Commercial multi-channel energy spectrometers have good performance, they have multiple input signal channels and multi-channel analyzers, which can simultaneously acquire the energy spectrum of multiple nuclear pulse signals. But the input signal channel of this general multi-channel energy spectrometer cannot be switched between the internal multi-channel analyzers, and an input signal channel can only be fixed to the corresponding multi-channel analyzers. Hence, to resolve this issue, this paper designed a nuclear pulse signal array switching circuit. The core of the array switching circuit is a switch array chip with low internal resistance and high bandwidth, which controls the signal connection between the input signal channel with the multi-channel analyzers. Using 137Cs and uranium ore as radioactive sources, the energy spectrum test and spectrum data analysis were carried out using a NaI detector, respectively, when the nuclear pulse signal passed through and did not pass through the array switching circuit. The results showed that the circuit demonstrates little effect on the energy resolution and linearity of the multi-channel analyzers but causes a small drift of the high-energy photopeak, and improve the reliability of the circuit by energy spectrum data accumulation. This circuit can make the application of a multi-channel energy spectrometers more flexible and reliable.
Special high-protein foods suitable for diabetics must be treated to ensure the complete absence of microorganisms and bacteria. It is also important to achieve that this treatment does not change the nutritional value of the product. Among the new decontamination technologies, low-energy electron-beam treatment has proven to be an effective technique for inactivating bacteria with minimal impact on food quality. The paper aims to analyze the influence of low-energy electron-beam irradiation on the microbiological properties and nutritional value of high-protein foods.
Jelena Stankovic-Petrovic, Zeljka Knezevic, Nikola Krzanovic
et al.
Passive solid state dosimeters, such as thermoluminescence dosimeters, provide integrated measurement of the total dose and are widely used in environmental monitoring programs. The objective of this paper is to provide a comprehensive review on the use of thermoluminescent dosimetry methods for monitoring radiation dose in the environment. The article presents the part of the research results of the project PREPAREDNESS (EMPIR 2016 call for Metrology for Environment joint research project) with a particular objective to harmonize procedures used by dosimetry services, relevant authorities and Institutes across the Europe. To achieve this, different monitoring routines that are based on passive environ mental dosimetry methods are investigated. Differences in performing specific steps such as preheating, reading, annealing, minimizing fading, and others, are analyzed. The investigation was performed by means of qualitative literature review that showed the lack of information about specific steps. The conclusion of this work is that thermoluminescent dosimetry measurement system has to be type-tested even though the testing procedure is complicated. In addition to this, control dosimeters should be introduced, International Organization for Standardization protocols should be followed during calibration, and finally, parameters influencing the measurement uncertainty have to be identified and well understood in order to pro duce ac cu rate dose measurement results.
Nenad Kartalovic, Saska Djekic, Sasa Djekic
et al.
The paper considers the application of nuclear magnetic resonance for measurement of fluid-flow. The paper is of an experimental nature. Flowmeter based on nuclear magnetic resonance is extremely precise. The combined measurement uncertainty can be 0.1 %. Such a value of measurement uncertainty indicates that it is a matter of a deterministic and not of a stochastic quantity. This high degree of reliability of the method is theoretically and mathematically described. The paper presents a measurement scheme for flow measurement. Water flow measurement was performed on the principle of nuclear magnetic resonance and on the basis of tritiated water (which is considered to be the most accurate classical method). The obtained results show that the measurement of flow based on nuclear magnetic resonance is more accurate (especially at higher flow). This is explained by the higher inertial mass of HTO tritiated water molecules than the standard H2 O mass and the possible transition of tritiated water to H3HeO. In this way, it has been proven that tracing water based on nuclear magnetic resonance is the only real tracing of water by water. The obtained results show that tracing water with tritiated or heavy water is not tracing water by water which is explained by different inertial masses.
Slavko Dimovic, Ivana Jelic, Vojislav Stanic
et al.
The aim of the study was to assess Cs+ ions transport phenomena from solidified spent ion exchange resin by mathematical modeling. The experimental results comparison was obtained by Hespe's Standard Leaching Method. For the leaching prediction rate as a function of time, diffusion and semi-empirical models were used. Due to the presence of spent ion exchange resin, the cement matrix absorbed a larger amount of water, swelled, and degraded. This phenomenon caused a significantly lower value of mechanical resistance to pressure. Also, through the increase of bentonite and zeolite content, the cement matrix decreased its mechanical resistance. The retention of cesium ions in the cement matrix was low and they were leached during the early phase of the investigation. The diffusion coefficient, De, decreased by three orders of magnitude with the addition of zeolite and bentonite in the cement matrix. Linear regression of experimental Cs+ leaching results, under static conditions, displayed that the semi-empirical parameter K3 than the absolute values of the parameters K2 and K1. Therefore, the contribution of matrix dissolution to the total radionuclides transport was irrelevant to the prevailing share of diffusion and surface washing processes.
Lead-cooled fast reactors have multilayered designs and large internal temperature differences, which cause challenges in simulating reactor physics. SuperMC, a large-scale integrated software system for neutronics design, is inherently able to address complex geometries and multi-temperature problems. The purpose of this study is to verify the applicability of SuperMC to the lead-bismuth-cooled fast reactor RBEC-M. The multi-temperature cross-section generation function of SuperMC was employed and showed good performance. Based on the ENDF/B-VII.1 library, the effective multiplication factor keff obtained by SuperMC showed good agreement with those from previous works. The relationship of keff and 15N enrichment applied to the fuel material was also studied, with the results showing that in creased 15N could significantly improve keff. The axial power profile and kinetics parameters for the bench mark were then calculated and analyzed. This work thus verified the applicability of SuperMC for comprehensive neutronics simulations for lead-bismuth-cooled fast reactors.
In this paper, the application of three-component gas mixtures as a working gas in Geiger-Mueller tubes was considered. In addition to the noble and quenching gas, an electronegative gas is used, at the same time, as the third component of gas mixture. This paper is mostly experimental. The experiments are carried out on the enlarged Geiger-Mueller counter tube model. By applying the similarity law for electric discharges in gases on the model and commercial Geiger-Mueller counting tubes, the model was verified. The obtained results showed that a small percentage of SF6 gas, in the working gas, stabilize operating point of Geiger-Mueller counter tubes and reduce dead time. <br><br><font color="red"><b> This article has been corrected. Link to the correction <u><a href="http://dx.doi.org/10.2298/NTRP1804417E">10.2298/NTRP1804417E</a><u></b></font>
Begzada Basic, Adnan Beganovic, Maja Gazdic-Santic
et al.
The personal dosimetry in Bosnia and Herzegovina started in 1960. After a brief interruption in 1990s, the dosimetry service resumed in 1999. Until 2013, the Radiation Protection Centre of the Institute of Public Health of Federation of Bosnia and Herzegovina has been the only institution in the country that could provide this service. In 2013, this Center covered more than 70 % (1,485) of all radiation workers in the country. They mostly worked in medical institutions (1,417 or 95.4 %), while others are exposed to radiation sources in industry and veterinary radiology. From 1999 to 2013, the majority of annual doses were less than 1 mSv (96.2 %). There are no registered cases of exceeding the annual dose limit (20 mSv). The results analysis shows the reduction of individual doses in last five years. Newly adopted practices in medicine, such as the positron emission tomography, could cause the increase of doses in the years to come.
Marija Radmilovic-Radjenovic, Petar Belicev, Branislav Radjenovic
Electron field emission limiting the accelerating gradient in superconducting cavities remains the dominant setback in cavity production. The need to understand and control the field emission has become increasingly important because of the prospect of using high-gradient structures in linear colliders. Since building an accelerator structure is a complicated and costly process, elimination of unnecessary steps has priority. In this paper an analysis of the influence of the enhanced field emission in superconducting radio frequency cavity together with modal field calculations by using COMSOL finite elements package has been presented. The obtained results reveal that the electric field required for the field emission is generated in the cavity irises. The imperfection of the cavity surface leading to very high fields is modelled by a simple cone. The estimated value of the enhancement factor for the cone tip of around 4 is in a good agreement with the data found in the literature. In addition, from the slopes and the intercepts of the Fowler-Nordheim plots, a dependence of the enhancement factor and the effective area on the work function has been estimated.
An algorithm for the Monte Carlo simulation of electron multiple elastic scattering based on the framework of SuperMC (Super Monte Carlo simulation program for nuclear and radiation process) is presented. This paper describes efficient and accurate methods by which the multiple scattering angular deflections are sampled. The Goudsmit-Saunderson theory of multiple scattering has been used for sampling angular deflections. Differential cross-sections of electrons and positrons by neutral atoms have been calculated by using Dirac partial wave program ELSEPA. The Legendre coefficients are accurately computed by using the Gauss-Legendre integration method. Finally, a novel hybrid method for sampling angular distribution has been developed. The model uses efficient rejection sampling method for low energy electrons (<500 keV) and larger path lengths (>500 mean free paths). For small path lengths, a simple, efficient and accurate analytical distribution function has been proposed. The later uses adjustable parameters determined from the fitting of Goudsmith-Saunderson angular distribution. A discussion of the sampling efficiency and accuracy of this newly developed algorithm is given. The efficiency of rejection sampling algorithm is at least 50 % for electron kinetic energies less than 500 keV and longer path lengths (>500 mean free paths). Monte Carlo Simulation results are then compared with measured angular distributions of Ross et al. The comparison shows that our results are in good agreement with experimental measurements.
In order to ensure the health and safety of female astronauts in space, the risks of space radiation should be evaluated, and effective methods for protecting against space radiation should be investigated. In this paper, a dose calculation model is established for Chinese female astronauts. The absorbed doses of some organs in two historical solar particle events are calculated using Monte Carlo methods, and the shielding conditions are 0 gcm-2 and 5 gcm-2 aluminum, respectively. The calculated results are analysed, compared, and discussed. The results show that 5 gcm-2 aluminum cannot afford enough effective protection in solar particle events. Hence, once encountering solar particle events in manned spaceflight missions, in order to ensure the health and safety of female astronauts, they are not allowed to stay in the pressure vessel, and must enter into the thicker shielding location such as food and water storage cabin.
The spatial and urban planning is one of the key instruments for the planned formation and development of locations for nuclear facilities, especially in terms of meeting the strict spatial conditionality, as well as in terms of the formation of protection zones in their surroundings. This paper systemizes the international criteria and requirements for the locations of nuclear facilities and analyses the spatial distribution of nuclear facilities in the surrounding countries of the Republic of Serbia. The research was conducted on the example of the location of the Vinca Institute of Nuclear Sciences, within which the fulfilment of spatial requirements, treatment of the location in the existing spatial and urban plans and relationship between other functions in the surrounding area were analysed. The paper proves the starting hypothesis that the general requirements related to both the spatial development of nuclear facilities locations and the protection from radiation have not been met in the Vinca location and its surroundings. It was determined that the spatial and urban plans encompassing the area of Vinca do not contain sufficiently specific planning solutions and that, as such, they do not provide a sufficient planning basis for meeting the necessary requirements and obligations regarding the protection from radiation. The paper also gives recommendations for further spatial development and protection of the Vinca location and its surroundings. The research condcted in this paper indicates the importance and priority of further research so that the necessary planning solutions for further development of the complex in Vinca and for the formation of protection zones could be defined through creating a new planning documentation. In addition, the paper particularly highlights the need for conducting a research to identify a location for permanent disposal of radioactive waste. It also indicates the necessity of considering the aspects of environmental protection and protection from radiation in the national and international context.
Senada Avdic, Beco Pehlivanovic, Mersad Music
et al.
This paper deals with correlation analysis of gamma dose rate measured in the test field with the five distinctive soil samples from a few minefields in Federation of Bosnia and Herzegovina. The measurements of ambient dose equivalent rate, due to radionuclides present in each of the soil samples, were performed by the RADIAGEMTM 2000 portable survey meter, placed on the ground and 1m above the ground. The gamma spectrometric analysis of the same soil samples was carried out by GAMMA-RAD5 spectrometer. This study showed that there is a high correlation between the absorbed dose rate evaluated from soil radioactivity and the corresponding results obtained by the survey meter placed on the ground. Correlation analysis indicated that the survey meter, due to its narrow energy range, is not suitable for the examination of cosmic radiation contribution.
Renata Havrankova, Jiri Havranek, Josef Kankovsky
et al.
The uranium processing plant MAPE Mydlovary in South Bohemia, Czech Republic, was in operation for about 30 years, from 1962 until 1991. Extensive remediation and reclamation work has been done in the area. In the study presented here we measured mass and volume activities of certain radionuclides in soil and water samples from the surroundings and measured gamma equivalent dose rates at the same locations. The average activity concentrations of 40K, 226Ra, and 238U in soil were 307.3 ? 4.4 Bq/kg, 133.4 ? 0.8 Bq/kg, and 113.2 ?3.8 Bq/kg, respectively, whereas in water they were 5.7 ? 0.3 Bq/L, 0.30 ? 0.03 Bq/L, and 1.8 ? 0.16 Bq/L, respectively. The gamma equivalent dose rate at 5 cm and 1 m height above ground was 0.15 ? ? 0.04 ?Sv/h and 0.15 ? 0.03 ?Sv/h, respectively. As shown by comparison with the findings for similar sites elsewhere in the world, as well as with the results of measurements at uncontaminated locations, these values are compatible with regulation limits and there is no reason for concern regarding the radiation protection for workers involved with further remediation and reclamation, or carrying out other activities in the area.
The VVR-S Nuclear Research Reactor at the ?Horia Hulubei? National Institute of Physics and Nuclear Engineering in Magurele, Bucharest, will be decommissioned applying the immediate dismantling strategy. The implementation of the decommissioning project started in 2010 and is planned for completion within 11 years. Good practices in decommissioning planning, organization, funding, and logistics are described in this paper.
The excited states of 93Mo have been investigated via the 93Nb(P,n?)93Mo reaction with proton beam energies of 2.5-4.3 MeV. The parameters of the nuclear level density formula were determined from the extensive and complete level scheme of 93Mo. The Bethe formula for the back-shifted Fermi gas model and the constant temperature model are compared with experimental level densities.