Radiation Source Research Articles

INNOVATIVE MEANS OF NORMALIZING PHYSICAL FACTORS THE ENVIRONMENT IN THE PROCESSES OF RECONSTRUCTION AND RESTORATION HISTORICAL HERITAGE OBJECTS

The problems of reconstruction and restoration of historical buildings and structures are relevant all over the world. It is especially important for Ukraine, where a large number of historical buildings and buildings of architectural value have been destroyed or damaged by military operations. The developed composite materials allow, due to their small thickness, to reduce the levels of electromagnetic fields and noise to values that meet modern international standards. A particularly important result is the reduction of low-frequency noise levels (by 12–30dB), which is practically not absorbed by building materials and structures. LED sources ultraviolet radiation can be used in the presence of people for at least 8 hours without reaching the maximum permissible exposure level of 30J/m2 according to SBM-2015. The use of LED ultraviolet radiation sources allows to increase the concentration of ions in deionized air to the standard concentration (500 cm-3) within 10 minutes according to SBM-2015 and disinfect the environment.

Tunable Luminescence in LiSc1‐yGayW2O8:Cr3+ Phosphors for LED Applications

AbstractAchieving emission peaks in the near‐infrared II regions (NIR II) and tunable near‐infrared (NIR) emission is still a huge challenge in the development of NIR phosphors. Here, a series of LiSc1‐yGayW2O8:Cr3+ phosphors are reported based on crystal engineering, whose luminescence can be tuned from NIR‐II to NIR I. LiScW2O8:Cr3+ possesses an ultra‐wide emission in the range of 850–1400 nm with peak at 1069 nm and a full width at half maximum (FWHM) of 225 nm and the main emission light is located in the NIR‐II region. Introducing Ga3+ into LiScW2O8:Cr3+ to form LiSc1‐yGayW2O8:Cr3+, the emission spectrum is blueshifted, which better aligns with the characteristic absorption lines of most functional groups. Additionally, the intensity of emission and thermal stability are also improved. The NIR phosphor‐converted light‐emitting diodes (pc‐LED) device is prepared by using the optimized LiSc0.5Ga0.5W2O8:0.12Cr3+ phosphor and green chip, and different characteristic absorptions are detected by measuring the NIR absorption of water and ethanol with the prepared pc‐LED as a radiation source. These results indicate that the ultra‐wide near‐infrared luminescence of LiSc1‐yGayW2O8:xCr3+ holds potential for applications in non‐destructive analysis.

Методы монохроматизации синхротронного излучения (обзор исследований)

The paper presents an analysis of studies related to the monochromatization of X-ray radiation (XR) at synchrotron radiation sources. A review of monochromators based on of X-ray diffraction on crystals is given, and the peculiarities of their technical realization are considered. The ideas about monochromators which include multilayer structures are examined. The authors also study technical problems arising during designing devices and its possible solutions. Introduction. The possibilities of using X-rays in scientific research are described. The high efficiency of synchrotron radiation sources is noted, and its characterization is given. Elementary information about diffraction of X-rays. The paper describes the properties of X-ray radiation and the possibilities of its using while studying various materials. Degree of monochromaticity. The degree of monochromaticity is an important characteristic of the synchrotron radiation (SR). Depending on the width of the wavelength band, “white”, “pink” and monochromatic beams are distinguished. Monochromators based on multilayer structures are used to obtain “pink” beams. Monochromatic radiation is formed using monocrystals. When conducting experiments with “white” beams, the monochromator is not used. The authors also describe the factors that violate the ideal fulfillment of the Wolf-Bragg condition and affect the degree of monochromaticity (heat, vibration). The reflectivity values at different beam grazing angles are noted to have different widths. Monochromators based on multilayer structures. Periodic structures combining thin layers of two heterogeneous materials make it possible to obtain “pink” beams. The wavelength bandwidth of such devices is one or two orders of magnitude greater than that of monochromators using crystals as optical elements. Configurations and geometry of optical elements. There are two types of X-ray diffraction on a crystal: Bragg and Laue diffraction. Bragg diffraction refers to reflective geometry, Laue diffraction is based on the passage of beams through the crystal. The section provides examples of monochromators with different configurations of crystals and X-ray mirrors. The arrangement of optical elements in a monochromator plays an important role in the geometry of the beam path. When designing monochromators, it is necessary to take into account the methods of fixation and orientation of the rotation axes of optical elements. Examples of monochromators with different configurations of crystals and X-ray mirrors are given. Focusing monochromators. It is possible to provide sagittal and meridional types of deformation by bending the optical element of the monochromator. Due to the curved crystal surface the beam is not only monochromatized but also subjected to focusing. Modern focusing monochromators are equipped with adaptivity elements allowing it to change the radius of curvature of the optical element. Examples of practical realization of such monochromators are presented. Thermal load of SR on optical elements. The SR is characterized by high brightness and a wide spectrum of emitted wavelengths. While operating optical elements of SR stations absorb a large amount of thermal power. The problems of heat dissipation have a fundamental influence on the quality of synchrotron radiation monochromatization. Additional information about monochromators. Examples of special design solutions for monochromators are given. Conclusion. The design of monochromators is relevant to the synchrotron radiation source 4+ “SKIF” under construction in Novosibirsk.

Cumulant method for identifying spatial distributions of laser beam intensity

The article considers the identification of spatial distributions of laser beam intensity, which is of significant practical importance for laser developers when certifying radiation sources. As an identification parameter, a measure of similarity of the measured axisymmetric distributions of laser radiation intensity with a given Gaussian distribution is proposed and investigated. To determine this measure, it is not necessary to first find the beam width at the waist. A mathematical apparatus for identification based on the use of cumulants of spatial intensity distributions is developed. A feature of the method is a limited number of cumulants of the Gaussian distribution, which makes it attractive for practical application. A comparative analysis of a number of two-dimensional distributions with a Gaussian distribution is carried out and it is shown that even with a small number of measured cumulants, high sensitivity of the method to the shapes of intensity distributions is ensured. A similarity measure for continuous one- dimensional intensity distributions of arbitrary shape is presented. The asymmetry measure of two-dimensional spatial distributions of laser beam intensity based on the ratio of moments and cumulants of the fourth and second orders is considered. The proposed measure of similarity of the measured axisymmetric intensity distributions with the Gaussian distribution is an alternative to the well-known propagation coefficient M 2 and can be used together with this coefficient.

Improving heat transfer efficiency via optimization and sensitivity assessment in hybrid nanofluid flow with variable magnetism using the Yamada–Ota model

Abstract The study aims to investigate the heat transfer efficiency in a hybrid nanofluid flow consisting of silver–molybdenum tetra sulphide (Ag–MoS4) with variable magnetism. The Yamada–Ota model is incorporated to account for viscous dissipation and heat source/sink effects, providing a comprehensive understanding of the fluid flow characteristics. However, the dissipative heat along with thermal radiation combined with the hybrid particles enriches the flow properties. The proposed model is simplified to its corresponding non-dimensional form for using proper similarity rules, and the set of transformed problems is handled numerically by employing the in-house MATLAB function bvp5c. The research utilizes a new statistical approach based on response surface methodology (RSM) and sensitivity evaluation to enhance the overall heat transmission performance. The work is conducted to obtain the relevant data on heat transfer rate. The concentration of nanoparticles, thermal radiation, and heat source are selected as the key parameters affecting the heat transfer efficiency. RSM is employed to optimize these parameters and determine the optimal conditions for enhanced heat transfer rate. Furthermore, the sensitivity analysis is performed to evaluate the efficiency of individual parameters on heat transportation. The findings of this study demonstrate that the hybrid nanofluid flow of Ag–MoS4 exhibits improved heat transfer efficiency compared to conventional fluids. Further, the Yamada–Ota conductivity model is also influential in enhancing the heat transfer properties.

The National Cancer Aid monitoring (NCAM-online) of ultraviolet radiation risk and protection behavior: a population-based observational trend study with four annual online survey waves

BackgroundUltraviolet (UV) radiation is the most important risk factor for skin cancer development. Sunlight is the main source of UV radiation in the general population. In addition, tanning beds are a source of artificial UV radiation. Since the incidence of skin cancer is increasing worldwide, it is necessary to monitor UV-related risk behaviors such as intentional indoor and outdoor tanning, as well as sun protection behavior in the general population and specific subgroups and settings. This is the aim of the National Cancer Aid Monitoring online (NCAM-online), a continuation and further development of the NCAM.MethodsThe NCAM-online is a longitudinal trend study consisting of four annual survey waves. Each year, 4,000 individuals aged 16–65 years living in Germany will be surveyed using online questionnaires. Each year, intentional indoor and outdoor tanning will be assessed. In addition, varying specific topics regarding skin cancer prevention, such as the utilization of skin cancer screening, will be addressed in the questionnaires.DiscussionThe findings of the NCAM-online will provide an important basis for the German Cancer Aid and Working Group on Dermatologic Prevention (Arbeitsgemeinschaft Dermatologische Prävention, ADP) to develop targeted prevention campaigns and projects aimed at preventing skin cancer. The explorative nature of the NCAM-online allows for the identification of new potential starting points for prevention and education. In addition, the longitudinal design allows for a description of the trend in the prevalence of intentional tanning. For tanning bed use, representative trend data from 2012 are available for Germany, to which NCAM-online will add annual data until 2027.

High-Accuracy Calibration Method of a Thermal Camera Using Two Reference Blackbodies.

Body temperature is one of the most important physiological parameters of a human being used to assess his basic vital functions. In medical practice, various types of measuring instruments are used to measure temperature, such as liquid thermometers, electronic thermometers, non-contact ear thermometers, and non-contact forehead thermometers. Such body temperature measurement techniques require the connection of appropriate sensors to a person, and non-contact thermometers operate over short distances and force a specific position of the person during the measurement. As a result, using the above methods, it is practically impossible to perform body temperature measurements of a moving human being. A thermal imaging camera can be used effectively for the purpose of the temperature measurement of moving objects, but the remote measurement of a human body temperature using a thermal imaging camera is affected by many factors that are difficult to control. Accurate remote measurement of human body temperature requires a measurement system that implements a specialized temperature determination algorithm. This article presents a model of a measurement system that facilitates the development of a highly accurate temperature measurement method. For the model, its parameters were determined on the calibration stand. The correct operation of the developed method and the effectiveness of temperature measurement have been confirmed by tests on a test stand using reference radiation sources.

Nuclear-excited source of coherent and incoherent radiation with direct nuclear pumping

Uranium fission fragments, as well as the products of 3He(n,p)3H and 10B(n,α)7Li nuclear reactions were utilized in the nuclear reactor for gas ionization and excitation. However, the 6Li(n,α)3H nuclear reaction was less examined. The use of lithium-6 as a surface source of excitation of the gas medium, due to the long path length of tritium nuclei in the gas, allows to excite large volumes of gas as opposed to using 235U or 10B.While investigating the luminescence of noble gases in the core of the IVG.1M research reactor, we noted an appearance of alkali metal lines and a sharp increase in the intensity of these lines at temperatures above 570 K. It was determined that the population of levels of lithium atoms has practically no effect on the population of the 2p-levels of atoms of noble gases. The selectivity of p- and s-levels deactivation by lithium atoms implies the possibility of creating inversion of population at 2p-1s transitions of noble gas atoms. Successful experiments to study the luminescence of gases upon excitation by 6Li(n,α)3H nuclear reaction products allow us to proceed to experiments to achieve the laser action threshold and study the lasing characteristics of gas mixtures at the IGR pulsed nuclear reactor with thermal neutron flux density up to 7∙1016 n/cm2s. For this purpose, an experimental device designs were proposed to perform experiments on the IGR reactor. A step-by-step procedure of fabrication of a nuclear-excited source for excitation of gas mixtures is provided. The results of reactor experiments aimed at determining the spectral and temporal characteristics of optical radiation during excitation of gas mixtures by 6Li(n,α)3H nuclear reaction products are presented.

Gamma, electron beam and X-ray irradiation effects on polymers in an advanced bone cement mixer device

The medical device industry has been investigating ways to increase the use of alternatives to cobalt-60 gamma radiation and ethylene-oxide gas sterilization, such as electron beam (E-beam) and X-ray radiation, due to regulatory and market pressures. One impediment to switching to E-beam or X-ray technology for sterilization is the lack of data on the effects of these radiation sources on medical device polymers. To provide such data this work considers irradiation and testing of a common single-use medical bone cement mixing system, the Stryker Advanced Cement Mixer (ACM®), that is composed of seven polymer materials. The ACM® devices considered here were processed to sterilization-relevant doses (15, 25, 50, and 70 kGy) using three radiation technologies: gamma, E-beam, and X-ray. The system and its polymer components were tested for product functionality, as well as mechanical and visual properties to determine how exposure effects may be influenced by radiation technology and dose level. We found that although there were instances of statistically significant differences in effects between the gamma-irradiated products and those irradiated with E-beam and X-ray, those effects were negligible in terms of retained functionality of the product and retained mechanical properties of the polymer components. Overall, results of this study demonstrate that, for of the effects studied, E-beam and X-ray are viable alternatives to cobalt-60 gamma radiation for sterilization of the polymer-based device investigated.

BSP – Computer code for evaluating protection against bremsstrahlung radiation from extended beta radiation sources

For a long time, radiation safety specialists have been aware of computer codes designed to calculate human dose exposure from beta or gamma radiation. However, these products have a major drawback: they do not consider the radiation fields generated by extended beta radiation sources due to bremsstrahlung. Existing solutions are either not widely available or use outdated nuclear-physical constants and methods for calculating dosimetric characteristics. A computer code was developed specifically for calculating shielding against bremsstrahlung. It allows to estimate effective, equivalent, exposure dose rate, ambient dose equivalent, and air kerma rate from bremsstrahlung. It utilizes the ANS/ANSI 6.4.3 materials data and the last dose conversion factors from ICRP 116.

Photodegradation of Polycyclic Aromatic Hydrocarbons Under Visible Light Using Modified g-C3N4 as Photocatalyst, Spectroscopic Studies

In this work, visible light was used for the photodegradation of polycyclic aromatic hydrocarbons (PAHs) using graphitic carbon nitride (g-C3N4) and it was modified as a photocatalyst. Modification of g-C3N4 was performed using SDS, MIL-101, and TiO2. The UV–Vis spectroscopy, XRD, and FTIR spectrometry were applied for characterization. The photodegradation of pyrene and anthracene was investigated using the photocatalyst. Results indicated that the modified photocatalytic has better photocatalytic properties than that unmodified due to the more surface area and better optical properties of the former. Results also revealed that the photodegradation efficiency significantly improved by using g-C3N4@TiO2 so that it degrades about 95% of the pyrene molecules within 12 h. While g-C3N4@ SDS and g-C3N4@ MIL-101 are degraded very low (below 10%) under the same circumstances. The LED lamp (8 W) was used as a source of radiation. Photodegradation of anthracene was also investigated; results revealed that the anthracene is degraded more quickly than the pyrene, so that after 6 h about 98% of anthracene is decomposed. The mechanism of photodegradation was discussed.

MPPD: A User-Friendly Posture Deformation Program for Mesh-Type Computational Phantoms.

Recently, the International Commission on Radiological Protection (ICRP) released adult Mesh-type Reference Computational Phantoms (MRCPs), which have great advantage in high deformability. Previous studies have exploited their high deformability to investigate the dosimetric influence of varying statures and postures, demonstrating significant variations in radiation doses. However, the previous studies are constrained by their inability to consider both stature and posture concurrently and by the limited range of postures analyzed. In the present study, a computer program named MPPD (Mesh-type Phantom Posture Deformer) was developed, a user-friendly graphical user interface that enables users to adjust the posture of adult MRCPs and corresponding library phantoms. The MPPD program was applied to deform five adult male phantoms of different statures into sitting and kneeling postures, showcasing its rapid computational speed and minimal RAM usage. The effectiveness of the MPPD program for dose calculation was also investigated by computing the detriment-weighted doses for MPPD-deformed adult male MRCPs, which showed good agreement with dose values for existing posture-deformed phantoms of the previous study. Furthermore, as an application of the MPPD program, the combined dosimetric impact of stature and posture was investigated, which is the inaugural effort to estimate doses by considering these factors concurrently. The result showed that the impact of stature and posture on radiation doses could largely vary depending on the radiation source, highlighting the importance of simultaneous consideration of stature and posture for accurate dose estimation.

Photons from macroscopic currents

Coherent states are a well-established tool of quantum optics to describe electromagnetic waves in terms of photons. However, they do not describe the near-field regime of macroscopic radiation sources. Instead, we generically use classical solutions of Maxwell’s equations to describe radiation in the near-field regime. The classical solutions provide linear relations between currents and emitted electromagnetic fields, whereas evolution of states at the quantum level involves photons. This begs the question how we can describe macroscopic fields from antennas or magnetic coils in terms of elementary photons. The present paper answers this question through the construction of generalized Glauber states for macroscopic radiation emitters.

Microprocessor Control of the Electric Drive of Variable Radiation Installation and Ensuring of Operation Reliability

Introduction. The introduction of energy-saving technologies has become particularly relevant in recent years, when energy prices have been constantly increasing. This is particularly important for greenhouse farms, where the main condition for growing plants indoors is the creation of artificial climatic conditions: temperature, humidity, and lighting.Problem Statement. Given the light and the dark stages of photosynthesis, it becomes possible to use a variable light field in the plant-growing photoculture, which is created by light installations with variable radiation. The development of an energy-saving electric drive and automated control systems for the parameters of artificial climatic conditions when growing plants indoors results in reducing energy consumption and increasing the reliability of the technological process in greenhouses of agro-industrial complex.Purpose. Implementation of energy-saving variable illumination irradiating systems with an automated control system for greenhouse farms.Materials and Methods. A lighting installation with rotation of the irradiator in the vertical and horizontal planes with a discrete electric drive and microprocessor control has been used.Results. The current state of variable irradiating systems with energy-saving radiation sources has been analyzed. The use of a discrete electric drive with an automated control system has been proposed. The installation with a DNAT-400 radiation source and a ZHO-01 reflector enables irradiating an area of up to 100 m2. The maximum exposure to photosynthetically active radiation is 30 W/m2, and the irradiation irregularity does not exceed 20%. At the same time, electricity savings reach about 10 thousand kWh per season. The yield and quality of products remain unchanged.Conclusions. The results of the research have confirmed the feasibility of practical implementation of variable irradiation system for energy efficiency of greenhouse operations.

Flexible and Ecological Cotton-Based Dosimeter for 2D UV Surface Dose Distribution Measurements.

This work presents a 2D radiochromic dosimeter for ultraviolet (UV) radiation measurements, based on cotton fabric volume-modified with nitroblue tetrazolium chloride (NBT) as a radiation-sensitive compound. The developed dosimeter is flexible, which allows it to adapt to various shapes and show a color change from yellowish to purple-brown during irradiation. The intensity of the color change depends on the type of UV radiation and is the highest for UVC (253.7 nm). It has been shown that the developed dosimeters (i) can be used for UVC radiation dose measurements in the range of up to 10 J/cm2; (ii) can be measured in 2D using a flatbed scanner; and (iii) can have the obtained images after scanning be filtered with a medium filter to improve their quality by reducing noise from the fabric structure. The developed cotton-NBT dosimeters can measure UVC-absorbed radiation doses on objects of various shapes, and when combined with a dedicated computer software package and a data processing method, they form a comprehensive system for measuring dose distributions for objects with complex shapes. The developed system can also serve as a comprehensive method for assessing the quality and control of UV radiation sources used in various industrial processes.

An In-depth Analysis of the Adverse Effects of Ionizing Radiation Exposure on Cardiac Catheterization Staffs.

Diagnostic and interventional angiograms are instrumental in the multidisciplinary approach to CAD management, enabling accurate diagnosis and effective targeted treatments that significantly enhance patient care and cardiovascular outcomes. However, cath lab staff, including interventional cardiologists, is consistently exposed to ionizing radiation, which poses inherent health risks. Radiation exposure in the cath lab primarily results from the use of fluoroscopy and cineangiography during diagnostic and interventional procedures. Understanding these risks and implementing effective radiation protection measurements are imperative to ensure the well-being of healthcare professionals while delivering high-quality cardiac care. Prolonged and repeated exposure can lead to both deterministic and stochastic effects. Deterministic effects, such as skin erythema and tissue damage, are more likely to occur at high radiation doses. Interventional cardiologists and staff may experience these effects when safety measures are not rigorously followed. In fact, while ionizing radiation is essential in the practice of radiation cardiology ward, cath lab staff faces inherent risks from radiation exposure. Stochastic effects, on the other hand, are characterized by a probabilistic relationship between radiation exposure and the likelihood of harm. These effects include the increased risk of cancer, particularly for those with long-term exposure. Interventional cardiologists, due to their frequent presence in the cath lab, face a higher lifetime cumulative radiation dose, potentially elevating their cancer risk. Protective measures, including the use of lead aprons, thyroid shields, and radiation monitoring devices, play a crucial role in reducing radiation exposure for cath lab personnel. Adherence to strict dose optimization protocols, such as minimizing fluoroscopy time and maximizing distance from the radiation source, is also essential in mitigating these risks. Ongoing research and advancements in radiation safety technology are essential in further for minimizing the adverse effects of ionizing radiation in the cath lab.

Force-free Wave Interaction in Magnetar Magnetospheres: Computational Modeling in Axisymmetry

Crustal quakes of highly magnetized neutron stars can disrupt their magnetospheres, triggering energetic phenomena like X-ray and fast radio bursts. Understanding plasma wave dynamics in these extreme environments is vital for predicting energy transport across scales to the radiation length. This study models relativistic plasma wave interaction in magnetar magnetospheres with force-free electrodynamics simulations. For propagation along curved magnetic field lines, we observe the continuous conversion of Alfvén waves to fast magnetosonic (FMS) waves. The conversion efficiency can be up to three times higher when counter-propagating Alfvén waves interact in the equatorial region. Alfvén waves generate FMS waves of twice their frequency during their first crossing of the magnetosphere. After the initial transient burst of FMS waves, Alfvén waves convert to FMS waves periodically, generating variations on timescales of the magnetospheric Alfvén wave crossing time. This decaying FMS wave tail carries a significant portion (half) of the total energy emitted. Plastic damping of “bouncing” Alfvén waves by the magnetar crust has minimal impact on the FMS efficiency. We discuss the implications of the identified wave phenomena for magnetar observations. Outgoing FMS waves can develop electric zones, potential sources of coherent radiation. Long wavelength FMS waves could generate FRBs through reconnection beyond the light cylinder.

THEORETICAL INVESTIGATION FOR YTTERBIUM EFFECT ON RADIATION SHIELDING CHARACTERISTICS OF 50Bi2O3-15Li2O-15PbO-(20-X)B2O3-Yb2O3 BORATE GLASSES

As the nuclear industry has developed and radiation technologies have become more widely used, the dose of radiation from both synthetically produced sources and radioisotopes has increased, as has the number of people being irradiated. It is of the utmost importance to utilise appropriate shielding materials in order to reduce the negative effects of radiation sources. Doped glasses are among the most significant candidate materials in the field of radiation shielding. To this end, it was aimed to investigate the charged particle, gamma-ray and neutron shielding characteristics of ytterbium doped glasses with composition of 50Bi2O3-15Li2O-15PbO-(20-x)B2O3-Yb2O3 (where x = 0.5, 1.0, 1.5, 2.0 and 2.5). In this regard, the radiation shielding parameters were estimated by using Phy-X/PSD, PAGEX, ESTAR, and SRIM codes. Furthermore, the results were compared comprehensively and comparatively. Charged particle (alpha, proton and electron), gamma ray and neutron shielding efficiencies were found to be proportional to ytterbium content. The glasses with the increasing amount of ytterbium exhibited higher shielding performances. It can be said that all the studied glasses and particularly Yb2.5 sample could be used as shielding materials in many radiation related applications.

Towards accurate dose assessment for emergency industrial radiography source retrieval operations: A preliminary study of 4D Monte Carlo dose calculations

The exposure devices utilizing high-activity gamma radiation sources for industrial radiography frequently encounter issues such as stuck or disconnected sources, posing a substantial risk of radiation exposure to the workers executing emergency source retrieval operations, emphasizing the importance of accurate dose assessment. In the present study, the radiation dose to the main worker during the process of source retrieval was calculated and compared for five emergency source retrieval procedures to retrieve stuck or disconnected sources, using 4D Monte Carlo dose calculation and a mesh-type reference computational phantom. For a stuck source, the dose values of the two source retrieval procedures (i.e., repair and cut methods) were found to be relatively small, which indicates that the worker might select either method based on personal preference or situational convenience. Conversely, for a disconnected source, the dose values of the three source retrieval procedures (i.e., fishing, connect/push, and hot stick methods) were much larger and show significant differences. Notably, the fishing method was associated with the lowest dose, whereas the hot stick method resulted in significantly higher doses, differences being as large as ∼5 times. These results underscore the fishing method as a preferable option, particularly over the hot stick method.

THE CONCENTRATION OF NATURAL RADIATION SOURCES (NRS), MAINLY 238U, 232Th, and 40K, IN BUILDING MATERIALS (SAND, CLAY BRICKS, AND CONCRETE BLOCKS) USED ALONG KANGUNDO ROAD, NAIROBI KENYA

This research aimed at assessing the concentration of Natural Radiation Sources (NRS), mainly 238U, 232Th, and 40K, in building materials (sand, clay bricks, and concrete blocks) used along Kangundo Road in Nairobi City County. Human exposure to ionising radiation is largely due to Natural Radiation Sources (NRS). These radioactive elements with long half-lives are found in the Earths lithosphere and in construction materials with radiation levels varying due to their geology. A purposive random sampling method was deployed in this work to collect samples of building materials for analysis. The radioactivity concentration levels in the sampled building materials were determined using a NaI (TI) spectrometer at Kenyatta University laboratory. The activity concentration of 40K varied from 151 ± 8 to 2392 ± 120 Bq/kg, 238U varied from 27 ± 2 to 412 ± 21 Bq/kg and 232Th ranged from 54 ± 3 to 612 ± 31Bq/kg. More than 70 per cent of the samples analysed had activity concentration surpassing the world permissible limits of 420 Bq/kg, 33 Bq/kg, 45 Bq/kg for 40K, 238U and 232Th respectively. The study therefore recommended that assessment of radioactivity concentration for samples with high radioactivity values.