Journal of Nuclear Research and Applications
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Journal of Nuclear Research and Applicationsendaily1Sun, 01 Aug 2021 00:00:00 +0430Sun, 01 Aug 2021 00:00:00 +0430A method to modify the response of neutron dosimeters in the fields with energy spectra different from the calibration field
https://jonra.nstri.ir/article_1281.html
One problem in neutron dosimetry is that dosimeter responses per unit dose-equivalent in measurement and calibration&nbsp;fields are different. Hence, the neutron dose suffers a large uncertainty. In this work, a correction method is introduced&nbsp;to modify the dosimeters response in the fields with known energy spectra. To examine it, responses of&nbsp;thermoluminescence dosimeters (TLDs) to fast neutrons in 241Am-Be (calibration), 252Cf and 239Pu-Be fields for four&nbsp;personal dose-equivalents (Hp (10) values) of 5, 10, 15 and 20 mSv are measured. The results obtained reveal that the&nbsp;maximum differences of the original responses measured in 252Cf and 239Pu-Be fields from 241Am-Be field are 15% and&nbsp;42%, respectively. After correction, above differences reduce to 4.7% and 10.8%. Finally, it can be concluded that the&nbsp;method proposed here, improves the accuracy of dose measurement in the neutron fields with known energy spectra.Preparation of 191Osâ€“phytate, an in-vivo radionuclide generator, for radiosynovectomy application
https://jonra.nstri.ir/article_1282.html
191Os is a parent radionuclide with a 15.4 d half-life. It decays by beta emission to 191mIr, which is a radionuclidewith a 4.96s half-life. It decays by the isomeric transition to stable 191Ir, emitting a 129-keV gamma photon. In thisstudy, 191Os&ndash;phytate was developed into an in-vivo radionuclide generator for simultaneous radiosynovectomy and&nbsp;imaging. 191Os-hexachloroosmate was used to prepare 191Os&ndash;phytate (100 &mu;Ci/50 &mu;l) using reaction condition&nbsp;optimization followed by an intraarticular injection to rat knee joints. Also, its distribution and stability were assessed.&nbsp;The imaging of 191Os cation and 191Os&ndash;phytate was performed by SPCET. The 191Os&ndash;phytate complex was obtained&nbsp;at pH=5.5 with normal saline at room temperature. Radio-TLC showed an overall radiochemical yield of 95-98%. The&nbsp;complex was injected into the rats&rsquo; knees, and the whole injected dose remained at the injection site even three days&nbsp;after injection. Due to the stability and retention of the complex in joints approved by biodistribution and imaging&nbsp;studies, the complex is a potential in vivo generator for cavital radiosynovectomy of minor joints.Modeling of Some Thermodynamic Properties of UF6 at Low Pressure Using Correlation Function
https://jonra.nstri.ir/article_1283.html
The properties of uranium hexafluoride (UF6) are of importance to the nuclear industry as a precursor for the enrichment. Therefore it is of importance to obtain the most accurate properties for such a strategic compound. In this paper, some thermophysical properties of uranium hexafluoride (UF6) at low pressure and bellow the critical temperature are predicted and modeled using its correlation function of second virial coefficient and virial equation of state (VEOS). Studied properties consist of Joule-Thomson coefficient, enthalpy, deviation function, fugacity coefficient, thermal expansion and isothermal compressibility. So far, several researchers have studied virial coefficients of UF6 and some of them have presented its correlation function of second virial coefficient. In this work, The studied correlation functions are the ones suggested by Dymond and Zarkova. The obtained results show that the correlation equations presented have a good ability to predict and model the thermophysical properties of uranium hexafluoride and its deviation from the ideal state especially in the temperature range from 360 K up to critical temperature.A comparative study for the rejection of nickel ions from waste water by PES, fMWCNTs/PES, TiO2/PES and TiO2-fMWCNTs/PES mixed matrix membranes
https://jonra.nstri.ir/article_1284.html
In this study, the neat polyethersulfone (PES) membrane and the mixed matrix membranes (MMMs) containing 20 wt. %polyethersulfone (PES) and different amounts of functionalized multi-walled carbon nanotubes (fMWCNTs), TiO2, and&nbsp;TiO2 coated on fMWCNTs were fabricated by wet phase inversion and conventional casting methods. The nickel ions&nbsp;rejection and permeate flux performance were then investigated and compared by these fabricated membranes. The&nbsp;characteristics of the membranes were performed by field emission scanning electron microscopy (FESEM), transmissionelectron microscopy (TEM), and contact angle (CA) measurement. The operational parameters such as polymer&nbsp;concentration, pressure, pH, time and nickel ion concentration for nickel ions rejection and permeability were firstly&nbsp;optimized on the neat PES membrane. The performance of MMMs containing various amounts of nanoparticles was then&nbsp;evaluated and compared under these optimized conditions. The obtained results indicated that the membrane containing 20&nbsp;wt. % PES, and operational conditions like pressure 15bar, low concentration of nickel, time =30min, and various amounts of&nbsp;pH were the best conditions to achieve the highest rejection percentage of nickel ions and permeate flux. In such operational&nbsp;conditions, PES/fMWCNTs and PES/TiO2 membranes have the highest nickel ion rejection and permeate flux,&nbsp;respectively. Totally the prepared mixed matrix membranes showed that they have higher ability to reject nickel ions from&nbsp;wastewater and a higher permeate flux value compared with the neat PES membrane.Investigation of Cut Control Equations in the Gas Centrifuge Cascades
https://jonra.nstri.ir/article_1285.html
Stage cut control and simulation are the most important aspects in the optimum binary mixture or multi-component multiobjective&nbsp;cascades. Numerical investigation revealed that by controlling the cut of a separation cascade, defined as the&nbsp;ratio of the product rate to the feed rate, it is always possible to separate a multi-component mixture into two specified&nbsp;groups of components, a light group, and a heavy group, in just one separation run. In this paper, the equations related to&nbsp;the cut control are introduced and it is proposed that for controlling stage cuts, putting one valve in the product section of&nbsp;each stage is enough. By solving the set of non-linear equations related to the machine behavior, valve, and pressure drop&nbsp;in the pipelines and junctions, the valve setting for each stage can be obtained. In the end, some examples of an optimal&nbsp;cascade are studied and valve setting parameters are obtained.A new algorithm for simulation of the functional symmetric and asymmetric cascades
https://jonra.nstri.ir/article_1289.html
Design of cascade based on operational functions of a single machine is an important goal in the isotope separation theory. By recognizing the behavior of gas in a centrifuge machine, a cascade with desirable properties and parameters can be designed. In the classical theory of multistage separation installation, it has been shown that in an ideal cascade (no mixing) the total number of separation elements flow is minimal, and accordingly, the maximum separation work unit (SWU) of the cascade occurs. In the practical form, the cut and separation factors may assume to be dependent on the feed flow. Using specific functional parameters, the algorithm, design the functional cascades (DFUNCAS), can design the functional symmetric and asymmetric cascades. DFUNCAS can design a cascade with stated waste and product concentration. Furthermore, the program can design symmetric and asymmetric cascades. In this work, four test cases were considered and the results show that the DFUNCAS can design any kind of cascade accurately.A New Algorithm for Simulation of the Functional Symmetric and Asymmetric Cascades
https://jonra.nstri.ir/article_1288.html
Design of cascade based on operational functions of single machine is an important goal in the isotope separation theory. By recognizing the behavior of gas in a centrifuge machine, a cascade with desirable properties and parameters can be designed. In the classical theory of multistage separation installation, it has been shown that in an ideal cascade (no mixing) the total number of separation elements flow is minimal and accordingly the maximum separation work unit (SWU) of the cascade occurs. In practical form the cut and separation factors may assume to be dependent of feed flow. Using specific functional parameters, the algorithm, design the functional cascades (DFUNCAS), can design the functional symmetric and asymmetric cascades. DFUNCAS can design a cascade with stated waste and product concentration. Furthermore the program can design symmetric and asymmetric cascade. In this work four test cases were considered and the results show that the DFUNCAS can design kinds of cascades carefully.