Shield Design Research Articles

Shielding factors for a fission-powered mars exploration rover

Background With the advances in compact fission power systems and Stirling converters, the efficiency and portability of electrical energy production systems has increased substantially thanks to NASA’s Kilopower project. These 1-10 kWe-class reactors are compact enough to be transportable by pressurized rovers, allowing an extended human reach across the surface of Mars to produce scientific data at a rate that greatly surpasses the rate of robotic rover data collection. If rovers were to harness fission power while mobile, it is possible for near-limitless range. This capability could allow one crew on Mars for under a “Conjunction” class mission as outlined in NASA’s Mars Design Reference Architecture (DRA) 5.0 to visit many geological sites of interest instead of requiring additional landings to explore distant features of the Martian surface. This study explored the parameters that affected the mass of the shielding required to protect the crew against a fission reactor embedded in the chassis of a pressurized rover. Methods An analytical approach was devised to estimate the required mass of a hypothetical solid tungsten shield under various conditions. Results Power levels below 3.4 kWe were found to be impractical for rover applications. Between 3.4 kWe and 10 kWe would be able to recharge the rover without returning to base camp. The increase in shielding mass from a 3.4 kWe reactor and a 10 kWe reactor was 6%. The reduction between a 10 kWe reactor at 3 m and 6 m was 7%. Varying the shield thickness in accordance with astronaut activities resulted in a 19% reduction. Powering the reactor off before exiting the vehicle resulted in an additional 65% reduction. Conclusions Knowledge of the crew activities and locations had the greatest impact on the required shielding mass and the mission activities should be well-understood and taken into account for shield design.

Enhanced impact tolerant core reinforced space shielding

The threat of orbital debris to space structures is well understood with efforts being made to develop superior shielding for objects operating in low Earth orbit. In traditional Whipple shield designs, the area between the front bumper and rear pressure wall, termed the stand-off distance, is left empty. One of the more recent discussions in shield design has been the utilization of a honeycomb sandwich core design. In this design an initial thin bumper plate is used to fragment the projectile, followed by a honeycomb design which is implemented to further slowdown the resulting fragments in the stand-off region. By using this implementation, the rear pressure wall is theoretically subject to less damage as a result of the impact, due to the addition of the honeycomb core. It is often argued that the addition of a honeycomb core within the Whipple shield induces a channeling behavior of the projectile, where the sharp edges of the honeycomb split the projectile, and the fragments generated are unable to escape the individual honeycomb core that it is propelled into. It is theorized that this channeling effect causes more damage than an impact where no honeycomb is present. This channeling effect induces a large amount of the mass of the projectile to impact the backplate over a much smaller area. As a result, the damage to the backplate is far more localized and of a higher intensity. In this paper the efficacy of this theory has been studied through an analytical approach, where Whipple shields with the honeycomb and standard 2-plate designs are subjected to hypervelocity impacts of orbital debris.

Structure‐function integrated design of electromagnetic interference shielding and mechanical properties of 2D carbon fiber reinforced polymer composites based on absorption loss regulation

Structure‐function integrated design of electromagnetic interference shielding and mechanical properties of <scp>2D</scp> carbon fiber reinforced polymer composites based on absorption loss regulation

Performance assessment of an innovative light and compact dust shield for DISC onboard Comet Interceptor/ESA space probes

The dust ejected by cometary nuclei encodes valuable information on the formation and evolution of the early Solar System. Multiple short-period comets have been studied in situ, but several perihelion passages considerably modified their pristine condition. Comet Interceptor is the first space mission selected by the European Space Agency to study a pristine dynamically new comet in situ. During a fast flyby through the comet coma, hypervelocity impacts with dust particles will represent not only an important source of information, but also a serious hazard to the spacecraft and its payload. Here we discuss the assessment tests performed on the dust shield of the Dust Impact Sensor and Counter instrument (DISC), part of the Comet Interceptor payload, which will be directly exposed to the cometary dust flux. Using a Light-Gas Gun, we shot mm-sized particles at ∼5 km/s, transferring momenta and kinetic energies representative of those foreseen for the mission. The impact effects on the DISC breadboard were compared to theoretical predictions by a ballistic limit equation for hypervelocity impacts. We find that, with a simple improvement in the dust shield design, DISC is compatible with the expected cometary environment.

Synergistic Cationic Shielding and Anionic Chemistry of Potassium Hydrogen Phthalate for Ultrastable Zn─I2 Full Batteries.

Electrolyte additives are investigated to resolve dendrite growth, hydrogen evolution reaction, and corrosion of Zn metal. In particular, the electrostatic shielding cationic strategy is considered an effective method to regulate deposition morphology. However, it is very difficult for such a simple cationic modification to avoid competitive hydrogen evolution reactions, corrosion, and interfacial pH fluctuations. Herein, multifunctional additives of potassium hydrogen phthalate (KHP) based on the synergistic design of cationic shielding and anionic chemistry for ultrastable Zn||I2 full batteries are demonstrated. K cations, acting as electrostatic shielding cations, constructed the smooth deposition morphology. HP anions can enter the first solvation shell of Zn2+ for the reduced activities of H2O, while they remain in the primary solvation shell and are finally involved in the formation of SEI, thus accelerating the charge transfer kinetics. Furthermore, by in situ monitoring the near-surface pH of the Zn electrode, the KHP additives can effectively inhibit the accumulation of OH- and the formation of by-products. Consequently, the symmetric cells achieve a high stripping-plating reversibility of over 4500 and 2600 h at 1.0 and 5mA cm-2, respectively. The Zn||I2 full cells deliver an ultralong term stability of over 1400 cycles with a high-capacity retention of 78.5%.

A method for optimizing different geometric shields of D-T neutron generators by combining BP neural network and Analytic Hierarchy Process

In this paper, an optimization of shielding structures with different geometries is established for the D-T neutron generator system by combining Back Propagation (BP) neural network and Analytic Hierarchy Process (AHP). The D-T neutron generator (Model NG-9) used in the system was developed independently by Northeast Normal University. After investigating the rule of shielding performance among spherical, cylindrical and cubic geometries, the spherical shield is selected for BP neural network prediction to determine the total dose rate through it. Information about spherical multilayer-shielding structures and properties calculated by MCNP code is used to train the neural network. The predicted result serves as a parameter of the evaluation function, which provides a comprehensive assessment of the dose rate penetrated the shield, the shielding mass, and the shielding volume. Together with AHP, the weight factors are determined for all the optimization objectives to construct the evaluation function. By comparing its values, the optimal shielding structures for spherical, cylindrical and cubic materials are found. Against MCNP simulated values, the total dose rates’ errors of the optimal shielding structures for the sphere, cylinder, and cube are 1.72 %, -4.94 %, and -5.17 %, respectively. This result demonstrates that the combination of BP neural network and AHP is more effective in addressing multi-objective optimization problems related to the design of radiation shielding for various geometries.

(G4-SEOPTIM): A GEANT4 application for shielded enclosure, designing and shielding optimizing: The case of a new Moroccan shielded enclosure

PurposeThis study aims to develop and validate a Geant4 simulation application using the latest G4RadioactiveDecayPhysics v5.1 library to optimize the shielding design of a Moroccan shielded enclosure. The goal is to ensure effective radiation protection by comparing simulation results with initial geometric calculations based on the attenuation law (Beer-Lambert Law) and implementing design optimizations to enhance safety and reduce costs. MethodsThe study began with a prototype design based on linear attenuation calculations, which were costly and offered limited patient safety. Using the Geant4 Monte Carlo toolkit, we simulated the decay of a Fluorine-18 source within the shielded enclosure to evaluate dose rate distributions. The simulation's accuracy was validated through comparison with experimental measurements, and the results informed the geometric optimization of the shielding enclosure. ResultsThe Geant4 simulations demonstrated that the current shielding design effectively reduces radiation doses to acceptable levels. However, the simulations also identified opportunities for further optimization of the enclosure's geometry, allowing for more precise and efficient use of shielding materials while maintaining safety standards. ConclusionThe study confirms the utility of Geant4 for optimizing radiation shielding designs. While the initial dimensions provided adequate protection, the simulation enabled more precise geometric optimization. This approach not only enhances radiation protection but also informs the design and construction of more efficient and cost-effective shielding enclosures. The adjustments made to the enclosure's faces significantly improved radiation protection, reducing the dose rate surrounding the shielded enclosure to acceptable levels.

Understanding the interaction forces between shield-triggered autoinjectors and skin: an in-depth noninvasive study

ABSTRACT Objective This noninvasive study aimed to understand the interaction between shield-triggered autoinjectors (AI) and skin at the point of activation, hypothesizing that the AI’s housing absorbs a significant amount of the user-applied force depending on shield design and skin characteristics. Methods Twenty-seven volunteers used a test device measuring applied force versus shield force and indentation depth relative to shield length (2,4,6,8 mm) in standing and sitting positions. Results Significant differences were found between applied and shield force for the different shield lengths. Shorter shields resulted in significantly lower force transfer coefficients, with means ranging from 0.72 for the 2 mm shield to 0.94 for the 8 mm shield. ANOVA revealed statistically significant factors (p < .05), including position and gender, with females generally having lower coefficient values. Indentation depth increased with higher forces and varied significantly between positions without significant shield length impact. Conclusion The findings confirm that an increase in shield length at the point of activation reduces skin friction with the housing, resulting in less force loss and a lower device activation force perceived by the user. Force loss can be further reduced by standing up. Understanding device-tissue interactions will support development of better AIs with fewer user failures.

Significantly improved optical and radiation transmission performance of borate glasses via Tb and Yb rare earth doping

The present study was intended to present new borate glass structure with attractive properties useful for optical and radiation shielding purposes. Therefore, a novel series of B2O3-glass samples defined as: 75B2O3 – 10Li2O – (15-x-y)PbO – x(Yb2O3) – y(Tb2O3), where the corresponding oxide fractions are expressed in mol percent and x and y varied between 1 and 2 mol%, were prepared by employing the well-known melting-and-quenching technique. The structural, physical, optical, and radiation interaction qualities of the glasses were probed based on established experimental and theoretical processes. There was a thin line between the density and molar volumes of the glasses, fluctuating between 3.168 and 3.224 g/cm3 and 28.602 and 29.117 cm3/mol, respectively. All the glass samples exhibited a transparency of over 80 % in the visible range and most parts of the infrared spectrum. The analysis of the gamma photon interaction parameters showed that density and chemical composition greatly influence the shielding abilities of the glasses. The mean free paths of the studied glasses were lower than some known shielding glasses and other materials. The value of ΣR for 1Y0T, 1Y1T, 1Y2T, and 2Y1T is 0.1059, 0.1066, 0.1051, and 0.1063 cm−1, respectively. The half value layers of the glasses had almost a constant minimum value of 0.005 cm at the minimum energy (0.015 MeV) and maximum values of 7.192, 7.100, 7.152, and 7.035 cm for 1Y0T, 1Y1T, 1Y2T, and 2Y1T, respectively at 10.000 MeV. The glasses are potentially more effective for radiation shielding and also desirable where there is lack of space for thicker shield designs. The present glasses had better fast neutron moderating capacities compared to some conventional moderators. None of the studied borate glasses showed a clear performance advantage to the others in terms of absorbing electrons, protons, alpha particles and heavy carbon ions. The studied borate glasses are recommended as transparent and effective radiation protection barriers in ionizing radiation facilities.

Structural Design of an Electrostatic Shield at −600 kV for the MITICA Beam Source

Structural Design of an Electrostatic Shield at −600 kV for the MITICA Beam Source

Radiation shielding calculation for interventional radiology: An updated workload survey using a dose monitoring software

Shielding design is an essential aspect of radiation protection. It is necessary to ensure that barriers safeguard workers, patients, the general public, and the environment from the harmful radiation emitted by X-ray machines. The National Council on Radiation Protection and Measurements (NCRP) 147 method is widely accepted within the radiation protection experts’ (RPEs) community for structural shielding design for medical X-ray imaging facilities. However, these indications are based on data collected in 1996. In recent years, interventional radiology procedures have seen significant developments. Therefore, it is important to evaluate whether updating the data on workload in the different specialities is necessary.We extracted all interventional radiology exposure data parameters from three angiographs from two vendors using dose monitoring software for 3066 procedures and 214,697 individual exposures. The workload distribution as a function of the kVp for five interventional rooms was calculated by summing all exposures and then normalising them by the number of patients.Analysing this data, we obtained new transmission curves through lead, concrete and gypsum wallboard, finding the parameters (α, β, and γ) in the Archer equation for the secondary radiation. Finally, our aim was to share an example of shielding calculations for haemodynamics and neuroangiography rooms to illustrate the impact of updated transmission data.

Design and Additive Manufacturing of Medical Face Shield for Healthcare Workers Battling Coronavirus (COVID-19).

During the coronavirus disease-19 pandemic, the demand for specific medical equipment such as personal protective equipment has rapidly exceeded the available supply around the world. Specifically, simple medical equipment such as medical gloves, aprons, goggles, surgery masks, and medical face shields have become highly in demand in the health-care sector in the face of this rapidly developing pandemic. This difficult period strengthens the social solidarity to an extent parallel to the escalation of this pandemic. Education and government institutions, commercial and noncommercial organizations and individual homemakers have produced specific medical equipment by means of additive manufacturing (AM) technology, which is the fastest way to create a product, providing their support for urgent demands within the health-care services. Medical face shields have become a popular item to produce, and many design variations and prototypes have been forthcoming. Although AM technology can be used to produce several types of noncommercial equipment, this rapid manufacturing approach is limited by its longer production time as compared to conventional serial/mass production and the high demand. However, most of the individual designer/maker-based face shields are designed with little appreciation of clinical needs and nonergonomic. They also lack of professional product design and are not designed according to AM (Design for AM [DfAM]) principles. Consequently, the production time of up to 4 – 5 h for some products of these designs is needed. Therefore, a lighter, more ergonomic, single frame medical face shield without extra components to assemble would be useful, especially for individual designers/makers and noncommercial producers to increase productivity in a shorter timeframe. In this study, a medical face shield that is competitively lighter, relatively more ergonomic, easy to use, and can be assembled without extra components (such as elastic bands, softening materials, and clips) was designed. The face shield was produced by AM with a relatively shorter production time. Subsequently, finite element analysis-based structural design verification was performed, and a three-dimensional (3D) prototype was produced by an original equipment manufacturer 3D printer (Fused Deposition Modeling). This study demonstrated that an original face shield design with <10 g material usage per single frame was produced in under 45 min of fabrication time. This research also provides a useful product DfAM of simple medical equipment such as face shields through advanced engineering design, simulation, and AM applications as an essential approach to battling coronavirus-like viral pandemics.

An Optimal Radiation Shield Design of a Small Modular Nuclear Power Reactor by Genetic Algorithm

One of the critical concerns in developing small modular nuclear reactors (SMRs) is employing efficient radiation shielding consistent with the design and implementation requirements. Besides observing the radiation shielding requirements, the design process entails developing compact, lightweight shielding as well as ensuring the safety of the staff and radiation-sensitive equipment around the reactor under different operating conditions. Conventional methods of radiation shielding design are based on experiments conducted. Therefore, the resultant design involves trial and error, rarely achieving an optimal, effective, and efficient design. In this study, a multi-objective method based on the genetic algorithm coupled with the MNCP calculation code has been used to enhance the radiation shielding system of a SMR. Using this method, the thickness of different shielding layers has been optimized to minimize the total dose (neutrons and gamma) at the output, the weight, and the overall volume of the shielding. To assess and compare the method used to an implemented conventional method, a sample design of the MRX nuclear power reactor is considered. Using the optimization technique, the radiation shielding of the reactor has been redesigned and compared with the original design. This paper discusses the existing deficiencies in the initial design of the primary shield of the reactor as a design implemented based on conventional methods. Similar to the original design, the main materials considered for radiation shielding in consecutive layers were water and steel, and the final layer contained lead. The thickness of the different layers and their arrangements have been optimized to assess the upgraded method. The calculations indicate that the overall thickness of the proposed shielding is suggested as 93.8 cm compared to 140 cm to obtain the total dose of neutrons and gammas, which is suggested as less than 10 µSv/h. The results imply a 38.56% reduction in volume and a 17.24% reduction in weight of the radiation shielding compared to the reference reactor design.

Optimal design of selected features of exhaust system shields using different optimization methods and artificial neural networks

The article presents problems related to methods of optimal design of heat shields used in exhaust systems of internal combustion engines. The optimization method proposed in this paper goes well beyond the scope of the standard design process. The paper uses a variety of local and global optimization algorithms, those both built into numerical simulation systems and in-house and external algorithms. An optimization criterion was defined and numerically implemented, together with constraints derived from the real requirements for this type of shielding. A simplified numerical model of finite element method providing the required accuracy adapted to the optimization task was developed. In addition, the work also presents a method for creating finite element surrogate models using artificial neural networks. The process of selecting the network topology and its learning allowed the development of a metamodel characterized by very good quality, for which, despite the relatively large number of design variables, the response errors are completely acceptable from a practical point of view. Numerical results were compared and developed for the used methods and algorithms.

The method for design of electromagnetic hybrid active-passive shielding by overhead power lines magnetic field

The method for design of electromagnetic hybrid active-passive shielding by overhead power lines magnetic field

Multi-objective optimization of molten salt microreactor shielding perturbations employing machine learning

Nuclear reactor shielding is a requirement for all reactors to prevent radiation from escaping the core. Shielding design can be an arduous process that requires significant computational resources to model even a single concept, for either deterministic and stochastic computations. As such, many developed shield concepts are under-optimized and unnecessarily large and/or expensive. Machine learning models have been previously trained and paired with advanced optimizers to assist in this process, providing a low-cost estimate of neutronic codes like MCNP. However, traditional models often require a large quantity of data, usually hundreds or thousands of iterations, to be accurately trained and deployed. Additionally, many neutronic modelers do not have the optimization background to build or deploy an effective shielding optimizer and would benefit from a simple Python framework.A molten salt reactor shielding problem is presented for optimization, utilizing a predictive machine learning model requiring only 21 iterations for training. This model is paired with a closed-loop optimizer using the Gekko Optimization Suite for Python. A baseline shield around the core is presented, and mass and cost constraints are applied at 172 metric tons and $1.4 million, respectively. An optimal shield is generated using the closed-loop optimizer (0.0377mREM/hr), allowing a similarly small dose to that of the baseline, but at a 10.8% reduced mass, a 11.9% reduced material cost, and 61 times computational cost reduction (98.4% improvement). The simple shield optimization framework resulting from this work offers acceleration and simplification of work for shield designers, allowing them to create improved designs in a fraction of the time.

Research on the temperature field of a horizontal reactor coolant pump canned motor

Abstract The temperature of the flywheel and rolling bearing is a key factor in the stability and safety of the canned motor reactor coolant pump(RCP). The horizontal Canned motor reactor coolant pump (HRCP) is the guarantee of the small modular reactor (SMR) security. HRCP is smaller than traditional RCP, The design of heat shield and flywheel cooling channel reduce the temperature of the flywheel and rolling bearing. In order to calculate the cooling performance of the above two structures. Based on the model,a thermal-fluid-solid coupling method has been used to investigate the safety of the HRCP. Results show that the temperature of the water-lubricated rolling bearing is lower than the allowable temperature; but the temperature of the flywheel is too high. In order to reduce the flywheel temperature, the author proposes a new flywheel cooling channel.it is found that this structure has an obvious effect on reducing the flywheel temperature. This structural design provides a reference for the improvement of the canned motor RCP and the optimization of the flywheel design.

Shielding mass estimation model for gas-cooled space nuclear reactors

The shielding is expected to be “mass-effective” for space nuclear power systems (SNPs) because it accounts for a significant portion of the total weight. Hence, the shield mass should be estimated rapidly but accurately especially in the early stage of SNPs’ design. In this paper, a simple mass estimation model was developed based on the preliminarily optimized shield design for the Jupiter Icy Moons Orbiter (JIMO) reactor. In the model, the reactor-induced 1 MeV equivalent silicon neutron fluence and photon absorbed dose at the unshielded payload were predicted by a circular surface source hypothesis at the core bottom, and the proportional coefficients were determined by the Monte Carlo calculation. Moreover, the attenuation factors of the shield were derived by solving the neutron/gamma coupled transport process within the shield body, and the correlations were established between the attenuation effect and the shield thicknesses. Afterwards, when given the radiation limits at the payload, the shield geometry and associated mass could be easily determined. Several detailed calculations corresponding to the variation of shield design were used to verify the estimation model. Those variations include the thickness of the Be-B4C layers, the effective density of the B4C and the number of the shielding layers. Additionally, the potential changes of the reactor such as the neutron energy spectrum and the structural materials in the core were also considered to evaluate the applicability of the model. Totally, the estimation model agrees with the detailed calculation within 15 % in a wide range, which suggests the model can be incorporated into the system code to help optimize the overall performance of the SNPs.

Optimization design for moderator, reflector, and shielding of Deuterium-Deuterium neutron source

Deuterium-Deuterium (D-D) neutron source, which could be used in both laboratory and outdoors due to its light weight, small volume and low cost, has been widely applied in thermal neutron imaging (TNI) and prompt gamma-ray neutron activation analysis (PGNAA). And the its optimization design is to obtain highly intense thermal neutrons and low dose rate around the facility with light weight and compact volume. In this paper, the genetic algorithm (GA) combined with MCNP6 was applied to globally optimize moderator, reflector, and shielding structures. As a result, the optimized thermal neutron intensity increased by 1.68 times, while the dose rate, weight and volume respectively decreased by 37%, 52%, and 27%, compared with the data based on the current design. This method could be an effective tool for the compact neutron source design.

The effects on heat and oxygen transport of different heat shield and sidewall insulation designs during continuous Czochralski silicon crystal growth

Numerical work has been done to optimize the hot zone for the continuous Czochralski growth of 8-inch diameter silicon crystals using a double-crucible system. Thicker insulation layers on a high-heel-shaped heat shield and the sidewall insulation led to a reduction in the heater power of more than 40%, a decrease in the oxygen content, and a significant flattening of the growth interface. This design also allowed a stronger argon gas flow near the outer free melt surface and the quartz crucible wall, which prevented the generation of an argon gas vortex in this area. Stronger flow of argon gas would assist in moving more SiO gas and dust out of the chamber. However, the reduction in the outer melt temperature compared to the original design could slow down the melting of the silicon granules.