Main Radiation Source Research Articles

Assessment of tracheobronchial and lung dose due to radon and thoron inhalation.

The main sources of natural background radiation are radon, thoron and their progeny, which may cause health risks to humans. Keeping in mind the importance of the subject, three samples each from 10 selected residential areas, including the centre of Babylon Governorate, Iraq, and its districts, were collected. Concentration of radon and thoron was measured using solid-state track detectors (CR-39). The arithmetic means of the concentration of radon and thoron were 47.367±19.56 and 133.246±16.585 Bqm-3, respectively; these values are considered safe when compared with the upper reference level of 200-600 Bqm-3 recommended by the International Commission for Radiological Protection (ICRP). The value of the inhalation equivalent dose from radon gas discovered in these areas with rate 37.893 nSv is less than the value of the global average of 1.15 mSv. This indicates that the risks related to inhalation of radon are low as the lung dose rate (DLung), tracheobronchial region (DT-B), annual effective dose (AED) and excess lifetime cancer risk (ELCR) is (1.894 nGyh-1, 22.736 nSv, 0.236 mSvy-1 and 0.835 x10-3), respectively. While the value of the inhalation equivalent dose (IED) from thoron as effective dose to lung DLung, AED and ELCR are equal to (0.133 nSv, 0.167 mSvy-1 and 0.587 x 10-3), respectively. To conclude, the rates in the study area are less than the ICRP recommended level of 3 mSv; therefore, the studied areas are safe from the health risks of inhalation of radon and thoron.

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.

Learning CT-free attenuation-corrected total-body PET images through deep learning.

Total-body PET/CT scanners with long axial fields of view have enabled unprecedented image quality and quantitative accuracy. However, the ionizing radiation from CT is a major issue in PET imaging, which is more evident with reduced radiopharmaceutical doses in total-body PET/CT. Therefore, we attempted to generate CT-free attenuation-corrected (CTF-AC) total-body PET images through deep learning. Based on total-body PET data from 122 subjects (29 females and 93 males), a well-established cycle-consistent generative adversarial network (Cycle-GAN) was employed to generate CTF-AC total-body PET images directly while introducing site structures as prior information. Statistical analyses, including Pearson correlation coefficient (PCC) and t-tests, were utilized for the correlation measurements. The generated CTF-AC total-body PET images closely resembled real AC PET images, showing reduced noise and good contrast in different tissue structures. The obtained peak signal-to-noise ratio and structural similarity index measure values were 36.92 ± 5.49 dB (p < 0.01) and 0.980 ± 0.041 (p < 0.01), respectively. Furthermore, the standardized uptake value (SUV) distribution was consistent with that of real AC PET images. Our approach could directly generate CTF-AC total-body PET images, greatly reducing the radiation risk to patients from redundant anatomical examinations. Moreover, the model was validated based on a multidose-level NAC-AC PET dataset, demonstrating the potential of our method for low-dose PET attenuation correction. In future work, we will attempt to validate the proposed method with total-body PET/CT systems in more clinical practices. The ionizing radiation from CT is a major issue in PET imaging, which is more evident with reduced radiopharmaceutical doses in total-body PET/CT. Our CT-free PET attenuation correction method would be beneficial for a wide range of patient populations, especially for pediatric examinations and patients who need multiple scans or who require long-term follow-up. • CT is the main source of radiation in PET/CT imaging, especially for total-body PET/CT devices, and reduced radiopharmaceutical doses make the radiation burden from CT more obvious. • The CT-free PET attenuation correction method would be beneficial for patients who need multiple scans or long-term follow-up by reducing additional radiation from redundant anatomical examinations. • The proposed method could directly generate CT-free attenuation-corrected (CTF-AC) total-body PET images, which is beneficial for PET/MRI or PET-only devices lacking CT image poses.

Measurement of the Convection Velocities in a Hypersonic Turbulent Boundary Layer Using Two-Point Cylindrical-Focused Laser Differential Interferometer

A two-point cylindrical-focused laser differential interferometer (2P-CFLDI) system and a conventional Z-type Schlieren were used to measure the hypersonic turbulent boundary layer on a flat plate at Mach number Ma = 6 and Reynolds number Re = 1.08 × 106 m−1. The boundary layer thickness at the measurement location and the noise radiation angle were obtained by post-processing the Schlieren image. The 2P-CFLDI data underwent cross-correlation analysis to calculate the mean convective velocities at different heights and compared with previous experimental and numerical results. The experimentally measured mean convective velocities agree with the trend of available DNS and experimental results. The mean convective velocity near the wall is significantly larger than the local mean velocity and is the main noise source region. Further filtering treatment shows that the convective velocity of the disturbed structure decreases gradually with the increase in the disturbance scale. The differences between convective velocities at different scales are significantly larger outside the boundary layer than inside the boundary layer, which is in agreement with the findings of the previous hot wire experiments. Near the wall, large-scale disturbances mainly determine the localized mean convective velocity, which are the main source of noise radiation for the hypersonic turbulent boundary layer.

СОВЕРШЕНСТВОВАНИЕ АКУСТИЧЕСКОГО ПОВЕДЕНИЯ КОРПУСА АВТОМАТИЧЕСКОЙ КОРОБКИ ПЕРЕДАЧ АВТОМОБИЛЯ КАТЕГОРИИ N2 НА ОСНОВЕ МЕТОДА МОДАЛЬНОГО ПРЕДСТАВЛЕНИЯ ДИНАМИЧЕСКОЙ СИСТЕМЫ

There is a global tendency nowadays in the development of transport vehicles to ensure high safety, energy efficiency and comfort, characterized primarily by ergonomic and vibroacoustic indicators. This forces engineers and scientists to constantly strive to reduce a noise level emitted by both the vehicle as a whole and individual units and systems. The paper is a continuation of a series of articles devoted to the development of a verified mathematical model of a promising automatic transmission (AT) for a N2 category vehicle, reliably characterizing its vibroacoustic behavior. The article represents the results of a computational and experimental study of the AT vibroacoustic behavior, including the stages of testing, processing and analysis of their results, verification of the computational model created in the Simcenter 3D software product, identification of the main sources of acoustic radiation and the development of proposals for its reduction. The vibroacoustic characteristics of the object of study are obtained, namely frequencies and corresponding acoustic pressure values, their localization on the AT housing is performed. The developed and verified AT model makes it possible to predict the level of vibration and acoustic radiation with satisfactory accuracy. Based on comparative evaluation modeling of various design modification options, the best ones are determined, which allow to obtain the minimum acoustic pressure level at the measurement points and neutralize the most significant forms of vibrations. The introduction of the developed scientifically-based technical solutions into the design made it possible to reduce the integral level of acoustic pressure in the entire range from 2 to 10 dBA.

Underestimation of Occupational Radiation Exposure During Endovascular Abdominal Aortic Aneurysm Repair.

During interventional procedures of endovascular abdominal aortic aneurysm repair (EVAR), the dosimeter was conventionally placed on chest facing toward the surgical table, instead of the main source of scatter radiation. Purpose of this study is to evaluate the underestimation of occupational radiation exposure. Phantom experiments were performed in a hybrid operating room equipped with an interventional angiography system. Electric personal dosimeters were placed at the level of eyes, chest, abdomen, and gonad of three positions, representing the principal operator (PO), assistant operator (AO), and sterile nurse (SN). Personal dose equivalent was measured with two different orientations of radiation detection, facing the table and facing the phantom, respectively. In addition to fluoroscopy, the dose produced by digital subtraction angiography was also measured to estimate the radiation exposure of routine EVAR. In this study, staff doses of 26 EVAR cases were also collected in our hospital to correlate the estimated dose. Our results show that the facing-phantom dose normalized by dose area product of patient is significantly higher than the facing-table dose when the latter is regularly seen in clinical practice. This underestimation could be even worse at a more distant position (e.g., AO and SN) as the incident angle of scatter radiation is larger. Besides, the estimated dose is highly correlated with the on-site measured dose (R 2 ~ 0.8) at chest and gonad of the PO.

Estimation of the annual effective dose from exposure to radon in drinking water in Croatia

Radon is known as the main source of radiation for the general public. Results of extensive measurements of radon in water samples collected from private wells, natural springs and public water supply in Croatia are presented and annual effective doses are estimated. Measurements were performed by two different methods: the emanometry method (by using the AlphaGUARD instrument with additional AquaKIT module) and/or the liquid scintillation method (by using LSC TriCarb 2900). Water samples were collected in public water supplies in urban areas as well as private wells and springs in rural areas. The obtained average radon activity concentration based on the extensive measurement of almost 1000 water samples is 4.1 ± 1.9 Bq/l, with a minimum value of 0.2 and maximum value of 36 Bq/l respectively. The wide range of measured values is a consequence of the source of the water sample (ground/natural water versus treated water) as well as the geological structures around the water source. All estimated ingestion doses due to radon assuming consumption of 2 l of water per day from the observed source were within the interval 6.3–36.8 μSv (with calculated average and standard deviation 19.3 ± 10.3 μSv) for the water consumption from private wells and natural springs and 2.4–40.0 μSv (with calculated average and standard deviation 13.0 ± 10.5 μSv) for the water consumption from the public water supplies.

Ionizing radiation effects on microorganisms and its applications in the food industry

There are two main types of radiation: ionizing and non-ionizing. Radiations are widely distributed in the earth’s crust with small amounts found in water, soil, and rocks. Humans can also produce them through military, scientific, and industrial activities. Ionizing and nonionizing radiations have a wide application in the food industry and medicine. γ-rays, X-rays, and electron beams are the main sources of radiation used in the food industry for food processing. This review discusses advantages and disadvantages of ionizing radiation on microorganisms and its potential applications in the food industry. We also looked at its advantages and disadvantages. &#x0D; Studies have revealed that ionizing radiation is used in the food industry to inactivate microorganisms in food products to improve hygiene, safety, and extend shelf life. Microorganisms such as bacteria and fungi are susceptible to high doses of irradiation. However, some bacterial and fungal species have developed an exceptional ability to withstand the deleterious effect of radiation. These organisms have developed effective mechanisms to repair DNA damage resulting from radiation exposure. &#x0D; Currently, radiation has become a promising technology for the food industry, since fruits, tubers, and bulbs can be irradiated to delay ripening or prevent sprouting to extend their shelf life.

The effectiveness of personal protective equipment made of metallized materials when exposed to extreme levels of infrared radiation

Introduction. The results of the study of the nature of the formation of the thermal state in workers under the influence of extreme levels of the heating microclimate with multifactorial exposure against the background of heavy physical labour, justify the need to develop and experimentally evaluate a set of preventive measures. Such measures need to prevent chronic overheating, with the mandatory use by workers of modern effective personal protective equipment from infrared radiation. &#x0D; The purpose of the study – the study of the effectiveness of personal protective equipment made of metallized materials in real production conditions, for the prevention of chronic overheating from exposure to extreme levels of infrared radiation with multifactorial exposure against the background of heavy physical labour. &#x0D; Materials and methods. To assess the possibility of using personal protective equipment in the conditions of modern forging and pressing production, there were taken protective clothing sets made of the material OXA-440, consisting of a cotton-asbestos lining and a metallized material with an aluminum surface. In the manufacture of prototypes of workwear, the topography and the estimated area of the irradiated area of the body surface, and the moisture and air tightness of metallized materials, were taken into account. The effectiveness of personal protective equipment was evaluated with taking into account the indicators of the thermal state of the workers of the main occupations who used two sets of the specified protective clothing alternately. The thermal state of the body was studied in accordance with the guidelines of the MUK 4.3.1895-04 and the provisions of the standard GOST R ISO 9886-2008. Studies on the hygienic assessment of workwear were carried out in the cold and warm periods of the year. A questionnaire survey was conducted to subjectively assess the usability, design and protective properties of workwear made of metallized material.&#x0D; Results. The main sources of thermal radiation in the studied production are incandescent to a temperature of over 1200°C with metal forgings of various lengths and various profile configurations, which largely determine the variability in the degree of radiation intensity of the radiant energy flow at the workplaces of blacksmiths and heaters. The formed thermal state of the workers of the specified occupational groups, dressed in standard cotton workwear, during the performance of the main work operations during the first half of the working shift in the cold and warm periods of the year, is estimated as the maximum permissible, requiring a limit of working time – no more than one hour per working shift. The use of workwear made of metallized materials in the cold period of the year led to a slight improvement in the thermal condition, which allowed to prolong the time spent at the workplace to 2 hours. When using the original design of a protective suit made of a metallized material characterized by moisture – and air-tight properties and covering a large area of the body surface during the warm period of the year, no improvement in the thermal condition of the workers was observed. According to the questionnaire survey, good reflective and mechanical properties of the test material were revealed. The expressed wishes and suggestions of the workers in the areas of improving the design of workwear suggest the development of new design samples of special protective clothing made of this metallized material, taking into account these comments.&#x0D; Limitations. The chosen research method determines the limitation on the possibility of its use in relation to a specific production, characterized by the multifactorial nature of the production environment against the background of heavy physical labour and extreme levels of infrared radiation determined by the specifics of the technological process. &#x0D; The obtained research results objectify the subject of further research – the development and evaluation of the effectiveness of new design samples of special protective clothing made of metallized materials.&#x0D; Conclusion. The results of the conducted studies have shown good reflective and mechanical properties of the new metallized materials. During the questionnaire survey, the workers expressed their wishes and suggestions for improving the design of workwear sets, which must be taken into account when creating new design samples of special protective clothing, for their subsequent use as the main means of protection when working under conditions of exposure to extreme levels of industrial infrared radiation.

Performance Evaluation of Radiation-Shielding Materials and Process Technology for Manufacturing Skin Protection Cream.

Personnel using X-ray devices, the main source of radiation in medical institutions, are primarily affected by scattered rays. When interventionists use radiation for examinations/treatments, their hands may enter the radiation-generating area. The shielding gloves used for protection against these rays restrict movement and cause discomfort. Here, a shielding cream that directly adheres to the skin was developed and examined as a personal protective device; further, its shielding performance was verified. Bismuth oxide and barium sulfate were selected as shielding materials and comparatively evaluated in terms of thickness, concentration, and energy. With increasing wt% of the shielding material, the protective cream became thicker, resulting in improved protection. Furthermore, the shielding performance improved with increasing mixing temperature. Because the shielding cream is applied to the skin and has a protective effect, it must be stable on the skin and easy to remove. During manufacturing, the bubbles were removed, and the dispersion improved by 5% with increasing stirring speed. During mixing, the temperature increased as the shielding performance increased by 5% in the low-energy region. In terms of the shielding performance, bismuth oxide was superior to barium sulfate by approximately 10%. This study is expected to facilitate the mass production of cream in the future.

Study on Electromagnetic Radiation Characteristics Based on HTS Maglev Levitation Test Line

As a new type of magnetic levitation train with the characteristics of self-stabilization and self-suspension, high-temperature superconducting magnetic levitation has developed to the test line research stage. In order to promote the rapid development of high-temperature superconducting magnetic levitation train engineering, and the main electromagnetic radiation sources are clarified by analyzing their working principles and structures. Then Ansoft Maxwell EM was used to build a 3D magnetic levitation train electromagnetic environment simulation model to simulate and predict the electromagnetic radiation characteristics of the magnetic levitation train system. Finally, a field EMF test was carried out to verify and assess the impact on the EM environment in the system. The results show that the permanent magnet track on the ground and the synchronous linear motor are the primary electromagnetic radiation sources, and the generated fields are mainly low-frequency fields and static magnetic fields. The low-frequency magnetic field inside the train decreases with the increase of frequency and is partially shielded by the carriage; The static magnetic field cannot be weakened by the carriage, and the static magnetic field inside the car decreases with the increase of height. All types of electromagnetic fields are far below the requirements of the relevant electromagnetic environmental standard limits, and have no effect on the electromagnetic radiation safety of the personnel inside the train and the surrounding environment; In considering of the special people who have pacemakers, static magnetic field suppression measures are studied, and the results show that the trains with high magnetic permeability permalloy as the shielding layer at the bottom of the vehicle greatly lower the static magnetic field within the train.

Enhancement of guided electromagnetic wave by pre-plasma formation in laser–plasma interaction

Previous studies have shown that adding a section of critical density plasma on the front surface of solid target can effectively improve the laser energy absorption efficiency. Here, we have investigated laser–plasma interactions with different scale lengths of plasma in front of the target created by a pre-ablation laser pulse. A variety of experimental diagnostics employed together with particle-in-cell simulations give us deep insight into these processes. We found that the laser-induced electromagnetic pulse (EMP) intensity inside the target chamber and the target normal sheath acceleration sheath field accelerated protons were promoted using pre-plasma. The transient current due to hot electron emissions is considered to be one of the main radiation sources of EMP emissions within our measurement bandwidth. In our experiment, this current was guided to a grounded conductive wire attached to the rear surface of the target and measured by proton dynamic imaging technique. The discharging currents together with the guided fields were enhanced more than twice. The reflection spectra of experiments and simulations are compared, which reveal that the energy absorption efficiency was increased with proper plasma scale length, resulting in all the measured signals promoted.

Thermal state of the body of workers exposed to extreme levels of infrared radiation and prevention overheating

Introduction. In an industrial environment, the thermal effect of a heating microclimate on a person through extreme levels of infrared radiation is a stressful factor that has a pronounced negative effect on the formation of the thermal state of the body, which requires the development of effective measures to prevent overheating. &#x0D; The purpose of the study is to investigate the peculiarities of the formation of the thermal state of the body in the conditions of a production experiment under exposure to extreme levels of infrared radiation against the background of long-term heavy factory work and the justification of a set of effective measures to prevent overheating. &#x0D; Materials and methods. The study of the thermal state of the body is conducted in the conditions of real blacksmithing production in accordance with the methodological instructions of MUK 4.3.1895–04 and the provisions of the standard GOST R ISO 9886–2008.&#x0D; Results. In modern forging and pressing production, one of the most unfavourable factors of the production environment is the intense thermal radiation from the metal heated to technological temperatures, which affects the total for 5–6 hours per shift against the background of high temperature from the heating furnaces themselves, which leads to the development of chronic overheating in workers. The main sources of thermal radiation include incandescent to a temperature of over 1200 °C with metal forgings of various lengths and various profile configurations, which largely determines the variability in the degree of radiation intensity of the radiant energy flow at the workplaces of blacksmiths and heaters. The formed thermal state of the workers of the studied occupational groups, dressed in standard cotton workwear, during the performance of the main work operations during the first half of the working shift in the cold and warm periods of the year, is estimated as the maximum permissible, requiring a limit of working time – no more than one hour per working shift. It is necessary to develop requirements for the working regime for prolonged heavy physical work in conditions of extreme exposure to a heating microclimate and the mandatory use of modern effective personal protective equipment (PPE) from infrared radiation.&#x0D; Limitations. The limitation of the study is the possibility of using the results obtained directly to a specific production, characterized by multifactorial effects against the background of extreme levels of the heating microclimate, rigidly determined by the technological process. The obtained indicators of the thermal condition of workers dressed in standard cotton workwear are estimated as the maximum permissible for a period of no more than one hour per work shift, which justifies the need to search for new effective personal protective equipment for the body of workers.&#x0D; Conclusion. It is necessary to develop requirements for the working regime during prolonged hard physical work in conditions of extreme exposure to a heating microclimate and the mandatory use of modern effective PPE from infrared radiation of extreme levels.

Environmental radioactivity assessment of the Brunei Darussalam coastline of the South China Sea

Radioactivity levels of naturally occurring radionuclides at the coast of Brunei Darussalam were evaluated along with their dose rates. Twenty-six berm and intertidal sediment samples were measured using gamma-ray spectrometry. The mean activity concentrations of 226Ra, 232Th and 40K in berm sediments were 10.07 ± 1.02 Bq/kg, below the minimum detectable activity, and 21.44 ± 1.23 Bq/kg, respectively, whereas for intertidal sediments they were 7.01 ± 0.87, 1.67 ± 0.15 and 4.99 ± 0.42 Bq/kg, respectively. With respect to the radiological health risk, the average hazard indices, absorbed gamma dose rate, effective dose equivalent, and excess lifetime cancer risk were found to be less than the global average. Calculation of the activity ratio showed that 40K is the main source of radiation in the coastal sediments. Furthermore, the difference in radioactivity levels between the berm sediments and intertidal sediments collected at the same location was investigated. Finally, a standard geological terminology of the littoral zone profile is proposed for describing coastal samples for universal communication among researchers.

Assessment of background radiation level in different tourism beach of Bengkayang, West Borneo

Environmental radiation and radioactivity monitoring has become important to investigate to generate a baseline database in Bengkayang Sea-Beach area, West Borneo. There is a need to conduct an environmental monitoring program to determine any change due to radioactivity radiation released from the nuclear installation in case of normal operation or emergency conditions, where Bengkayang is a candidate site of Indonesia’s Nuclear Power Plant. In this study, the background radiation levels have been measured at 9 different tourism beach areas of Bengkayang. Natural background radiation is the main source of radiation for the public of tourism. Calibrated gamma dose monitor were used for the measurement of dose level where reading was taken by placing the survey meter at ground level and at a height of 1 m from the ground (gonad level). The observed background radiation dose rate of 9 beach areas is below the world average. The mean Annual Effective Dose Equivalent (AED) is found comparable to other studies. The radiation the population receives due to beach sands mainly results from the time spent on the beach during recreation. The results show that 9 tourism beaches of Bengkayang are considered as safe areas with natural background radiation.

The potential therapeutic efficacy of intravenous versus subconjunctival mesenchymal stem cells on experimentally ultraviolet-induced corneal injury in adult male albino rats.

The X-rays and the visible light are the main source of ultraviolet radiation (UVR). About 90% of ultraviolet B (UVB) is absorbed by the cornea which may promote corneal inflammation, oedema and damage of its epithelial layer. Bone marrow mesenchymal stem cells (BM-MSCs) have been demonstrated to ameliorate the injured corneal tissue and accelerate its wound healing. This study aimed to compare the healing effect of intravenous (IV) versus subconjunctival (SC) BM-MSCs on the rats' corneas subjected to UVB-irradiation. Ten rats were used as donors for BM-MSCs and the other 40 were allocated into four equal groups: group I (control group), group II (ultraviolet-irradiated group), group III (ultraviolet-irradiated + IV BM-MSCs-treated group) and group IV (ultraviolet-irradiated +SC BM-MSCs-treated group). Rats of all groups were euthanized after 3 weeks and the corneal specimens were processed for histopathological, immunohistochemical and electron microscopy assessment. Ultraviolet-irradiated group showed remarkable thinning of epithelial thickness, wide partial epithelial separation, and desquamation. Neovascularisation of the disorganised stroma and disrupted Descemet's membrane were observed. The superficial and basal epithelial cells appeared irregular and separated by wide intercellular spaces and inflammatory cells. Immunohistochemical examination showed a significant decrease in proliferating cell nuclear antigen immunoreaction. In contrast, minimal changes were observed in rats treated with BM-MSCs with more improvement associated with the subconjunctival administration compared to IV route. Local SC injection of BM-MSCs has an amazing regenerative efficacy on the corneal injury compared to the systemic IV route.

Inhomogeneity within Local Interstellar Clouds* *All of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute. The specific observations analyzed can be accessed via https://doi.org/10.17909/gabn-m136. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support to MAST for these

Analysis of interstellar absorption lines observed in high-resolution Hubble Space Telescope spectra of nearby stars provides temperatures, turbulent velocities, and kinetic properties of warm interstellar clouds. A new analysis of 97 interstellar-velocity components reveals a wide range of temperatures and turbulent velocities within the Local Interstellar Cloud (LIC) and the nearby Cluster of Interstellar Clouds (CLIC). These variations appear to be random with Gaussian distributions. We find no trends of these properties with stellar distance or angles from the Galactic Center, magnetic field, the main source of extreme-UV radiation (the star ϵ CMa), the center of the LIC, or the direction of inflowing interstellar matter into the heliosphere. The spatial scale for temperature variations in the LIC is likely smaller than 5100 au, a distance that the Sun will traverse in 1000 yr. Essentially all velocity components align with known warm clouds. We find that within 4 pc of the Sun, space is completely filled with partially ionized clouds, but at larger distances space is only partially filled with partially ionized clouds. We find that the neutral hydrogen number density in the LIC and likely other warm clouds in the CLIC is about 0.10 cm−3 rather than the 0.20 cm−3 density that may be representative of only the immediate environment of the LIC. The ≤3000–12,000 K temperature range for the gas is wider than the predictions of thermal equilibrium theoretical models of the warm neutral medium and warm ionized medium, and the high degree of inhomogeneity within clouds argues against simple theoretical models.

Assessment of possible risks on human health by estimation of annual effective doses associated with radon in drinking water

Radon is the main source of radiation that people receive naturally. Twenty-four samples of drinking water were collected and analyzed from all communities of Yerevan city, Armenia, in order to assess Radon associated radiological risk on population health through the drinking water. The measurements were performed by Alfarad Plus - ARP radon meter. The obtained values were compared with the national and international recommended values and they were within the Maximum contaminant level recommended by the US Environmental Protection Agency, WHO and EU commission, also the national norms. As a consequence of direct consumption of drinking water annual effective doses due to the ingestion and inhalation of Radon were calculated. Annual committed effective dose received from drinking water consumption are within the recommended limit of WHO and EU Council (100 μSv y−1) and UNSCEAR [United Nations Scientific Committee on the Effects of Atomic Radiation] (1000 μSv y−1).

Improving the Density of Functional Fabrics to Protect Radiation Workers in Radiology Departments

In medical institutions, the high weight of shielding clothing restrains the activities of medical workers. Although lightweight shielding clothing is being manufactured to solve this problem, the weight can only be reduced by 10%–20%. Flexible shielding fibers are mainly used to minimize activity restrictions; however, it is difficult to maintain the reproducibility of shielding performance. When weaving fibers with a yarn that contains a shielding material, the content of the shielding material in the yarn, tensile strength, and problems encountered during weaving should be considered. Therefore, in this study, a high-density shielding fabric weaving process was developed to weave a functional shielding fabric for actively utilizing it for low-dose shielding. The yarn was manufactured using 5 wt% barium sulfate, and the shielding performance was evaluated using the existing plain weave and two fabrics that underwent the newly developed high-density twill weave process. As a result of the experiment, the density of the fabric woven by the twill method increased by 82 g/m³, documenting a difference of 7.46% in the high-energy region and 11.71% in the low-energy region, thus indicating that the Twill method improves the shielding effect. Therefore, it is possible to mass produce lightweight, high-density shielding fabric that can protect against scattered rays that represent the main source of radiation in medical institutions.

Minimum dose path planning during reactor coolant system maintenance with corrosion product activity

To facilitate the periodic maintenance of the reactor coolant system, the nuclear power plant must be shut down. However, maintenance work on the primary loop components could result in post-shutdown radiation exposure. Activated corrosion products are the main source of radiation inside the containment building during post-shutdown. Traditionally, radiation detectors are used to measure in-containment radiation to protect workers from radiation risk during maintenance. However, these devices cannot predict corrosion product activity and the subsequent radiation dose. This study presents a minimum dose path planning methodology for protecting workers during the reactor coolant system maintenance in a typical pressurized water reactor nuclear power plant. Specifically, the study uses the corrosion product release and activation (CoPRA) code to estimate the corrosion product activity from the primary loop’s three major post-shutdown source terms. Subsequently, the FLUKA Monte Carlo code is used to simulate dose rates from the corrosion product activity, and the Three-Degree of Vertex shortest path algorithm is implemented to find the minimum dose path. Comparison results show that the predicted dose is consistent with the measured dose from the nuclear power plant. The results also show the flexibility and adaptability of the proposed method in finding the shortest path with the minimum dose in different reactor operating conditions.