Rodents cutting the installation system with their teeth were a frequent issue with electric installation in the era of classical architecture. However, contemporary architectural systems with photovoltaic sources of energy, accompanied by premises' smart systems of information and energy transfer, have microorganisms destroying the optical and other types of installation. This work represents building systems of residential premises with photovoltaic sources of energy which point out the segments of urban areas jeopardized by the possible appearance of microorganisms. Afterward, a review of laser techniques for the detection, identification, and destruction of such microorganisms was given. It was concluded where to direct the further laser system development to protect smart buildings from biological contamination.
The steady-state thermal-hydraulic analysis of the core of the Boiling Water Reactor (BWR/6) at nominal operating conditions is presented in this paper. The BWR/6 is produced by General Electric USA. The analysis' goal is to keep the thermal safety margin under control and the core integrity intact under steady-state operating conditions. The effects of operating conditions such as power distribution, power level, and coolant mass flow rate on the pro- posed core's performance are investigated. For this purpose, the one-dimensional computer code MITH was used. The code's reliability was tested using the General Electric benchmark 3579 MW reactor. Two-channel models were tested (the average and the hot channel). Ther- mal-hydraulic parameters such as fuel-centerline, fuel-surface, outer clad surface and coolant temperature, critical and actual local heat flux, critical and minimum critical heat flux ratio and pressure drop are evaluated along the tested channels. Temperatures, as well as actual and critical heat flux distribution profiles, were obtained. The tested operating conditions had a significant influence on these parameters, and also on the thermal-hydraulic performance. The obtained results are in good agreement with the data from the tested core. The obtained results are well within the safety margins. The good agreement between tested reactor data and MITH code calculation concerning the reactor demonstrates the reliability of the analysis methodology from a thermal-hydraulic perspective.
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.
Anamaria Pazanin, Damijan Skrk, Nika Zalokar
et al.
The purpose of this research was to determine the impact of collimation in thoracic spine radiography on patient exposure and image quality. The study was performed on 84 patients referred to thoracic spine radiography. Patients were randomly divided into two equal groups of 42. The first group was imaged according to the standard collimation protocol used in one of the hospitals in Croatia while the second group was imaged by applying ?optimal? collimation, image field size was individually collimated for each patient or according to the greatest image field collimation depicted in professional literature. For each patient body mass index, image field size, exposure conditions and dose area product were noted and absorbed doses by organs were calculated, image quality was assessed. There were no statistically significant differences in BMI between the two groups of patients. With the optimal collimation the size of the imaging field in the anteroposterior projection was reduced by 45 % ( p < 0.001) and in the lateral projection by 41 % (p < 0.001). The study also showed reduced values of DAP for anteroposterior projection by 34 % ( p = 0.007) and for lateral projection by 23 % ( p = 0.040). The mean absorbed dose to the selected organs decreased by 26 % in the anteroposterior projection and by 28 % in the lateral projection. In addition, the optimal collimation protocol improved image quality by 13 % in anteroposterior projection. No differences in image quality were found in lateral projection. By carrying out this research we have demonstrated that optimal collimation in thoracic spine imaging has a strong influence on patient exposure to radiation and has a positive impact on image quality.
An electron beam from the UELR-10-15S2 accelerator (average energy of 9.92 ? 0.48 MeV) was applied to irradiate food and medical items at the Research and Development Center for Radiation Technology, Vietnam Atomic Energy Institute, Vietnam. The materials are under an electron beam window, such as irradiation products, conveyor, magnet and shielding material for the magnet coil, bombarded by electrons and generated X-ray (bremsstrahlung effect). In this article, X-ray conversion efficiency from polypropylene, aluminum, iron, and lead bombarded by an electron beam from the UELR-10-15S2 accelerator is measured by the film dosimeter and simulated by the MCNP4c2 code, and there is good agreement between the calculation and measurement results. The results show that X-ray conversion efficiency is the highest from lead (4.3 %), so the gamma - neutron reaction (Q-value of -6.74 MeV for 207Pb) has to be studied in food and medical items irradiated by a 10 MeV eelectron beam.
Mahmoud Abbas, Sara Yoseph, Ahmed El-Khatib
et al.
To understand the nuclear structure for most elements, it is essential to investigate the nuclear excitations by using high precision gamma-ray spectroscopy in which intensive measurements should be carried out. This is becoming a new challenge for the radiation scientific community nowadays, where the instrumentations and technical advances must be developed to be used in a wide range of applications. To discover the weakest nuclear reaction, the maximum probability of the detection system of the total energy of any released individual photon must be determined. In this work, a new mathematical method to calculate the absolute full-energy peak efficiency of asymmetrical polyhedron germanium detector is presented. This type of detector can be arranged in array, forming ?complex detectors of encapsulated germanium crystals?, with the solid angle reaching 82 % of total solid angle coverage, i. e., with the highest possible efficiency and with a good quality of spectral response. In addition, the photon path length was enclosed in the mathematical method to determine its attenuation through different materials such as, the detector active medium and any other material in-between source-detector system during the measuring process. The comparison between the efficiency calculated in this work and that of the published Monte Carlo simulation showed a good agreement and a small variation. However, the method discussed in the current work can be useful in nuclear safeguards, in overcoming the huge difficulties in identification of the energy range of radioactive isotopes and their quantities in nuclear waste.
Editorial Board of the Nuclear Technology & Radiation Protection journal regrets to in form the audience of the journal that in the list of authors of the article APPLICATION OF AN ELECTRONEGATIVE GAS AS A THIRD COMPONENT OF THE WORKING GAS IN THE GEIGER-MULLER COUNTER by Luka S. PERAZIC, Cedomir I. BELIC, and Dalibor B. ARBUTINA published in the Vol. 33 (2018), 3, pp. 268-274, was made a mistake concerning the third author''s name. It should be as follows: Dalibor S. ARBUTINA Editorial Board offers an apology for this mistake to Mr. Dalibor S. Arbutina and the readers of the Nuclear Technology & Radiation Protection journal. <br><br><font color="red"><b> Link to the corrected article <u><a href="http://dx.doi.org/10.2298/NTRP1803268P">10.2298/NTRP1803268P</a></b></u>
Taher Yousefi, Hamid Mahmudian, Meisam Torab-Mostaedi
et al.
To improve the mechanical properties, the cobalt ferrocyanide precipitation was carried out on clinoptilolite as an inorganic polymer. In this work the combination of two important factors, stability (zeolite) and high adsorption capacity (cobalt ferrocyanide) were considered to improve the ions uptake ability of adsorbent. The modification was approved by X-ray diffraction, Scanning electronic microscopy and Fourier transform infrared spectroscopy. The modified zeolite was applied to remove Sr(II) and Cs(I) ions from aqueous solution in a batch system. The adsorption capacities of modified zeolite for Cs(I) and Sr(II) improved to 90 and 130 mgg-1, respectively. The Sr(II) and Cs(I) removal were investigated as a function of shaking time, pH, Sr(II), and Cs(I) initial concentration and temperature. The experimental data were fitted well to Langmuir isotherm model for two sorbet metal ions. The time dependence sorption data showed that the uptakes of Cs(I) and Sr(II) were very rapid and apparent sorption equilibriums were achieved within 100 min of contact time. The kinetic experimental data were fitted to the pseudo-first order, pseudo-second order, the double exponential, Elovich and intraparticle diffusion models. The sorption rates and capacities as well as rate constants were evaluated.
When using gamma ray spectrometry for radioactivity analysis of environmental samples (such as soil, sediment or ash of a living organism), relevant linear attenuation coefficients should be known - in order to calculate self-absorption in the sample bulk. This parameter is additionally important since the unidentified samples are normally different in composition and density from the reference ones (the latter being e. g. liquid sources, commonly used for detection efficiency calibration in radioactivity monitoring). This work aims at introducing a numerical simulation method for calculation of linear attenuation coefficients without the use of a collimator. The method is primarily based on calculations of the effective solid angles - compound parameters accounting for the emission and detection probabilities, as well as for the source-to-detector geometrical configuration. The efficiency transfer principle and average path lengths through the samples themselves are employed, too. The results obtained are compared with those from the NIST-XCOM data base; close agreement confirms the validity of the numerical simulation method approach.
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.
A sensitivity analysis of a point kernel code was performed to investigate the effect of mesh division of a volume source on the radiation flux at points of interest. The QAD-CGGP, known as a representative point kernel code, was employed for a series of calculations and these calculation results compared with the reference data obtained from the MCNP5-1.60 code. The spherical volume source widely used in radiation shielding was also considered in this work and the mesh division along the radius was performed in two ways (regular and irregular). In addition, an approximate equation was defined to correct the significant error that occurs as an outcome of the point source assumption. As a result, in the case of a regular mesh division, a minimum mesh size of 1 cm is required to produce accurate results in comparison to the MCNP ones, while in the other instance, a half-level mesh division is sufficient to obtain the same result from the standpoint of the level of accuracy. In addition, by introducing the approximate equation presented in this paper, a significant error resulting from the point source assumption is exponentially reduced from a maximum of ~30% to a maximum of ~11%. Therefore, it is to be expected that the appropriate level of mesh division is required so as to increase the accuracy of the calculation using a point kernel method.
The partitioning and transmutation strategy has increasingly attracted interest for the safe treatment and disposal of high level liquid waste, in which the partitioning of high level liquid waste is one of the critical technical issues. An improved total partitioning process, including a tri-alkylphosphine oxide process for the removal of actinides, a crown ether strontium extraction process for the removal of strontium, and a calixcrown ether cesium extraction process for the removal of cesium, has been developed to treat Chinese high level liquid waste. A test system containing 72-stage 10-mm-diam annular centrifugal contactors, a remote sampling system, a rotor speed acquisition-monitoring system, a feeding system, and a video camera-surveillance system was successfully developed to carry out the hot test for verifying the improved total partitioning process. The test system has been successfully used in a 160 hour hot test using genuine high level liquid waste. During the hot test, the test system was stable, which demonstrated it was reliable for the hot test of the high level liquid waste partitioning.
Fiifi Asah-Opoku, Zhihua Liang, Ziaul Huque
et al.
Global energy problems range from the increasing cost of fuel to the unequal distribution of energy resources and the potential climate change resulting from the burning of fossil fuels. A sustainable nuclear energy would augment the current world energy supply and serve as a reliable future energy source. This research focuses on Monte Carlo simulations of pressurized water reactor systems. Three different fuel grades - mixed oxide fuel (MOX), uranium oxide fuel (UOX), and commercially enriched uranium or uranium metal (CEU) - are used in this simulation and their impact on the effective multiplication factor (Keff) and, hence, criticality and total radioactivity of the reactor core after fuel burnup analyzed. The effect of different clad materials on Keff is also studied. Burnup calculation results indicate a buildup of plutonium isotopes in UOX and CEU, as opposed to a decline in plutonium radioisotopes for MOX fuel burnup time. For MOX fuel, a decrease of 31.9% of the fissile plutonium isotope is observed, while for UOX and CEU, fissile plutonium isotopes increased by 82.3% and 83.8%, respectively. Keff results show zircaloy as a much more effective clad material in comparison to zirconium and stainless steel.
Dragan Brajovic, Milos Vujisic, Mirko Stojkanovic
et al.
This paper investigates the stabilization of electrical discharges in gases by means of external ionizing radiation. Discharges in a gas-filled surge arrester model were studied in both passive and active regimes of the device. An originally developed model of the gas-filled surge arrester was used. Gas pressure and the interelectrode gap were the variable parameters in our measurements. Applied radiation types included ?-particles, ?-rays, X-rays, and neutrons. Measurements were performed under highly controlled laboratory conditions. The combined measurement uncertainty of the applied procedure was estimated as being under the 5% level. The results obtained are followed by a theoretical explanation. The crucial result is the conclusion that ionizing radiation does not necessarily degrade the gas-filled surge arrester?s functionality but that it, rather, improves it under certain conditions.
Short-lived exotic nuclei can be produced and separated with the high-energy nuclear beam facility called fragment separator at the Centre for Heavy Ion Research. These nuclides can be injected and stored in the storage ring called experimental storage ring. The lower lifetime limit of the presently existing methods for mass measurements on these nuclides at the experimental storage ring is about a few seconds. We have developed and investigated an isochronous operational mode of the future collector ring, that makes mass measurements feasible for nuclides with lifetimes down to a few microseconds. A mass resolving power of about 150 000 is expected.
Sotiria Papandreou, Marilia Savva, Konstantinos Karfopoulos
et al.
The activity concentration of 7Be in atmospheric aerosol can exhibit seasonal variations due to various physical processes taking place in the troposphere and stratosphere, as well as due to solar activity. An investigation of these variations has been carried out at the Nuclear Engineering Department of the National Technical University of Athens over a two year period (3/2008-4/2010). In the framework of this study, sampling and analysis methods were appropriately selected to allow for the observation of short-term 7Be air activity concentration variations, using a 4-hour sampling interval, while taking in consideration type A and type B uncertainties introduced in the measurements. In order to study the role of precipitation in surface air 7Be activity concentration variations, a procedure for collecting and analyzing rainwater was developed. The techniques used in the present study allowed for the observation of seasonal and diurnal 7Be concentration variations, as well as correlations between 7Be activity concentration and the meteorological parameters of air temperature and relative humidity.