Nuclear Reactor science and Technology
Ali Zahian; Mahdi Aghaie
Abstract
In this analysis, nanofluid properties are evaluated by interaction correlations between particles using molecular dynamics (MD) method, and thermal-hydraulics characteristics of nanofluids in a WWER-1000 reactor is investigated by Computational Fluid Dynamics (CFD). This study conceptualizes power increase ...
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In this analysis, nanofluid properties are evaluated by interaction correlations between particles using molecular dynamics (MD) method, and thermal-hydraulics characteristics of nanofluids in a WWER-1000 reactor is investigated by Computational Fluid Dynamics (CFD). This study conceptualizes power increase by changing the cooling from pure water to nanofluid without changing the safety parameters. The Copper nanoparticles are used in primary loop cooling system, to evaluate the heat removal from the core. Thermophysical properties such as thermal conductivity and shear viscosity of Cu-Water nanofluids are obtained by MD in operating pressure and temperature of the Bushehr reactor core. These properties have been used in thermal-hydraulics analysis and nanofluids are considered as a homogeneous fluid. Thermal hydraulic properties of coolant have been calculated for different volume fractions of nanofluids. Thermal hydraulic simulation illustrated enhancement of the thermal characteristics of the core, due to the increment in heat transfer coefficient and thermal diffusivity. The thermal-hydraulic analysis of the reactor core has been performed in steady state at different powers. The requirements for changing the reactor power are not to change the fuel center temperature and Outer Cladding Surface temperature compared to the current state.
Nuclear Reactor science and Technology
Mohammad Askari; Nikoo Darestani Farahani; Mehdi Bakhshzad Mahmoudi; Fereydoun Abbasi Davani
Abstract
Metal surface cleaning or etching techniques using reactive plasma are emerging as one of the dry processing techniques for surface contaminants with high bond energy, especially for cleaning and decontamination of nuclear components and equipment. In this study, the plasma reaction due to the discharge ...
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Metal surface cleaning or etching techniques using reactive plasma are emerging as one of the dry processing techniques for surface contaminants with high bond energy, especially for cleaning and decontamination of nuclear components and equipment. In this study, the plasma reaction due to the discharge of a dielectric barrier of a mixture of 95% helium and 5% fluorine with cobalt oxide film (Co3O4) grown on the surface of stainless steel 304 was studied experimentally. Experimental results show that cobalt oxide becomes a powder after plasma irradiation and is easily separated from the surface of the base metal. The optimal plasma generating conditions of the dielectric barrier discharge used in this experimental study were obtained at atmospheric pressure, voltage 4.5 kV, and frequency 25 kHz with an etching rate of 10.875 μmol.min-1. The samples were analyzed before and after plasma irradiation, using Scanning Electron Microscopy with Energy Dispersive X-ray spectroscopy and the purification rate was performed using a sequential weighting of the samples with scales 10-4 g accurately obtained. The results show the ability of this method to effectively remove the surface contamination of cobalt from the surface of stainless steel 304.