جستجوی مقالات مرتبط با کلیدواژه "آب سنگین" در نشریات گروه "فیزیک"

By replacing hydrogen with deuterium in water molecules, the energy level of molecular bonds changes which cause different physical, chemical, nuclear, and biological properties. Owing to that, the Equation of State (EOS) is an important and appropriate tool for studying the thermophysical behavior of materials and predicting them in different conditions in terms of pressure, temperature, and volume. Due to the importance of heavy water and its role in various researches, especially nuclear research and its application in medicine and industry, the present work aims to calculate the fugacity and virial coefficients of this material using the new generalized state equations and to compare the results obtained with experimental data to have an accurate evaluation of the equations used. The generalized equations in this research include the generalization of the equations based on the Redlich-Kwong equation (RK) and the Dietrici equation (D). The studies showed that generalization improves the results of the second virial coefficient below the critical temperature, which is more effective in the RK equation and leads to appropriate results according to the experimental data. However, in the case of fugacity, generalization improves the results in Equation D and further deviates the results in the RK equation. The results show that below the critical temperature, the van der Waals and Dietrici models do not offer a good prediction of the behavior of the third virial coefficient. Therefore, more other models should be used to predict their behavior quantitatively and qualitatively.

Heavy water has two heavy hydrogen atoms or deuterium. Chemical properties of heavy water are similar to light water, but their physical, thermodynamic, and nuclear properties are different. On the other hand, the Equation of State (EOS) is an important and suitable tool for studying the thermophysical behavior of materials and predicting them in different conditions in terms of pressure, temperature and amount. At present, there are different equations of state that can be categorized as theoreticall, empericall and semi-emperical. Regarding to the importance of heavy water and its role in various researches, in particular nuclear researches, and the application of this material in medicine and industry, the thermodynamic regularities of this material have been studied in this research using different semi-experimental equations of state based on van der Waals and Dieterici models. The comparison between calculations with the experimental data showed that the equations of state predicted the thermodynamic regularities of heavy water well qualitatively, but their quantitative behavior is different.

Measurement of cadmium ratio is one of the basic parameters in nuclear reactors. In this paper, the amount of cadmium ratio for the Esfahan Heavy Water Zero Power Reactor (EHWZPR) in two pitches of 18 and 20cm have been measured. For the cadmium ratio measurements Mn-Ni foils were used. The activity of the Mn-Ni foils were obtained by plastic scintillator and NaI(Tl) detectors for beta and gamma rays. Also, changes of the cadmium ratio in the axial direction of the reactor, asymptotic region or stable spectrum were obtained. The length of stable spectrum of the reactor increased to approximately 19cm, in pitch of 20 to 18, due to the reduced number of fuel rods and critical height of heavy water. To verify the measured values, the Esfahan Heavy Water Zero Power Reactor was simulated with the MCNPX-2.6.0 code. The  results of simulation were in good agreement with those of the experiments.