Mohamed Elsafi, Aljawhara Almuqrin, Mohammad Sayyed
This work focuses on the preparation of borotellurite glasses doped with BaO, Bi2O3, and Er2O3, and the investigation of their radiation attenuation parameters. A narrow beam experiment was conducted to assess the attenuation factors of the glasses. A positive relationship was observed between the linear attenuation coefficient and the concentration of Er2O3. The linear attenuation coefficient for the Er2O3-free glass at 0.059 MeV is 19.729 cm-?, while for the sample with 3 mol % Er2O3, it is 26.113 cm-?. At 0.662 MeV, the linear attenuation coefficient for the Er2O3-free glass and the glass with 3 mol % Er2O3 are 0.426 cm-? and 0.461 cm-?, respectively. The mean free path of the glasses exhibited an inverse relationship with increasing Er2O3 content. For the glass containing 1 mol % Er2O3, the mean free path values are 0.046 cm, 2.285 cm, and 3.556 cm at 0.059 MeV, 0.662 MeV, and 1.173 MeV, respectively. The half-value layer was calculated, and the results indicated that the addition of Er2O3 causes a decrease in the half-value layer, suggesting an enhancement in the radiation attenuation performance of the prepared glasses as more Er2O3 is added.
Three NaI(Tl) detectors of 10 cm x 15 cm, in pairs and the three-detector system, were used to acquire spectra of 133Ba and 134Cs, and to consider registration of gamma radiation from de-excitation of their daughters (133Cs and 134Ba, respectively). The sources were measured for 7200 seconds real time (detector pairs) and 10 000 seconds real time (three-detector system) in the non-coincident mode of counting, as well as in the modes of double and triple gamma coincidences. Based on the photopeak detection efficiencies, minimum detectable activity and ratios of counting rates in the source and background spectra for individual detectors, the non-coincident mode is found to be optimal for 133Ba detection via the 356 keV gamma peak, whereas the mode of double coincidences is found to be optimal for 134Cs detection via the 605 keV and 796 keV gamma peaks.
In this paper, the results of measurements of indoor radon activity concentration in fourteen elementary schools in Tuzla, Bosnia and Herzegovina, are presented. Measurements were performed with CR-39 solid-state nuclear track detectors. Radon activity concentration in investigated locations was 6.8-143 Bqm-3. To assess the indoor radon hazards for people, the annual effective dose, excess lifetime cancer risk, and the relative risk of lung cancer were estimated.
Small modular reactors represent a promising technology for power generation, offering solutions to the energy crisis and mitigating greenhouse gas emissions. As Ukraine considers the deployment of NuScale, UK SMR, and SMR-160, it is crucial to address the safe management of spent nuclear fuel. This study focuses on evaluating the radiological characteristics of spent nuclear fuel from the selected small modular reactors and for comparison, from the VVER-1000 reactor. Using the Monte Carlo code Serpent, depletion calculations were performed for an assembly in an infinite 2-D geometry, and the activity, decay heat, and inhalation toxicity of the spent nuclear fuel were assessed. We determined the main nuclides contributing to the radiological characteristics and quantified the mass content of these nuclides. The total number of spent nuclear fuel assemblies produced during the entire life of each small modular reactor type was estimated. The radiological characteristics assessed for the three small modular reactors do not exceed those observed for VVER-1000 reactors currently operating in Ukraine. So, spent nuclear fuel generated by the selected small modular reactors will introduce no new challenges to Ukraine's radioactive waste management system. The results of this work provide valuable insights for identifying the optimal small modular reactor technologies for Ukraine concerning safe spent nuclear fuel management.
This study investigates the effects of successive neutron and gamma radiation on the parameters of commercial solar cells. Several solar panels have been exposed to neutron radiation and then, after 30 days of recovery, to gamma radiation. A series of measurements of solar cell parameters have been undertaken to determine the reliability of solar cells in the condition of successive irradiation of different types of rays. Solar cell parameters have been measured before and after every step of irradiation. The process of annealing has also been observed. This paper aims to present the effects of both neutron and gamma radiation on the same solar cell sample.
Cornelius Holtorf is UNESCO Chair on Heritage Futures at Linnaeus University. He reads prehistoric archaeology, social anthropology and physical anthropology in Germany, England and Wales. In 1998 he gained his PhD and was subsequently employed in research and teaching at the University of Gothenburg (1998-1999), the University of Cambridge (1999-2002), the Swedish National Heritage Board in Stockholm (2002-2004) and the University of Lund (2005-2008). Since 2008 Cornelius have been working at Kalmar where he is currently a Professor of Archaeology at Linnaeus University and Director of the Graduate School in Contract Archaeology (GRASCA).
Marija Radmilovic-Radjenovic, Zeljka Nikitovic, Branislav Radjenovic
Surface roughness represents the measure of the irregularities on the surface contributing to the local field enhancement. The traditional Fowler-Nordheim equation established for perfectly planar surfaces is not suitable for describing emission from rough surfaces. Instead, it is more appropriate to use the equation that accounts for the field enhancement factor describing the effect of the surface morphology. In superconducting radio frequency cavities, field emission may occur in the irises while the tips on the cavity surface may act as an emitter leading to the high electric field. For this study, calculations for hemispherical, cylindrical, and conical tips have been performed using a Multiphysics software package COMSOL. The focus was put on the dependence of the field enhancement factor on the shape and the radius of the protrusions. The electric field strength and the current density increase with increasing the root mean square average of the profile heights due to field enhancement at the cavity irises. The lowest value of the electric field has been achieved for the hemisphere. The calculated values for the field enhancement factors are consistent with the data from the literature, in which case the protrusion may represent a small local bump on the surface of a superconducting cavity. Based on the fit of the results, presented here, the relation between the enhancement factor and the radius has been suggested. The accurate estimation of the field emission may play a crucial role in the design of accelerators and other technological applications with requirements of extremely high precision.
Slavko Dimovic, Ivana Jelic, Marija Sljivic-Ivanovic
The probability of Cs+ and Co2+ ions retention by immobilization processes in the cement matrix was determinate as the subject of analyses: matrix design, water/cement ratio, and structure porosity. Comparison of experimental results was accomplished by Hespe standard leaching method. Diffusion and semi-empirical models were used for the assessment of the washing rate as a function of time. The higher value of cement matrix mechanical resistance corresponds to a lower value of Co2+ and Cs+ ions leaching. The Co2+ leaching level was more than two orders of magnitude less than the leaching level of Cs+. The influence of bentonite and zeolite on Co2+ leaching reduction was significantly smaller in comparison with Cs+, while zeolite had a higher Cs+ and Co2+ sorption ability than bentonite. Under static leaching conditions, the contribution of diffusion to the total transport of ions in the matrix porous medium was dominant. The contribution of matrix dissolution was insignificant concerning the dominant contribution of diffusion and surface washing. The semi-empirical model showed a better approximation of the Co2+ and Cs+ ions laboratory leaching process.
The use of a new Monte Carlo Serpent code for the calculation of water-cooled reactors is presented and a calculation scheme of the fuel assembly for VVER-1000 reactors developed. The calculation of neutron-physical characteristics for the fuel assembly of VVER-1000 is carried out for different states and the results obtained by the Serpent model compared with the results of other reactor codes. The analyses of these results are presented in the paper submitted here. Based on this article, the Monte Carlo Serpent code could be used for neutron-physical calculations of VVER-1000 reactors.
The effect of anisotropic scattering on the eigenvalues of a multiplying (c >1) and non-multi-plying (c < 1) slab in one-speed neutron transport equation is studied. We have made some calculations, not only for the cases c<1 and 0 < g < 1, but also the cases of c >1 and -1<g<0 by using the linear and quadratic approximations of the Henyey-Greenstein scattering kernel. The asymmetry parameter g consists of isotropic, backward and forward bias. An extensive numerical survey is carried out for the eigenvalues in order to provide an accurate evaluation. The numerical results indicate that the discrete eigenvalue increases with forward scattering and decreases with backward scattering in expansions of linear and quadratic anisotropic scattering.
Salvatore Cappello, Calogero Pace, Aldo Parlato
et al.
Technologically-enhanced electronic image sensors are used in various fields as diagnostic techniques in medicine or space applications. In the latter case the devices can be exposed to intense radiation fluxes over time which may impair the functioning of the same equipment. In this paper we report the results of gamma-ray irradiation tests on CMOS image sensors simulating the space radiation over a long time period. Gamma-ray irradiation tests were carried out by means of IGS-3 gamma irradiation facility of Palermo University, based on 60Co sources with different activities. To reduce the dose rate and realize a narrow gamma-ray beam, a lead-collimation system was purposely built. It permits to have dose rate values less than 10 mGy/s and to irradiate CMOS Image Sensors during operation. The total ionizing dose to CMOS image sensors was monitored in-situ, during irradiation, up to 1000 Gy and images were acquired every 25 Gy. At the end of the tests, the sensors continued to operate despite a background noise and some pixels were completely saturated. These effects, however, involve isolated pixels and therefore, should not affect the image quality.
The present study deals with the radiomodulatory influence of Tinospora cordifolia (Amrita) root extract on the peripheral blood of Swiss albino mice after 5.0 Gy gamma irradiation in the presence (experimental) or absence (control) of Tinospora cordifolia (75 mg/kg b.wt/day). The animals from different groups were necropsied and their blood collected on days 1, 3, 7, 15, and 30 postirradiation. A considerable decrease was recorded in the number of erythrocyte and total leucocyte counts, differential leucocytes, hemoglobin content, and hematocrit percentage in the irradiated control group, while a recovery pattern was recorded in experimental animals, however, without the attainment of normal levels up to the end of the experiment. Furthermore, Tinospora cordifolia root extract pretreatment significantly ameliorated radiation-induced elevation in cholesterol and lipid peroxidation levels, whereas, a decline in glutathione and total proteins concentration was noted.