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To validate radiation safety of the ionization source being designed, the results of numerical simulation of dose fields using certified software are used. In this work, an algorithm to assess the radiation environment near a newly designed intense fusion neutron source (MIN facility, Troitsk) is designed and applied. The CORIDA software was used to develop a 3D detailed model of the facility and perform variant calculations of the dose rate fields during pulses and after them taking into account gamma radiation from activated materials. The results obtained made it possible to specify radiation shield parameters and determine the forbidden time intervals after pulses for staff access. [ABSTRACT FROM AUTHOR]

AbstractThis work proposes a new propellant management configuration for an ammonia-fueled nuclear thermal propulsion system. The suggested configuration maximizes the advantage deriving from the autogenous pressurization of ammonia by exploiting the thermal power lost by the nuclear reactor toward the vacuum space due to leaking radiation. In this layout, a tank containing ammonia in saturated conditions is placed near the nuclear reactor and receives an input thermal power proportional to the dose of gamma rays and neutrons absorbed by the tank walls and the ammonia itself. Such a thermal power accelerates the vaporization process of the saturated ammonia, thus increasing the pressure in the tank. A pressure regulator valve exploits this overpressure to pressurize the ammonia propellant contained in a run tank to the level required by the mission by connecting the two ammonia volumes. The pressure achieved inside the run tank pushes the propellant with an adequate mass flow rate inside the nuclear reactor. The developed lumped parameter analysis shows how this propellant management system can provide a constant mass flow to the nuclear reactor without using a turbopump assembly. Moreover, it is shown how the proposed concept allows for a reduction in the radiation shield mass. [ABSTRACT FROM AUTHOR]

Nuclear power industry requires structural materials that effectively absorb neutron radiation. For this purpose, boron and boron-rich compounds and, in particular, boron carbide B4C and its composites are widely used. Both theoretically and experimentally it has been shown that one such promising class of materials is boron carbide compositions with tungsten B4C-W: tungsten phase inclusions containing heavy W atoms provide effective attenuation of the secondary gamma-radiation that accompany the absorption of primary neutrons by the boron 10B isotope atoms. In this work, the composites with multilayer morphologies -- W/B4C/W, W/B4C/W2B5, W2B5/B4C/W2B5, etc. -- in which boron carbide layers alternate with metallic tungsten and/or tungsten pentaboride ones, are produced and investigated. Surface metallization of boron carbide crystals or grains with tungsten powder, plate or coating is done by SPS (Spark-Plasma Sintering) and also by standard thermal sintering. SEM (Scanning Electron Microscopy) structural-morphological, XRD (X-Ray Diffraction) phase- and EDS (Energy Dispersive Spectrometry) chemical-compositions analysis of the obtained samples establishes that transition layers of W2B5 are formed on the B4C-W interfaces, which ensures component-layers strong bonding. [ABSTRACT FROM AUTHOR]

Abstract Commonly used materials for protection against ionizing radiation (gamma and X-ray energy range) primarily rely on high-density materials, like lead, steel, or tungsten. However, these materials are heavy and often impractical for various applications, especially where weight is a key parameter, like in avionics or space technology. Here, we study the shielding properties of an alternative light material—a graphene-based composite with a relatively low density ~ 1 g/cm3. We demonstrate that the linear attenuation coefficient is energy of radiation dependent, and it is validated by the XCOM model, showing relatively good agreement. We also show that the mass attenuation coefficient for selected radiation energies is at least comparable with other known materials, exceeding the value of 0.2 cm2/g for higher energies. This study proves the usefulness of a commonly used model for predicting the attenuation of gamma and X-ray radiation for new materials. It shows a new potential candidate for shielding application.

Abstract Since the beginning of research into radiation and protection against it, the importance of searching for proper materials against radiation hazards has been recognized. Gamma radiation protection materials usually deal with heavy elements with high prices, which are hard to maintain. Polyurethane-based (PU) materials are popular in sound and thermal insulation due to, their low-weight properties and, most importantly, fast and convenient construction ingredients. PU foams (PUF) can be used as radiation shield and noise and heat resistance due to their approachability, light-weight, high resistance, and comfortable construction. This study involved simulation and an experiment to construct and investigate the properties of Polyurethane material doped with lead oxide as a gamma shield. The shield was considered in several weight fractions of lead, yielding several samples. The MCNPX 2.6 Monte Carlo code has been utilized for simulation procedure, and 137Cs was employed as the gamma source in both simulation and experiment. The results offer a promising response against the gamma radiation and are suitable for attenuating gamma rays.

Since the beginning of research into radiation and protection against it, the importance of searching for proper materials against radiation hazards has been recognized. Gamma radiation protection materials usually deal with heavy elements with high prices, which are hard to maintain. Polyurethane-based (PU) materials are popular in sound and thermal insulation due to, their low-weight properties and, most importantly, fast and convenient construction ingredients. PU foams (PUF) can be used as radiation shield and noise and heat resistance due to their approachability, light-weight, high resistance, and comfortable construction. This study involved simulation and an experiment to construct and investigate the properties of Polyurethane material doped with lead oxide as a gamma shield. The shield was considered in several weight fractions of lead, yielding several samples. The MCNPX 2.6 Monte Carlo code has been utilized for simulation procedure, and 137Cs was employed as the gamma source in both simulation and experiment. The results offer a promising response against the gamma radiation and are suitable for attenuating gamma rays. [ABSTRACT FROM AUTHOR]

The Saba thyroid shield is a new X-ray dose reduction tool for radiosensitive organs that can reduce the X-ray dose without degrading the image quality. This study investigated its effectiveness in reducing the X-ray dose on the thyroid surface during diagnostic X-ray. This study was conducted in the lab of the Medical Physics Department at Umm-Alqura University. The experiments were performed in the year 2022. A mixed fission product phantom and a solid-state detector were used to measure the radiation dose on the thyroid surface during diagnostic X-ray using a tube voltage within 40–120 kVp. The effectiveness of the Saba thyroid shield was examined in two settings: in-field and out-of-field. Measurements were conducted for these two settings without and with the Saba thyroid shield, and the attenuation percentages were computed. Analysis of covariance was used to test the tool's effectiveness in X-ray dose reduction. The average in- and out-of-field dose attenuation percentages using the Saba thyroid shield were 80.12 ± 0.12% and 81.13 ± 0.18%, respectively. A significant difference was shown between the measurements done without and with the Saba thyroid shield (p = 0.000) for both the in-field and out-of-field doses. The in-field and out-of-field dose reduction levels using the shield were approximately the same. This study demonstrated that the newly developed Saba thyroid shield made of copper and bismuth effectively reduces both the in-field and out-of-field radiation doses. [ABSTRACT FROM AUTHOR]

The harsh radiation environment of Jupiter imposes significant constraints on the shield design of spacecraft. Due to these constraints, traditional aluminum shields cannot meet the radiation shielding requirements needed for the exploration of Jupiter. In this paper, the design for a highly efficient radiation shield structure is proposed that utilizes a combination of high-Z/low-Z elements. A typical exploration orbit of Jupiter is selected, and the energetic particle radiation environment is calculated using the D&G83 model. The Geant4 toolkit is used to evaluate the shielding performance of materials, and quantitative simulations are performed to analyze the shielding efficiency of bilayer and trilayer shield structures under an areal density constraint of 4.5 g/cm2. Based on the simulations, an optimal shield structure is determined. The simulation results show that the integral electron flux with energy greater than 3 MeV is approximately three orders of magnitude greater than that of geostationary orbit with an orbit of 4000 km at the perijove and 5420000 km at the apojove, resulting in an enormous total dose effect. The optimal shield structure is a bilayer structure that comprises of a tantalum outer layer with a density of 3.5 g/cm2 and a polyethylene inner layer with a density of 1.0 g/cm2. This shield has the ability to reduce the total radiation dose to 1559 Gy per year, which is 32 % lower than that of traditional aluminum shields. Findings in this research are critical for design of radiation shields, and can be used for performing reliability analyses and predicting the lifespan of spacecraft during the development process. [ABSTRACT FROM AUTHOR]

In the validation of microclimate simulation software, the comparison of simulation results with on-site measurements is a common practice. To ensure reliable validation, it is crucial to utilize high-quality temperature sensors with a deviation smaller than the average absolute error of the simulation software. However, previous validation campaigns have identified significant absolute errors, particularly during periods of high solar radiation, possibly attributed to the use of non-ventilated radiation shields. This study addresses the issue by introducing a ventilated radiation shield created through 3D printing, aiming to enhance the accuracy of measurements on cloudless summer days with intense solar radiation. The investigation employs two pairs of sensors, each comprising one sensor with a ventilated and one with a non-ventilated radiation shield, placed on a south-oriented facade with two distinct albedos. Results from the measurement campaign indicate that the air temperature measured by the non-ventilated sensor is elevated by up to 2.8 °C at high albedo and up to 1.9 °C at a low albedo facade, compared to measurements with the ventilated radiation shield. An in-depth analysis of means, standard deviations, and 95% fractiles highlights the strong dependency of the non-ventilated sensor error on wind velocity. This research underscores the importance of employing ventilated radiation shields for accurate microclimate measurements, particularly in scenarios involving high solar radiation, contributing valuable insights for researchers and practitioners engaged in microclimate simulation validation processes. [ABSTRACT FROM AUTHOR]

Abstract Background Radiation shielding in radiology has historically been achieved with lead; however, there has been an increasing demand for radiation shielding to be more environmentally friendly. Barium has shown promise as a substitute in many radiology applications. This study aims to investigate a barium sulphate shield in protecting the thyroid and the eye lens during panoramic radiography. Methods During a simulated panoramic examination, an anthropomorphic phantom and a solid-state detector measured the radiation dose to the surface thyroid and the eye lens. The measurements were taken using no shield and a barium sulphate shield. A Welch's T-test was employed to compute the shield's effect on radiation. Two radiologists assessed the image quality with and without the thyroid shields. Results The dose reduction was between 66 and 75% for the barium shield at the thyroid. The dose reduction ranged between 15 and 61% in the eye region. Images using a barium shield were deemed adequate for diagnostic interpretation. Conclusions Barium shields effectively reduce the radiation dose in the thyroid region during panoramic radiography without degrading image quality. The dose reduction depends on the tube voltage and the area of interest.

Background: Radiation shielding in radiology has historically been achieved with lead; however, there has been an increasing demand for radiation shielding to be more environmentally friendly. Barium has shown promise as a substitute in many radiology applications. This study aims to investigate a barium sulphate shield in protecting the thyroid and the eye lens during panoramic radiography. Methods: During a simulated panoramic examination, an anthropomorphic phantom and a solid-state detector measured the radiation dose to the surface thyroid and the eye lens. The measurements were taken using no shield and a barium sulphate shield. A Welch's T-test was employed to compute the shield's effect on radiation. Two radiologists assessed the image quality with and without the thyroid shields. Results: The dose reduction was between 66 and 75% for the barium shield at the thyroid. The dose reduction ranged between 15 and 61% in the eye region. Images using a barium shield were deemed adequate for diagnostic interpretation. Conclusions: Barium shields effectively reduce the radiation dose in the thyroid region during panoramic radiography without degrading image quality. The dose reduction depends on the tube voltage and the area of interest. [ABSTRACT FROM AUTHOR]

In this study, a super-insulated pipe incorporating Multi-Layer Insulation (MLI) and vacuum is numerically analyzed to overcome the challenges faced during the transportation of cryogenic fluids like nitrogen. A super-insulated pipe incorporating an inner process pipe of SS 304 L insulated by twenty-four consecutive layers has been used. Each layer consists of aluminized mylar (as a radiation shield) and dacron netting (as a spacer material). High vacuum (10-9 torr) is applied and numerically analyzed at multiple flow rates, i.e., 250 LPH, 500 LPH and 1000 LPH. The results show a gradual increase in temperature along the flow direction from 77 K to 79 K at the most. Moreover, the temperature increases with the increase in the length of the pipe and decreases with the increase in the flow rate of LN2. [ABSTRACT FROM AUTHOR]

Barium Bismuth Oxide Borate (BBOB) has been synthesized for the first time using solution combustion technique. SEM analysis reveal flower shape of the nanoparticles. The formation of the nanoparticles has been confirmed through XRD & FTIR studies which gives the physical and chemical structure of the novel material. The UV light absorption is observed in the range 200–300 nm. The present study highlights the radiation shielding ability of BBOB for different radiations like X/Gamma rays, Bremsstrauhlung and neutrons. The gamma shielding efficiency is comparable to that of lead in lower energy range and lesser than lead in the higher energy range. The bremsstrauhlung exposure constant is comparably larger for BBOB NPs than that of concrete and steel however it is lesser than that of lead. The beauty of BBOB nanoparticles lies in, high absorption of radiations and low emission of secondary radiations when compared to lead. In addition, the neutron shielding parameters like scattering length, absorption and scattering cross sections of BBOB are found to be much better than lead, steel and concrete. Thus, BBOB nanoparticles are highly efficient in absorbing X/Gamma rays, neutrons and bremsstrauhlung radiations.

Recommendations are given to improve the efficiency of radiation protection of transport casks for SNF transportation. The attenuation of γ-quanta of long-lived isotopes 134Cs, 137mBa(137Cs), 154Eu and 60Co by optimizing the thicknesses and arrangement of layers of Fe and Pb radiation shields of transport casks is studied. The fixed radiation shielding mass (fixed mass thickness) is chosen as the main optimization criterion. The effect of the placement order of Fe and Pb layers in a combined two-layer radiation shield with an equivalent thickness of 30 cm is studied in detail. It is shown that with the same mass thicknesses of the Fe and Pb layers, the placement of Fe in the first layer, and Pb - in the second one provides more than twofold attenuation of γ-quanta compared to the reverse placement: Pb - in the first layer, Fe - in the second. The increase in the efficiency of attenuation of γ-quanta for TC with combined shielding of Fe and Pb is shown to be achieved by designing the first layer of radiation shielding around the canister with SNF from Fe of the maximum possible thickness.

AbstractThe aim of this review is to show the possibilities of food production during space travel and to demonstrate the potential of technological solutions that can play a significant role in achieving the goal of colonizing other planets. The paper briefly outlines the conditions of space flight and the associated possible threats that may occur. It is assumed that the basic problem is cosmic radiation, which not only can significantly affect the health of astronauts, but also prevent potential cultivation of plants or animal breeding on board a spacecraft. The solution to this problem proposed here is a shield which provides protection against collisions with high kinetic energy particles, while reducing the speed of corpuscular radiation. Particular attention is given to various biotechnological and bioengineering methods that could be used for food production on board a spacecraft. Technological development in the field of bioprinting or genetic modification of organisms may play a key role in the success of long-distance technological missions. Moreover, organisms such as algae, fungi and insects are indicated as a potential source of energy for future colonizers. In sum, the review covers both the field of engineering and biotechnology, as well as the possibility of checking these technological methods in the test flights.

Measuring climate data is a lengthy and technically challenging task. To record temperature data, small meteorological stations are located on the facade of the Research Centre building. Due to the position of the meteorological stations, which are mounted directly on the facade of the building, the temperature measurement sensor is not only affected by the solar radiation falling on the sensor housing, but also by the solar radiation falling on the facade of the building. The illuminated surface of the facade gradually heats up during the day and warms the air flowing near the facade. The temperature readings during the day may therefore be significantly distorted. To avoid this phenomenon, better-quality radiation shields have been purchased. The new radiation shield is characterized by a design that resembles eddy currents. The relationship between the shape of the outer and inner spiral is optimized, allowing vortices to form even in virtually windless conditions. In this paper, we would like to point out the differences in the measured air temperature data, according to the radiation shield used and the distance of the temperature sensor from the building facade.

A novel material bismuth–copper–boron nanocomposite has been synthesized in the present study using the solution combustion technique. The microstructure of the compound has been studied using SEM, XRD and FTIR techniques which are used to explore the physical and chemical structure of the novel material. The optical properties are studied using a UV–visible analysis. The radiation shielding efficiency has been investigated in detail theoretically and experimentally. Several gamma shielding parameters, neutron and bremsstrahlung shielding parameters have been estimated for the novel material in the present study. The linear and mass attenuation coefficient decreases with an increase in energy whereas the tenth value layer thickness increases with an increase in energy. The radiation protection efficiency is found to be high in the lower energy range when compared to the higher energy range. Crystalline size is determined by PXRD studies which proves the crystalline nature of the novel material. The chemical structure and functional groups are determined by the FTIR analysis and energy gap is found out to be 2.87 eV from UV visible studies. The studied sample has shown good gamma shielding ability in the lower energy range. EDX spectrum confirms the presence of bismuth, boron and copper nanocomposites. In addition, the said material is found to possess good absorption ability for neutrons and bremsstrahlung radiations. [ABSTRACT FROM AUTHOR]

Concerns about the impact of space radiation on spacecraft and their internal instruments have prompted the need for effective protection. However, excessive protection can increase the costs and difficulty of space launches, making it crucial to achieve better shielding protection of lighter weights. In real space orbits, we observed the interference of charged particles on photon-counting imaging detectors and plan to address this issue by adding a shielding ring to the side wall of the detector input terminal. Additionally, a local protection structure was proposed for electronics, where the outer edge was increased to enable particles to reach the same thickness as the shielding box within the PCB range. This approach resulted in an omnidirectional spatial shielding thickness that was nearly identical at any point on the PCB surface. Furthermore, we used the Monte Carlo method to calculate the energy loss of electrons and protons in materials such as aluminum (Al), tantalum (Ta), and high-density polyethylene (HDPE). Through this analysis, we determined the optimal mass ratio of Al, Ta, and HDPE to achieve the lowest ionization doses at an object's location in the particle environment of the FY-3 satellite orbit. This protection strategy provides a useful design concept for photoelectric detection instruments with high sensitivity. [ABSTRACT FROM AUTHOR]

Molecular weight (Mw) is an important feature that affects the physicochemical properties of polymers and their matrices. This study focused on the impact of increasing the Mw of polyethylene glycol (PEG) (4, 8 and 20 K) mixed with polyvinyl alcohol (PVA). Graphene oxide (GO) nanosheets were employed to reinforce the polymer matrix by aquatic mixing-sonication-casting to prepare the nanocomposites and investigate their optical properties. Fourier transform infrared spectroscopy revealed strong interfacial interactions among the components and successful fabrication of the nanocomposites. Optical microscopy and scanning electron microscopy confirmed the fine homogeneity of the polymers and the excellent dispersion of nanosheets in the matrix. The absorption peak was located in the ultraviolet region related to GO. PEG Mw and GO additive significantly improved optical properties such as absorbance, real and imaginary dielectrics and the absorption coefficient constant up to 75%, 40%, 120% and 77%, respectively. An enhancement in the optical properties was also observed after the energy gap values for allowed and forbidden transitions were improved up to 90% and 375%, respectively. These findings suggest the potential of these materials for several applications, such as in photovoltaic devices and heavy metal ion absorption for nuclear waste management.

Measuring climate data is a lengthy and technically challenging task. To record temperature data, small meteorological stations are located on the facade of the Research Centre building. Due to the position of the meteorological stations, which are mounted directly on the facade of the building, the temperature measurement sensor is not only affected by the solar radiation falling on the sensor housing, but also by the solar radiation falling on the facade of the building. The illuminated surface of the facade gradually heats up during the day and warms the air flowing near the facade. The temperature readings during the day may therefore be significantly distorted. To avoid this phenomenon, better-quality radiation shields have been purchased. The new radiation shield is characterized by a design that resembles eddy currents. The relationship between the shape of the outer and inner spiral is optimized, allowing vortices to form even in virtually windless conditions. In this paper, we would like to point out the differences in the measured air temperature data, according to the radiation shield used and the distance of the temperature sensor from the building facade. [ABSTRACT FROM AUTHOR]

Work of researchers from various areas is focused on problematics of urban heat islands. Its importance is rising with the global climate change. The difference of the air temperatures within the area can be also caused by the measurement error. Usual error is not the accuracy of the sensor, but the radiation shield or location of the weather station. In this case, averaged difference can be up to 80 %. Difference of temperatures between the weather stations within the analyzed area can vary from 0.2 up to 6 °C. Difference depends usual on the size of the city and the location influenced by the surrounding geomorphology. In this paper three different radiation shields are compared which influenced the measurement and analyzed are also the results from four different weather stations, two of them are within the University of Zilina campus. One of them is placed on the roof, which is a usual location for the solar radiation measurement; the second one is placed on the grass land at the end of the campus. Other two stations belong to the national weather institute. Comparison is made for two very hot days of August 2020. Averaged difference was 0.3 °C for the whole month and 0.5 °C for selected days.

In this study, a super-insulated pipe incorporating Multi-Layer Insulation (MLI) and vacuum is numerically analyzed to overcome the challenges faced during the transportation of cryogenic fluids like nitrogen. A super-insulated pipe incorporating an inner process pipe of SS 304 L insulated by twenty-four consecutive layers has been used. Each layer consists of aluminized mylar (as a radiation shield) and dacron netting (as a spacer material). High vacuum (10−9 torr) is applied and numerically analyzed at multiple flow rates, i.e., 250 LPH, 500 LPH and 1000 LPH. The results show a gradual increase in temperature along the flow direction from 77 K to 79 K at the most. Moreover, the temperature increases with the increase in the length of the pipe and decreases with the increase in the flow rate of LN2.

This research work investigates the performance of domestic refrigerators. Test were carried out on two configurations of household refrigerators; a conventional refrigerator and a refrigerator that was modified by incorporating a radiation shield. In this work, plywood was used as thermal radiation shield placed between the back of the refrigerator and the condenser and compressor. Pressure gauges were welded to the evaporator inlet and condenser outlet. Thermocouples were attached to the compressor inlet and outlet, condenser outlet and evaporator inlet in order to obtain data from the test. The pressure and temperature data obtained was applied to evaluate the performance of the two systems. With further repeated tests, the coefficient of performance (COP) of the refrigeration systems were determined at normal ambient condition. The highest evaporator temperature obtained for the conventional refrigeration system (CRS) and modified refrigerators system (MRS) were -5oC and 0oC respectively. Interestingly, an efficiency improvement of about 10% was achieved for the MRS. The result shows a remarkable improvement in the COP of the MRS. Therefore, for a better performance, thermal radiation shield can be recommended to be incorporated in vapour compression refrigeration system.

Molecular weight (Mw) is an important feature that affects the physicochemical properties of polymers and their matrices. This study focused on the impact of increasing the Mw of polyethylene glycol (PEG) (4, 8 and 20 K) mixed with polyvinyl alcohol (PVA). Graphene oxide (GO) nanosheets were employed to reinforce the polymer matrix by aquatic mixing-sonication-casting to prepare the nanocomposites and investigate their optical properties. Fourier transform infrared spectroscopy revealed strong interfacial interactions among the components and successful fabrication of the nanocomposites. Optical microscopy and scanning electron microscopy confirmed the fine homogeneity of the polymers and the excellent dispersion of nanosheets in the matrix. The absorption peak was located in the ultraviolet region related to GO. PEG Mw and GO additive significantly improved optical properties such as absorbance, real and imaginary dielectrics and the absorption coefficient constant up to 75%, 40%, 120% and 77%, respectively. An enhancement in the optical properties was also observed after the energy gap values for allowed and forbidden transitions were improved up to 90% and 375%, respectively. These findings suggest the potential of these materials for several applications, such as in photovoltaic devices and heavy metal ion absorption for nuclear waste management. [ABSTRACT FROM AUTHOR]

Omemh Bawazeer Medical Physics Department, Umm Al-Qura University, Mecca, Saudi ArabiaCorrespondence: Omemh BawazeerMedical Physics Department, Umm Al-Qura University, Mecca, Saudi ArabiaTel +966 563349226Email oabawazeer@uqu.edu.saPurpose: To optimize the maintenance of radiation shields, this study aims to analyze annual inspection files to assess the integrity of radiation shields and their associated factors with regard to defects in radiation shields in clinical settings.Methods: A multicenter cross-sectional study was conducted at hospitals in Saudi Arabia. The data from annual inspection files of 1019 clinical lead radiation shields were analyzed. The factors of shield shape, unit where a shield is used, shield thickness, short-term use and number of users were examined. In addition to the inspection file analysis, radiation attenuation measurements were obtained for a subset of shields to compare newly purchased shields with older shields. Statistical analyses were performed using Fisher’s exact test and a t-test.Results: The results show that the highest percentage of failing shields were found in the emergency unit, fluoroscopy unit and operation room with a failure of approximately 7.14%, 5.61%, and 3.98%, respectively, of these shields. Fluoroscopy and operation room units were statistically significantly associated with shield defects. There was no association between shield damage and shape of shield, shield thickness, short-term use or number of users. Radiation attenuation measurements were similar for new and older shields.Conclusion: As fluoroscopy units and operating rooms have a higher percentage of damaged shields, it is recommended that the shields employed in these units should be regularly inspected more frequently than once a year. The study highlights that the shields’ age, transmission measurements that confirm that the correct shields are purchased according to the required kVp, physical appearance, and cleanliness should be recorded in annual inspection files. This study highlights the need for uniform inspection files of radiation shields across hospitals. National and international organizations may apply these findings to develop appropriate recommendations.Keywords: radiation shield, lead shield, body apron

We report the status of the cold neutron triple-axis spectrometer (Cold TAS) and thermal neutron triple-axis spectrometer (Thermal TAS) installed at HANARO. Cold TAS, whose specifications are standard across the world, is in the final phase of commissioning. Proper instrument operation was confirmed through a feasibility study of phonon measurements and data analyses with resolution convolution. In contrast, Thermal TAS is in the initial phase of commissioning, and improvement of the monochromator drum is now in progress from the viewpoint of radiation shielding. In addition, we report recent activities in the development of neutron basic elements, that is, film-coated Si-wafer collimators, which are promising for use in triple-axis spectroscopy, particularly in Cold TAS.

The measurement of outdoor environmental and climatic variables is needed for many applications such as precision agriculture, environmental pollution monitoring, and the study of ecosystems. Some sensors deployed for these purposes such as temperature, relative humidity, atmospheric pressure, and carbon dioxide sensors require protection from climate factors to avoid bias. Radiation shields hold and protect sensors to avoid this bias, but commercial systems are limited, often expensive, and difficult to implement in low-cost contexts or large deployments for collaborative sensing. To overcome these challenges, this work presents an open source, easily adapted and customized design of a radiation shield. The device can be fabricated with inexpensive off-the-shelf parts and 3-D printed components and can be adapted to protect and isolate different types of sensors. Two material approaches are tested here: polylactic acid (PLA), the most common 3-D printing filament, and acrylonitrile styrene acrylate (ASA), which is known to offer better resistance against UV radiation, greater hardness, and generally higher resistance to degradation. To validate the designs, the two prototypes were installed on a custom outdoor meteorological system and temperature and humidity measurements were made in several locations for one month and compared against a proprietary system and a system with no shield. The 3-D printed materials were also both tested multiple times for one month for UV stability of their mechanical properties, their optical transmission and deformation under outdoor high-heat conditions. The results showed that ASA is the preferred material for this design and that the open source radiation shield could match the performance of proprietary systems. The open source system can be constructed for about nine US dollars, which enables mass development of flexible weather stations for monitoring needed in smart agriculture.

Concerns about the impact of space radiation on spacecraft and their internal instruments have prompted the need for effective protection. However, excessive protection can increase the costs and difficulty of space launches, making it crucial to achieve better shielding protection of lighter weights. In real space orbits, we observed the interference of charged particles on photon-counting imaging detectors and plan to address this issue by adding a shielding ring to the side wall of the detector input terminal. Additionally, a local protection structure was proposed for electronics, where the outer edge was increased to enable particles to reach the same thickness as the shielding box within the PCB range. This approach resulted in an omnidirectional spatial shielding thickness that was nearly identical at any point on the PCB surface. Furthermore, we used the Monte Carlo method to calculate the energy loss of electrons and protons in materials such as aluminum (Al), tantalum (Ta), and high-density polyethylene (HDPE). Through this analysis, we determined the optimal mass ratio of Al, Ta, and HDPE to achieve the lowest ionization doses at an object’s location in the particle environment of the FY-3 satellite orbit. This protection strategy provides a useful design concept for photoelectric detection instruments with high sensitivity.

The aim of this review is to show the possibilities of food production during space travel and to demonstrate the potential of technological solutions that can play a significant role in achieving the goal of colonizing other planets. The paper briefly outlines the conditions of space flight and the associated possible threats that may occur. It is assumed that the basic problem is cosmic radiation, which not only can significantly affect the health of astronauts, but also prevent potential cultivation of plants or animal breeding on board a spacecraft. The solution to this problem proposed here is a shield which provides protection against collisions with high kinetic energy particles, while reducing the speed of corpuscular radiation. Particular attention is given to various biotechnological and bioengineering methods that could be used for food production on board a spacecraft. Technological development in the field of bioprinting or genetic modification of organisms may play a key role in the success of long-distance technological missions. Moreover, organisms such as algae, fungi and insects are indicated as a potential source of energy for future colonizers. In sum, the review covers both the field of engineering and biotechnology, as well as the possibility of checking these technological methods in the test flights. [ABSTRACT FROM AUTHOR]

Static thermoelectric generator (TEG) systems have been widely used for recovering the high-temperature heat from the industrial sector. To control the heat loss through the gap uncovered by the thermoelectric legs for system performance improvement, a novel strategy of inserting the radiation shields in the gap that introduced additional surface and spacing resistances and regulated the gap radiation loss, was proposed. With a constructed high-fidelity theoretical model which used the finite element method to consider the temperature-dependent properties of the thermoelectric materials, comprehensive comparisons were conducted between the systems with/without radiation shields and using three commonly adopted strategies to evaluate the effectiveness and potential of this strategy. Compared to the base case without radiation shields, inserting one radiation shield with an emissivity of 0.5 enhances the TEG efficiency and system power by 15 % and 9.5 % respectively. The system using the proposed strategy outperforms that using the commonly adopted strategies, especially the strategies of lowering the gap pressure and filling the gap with thermal insulation materials, highlighting the potential of the proposed strategy. Besides, the influences of the shield emissivity and number were studied; from it, less than two radiation shields made by the polished copper are recommended for practical applications. • TEG systems with two-segmented legs to reuse industrial high-temperature heat. • Proposed a novel strategy of inserting radiation shields to reduce the gap radiation loss. • Enhanced the power by 9.5 % with inserting one radiation shield with an emissivity of 0.5. • Proved the potential of the proposed strategy via comparing commonly used strategies. • Recommended less than two radiation shields made by the copper for industrial TEG systems. [ABSTRACT FROM AUTHOR]

Polymer composites reinforced with heavy metals have wide applications in the nuclear industry as radiation shielding materials against emitted radiation from nuclear equipment. In this study, considering bismuth oxide as reinforcement, various polymers including thermoplastic polymers, such as high-density polyethylene, low-density polyethylene, polypropylene, polyvinyl acetate, polymethyl methacrylate, and thermosetting epoxy resin have been considered as matrices. After preparing various samples of polymer composites loaded with 60 % by weight of bismuth oxide, some physical, mechanical, and radiation shielding properties (neutron and gamma attenuation coefficients) of these polymer composites have been measured and compared with each other. First, the density of the samples was measured, and the response of these samples to varying compressive force was investigated. The stress-strain diagrams of composites with different matrices were compared. Subsequently, the linear and mass attenuation coefficients of the composites were measured over a wide range of energies (32–1480 keV) against direct and collimated beams from various standard gamma-ray sources (134Cs, 60Co, 154Eu, 133Ba, and 22Na) using an HPGe detector. A collimated beam from an Am–Be source was utilized to measure and compare the attenuation properties of the composite samples against neutron flux. Furthermore, the properties of the composites against neutron and gamma radiation were calculated using the MCNP Monte Carlo code over a broad energy range, and the results were compared and validated with the experimental data. The comparison of the calculated and measured results shows reasonable agreement. The results indicate that in situations where high attenuation properties coupled with high strength are desired, polymeric composites with an epoxy matrix can be considered as radiation shielding materials. If the use of flexible and malleable material is required, such as for reactor piping shielding or the fabrication of protective gloves and clothing in a radiation environment, among the polymers studied, polyvinyl acetate is a more suitable matrix. [ABSTRACT FROM AUTHOR]

Exposure to radiation over an extended period causes adverse effects on the human body and also impacts the environment. To mitigate the radiation effects, a protective is necessary, making the need for suitable materials crucial. Polymers, as promising materials in the present time, take centre stage in this review as the primary material for radiation shields, particularly against gamma rays. Another material is lead, which has been proven in previous studies to be effective in shielding against gamma radiation due to its advantages such as high atomic number and density. Additionally, composites made from polymers allow the production of flexible radiation shielding materials. This review provides information on the properties of polymers, basic parameters of radiation protection, radiation interaction with materials, preparation methods for polymer composites, degradation and radiation resistance of polymers, the development of polymer-lead as radiation shielding material, and the recycling of polymer composites. This overview will assist researchers conducting studies in the field of gamma radiation shielding materials. • Development of polymer-lead as flexible gamma radiation shielding. • Exploring strategies for the recycling and sustainability of polymer-lead shielding. • Investigating the development and efficiency of polymer-lead composites shield. • Advance development of ionizing radiation shields based natural polymers filled with lead. [ABSTRACT FROM AUTHOR]

• A novel radiation shield was proposed. • The middle plates could effectively guide the airflow to the sensor probes. • The temperature error could be decreased by reducing the radiation interference. • This new shield may potentially reduce the temperature error to within 0.1°C. To reduce the influence of radiation on temperature measurement, this research introduces a novel radiation shield. To reduce solar radiation effects, aluminum foil was used to cover the external surfaces of the plates. In addition, to reduce indirect radiation effects, a black coating was applied to cover the internal surfaces of the plates. The middle plates facilitate airflow to the sensors, thus accelerating the diffusion of radiant heat and reducing radiation interference. Temperature errors of the sensors equipped with the new radiation shield induced by various radiations (direct solar radiation, reflected radiation, diffused radiation, long-wave radiation) were quantified by employing computational fluid dynamics (CFD) and neural network methods. The experimental results showed that the mean absolute error, root mean square error, and correlation coefficient between the experimental and predicted temperature errors were 0.036 °C, 0.046 °C, and 0.99, respectively. [ABSTRACT FROM AUTHOR]

Transparent heavy metal oxide glasses are becoming increasingly important because of their effectiveness in reducing unwanted occupational and public radiation exposure in the medical settings; and for the clear view it offers when properly used during the construction of diagnostic radiology facilities, mobile shields and eye wears. WinXCom computer program was used to determine the mass attenuation coefficients of the studied glass systems; while other shielding parameters were determined by using appropriate equations. All these shielding parameters were determined at 20 keV, 30 keV, 40 keV and 60 keV; these are the average energies of photons commonly used in diagnostic radiology. The outcome of this work shows that increment in Bi 2 O 3 led to better MAC and HVL at 20 and 30 keV while increment in TeO 2 led to better MAC and HVL at 40 and 60 keV B1, B3 and B4 showed different improved shielding properties at 20, 40 and 60 keV zBi 2 O 3 –30B 2 O 3 -(70-z) TeO 2 glass system showed better shielding qualities when compared with commonly used materials in diagnostic radiology. [ABSTRACT FROM AUTHOR]

The article shows new designed cermets and processes concerning primary to applications as thermal insulation materials with low emissivity. A new projected microstructure was obtained where dense regions (micropellets) rest inside the main porous pellet. The feature resembles a frozen hypercube, therefore such architecture is called hyper-pellet/ cermet. The processing method to obtain the hyper-cermet is based on sequential tape castings and sintering techniques. Ni-zirconia lamellae were prepared by a special mechanochemical process followed by sintering, which remain inside the main pellets as a dense region. The whole pellet is turned to be porous by employing pore-forming additives. All the constituents and porosity shapes are aligned along the disc/ flake planes. Thermal conductivity is estimated for the materials up to 800 °C by a flash diffusivimeter. Ceramographic analyses show graded density regions with directional constituents and pores. Applications of such materials are foreseen as temperature insulation materials and thermal radiation shields. [ABSTRACT FROM AUTHOR]

Abstract High mountain areas are poorly represented by official weather observatories. It implies that new instruments must be evaluated over snow-covered and strongly insolated environments (i.e. mid-latitude mountain areas). We analyzed uncertainty sources over snow covered areas including: 1) temperature logger accuracy and bias of two widely used temperature sensors (Tinytag and iButton); 2) radiation shield performance under various radiation, snow, and wind conditions; 3) appropriate measurement height over snow covered ground; and 4) differences in air temperature measured among nearby devices over a horizontal band. The major results showed the following. 1) Tinytag performance device (mean absolute error: MAE ≈ 0.1–0.2 °C in relation to the reference thermistor) was superior to the iButton (MAE ≈ 0.7 °C), which was subject to operating errors. 2) Multi-plate radiation shield showed the best performance under all conditions (> 90% samples has bias between ±0.5 °C). The tube shield required wind (> 2.5 m s−1) for adequate performance, while the funnel shield required limited radiation (< 400 W m−2). Snow cover causes certain overheating. 3) Air temperatures were found to stabilize at 75–100 cm above the snow surface. Air temperature profile was more constant at night, showing a considerable cooling on near surface at midday. 4) Horizontal air temperature differences were larger at midday (0.5 °C). These findings indicate that to minimize errors air temperature measurements over snow surfaces should be carried out using multi-plate radiation shields with high-end thermistors such as Tinytags, and be made at a minimum height above the snow covered ground. Graphical abstract Unlabelled Image Highlights • Autonomous dataloggers are an appropriate option in snow-covered areas. • Tinytag devices showed a robust and constant performance, as opposed to iButtons. • Shield design must be kept in mind in function of snow-wind-radiation conditions. • Air temperature showed stabilization at 75–100 cm above the snow cover surface. • Air temperature differences are largest at midday due to solar radiation. [ABSTRACT FROM AUTHOR]

Abstract High collecting temperature in parabolic trough collectors (PTCs) induces considerable radiative heat loss of solar receivers, which causes significant negative effects on heat-collecting efficiency. Structural optimized solar receivers with inner radiation shield achieved superior thermal performance for reducing heat loss. Based on widely commercial EuroTrough and PTR70 solar receivers, the optimized solar receivers are numerically applied to a small thermal-collection field with 72 m loop using molten salt as heat transfer fluid to validate their enhanced overall performance. Mathematical models relying on spectrum parameter calculation and working fluid volume unit method are established to simulate the energetic and exergetic performances of the solar receivers. The influence of solar irradiance on parabolic trough collector system is studied, and all-day system efficiencies in different areas in China are investigated to validate the performance of the proposed solar receivers in real condition. Results show that the PTCs with novel solar receivers exhibit outstanding energetic and exergetic performances compared with conventional receivers. The heat loss reduction percentage of the novel receivers reaches approximately 24.0% when the absorber temperature is 600 °C. The heat-collecting efficiency and exergetic efficiency are effectively raised by 7.1% and 4.7%, respectively, at an inlet temperature of 580 °C. Highlights • Energetic and exergetic performance of PTC with novel solar receivers is studied. • Mathematical models with spectral radiant distribution are built and validated. • All-day PTC system efficiency in different areas in China is calculated. • The radiation heat loss of the novel receiver is reduced by around 24.0%. • Thermal and exergetic efficiencies of novel receiver are raised by 7.1 and 4.7%. [ABSTRACT FROM AUTHOR]

• The neutronic parameters for the ARGUS reactor are calculated. • The 6 group effective delayed neutrons fractions are obtained. • The hot full power k eff and fuel burnup are calculated. • The control rods worth, the shot down margin and the safety reactivity factor are calculated. • The temperature coefficient of reactivity and void coefficient of reactivity are calculated. • Two different types of radiation shield for gamma and neutron radiations are designed. In this research, an aqueous homogeneous reactor is simulated and its neutronic parameters are investigated. Due to the negative reactivity caused by temperature change and void formation, the cold excess reactivity is considered equal to 4 β eff. Also, calculations of radiation shielding and neutronic characterization of the reactor are performed. For different heights of uranyl sulfate fuel, the effective multiplication factor (k eff) of the reactor is calculated under cold zero power and hot full power conditions to assess the required excess reactivity. The amount of fuel burnup and changes in the k eff are investigated for 500 days, finally 200 operating days are chosen as the working duration of the reactor. The control rods worth (CRW) for different diameters of boron carbid and reactor safety parameters including shot down margin (SDM) and safety reactivity factor (SRF), temperature and void coefficients of reactivity are analyzed. In order to design a suitable radiation shield for this reactor, two different shields are considered. The first shield is a combination of polyethylene thicknesses and barite concrete, and the second shield is made only of barite concrete. The total thickness of the first and second shield was 230 and 180 cm, respectively. Due to the problems of using polyethylene (e.g. problems related to machining, shield dimensions and low melting temperature), the second shield is chosen as the suitable radiation shield for this reactor. Using this radiation shield, the total dose rates of neutron and gamma rays satisfy the ICRP dose limits. [ABSTRACT FROM AUTHOR]

Innovative multifunctional materials that combine structural functionality with other spacecraft subsystem functions have been identified as a key enabling technology for future deep space missions. In this work, we report the structure and performance of multifunctional polymer matrix composites developed for aerospace applications that require both structural functionality and space radiation shielding. Composites comprised of ultra-high molecular weight polyethylene (UHMWPE) fiber reinforcement and a hydrogen-rich polybenzoxazine matrix are prepared using a low-pressure vacuum bagging process. The polybenzoxazine matrix is derived from a novel benzoxazine resin that possesses a unique combination of attributes: high hydrogen concentration for shielding against galactic cosmic rays (GCR), low polymerization temperature to prevent damage to UHMWPE fibers during composite fabrication, long shelf-life, and low viscosity to improve flow during molding. Dynamic mechanical analysis (DMA) is used to study rheological and thermomechanical properties. Composite mechanical properties, obtained using several standardized tests, are reported. Improvement in composite stiffness, through the addition of carbon fiber skin layers, is investigated. Radiation shielding performance is evaluated using computer-based simulations. The composites demonstrate clear advantages over benchmark materials in terms of combined structural and radiation shielding performance.

Temperature measurements of InterMET Inc. aluminum-coated iMET-XQ sensors were tested in an outdoor setting under a variety of solar radiation and wind speed conditions. Twelve unshielded sensors were mounted side-by-side on the tower of a South Alabama Mesonet weather station next to a reference sensor on the tower. The iMET-XQ temperatures were most precise and accurate in solar radiation values that were close to zero, regardless of wind speed. Under overcast conditions, wind speeds of 2 m s−1 were sufficient to obtain precise and accurate temperature measurements. During the day-time, aspiration of wind speeds higher than or equal to 3 m s−1 is sufficient. An iMET-XQ was placed in a radiation shield next to the tower reference sensor to test the need for a radiation shield. A second iMET-XQ was placed unshielded on the tower. The iMET-XQ sensors with aluminum coating do not need to be shielded, but they do need to be aspirated. It is recommended that, when taking temperature measurements using unmanned aerial vehicles (UAV) with iMET-XQ sensors, the UAV either fly at 3 m s−1, be embedded in winds of those speeds, or to use the propeller wash of the UAV to aspirate the sensors.

Abstract Glasses in the series, 49B 2 O 3 -25SiO 2 -(26-x)Bi 2 O 3 -xBaO (with x between 2 and 8 wt%) are considered for radiation shielding applications based on the gamma-ray half-value layer (HVL) and mass neutron removal cross-section. Theoretical data for the calculation of the HVL is obtained from the NIST XCOM software. The calculated HVL shows good correspondence to the experimentally determined values. The mass neutron removal cross-section and the half-value layer of the glass system are optimized using the genetic algorithm. The genetic algorithm is used alongside regression analysis to determine the relative concentration of each oxide needed to obtain the best radiation shielding parameter values. The use of numerical methods is employed to ascertain simple functions that can be used instead of traditional analytical functions in modeling the behavior of glasses. The auto-Zeff software is used to generate a plot of the effective atomic number over a spectrum of photon energies, while spectroscopic techniques are used to examine the structure and optical properties to determine what advantages the glasses have over concrete or water. This approach had fast convergence due to increased numerical stability. The optimal solution is equal to barite concrete in gamma-ray shielding and limonite concrete in neutron shielding. Highlights • The genetic algorithm is successfully applied to the optimization of oxide glass. • B 2 O 3 -SiO 2 -Bi 2 O 3 -BaO glasses have HLV below 2.8 cm at 662 keV. • B 2 O 3 -SiO 2 -Bi 2 O 3 -BaO is comparable to heavy concrete in shielding parameters. • The correlation between wt. fraction and shielding parameter simplifies optimization. • Higher oxygen content in HMO glasses improves neutron shielding. [ABSTRACT FROM AUTHOR]

Highlights • Conduction/radiation combined heat transfer is analyzed for applications in VIP. • Influences of emissivities and contact resistance on heat transfer are studied. • Conduction/radiation interaction can increases heat transfer by more than twice. • Use of reflective shields with contact resistance are recommended in VIPs. Abstract Combined heat transfer of conduction and radiation is investigated with thermal contact resistance boundary condition to scrutinize the effect on heat transfer and to evaluate the thermal performance of vacuum insulation panels (VIPs). Numerical analysis shows that introduction of contact resistance flattens temperature profile and reduces both the conductive and the radiative heat transfer. In VIPs, if interstitial material is purely absorbing/emitting and well contacting the radiation shield, center-of-panel thermal conductivity can be more than twice larger than that estimated by separate analysis of conduction and radiation, especially when the optical thickness of the layer is moderate and the wall emissivity is low. On the other hand, this error decreases with increased scattering albedo and reduced conduction/radiation interaction. In any case, use of low-emissivity shields greatly improves the insulation performance. Further, contact resistance between the interstitial material and the shields reduces the heat transfer substantially. Thus, insulation performance of VIP with artificial core structures can be greatly improved by employing rough or embossed, and highly reflecting shields. [ABSTRACT FROM AUTHOR]

In light of global climate change, ecological studies increasingly address effects of temperature on organisms and ecosystems. To measure air temperature at biologically relevant scales in the field, ecologists often use small, portable temperature sensors. Sensors must be shielded from solar radiation to provide accurate temperature measurements, but our review of 18 years of ecological literature indicates that shielding practices vary across studies (when reported at all), and that ecologists often invent and construct ad hoc radiation shields without testing their efficacy. We performed two field experiments to examine the accuracy of temperature observations from three commonly used portable data loggers ( HOBO Pro, HOBO Pendant, and iButton hygrochron) housed in manufactured Gill shields or ad hoc, custom-fabricated shields constructed from everyday materials such as plastic cups. We installed this sensor array (five replicates of 11 sensor-shield combinations) at weather stations located in open and forested sites. HOBO Pro sensors with Gill shields were the most accurate devices, with a mean absolute error of 0.2°C relative to weather stations at each site. Error in ad hoc shield treatments ranged from 0.8 to 3.0°C, with the largest errors at the open site. We then deployed one replicate of each sensor-shield combination at five sites that varied in the amount of urban impervious surface cover, which presents a further shielding challenge. Bias in sensors paired with ad hoc shields increased by up to 0.7°C for every 10% increase in impervious surface. Our results indicate that, due to variable shielding practices, the ecological literature likely includes highly biased temperature data that cannot be compared directly across studies. If left unaddressed, these errors will hinder efforts to predict biological responses to climate change. We call for greater standardization in how temperature data are recorded in the field, handled in analyses, and reported in publications. [ABSTRACT FROM AUTHOR]

A novel solar evacuated receiver as the key part of parabolic trough collector (PTC) was designed and constructed by authors. The novel evacuated receiver (NER) with an inner radiation shield can significantly decrease heat loss at higher operating temperatures when compared with the traditional evacuated receiver (TER). A thermodynamic model relying on the spectrum parameter model of radiation heat transfer was developed to predict the performances of evacuated receivers. Also, experiments using the novel evacuated receiver and traditional evacuated receiver were conducted in the laboratory under different parametric conditions to validate results obtained for the simulation. A comparison between simulation results and experimental data demonstrated that the model was able to yield satisfactory consistencies and predictions to a reasonable accuracy (with the root mean square deviations less than 6%). Results indicated that the novel evacuated receiver has a role in decreasing the total heat loss of receiver compared with the traditional receiver when the working temperature is higher than 296 °C, the heat loss reduction percentage of the novel evacuated receiver reaches 19.1% when the operating temperature is 480 °C, and the value of this percentage would be greater at higher working temperatures. [ABSTRACT FROM AUTHOR]

Percutaneous angioplasty (PTA) for dysfunctional hemodialysis is usually performed by radiologists, but not cardiologists, in Taiwan, so that the radiation dose in patients and physicians are usually unknown and related studies are rare. In this study, we are pioneering an investigation into the radiation dose in percutaneous angioplasty for arteriovenous shunt assembling and the effect of RADPAD device, a lead-free surgical drape containing Bi and Ba, on the decrease of a radiation dose in the non-targeted organs of the patient and also the operator. The radiation dose in a typical digital subtraction angiography (DSA) by the PTA protocol under a fixed field of view (FOV), was measured with optically simulated luminescent dosimeters arranged in a PIXY RS-102 anthropomorphic phantom. The results indicate that there is a significant dose reduction at the hands (0.022±0.002 mGy before treatment vs. 0.014±0.001 mGy after treatment; P=0.021), but not at the lens (0.027±0.003 mGy before treatment vs. 0.018±0.001 mGy after treatment; P=0.058), and the gonads (0.026±0.003 mGy before treatment vs. 0.020±0.001 mGy after treatment; P=0.058), of the cardiologist/operator after treatment with the RADPAD drape. At the patient's abdomen, the dose significantly decreased from 1.597±0.104 mGy to 0.031±0.002 mGy (P<0.001) after treated with the RADPAD shield. For the chest, lens and thyroid in the patient, the doses were respectively 0.154±0.100 mGy (compared to 0.049±0.001 mGy after treated with the RADPAD drape; P=0.0002), 0.066±0.001 mGy (compared to 0.021±0.001 mGy after the RADPAD treatment; P=0.009), and 0.208±0.002 mGy (compared to 0.042±0.003 mGy after shielded with the RADPAD drape; P<0.0001), which represents an apparent reduction in dose. However, no significant difference was found in the dose-area product between before (179.9±0.1mGy.cm 2 ) and after (177.4±0.1mGy.cm 2 ) the treatment (P=0.38). In conclusion, the RADPAD drape significantly reduced radiation exposure to the patient during the PTA for the arteriovenous shunt assembling, which is suggested should be applied to the current cardiac catheterization. [ABSTRACT FROM AUTHOR]

The cryo-condensation pump used in EAST-NBI is composed of cryo-condensation panels cooled by liquid helium and radiation shields cooled by liquid nitrogen. The transmission probability of radiation shields has great influence on the performance of the cryo-condensation pump. The Monte-Carlo method is applied to simulate the trajectories of the deuterium molecules and to study the effects of the structure of the radiation shields on the transmission probability. By adding imaginary walls, the distribution of positions and flying directions of the molecules is presented. The results indicate that the uniformity of the molecules is the direct factor to influence the transmission probability. [ABSTRACT FROM AUTHOR]