Numerical Simulation of Radon Atmospheric Dynamic Diffusion from a Flat Ground Uranium Tailings Impoundment

2013 ◽  
Vol 807-809 ◽  
pp. 628-631
Author(s):  
Xiao Yong Peng ◽  
Xin Zhang ◽  
Shuai Huang ◽  
Xu Sheng Chai ◽  
Lan Xia Guo
Keyword(s):  
Numerical Simulation ◽  
Mass Fraction ◽  
Space Distribution ◽  
Time And Space ◽  
Tailings Impoundment ◽  
Diffusion Characteristics ◽  
Atmospheric Dynamic ◽  
Uranium Tailings ◽  
Dynamic Diffusion ◽  
Flat Ground

with a flat ground uranium tailings impoundment as the object of the paper, CFD technology was used to study the atmospheric dynamic diffusion characteristics and the evolution of time and space distribution of radon in the uranium tailings impoundment. Results show that, within 1500m range of the leeward of uranium tailings impoundment the falling gradient of radon mass fraction improves with distance increases at the same moment, however the falling gradient flattens with the increase of time gradually; During the first 30 minutes, the radon mass fraction of tailings impoundment in the leeward direction has a larger growth gradient, then flattens out slowly, and stabilizes after 75 minutes.

Numerical Simulation of Atmospheric Migration of Particles from Uranium Tailings Impoundment

2012 ◽  
Vol 253-255 ◽  
pp. 1014-1018
Author(s):  
Xiao Yong Peng ◽  
Fen Wan ◽  
Qing Fang Xie ◽  
Xin Zhang ◽  
Shuai Huang
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Particle Concentration ◽  
Dust Emission ◽  
Local Concentration ◽  
Discrete Phase Model ◽  
Local Pollution ◽  
Tailings Impoundment ◽  
And Migration ◽  
Uranium Tailings

Based on the discrete phase model (DPM), this paper studies the concentration distribution and settlement regularity of particles which sizes are 10μm and 100μm under the wind speed of 0.5, 1, 2, and 4m/s with the method of numerical simulation. The simulation results show that the particle concentration of 10μm at the downwind direction of tailing is constantly decreasing with the increase of wind speed and migration distance, and the particle concentration of 100μm is gradually increasing, as well as the local pollution also become gradually worse. As wind speed is 0.5m/s, the local concentration of 10μm particles at the beach face of uranium tailings impoundment is higher, and there is much deposition within 2000m of the downwind direction. While the dust emission rate of 100μm is less and its concentration is lower.10μm particles are taken away by the wind, and its concentration would fall rapidly with wind speed increased to 4.0m/s. The concentration of 100μm particle would increase and local pollution becomes more serious.

Numerical Simulation of Atmospheric Diffusion of Radon Emanating From Flat Ground Uranium Tailings Impoundment in Different Heights

2012 ◽  
Vol 518-523 ◽  
pp. 1677-1681 ◽  
Author(s):  
Xiao Yong Peng ◽  
Zhen Hao Liu ◽  
Qing Fang Xie ◽  
Xin Zhang ◽  
Fen Wan ◽  
...  
Keyword(s):  
Radon Concentration ◽  
Concentration Distribution ◽  
National Standard ◽  
Radon Emanation ◽  
Atmospheric Diffusion ◽  
Tailings Impoundment ◽  
Effective Doses ◽  
The Difference ◽  
Uranium Tailings ◽  
Flat Ground

The atmospheric diffusion and concentration distribution of radon (emanation rate is 6.06 Bq/m2s ) emanating from the flat ground uranium tailings impoundment at various heights(0m, 10m, 20m, and 30m) are simulated. The numerical results show that the different height of the tailings impoundment will mainly influence the radon concentration that could change in the range of 16~250 Bq/m3 at the downwind region of 0-300m. The radon concentration and annual effective doses for public from radon decrease sharply with the increasing distance away from tailings impoundment, are higher than that of the decommissioned uranium tailings impoundment (its height is 30m, radon emanation rate is 0.74 Bq/m2s ). The annual effective doses for public from radon are highly up to 1.12 mSv/a, and are 0.12 mSv/a greater than the national standard in the range of 800m. Considering the difference of average radon emanation rate and other factors, the protective distance from radon should be adjusted appropriately.

Numerical Simulation of Influence of Vegetation on Atmospheric Diffusion of Radon Emanating from Uranium Tailings Impoundment

2012 ◽  
Vol 253-255 ◽  
pp. 1009-1013 ◽  
Author(s):  
Xiao Yong Peng ◽  
Qing Fang Xie ◽  
Fen Wan ◽  
Shuai Huang ◽  
Xin Zhang
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Radon Concentration ◽  
Simulation Method ◽  
Atmospheric Diffusion ◽  
Local Pollution ◽  
Tailings Impoundment ◽  
Radon Diffusion ◽  
The One ◽  
Uranium Tailings

Using the numerical simulation method, this thesis studies the radon concentration distribution in downwind area of the flat ground uranium tailings impoundment with and without vegetation on the beach face under the wind speed of 0.5, 1.0, 2.0 and 4.0m/s. The numerical results show that the radon concentration decreases gradually with the increasing wind speed and distance from uranium tailings impoundment. As the wind speed is 0.5m/s, the radon concentration is higher in downwind area of uranium tailings impoundment, and accumulation range is larger and local pollution also becomes more serious. However, radon concentration and accumulation range falls rapidly with wind speed increased to 4.0m/s. At the same wind speed, radon concentration under the condition of beach face with vegetation is higher than the one without vegetation within 600m range of uranium tailings impoundment along the downwind direction, but radon concentration is lower under the condition of beach face with vegetation out of 600m range. It illustrates that vegetation can inhibit radon diffusion to some extent.

Time Trends and Geographical Variation in Parkinson's Disease in Scotland

1992 ◽  
Vol 37 (4) ◽  
pp. 112-115 ◽  
Author(s):  
W.C.S. Smith ◽  
W.J. Mutch
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Time Trends ◽  
Geographical Variation ◽  
The Elderly ◽  
Epidemiological Studies ◽  
Space Distribution ◽  
Mortality Data ◽  
Time And Space ◽  
Factors Affecting

Parkinson's disease is a common and disabling condition which principally affects the elderly. The time and space distribution of Parkinson's disease has been examined to determine if it provides clues as to aetiology and factors affecting its distribution. Previous studies have used mortality data,1 data from epidemiological studies,2 and pre scribing information particularly with regard to the use of levodopa.3 These studies have looked within countries and between countries.

scholarly journals DISTRIBUCIÓN Y ABUNDANCIA ESPACIO- TEMPORAL DE LOS PECES EN LA LAGUNA DE CUYUTLÁN, COLIMA, MÉXICO.

2004 ◽  
Vol 19 (1-2) ◽  
pp. 19
Author(s):  
E. G. Cabral-Solís ◽  
E. Espino-Barr
Keyword(s):  
Diversity Index ◽  
Space Distribution ◽  
Time And Space ◽  
Know How ◽  
Crevalle Jack

Se analiza la abundancia en tiempo y espacio de los peces recolectados durante 18 muestreos mensuales en 21 estaciones distribuidas en la Laguna de Cuyutlán, México, durante el período de marzo a junio de 1999 y de octubre de 1999 a diciembre de 2000. Se recolectaron 1,719 organismos ícticos que pertenecen a 22 familias. Las especies más abundantes fueron: la mojarra rayada (Gerres cinereus) con 43.86 %, lebrancha (Mugil curema) con 24.89 %, mala capa (Diapterus peruvianus) con 6.34 %, sardina crinuda (Opisthonema libertate) con 5.29 % y con 3 % el jurel (Caranx caninus) y la piña (Oligo plitesaltus).La riqueza específica varió de 3.52 en mayo de 1999 a 15.48 en octubre de 2000. La equitatividad fluctuó de 0 en la estación 18, ubicada en el vaso de Palo Verde, a 0.93 en la estación 20 ubicada en el mismo vaso. El índice de diversidad presentó valores de 0.33 en mayo 1999 a 1.06 en octubre 2000. La laguna puede dividir se en dos vasos por sus características físicas y biológicas. La apertura de la Boca de Tepalcates aumentó la diversidad de especies de peces, pero habrá que dejar pasar el tiempo para conocer los cambios en biomasa. Time and space distribution and abundance of the fishes in the Cuyutlan Lagoon, Colima, Mexico Monthly sampling in 21 sites in the Cuyutlán Lagoon, México were carried out from March to June 1999 and October 1999 to December 2000, where 1,719 fish from 22 families were collected. The most abundant were: yellowfin mojarra (Gerres cinereus ) with 43.86 %, white mullet (Mugil curema ) in 24.89%, mojarra (Diapterus peruvianus ) with 6.34 %, Pacific thread herring (Opisthonema libertate ) with 5.29 % and with 3 % Pacific crevalle jack (Caranx caninus ) and long jaw leather jack (Oligoplites altus ). The specific richness changed from 3.52 in May 1999 to 15.48 in October 2000. The equitativity fluctuated from 0 in the 18th station named Palo Verde to 0.93 in the 20th site in the same area. The diversity index presented values from 0.33 in May 1999 to 1.06 in October 2000. By its physical and bio logical characteristics the lagoon can be divided in to two different areas. The opening of the channel Boca de Tepalcates increased the diversity of species of fish, but it will take time to know how the bio mass is going to change.

Assumed Multivariate Beta-PDF Modeling for Turbulent Nonpremixed Flames

2007 ◽  
Author(s):  
Susumu Noda ◽  
Kunihiko Yamamuro ◽  
Yuzuru Nada ◽  
Masato Fujisaka
Keyword(s):  
Numerical Simulation ◽  
Reaction Mechanism ◽  
Moment Method ◽  
Mass Fraction ◽  
Reaction Rate ◽  
Single Step ◽  
Present Approach ◽  
Nonpremixed Flames ◽  
Good Prediction ◽  
Irreversible Reaction

Numerical simulation based on a moment method is conducted to investigate the feasibility of an assumed probability density function (PDF) approach in the configuration of a turbulent jet nonpremixed flame. In this study, a multivariate β-PDF is employed to account for turbulence-chemistry interaction. The multivariate β-PDF approach has an advantage that only one additional transport equation of sum of composition variances is solved to determine the shape of species PDF to transport equations of mean compositions. The numerical simulation is carried out for H3 flame. Reaction mechanism is a single-step irreversible reaction including H2, O2 and H2O species. The results are compared with those from measurements and a combined PDF/moment method that detailed reaction mechanism is applied. Velocity distributions obtained by the multivariate β-PDF approach show good agreement with measurements and combined PDF/moment results, which indicates that the present approach can predict the flow pattern of nonpremixed flames. The present approach also provides good predictions in terms of mean temperature and mass fraction. PDFs of mass fraction obtained by the present approach are similar to those by the combined PDF/moment method. On the other hand, the variance of temperature is underpredicted, which is attributed to an approximation of temperature variance. In order to achieve a good prediction of the reaction rate, a PDF approximation of enthalpy is proposed for the evaluation of mean reaction rate.

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