Meftah B.,Algerian Atomic Energy Commission |
Zouhire B.,Algerian Atomic Energy Commission |
Amina M.,University of Science and Technology Houari Boumediene
Journal of Nuclear Science and Technology | Year: 2014
Nuclear safety analysis remains of crucial importance for both the design and the operation of nuclear reactors. Safety analysis usually entails the simulation of several selected postulated accidents, which can be divided into two main categories, namely reactivity insertion accident (RIA) and loss of flow accident (LOFA). In this paper, thermal-hydraulic simulations of fast LOFA accident were carried out on the new core configuration of the material test research reactor NUR. For this purpose, the nuclear reactor analysis PARET code was used to determine the reactor performance by calculating the reactor power, the reactivity and the temperatures of different components (fuel, clad and coolant) as a function of time. It was observed that during the transient the maximum clad temperature remained well below the critical temperature limit of 110°C, and the maximum coolant temperature did not exceed the onset of nucleate boiling point of 120°C. It is concluded that the reactor can be operated at full power level with sufficient safety margins with regard to such kind of transients. © 2014 Atomic Energy Society of Japan.
Bensmain B.,Algerian Atomic Energy Commission |
Bensmain B.,University of Science and Technology Houari Boumediene |
Chegrouche S.,Algerian Atomic Energy Commission |
Barkat M.,Algerian Atomic Energy Commission |
And 2 more authors.
Hydrometallurgy | Year: 2016
This work investigates the dissolution of various uranium oxides in nitric acid medium and the most predominant occurring reaction was determined on the basis of the thermodynamic and kinetic studies. Six uranium oxides were dissolved and studied. The Gibbs free energies of all the reactions ΔrG°(T) were analyzed by Ulich model (Ulich, 1930) and the predominant dissolution reaction was found to be:3U3O8(s) + 20HNO3(aq) → 9 UO2 (NO3)2(aq) + 2NO(g) + 10H2O Three reaction order rate models namely the first, the second and the third order were applied on the predominant reaction reported above. According to the kinetics results, our reaction best fits the second order equation rate. © 2015 Elsevier B.V. All rights reserved.
Bensemma N.,Nuclear Research Center of Birine |
Trefalt G.,Jozef Stefan Institute |
Glinsek S.,Jozef Stefan Institute |
Kosec M.,Jozef Stefan Institute |
And 2 more authors.
Journal of Electroceramics | Year: 2013
Lead-free (1-x) BaTiO3 -x BaMg1/3Nb 2/3O3 ceramics with x = 0.03, 0.04, 0.05 and 0.06 were prepared by solid-state synthesis. The effects of the Ba(Mg1/3Nb 2/3)O3 addition on the phase composition, dielectric and ferroelectric properties, as well as the electromechanical response of the classic ferroelectric BaTiO3 were investigated. The room-temperature X-ray diffraction analyses of all the ceramics revealed a perovskite phase after sintering at 1300 C with a composition-dependent symmetry. The samples with a lower concentration of Ba(Mg1/3Nb2/3)O3, i.e., x = 0.03 and 0.04, were tetragonal, while the samples with x = 0.05 and 0.06 were found to be cubic. The result is in agreement with the dielectric, ferroelectric and electromechanical properties. With x increasing from 0.03 to 0.06 the temperature of the diffused maximum of the dielectric permittivity decreased from 348 K to 265 K. All the ceramics showed a large electromechanical response: the calculated room-temperature electrostrictive coefficient M 33 of the sample with x = 0.06 was 1.4 · 10-16 m2/V2, which is comparable to the value measured for Pb(Mg1/3Nb2/3)O3 ceramics. © 2013 Springer Science+Business Media New York.
Khechana M.,8 May 1945 University of Guelma |
Djamaa M.C.,8 May 1945 University of Guelma |
Djebala A.,8 May 1945 University of Guelma |
Boumazza Z.,Algerian Atomic Energy Commission
International Journal of Advanced Manufacturing Technology | Year: 2015
During the machining of mechanical parts, structural damages such as cracks can appear on the finished surface, consequently, the measured cutting forces being perturbed. It is difficult to detect directly such damages starting from the measured signals because they are always mixed with the measuring noise. In this paper, a method based on the wavelet multiresolution analysis is applied to extract the required information relating to the existence of structural damages in a disk using the cutting force signals measured by a Kistler dynamometer during the disk machining. In order to simulate the structural damage, a longitudinal crack is voluntarily created on the cylindrical surface of the disk. Since periodic impacts are produced each time the cutting tool comes into contact with the structural damage, an optimized wavelet multiresolution analysis is used as a filtering and a denoising tool. The experimental results show the validity of this method within the detection of single and multiple defects created on the disk surface during the machining processes. © 2015 Springer-Verlag London