deposited into the ocean by atmospheric deposition outside the domain of the model. Direct releases of 137Cs were estimated for 1 yr after the accident by comparing simulated results and measured activities adjacent to the accident site. The contributions of each source were estimated by analysis of 131I/137Cs and 134Cs/137Cs activity ratios and comparisons between simulated results and measured activities of 137Cs. The estimated total amounts of directly released 131I, 137Cs, and 137Cs were 11.1 ± 2.2 PBq, 3.5 ± 0.7 PBq, and 3.6 ± 0.7 PBq, respectively. Simulated 137Cs activities attributable to direct release were in good agreement with measured 137Cs activities not only adjacent to the accident site, but also in a wide area in the model domain, therefore this implies that the estimated direct release rate was reasonable. Employment of improved nudging data by JCOPE2 improved both the offshore transport result and the reproducibility of 137Cs activities 30 km offshore. On the other hand, simulated 137Cs activities attributable to atmospheric deposition were low compared to measured activities. The rate of atmospheric deposition into the ocean was underestimated because of a lack of measurements of deposition into the ocean when atmospheric deposition rates were being estimated. Simulated 137Cs activities attributable to the inflow of 137Cs deposited into the ocean outside the domain of the model were in good agreement with measured activities in the open ocean within the model domain after June 2012. The consideration of inflow is important to simulate the 137Cs activity in this model region in the later period of the simulation. The contribution of inflow increased with time and was dominant (more than 99%) by the end of February 2012. The activity of directly released 137Cs, however, decreased exponentially with time and was detectable only in the coastal zone by the end of February 2012.

scholarly journals HYDROTHERMAL MONITORING: SURRY NUCLEAR POWER PLANT

1974 ◽  
Vol 1 (14) ◽  
pp. 143
Author(s):  
C.S. Fang ◽  
G. Parker ◽  
W. Harrison
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Thermal Effects ◽  
Nuclear Power ◽  
Monitoring Program ◽  
First Year ◽  
James River ◽  
Background Data ◽  
Monitoring Effort ◽  
One Year

A hydrothermal monitoring program has been designed and deployed to gather data on the temperature distribution in the tidal James River near the outfall of the Surry Nuclear Power Plant at Surry, Virginia, U.S.A. Monitoring to date has included two years of background data (1971 and 1972) taken prior to plant operation, and one year (19 73) of data with the plant in operation. The results of the first year post operational monitoring effort has been compared with the pre-operation background data and with the thermal effects that were predicted from studies by Carpenter and Pritchard on the James River Hydraulic Model at Vicksburg, Mississippi.

scholarly journals Large-eddy simulation of turbulent winds during the Fukushima Daiichi Nuclear Power Plant accident by coupling with a meso-scale meteorological simulation model

2015 ◽  
Vol 12 (1) ◽  
pp. 127-133 ◽  
Author(s):  
H. Nakayama ◽  
T. Takemi ◽  
H. Nagai
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Regional Scale ◽  
Potential Temperature ◽  
Measurement Data ◽  
Radioactive Material ◽  
Small Scale ◽  
Energy Agency ◽  
Meso Scale

Abstract. A significant amount of radioactive material was accidentally discharged into the atmosphere from the Fukushima Dai-ichi Nuclear Power Plant from 12 March 2011, which produced high contaminated areas over a wide region in Japan. In conducting regional-scale atmospheric dispersion simulations, the computer-based nuclear emergency response system WSPEEDI-II developed by Japan Atomic Energy Agency was used. Because this system is driven by a meso-scale meteorological (MM) model, it is difficult to reproduce small-scale wind fluctuations due to the effects of local terrain variability and buildings within a nuclear facility that are not explicitly represented in MM models. In this study, we propose a computational approach to couple an LES-based CFD model with a MM model for detailed simulations of turbulent winds with buoyancy effects under real meteorological conditions using turbulent inflow technique. Compared to the simple measurement data, especially, the 10 min averaged wind directions of the LES differ by more than 30 degrees during some period of time. However, distribution patterns of wind speeds, directions, and potential temperature are similar to the MM data. This implies that our coupling technique has potential performance to provide detailed data on contaminated area in the nuclear accidents.

scholarly journals STUDIES OF 137CS TRANSFER IN SOIL‐FERN SYSTEM

2005 ◽  
Vol 13 (3) ◽  
pp. 97-102 ◽  
Author(s):  
Donatas Butkus ◽  
Marina Konstantinova
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Transfer Factor ◽  
Nuclear Power ◽  
Activity Concentration ◽  
Root Systems ◽  
137Cs Activity ◽  
Chernobyl Nuclear Power Plant ◽  
Activity Concentrations ◽  
Better Than

Fern accumulates radionuclides in abundance, including 137Cs. Tranfer of 137Cs and 40K in plants which have different root systems (fern or grass), or have no roots at all (moss) was compared. Samplings were performed in regions contaminated with 137Cs after Chernobyl Nuclear Power Plant (ChNPP) accident in 1994 and 1997–2000. The male fern (Dryopteris filix‐mas) most prevailing in Lithuania was studied. Fern accumulates 137Cs more effectively than grass or moss. The average 137Cs activity concentration in fern is 180±60 Bq kg−1 and the transfer factor is 0,074 m2kg−1. The fern stipe accumulates 137Cs most of all (200±90 Bqkg‐1), the transfer factor is 0,087 m2 kg−1. Accumulation of 137Cs is influenced by the content of K in the soil. 137Cs and 40K activity concentrations in fern are higher than those in the soil what shows that fern accumulates 137Cs better than 40K. Fern can clean the soil because this plant accumulates radionuclides in its stipe rather than roots.

TRANSFORMATION OF RADIOCESIUM SPECIATION IN PONDS AT THE VICINITY OF FUKUSHIMA DAI-ICHI NUCLEAR POWER PLANT AND ITS DYNAMICS IN “SEDIMENTS-WATER” SYSTEM

2021 ◽  
pp. 38-45
Author(s):  
A. V. Konoplev ◽  
◽  
Y. Wakiyama ◽  
T. Wada ◽  
M. Ivanov ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Water System ◽  
137Cs Activity ◽  
Exclusion Zone ◽  
Activity Concentrations ◽  
Dam Reservoirs ◽  
Radiocesium Interception Potential ◽  
The Subject

The paper is concerned with the results of 137Cs monitoring in the irrigation ponds of the Okuma town in the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) exclusion zone. The 137Cs activity concentrations in the ponds appeared to be higher than those in the rivers and dam reservoirs in the region. The study has revealed a trend for a decline in 137Cs activity concentrations, both particulate and dissolved. The rate of particulate 137Cs decline was much higher than that of dissolved. The total distri- bution coefficient Kd (137Cs) in the suspended sediment-water system in the studied ponds was decreasing in time with the rate constant of 0.12-0.18 year-1. Assuming that the decrease in Kd is associated with decomposition of hot glassy particles, the time scale of 137Cs leaching from them in these water bodies was estimated to be 5-8 years. These estimates are consistent with the findings of recent laboratory experiments on the subject. With respect to seasonal variations, the highest levels of dissolved 137Cs in the studied ponds were observed from June to October as a function of specific pond and monitoring year. Based on data about 137Cs speciation in the bottom sediment top layer of the ponds and its distri- bution in the sediment-water system, the exchangeable radiocesium interception potential RIPex(K) for the ponds sediments was estimated to be 1650-2250 mg-eq/kg, which is within the range of values measured by laboratory studies.

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