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Cohen D.D.,Australian Nuclear Science and Technology Organisation | Crawford J.,Australian Nuclear Science and Technology Organisation | Stelcer E.,Australian Nuclear Science and Technology Organisation | Bac V.T.,Institute of Nuclear science and Technology
Atmospheric Environment | Year: 2010

Fine particulate matter (PM2.5), source fingerprints and their contributions have been measured and reported previously at Hanoi, Vietnam, from 25 April 2001 to 31 December 2008. In this study back trajectories are used to identify long range transport into Hanoi for two of these sources, namely, windblown dust (Soil) from 12 major deserts in China and emissions from 33 coal fired power plants (Coal) in Vietnam and China. There were 28 days of extreme Soil events with concentrations greater than 6μgm-3 and 25 days of extreme Coal with concentrations greater than 30μgm-3 from a total of 748 sampling days during the study period. Through the use of back trajectories it was found that long range transport of soil from the Taklamakan and Gobi desert regions (more than 3000km to the north west) accounted for 76% of the extreme events for Soil. The three local Vietnamese power stations contributed to 15% of the extreme Coal events, while four Chinese power stations between 300km and 1700km to the north-east of Hanoi contributed 50% of the total extreme Coal events measured at the Hanoi sampling site. © 2010 Elsevier Ltd.

Cohen D.D.,Australian Nuclear Science and Technology Organisation | Crawford J.,Australian Nuclear Science and Technology Organisation | Stelcer E.,Australian Nuclear Science and Technology Organisation | Bac V.T.,Institute of Nuclear science and Technology
Atmospheric Environment | Year: 2010

PM2.5 particulate matter has been collected on Teflon filters every Sunday and Wednesday at Hanoi, Vietnam for nearly eight years from April 2001 to December 2008. These filters have been analysed for over 21 different chemical species from hydrogen to lead by ion beam analysis techniques. This is the first long term PM2.5 dataset for this region. The average PM2.5 mass for the study period was (54 ± 33) μg m-3, well above the current US EPA health goal of 15 μg m-3. The average PM2.5 composition was found to be (29 ± 8)% ammonium sulfate, (8.9 ± 3.3)% soil, (28 ± 11)% organic matter, (0.6 ± 1.4)% salt and (9.2 ± 2.8)% black carbon. The remaining missing mass (25%) was mainly nitrates and absorbed water. Positive matrix factorisation techniques identified the major source contributions to the fine mass as automobiles and transport (40 ± 10)%, windblown soil (3.4 ± 2)%, secondary sulfates (7.8 ± 10)%, smoke from biomass burning (13 ± 6)%, ferrous and cement industries (19 ± 8)%, and coal combustion (17 ± 7)% during the 8 year study period. © 2009 Elsevier Ltd.

Nasseri M.M.,Institute of Nuclear Science and Technology
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2015

Abstract The production of pyroelectric type X-ray generators has a long term background. In case of using X-ray generators containing two pyroelectric crystals, some parameters have not been practically measured yet. This article aims to calculate such parameters by means of Geant4 Mont Carlo codes. The obtained edge energy of initial electrons was 3 keV at a constant pressure of 1mTorr and electric field of 250 kV/cm. The amplification coefficient production of electrons was increased reaching to a constant value of 2.7. The observed mean energy of produced gas ions was approximately 39 eV, equivalent to 5.7% of the emitted electrons. The efficiency of the generated X-ray was about 63% and did not show a considerable change as the energy of initial electrons increased. © 2015 Elsevier B.V.

Tabbakh F.,Nuclear Science and Technology Research Institute, Iran | Khalafi H.,Institute of Nuclear Science and Technology
Nuclear Science and Techniques | Year: 2010

Accelerator-based target design and optimization is an approach for neutron generation. The target plays an important role for a neutron source on an electron accelerator. For optimizing a neutron source using 10 MeV electron beams of Rhodotron-TT200, Pb, Ta, or W alloys with Be were calculated as photo-neutron converter. The neutron yield, flux and energy were simulated using the MCNPX code. The results indicate that a 10 MeV electron beam is capable of producing high-intensity neutron flux of 1013n·cm-2·s-1 with average energy of 0.8 MeV.

Cooper A.,University of Tokyo | Le T.N.,Institute of Nuclear Science and Technology | Iimoto T.,University of Tokyo | Kosako T.,University of Tokyo
Journal of Environmental Radioactivity | Year: 2011

Radon adsorption by activated charcoal collectors such as PicoRad radon detectors is known to be largely affected by temperature and relative humidity. Quantitative models are, however, still needed for accurate radon estimation in a variable environment. Here we introduce a temperature calibration formula based on the gas adsorption theory to evaluate the radon concentration in air from the average temperature, collection time, and liquid scintillation count rate. On the basis of calibration experiments done by using the 25 m3 radon chamber available at the National Institute of Radiological Sciences in Japan, we found that the radon adsorption efficiency may vary up to a factor of two for temperatures typical of indoor conditions. We expect our results to be useful for establishing standardized protocols for optimized radon assessment in dwellings and workplaces. © 2010 Elsevier Ltd.

Asadollahzadeh Goudarzi M.,University of Isfahan | Rezaee Ebrahim Saraee K.,University of Isfahan | Tabesh A.R.,Malek-Ashtar University of Technology | Teymuri B.,Malek-Ashtar University of Technology | Mansouri H.,Institute of Nuclear Science and Technology
Progress in Nuclear Energy | Year: 2015

Calculation of the primary circuit's coolant activation due to fission products (FPs) has been investigated for the eastern-type pressurized water reactor (VVER1000-V446). The reactor has been considered under normal full power operational condition for the first fuel cycle. Determination of the reactor coolant activity is based on time-dependent fission product core inventories. ORIGEN2.1 code has been used to determine the time-dependent fission product core inventories. The fission products activity in the primary coolant is calculated using a set of ordinary differential equations (ODEs) which governs the FPs concentration in the primary coolant. Results for 87 FPs have been calculated. The results of these calculations have been found to agree well with the corresponding available values found in the Final Safety Analysis Report (FSAR) of the Bushehr Nuclear Power Plant (BNPP). © 2014 Elsevier Ltd. All rights reserved.

Borhani zarandi M.,University of Yazd | Amrollahi Bioki H.,University of Yazd | Mirbagheri Z.-A.,University of Yazd | Tabbakh F.,Institute of Nuclear Science and Technology | Mirjalili G.,University of Yazd
Applied Radiation and Isotopes | Year: 2012

In this paper a series of low-density polyethylene (LDPE) blends with different percentages (10%, 20%, and 30%) of EVA and sets of low-density polyethylene sheets were prepared. This set consists of four subsets, which were made under different cooling methods: fast cooling in liquid nitrogen, cooling with cassette, exposing in open air, and cooling in oven, to investigate the crystallinity effects. All of the samples were irradiated with 10MeV electron-beam in the dose range of 0-250kGy using a Rhodotron accelerator system. The variation of thermal conductivity (k) and specific heat capacity (C p) of all of the samples were measured. We found that, for the absorption dose less than 150kGy, k of the LDPE samples at a prescribed temperature range decreased by increasing the amount of dose, but then the change is insignificant. With increasing the crystallinity, k of the LDPE samples increased, whereas C p of this material is decreased. In the case of LDPE/EVA blends, for the dose less than 150kGy, C p (at 40°C) and k (in average) decreased, but then the change is insignificant. With increasing the amount of additive (EVA), C p and k increased. © 2011 Elsevier Ltd.

Tafreshi M.A.,Institute of Nuclear Science and Technology
Journal of Fusion Energy | Year: 2014

In this paper, the theoretical ML model has been used to study the effect of three preliminary parameters (gas pressure, discharge voltage and the kind of the gas), to the current, azimuthal magnetic flux density, and the plasma layer pressure, in the Filippov type plasma focus device, Dena. Among others, it has been shown that to have an optimum pinch, the mentioned parameters should be selected in a manner so that the plasma sheath moves with an optimum velocity. A higher or lower velocity leads to pinch formation in an inappropriate time, when the plasma pressure is relatively low. © 2014 Springer Science+Business Media New York.

Long N.Q.,Institute of Nuclear Science and Technology | Truong Y.,Dalat Nuclear Research Institute | Hien P.D.,Vietnam Atomic Energy Agency | Binh N.T.,Dalat Nuclear Research Institute | And 3 more authors.
Journal of Environmental Radioactivity | Year: 2012

Radionuclides from the reactor accident at the Fukushima Dai-ichi Nuclear Power Plant were observed in the surface air at stations in Hanoi, Dalat, and Ho Chi Minh City (HCMC) in Vietnam, about 4500 km southwest of Japan, during the period from March 27 to April 22, 2011. The maximum activity concentrations in the air measured at those three sites were 193, 33, and 37 μBq m -3 for 131I, 134Cs, and 137Cs, respectively. Peaks of radionuclide concentrations in the air corresponded to arrival of the air mass from Fukushima to Vietnam after traveling for 8 d over the Pacific Ocean. Cesium-134 was detected with the 134Cs/ 137Cs activity ratio of about 0.85 in line with observations made elsewhere. The 131I/ 137Cs activity ratio was observed to decrease exponentially with time as expected from radioactive decay. The ratio at Dalat, where is 1500 m high, was higher than those at Hanoi and HCMC in low lands, indicating the relative enrichment of the iodine in comparison to cesium at high altitudes. The time-integrated surface air concentrations of the Fukushima-derived radionuclides in the Southeast Asia showed exponential decrease with distance from Fukushima. © 2011 Elsevier Ltd.

Rasouli H.,Institute of Nuclear Science and Technology | Rasouli H.,K. N. Toosi University of Technology | Rasouli C.,Institute of Nuclear Science and Technology | Koohi A.,Institute of Nuclear Science and Technology
Review of Scientific Instruments | Year: 2013

In this work, a nonlinear model is introduced to determine the vertical position of the plasma column in Damavand tokamak. Using this model as a simulator, a nonlinear neural network controller has been designed. In the first stage, the electronic drive and sensory circuits of Damavand tokamak are modified. These circuits can control the vertical position of the plasma column inside the vacuum vessel. Since the vertical position of plasma is an unstable parameter, a direct closed loop system identification algorithm is performed. In the second stage, a nonlinear model is identified for plasma vertical position, based on the multilayer perceptron (MLP) neural network (NN) structure. Estimation of simulator parameters has been performed by back-propagation error algorithm using Levenberg-Marquardt gradient descent optimization technique. The model is verified through simulation of the whole closed loop system using both simulator and actual plant in similar conditions. As the final stage, a MLP neural network controller is designed for simulator model. In the last step, online training is performed to tune the controller parameters. Simulation results justify using of the NN controller for the actual plant. © 2013 American Institute of Physics.

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