Nuclear Radiation Environment Research Articles

Design and analysis of a HTS internally cooled cable for the Muon Collider target and capture solenoid magnets

The Muon Collider is one of the options considered as the next step in High Energy Physics. It bears many challenges, last not least in superconducting magnet technology. The target and capture solenoid is one of them, a channel of approximately 18 m length consisting of co-axial solenoid magnets with a 1.2 m free bore and peak field on axis of 20 T. One of the main concerns come from the nuclear radiation environment that may influence the stable operation of the coil, as well as its material integrity. Energetic photons cause large radiation heat load, of the order of several kW in the cold mass, and deposit a considerable dose, several tens of MGy. Neutrons cause material damage, at the level of 10-3 DPA. These values are at the present limit of superconducting coil technology. We describe here the conceptual design of the target and capture solenoid, focusing on the HTS cable design, which is largely inspired by the VIPER concept developed at MIT. We show how to address margin and protection, cooling and mechanics specific to the HTS cable selected.

Research on the degradation of resolution in cameras based on CMOS image sensor under γ- and X-rays irradiation

Remote control engineering in industry usually requires cameras to assist target identification and detection, but the cameras working in nuclear environments face the threat of radiation-induced degradation. Both γ- and X-rays in nuclear environments will cause ionizing radiation damage, but the difference in degradation of camera’s performance induced by ionizing radiation damage with equivalent total ionizing dose (TID) of these two rays is unclear, which is crucial for the evaluation of camera performance in a nuclear radiation environment. In order to figure out the degradation of CMOS cameras by ionization radiation damage under different rays, this study conducted irradiation experiments on CMOS image sensors under X-ray with 10 keV and 60Co-γ ray with 1.25 MeV, respectively, and then tested and calculated the resolution of camera based on this CMOS image sensor. After comparing and analyzing the results, it was found that the dark current and full well capacity of the CIS, as well as the resolution of the camera, were more severely degraded after X-ray irradiation. Further analysis found that the interface dose enhancement effect of X-ray, as well as the generation of high-density oxide trapped charges in the gate oxide, aggravated the degradation of full well capacity on the CIS after X-ray irradiation, resulting in more severe degradation in the resolution of the CMOS camera. This study provides theoretical basis for the safety and reliability evaluation of cameras in strong nuclear radiation environments.

Transient synergistic damage mechanism and characterization of silicon bipolar junction transistor

The silicon bipolar junction transistor (Si BJT) is widely used as a discrete device, but it is susceptible to damage from both ionization and displacement in nuclear radiation environments. Current research primarily focuses on steady-state irradiation to study the synergistic damage mechanism caused by ionization and displacement, with a lack of research on transient synergistic damage. This paper studies the energy deposition and distribution with different incident angles and energies when neutrons and photons are simultaneously incident, and found similarities in the energy deposition between low-energy photons and 1 MeV neutrons as well as high-energy photons and 1 MeV neutrons in synergistic damage. Additionally, transient current under simultaneous neutron and photon irradiation was calculated using COMSOL software. Simulation results indicate that by adjusting the number of photons, it is feasible to simulate the transient electrical characteristics of high-energy photons utilizing low-energy photons for synergistic damage. Hence, a novel characterization method, combining laser simulation and neutron sources, is developed to test the transient electrical characteristics of Si BJT with synergistic damage.

Minimum dose walking path planning in a nuclear radiation environment based on a modified A* algorithm

An additional cost function for the case with turning points is introduced to the A* algorithm, which can reduce unnecessary turning points. Therefore, the modified A* algorithm consists of three parts: the actual cost function, the estimated cost function, and the turning point cost function. The three functions are normalized so that they can be compared without dimensionality to obtain the optimal path planning in radiation environments. Based on the Geant4 Monte Carlo program, the radiation field model is established and the dose distribution data is obtained. We assign weights to the functions to smooth out the three different cost functions and avoid scenarios in which one function is much greater than the other two. In a small-scale simulation experiment, the path generated by the modified algorithm is consistent with that calculated by the traditional A* method, but the number of turning points is significantly reduced. The modified algorithm takes less time and the cumulative dose on the path is slightly lower. Modified A*, traditional A* and PRM algorithms are used for path planning and comparison in the complex radiation environment of multiple γ sources. The PRM algorithm takes the least computation time to search the path, but the cumulative exposure dose is random. For the path planning of multi-task operation in a radiation field, the cumulative radiation dose of the path planned by the modified A* algorithm is equivalent to that of the traditional A* algorithm, but the modified A* algorithm significantly reduces the number of turning points, the calculation time is significantly shortened, and the execution efficiency is improved. The modified A* algorithm can be used as a reference for path planning for workers in radiation workplaces.

Effect of mixed rare earth cations on structure, optical, mechanical and radiation shielding parameters of Na2O–B2O3 glass

The value of rare earth-containing glasses continues to increase, resulting in a higher cost for producing such glasses. The reduction in rare earth content reduces the cost of the production process. Investigating whether it is possible to prepare glasses with low rare earth (such as Dy and Sm) contents is valuable. In this work, the impacts of Dy2O3/ Sm2O3 substitutions on borate glass's structural, optical, and mechanical features were investigated. The optical studies reflected the structural modifications. For example, Urbach tail increased from 0.39 to 0.69 eV with further Dy2O3/ Sm2O3 substitutions. This increasing behavior refers to a less stable glass matrix. This outcome was substantiated by the diminished values of all elastic parameters in the current glasses upon additional Dy2O3/ Sm2O3 substitutions. Nonlinear optical parameters were examined across various wavelengths and compositions, revealing negligible variations within the visible and near-infrared (Vis-NIR) spans. However, a notable decrease was observed in the UV region, exhibiting a rapid decline with increasing substitutions. Furthermore, induced defects within the internal structure of the glassy network, notably non-bridging oxygens with additional Dy2O3/ Sm2O3 substitution, resulted in heightened nonlinear optical parameters. Simultaneously, all elasticity moduli decreased with further Dy2O3 additions in the current glassy system, attributed to increased disorder caused by defect production, dangling bonds, and non-bridging oxygens in the glassy matrix.In addition, the half-value layers of all glass samples were compared to those of typical and widely used shielding materials. Through this analysis, certain glass samples demonstrated superior qualities compared to conventional shielding materials. Notably, the glass sample with the highest Sm2O3 level (and correspondingly the lowest Dy2O3 value) exhibited particularly favorable attributes. Consequently, our glass samples show potential as effective shields in nuclear radiation environments.

Elucidating the influences of MoO3 in Na2O- ZnO - B2O3 - SiO2: Fabrication, optical, and γ-ray protection properties for the novel high-density glasses

The melt-quenching method was employed to synthesize glasses with varying compositions within the xMoO3-(30−x) Na2O- 5ZnO - 43.5B2O3 - 21.5SiO2 system, where (0 ≤x≤ 10) mol%. The densities increased from 2.93 to 3.67 g/cm3, while their molar volumes decreased from 22.48 to 20.18 cm3/mol. Based on the measurements, the optical band gap of the base glass was 3.53 eV. At its highest MoO3 content, this value decreased to 2.34 eV. The Urbach energy values for NaMo0, NaMo2, NaMo4, NaMo6, and NaMo10 glasses were 0.258, 0.323, 0.348, 0.37, and 0.435 eV, respectively. With an increase in molybdenum level, it was observed that the refractive index values also increased. These structural, optical, and radiation shielding behaviors were attributed to the structural modifications resulting from substituting Na2O with MoO3, leading to improved radiation shielding efficiency with the addition of MoO3. The Fast Neutron Removal Cross Section (FNRCS) (∑R) for the NaMo0, NaMo2, NaMo4, NaMo6, and NaMo10 glasses were 0.116 cm−1, 0.12 cm−1, 0.127 cm−1, 0.131 cm−1, and 0.135 cm−1, respectively. From the current work, we may conclude that NaMo glasses can serve as efficient shields in nuclear radiation environments. In general, it can be deduced that adding Na2O-ZnO-B2O3-SiO2 glasses improves their optical characteristics and enhances their capacity to absorb neutrons and photons for use in nuclear medicine applications.

Fuzzy optimal control of multilayer coverage based on radon exhalation dynamics in uranium tailings

Radon exhalation from uranium tailings has seriously affected environmental safety and human health. Many uncertain parameters, such as diffusion coefficient, porosity, percolation rate, material particle size, etc., are related to the diffusion and migration of radon. Moreover, cover materials, cover layers, and cover thickness are the main instruments to control radon exhalation, and the radon reduction effect of single-layer mulching is often inferior to that of the multilayer. Hence, achieving radon control with multilayer coverage under uncertain environment is an urgent problem that must be solved in the area of nuclear safety and radiation environment. In an attempt to address the issue, a dynamic model of radon exhalation with multilayer coverage is constructed using radon percolation-diffusion migration equation, and triangular membership functions inscribe the model parameters; the objective functions of the left and right equations of the model are constructed, and their extreme value intervals are obtained using immunogenetic algorithm. Then, subject to the total cost and thickness of multilayer covering materials, the fuzzy objective and constraint models of radon exhalation are constructed, and the fuzzy aggregation function is reconstructed according to the importance of the fuzzy objective and constraint models, where ultimately, the optimal radon control decision by swarm intelligence algorithm under different possibility levels and importance conditions can be obtained. An example is then used to validate the effectiveness of the radon exhalation model, and to demonstrate that fuzzy optimization provides a database of decision-making schemes regarding multilayer coverage, and guidance for optimal control and flexible construction management.

Design of Nuclear Radiation Monitoring System in Floor Exploration Based on Deep Learning.

Nuclear radiation environmental monitoring has become an important issue in floor surveys. From the perspective of regional environmental nuclear radiation monitoring, it is of great practical significance to establish a scientific and reliable wireless sensor monitoring network for timely and accurately grasping nuclear radiation status and ensuring nuclear safety. In this article, we design a regional environmental nuclear radiation monitoring system based on Zigbee wireless sensor network by using Zigbee wireless technology. First, the network topology suitable for nuclear radiation environment monitoring is designed. Second, the JN5121 module is selected as the core of the Zigbee wireless sensor to build the network hardware platform. Finally, the article focuses on the receiving mechanism, data transmission, coordination between network nodes, network structure, and dynamic network management, and carries on the software development to the Zigbee wireless environment monitoring network. The system can measure the data in real time, display the dose rate of y radiation effectively, and realize the functions of remote control, field control, security alarm, and environmental monitoring. It has good promotion and application value.

Image Feature Extraction in Nuclear Radiation Environment

Image Feature Extraction in Nuclear Radiation Environment

Design method research of a radiation-resistant zoom lens

In a strong nuclear radiation environment, the life of a traditional zoom lens is extremely short. To improve the life of the zoom lens, a novel method to design the zoom optical system is proposed, in which the front fixed group is all made of Silica lens with stronger irradiation performance. Firstly, the radiation-resistant performance of the glass lens is tested, and the transmittance of the optical system is analyzed. Then, a specific zoom optical system was proposed for the problem of difficult chromatic aberration correction in the front fixed group, and a calculation method of the initial structure parameters is analyzed theoretically. Finally, a 6× radiation-resistant zoom optical system is designed by using only two specific radiation-resistant glass materials. The imaging experiment demonstrates the better imaging performance of the radiation-resistant zoom system, which verifies the feasibility of the design method proposed in this paper.

Low dose rate γ-ray detection using a MAPS camera under a neutron radiation environment.

We present γ-ray radiation detection in a neutron radiation environment using a monolithic active pixel sensor (MAPS) camera without conversion or shielding layers. The measured output signal is the sum of the pedestal value, noise, and real radiation response signal. The sensor response shows that the MAPS camera is sensitive to neutrons and can capture a single photon. The number of pixels with a signal exceeding 100 exhibits a strong dependence on the dose rate and is the best indicator of this value. Therefore, a MAPS camera can be efficiently used as a radiation detection sensor in a robotic system, further limiting human errors in performing radiation detection in complex nuclear radiation environments.

Study of the Sensing Characteristics of Irradiated Fiber Bragg Gratings and Fabry-Perot Interferometers Under Gamma Radiation

The sensing characteristics of irradiated fiber Bragg gratings (FBGs) and Fabry-Perot interferometers (FPIs) were investigated under a 2 MGy dose of gamma radiation. The study found that the pressure sensitivity of FP sensors after irradiation was stable, while the temperature sensitivity of FBG sensors was unstable, and both wavelengths displayed a shift. These findings offer the possibility for the application of FP pressure sensors in the gamma radiation environments, and FBG sensors require further research to be suitable for application in the nuclear radiation environments.

Study of phase changes induced by gamma irradiation in welded stainless steel alloys 304 and 316

Structural steels for use in nuclear radiation environments are of great importance for applications ranging from nuclear reactors to the design of radiation-proof containers, buildings, and vehicles. The damage caused by nuclear high energy radiations to the structural materials is invisible, slow, and accumulative. This can lead to catastrophic and unexpected failure with very little warning time. This research work has focused on the effects of the high energy gamma radiations on structural steel alloys (SS304 and SS316). Of particular interest here was the behavior of welded joints of these alloys under gamma radiation. While the changes in the mechanical properties has been reported in previous work by several researchers, this report deals with the associated phase changes that occur in welded and base (unwelded) alloys after gamma irradiation up to 96 h. The results had earlier indicated that while tensile properties deteriorate, the surface hardness increases. The steel alloys have been characterized using X-ray diffraction and FE-SEM techniques. The XRD results show that though the welding process introduces large amounts of the ferrite phase in the welded zones for both steels, however prolonged gamma irradiation appears to enhance the austenitic γ-steel phase with a reduction in the amount of the ferritic phase. Molybdenum in SS316 and chromium in both steels appear to be responsible for the observed phase- and mechanical property- changes.

Molecular dynamics simulation of phase transition by thermal spikes in monoclinic ZrO<sub>2</sub>

Owing to its excellent corrosion, radiation and high temperature resistance, ZrO<sub>2</sub> has been considered as a strong candidate material for inert fuel for the incineration of actinides. In this paper, a combination of thermal spike model and molecular dynamics is used to simulate the phase transition process of ZrO<sub>2</sub> in the nuclear radiation environment. Based on the thermal spike model, two coupled diffusion equations are established with considering the multiple physical process of energy deposition and transmission after the implantation of swift heavy ions into target material. The space-time evolution characteristics of ZrO<sub>2</sub> lattice temperature are obtained by solving the coupled diffusion equations numerically. Then the phase transformation of ZrO<sub>2</sub> form monoclinic phase to tetragonal phase under the thermal spike is investigated on an atomic scale by means of molecular dynamics. It is found that a cylindrical track with a radius of 7 nm is generated in the center of ZrO<sub>2</sub> after the implantation of swift heavy ion with an electronic energy loss of 30 keV·nm<sup>–1</sup>. The lattice melts immediately in the center of track, accompanied with the coordination number of Zr decreasing from 7 to 4–6. Then at about 2 ps, the melting zone gradually turns cool and recrystallized. And in the center of the melting zone, voids begin to form and are surrounded by a highly disordered amorphous region. Meanwhile, tetragonal phase of ZrO<sub>2</sub>, whose coordination number of Zr is 8, is formed at the periphery of the amorphous region, which is also confirmed by the XRD calculation results. As energy transfers from track center to the surround, the tetragonal region gradually develops into the whole system, accompanied with the increase of voids size. The simulation results indicate that the irradiation of ZrO<sub>2</sub> with swift heavy ions can lead to a transformation from the monoclinic to the tetragonal phase when the deposited electronic energy loss exceeds an effective threshold ~21 keV·nm<sup>–1</sup>, greater than the experimental value (12 keV·nm<sup>–1</sup>), which was mainly due to the large difference between the simulated and measured incident ion fluences and the accuracy of the force field used in the molecular dynamics.

Integrating the radiation source position into a grid map of the environment using a mobile robot

In this paper, we present a detection method to identify the radiation source position and visualize the surrounding area. Using a mobile robot capable of autonomous positioning, four main steps can be followed to map an environment with radiation sources. First, a fast simultaneous localization and mapping system is used to build an occupancy grid map to display the entire physical zone. Secondly, the robot collects data on the radiation parameters along the appointed detection path. Thirdly, a Markov Chain Monte Carlo algorithm estimates the source position coordinates and intensity. Finally, a map with the source position is formatted to describe the radiation field. The experiment demonstrated that this method is feasible and allows visualization of a nuclear radiation environment.

Analysis of nuclear radiation damage effect on typical materials

In order to evaluate the effects of nuclear radiation on several typical materials, the mathematical models of radiation damage characteristics of three materials are established based on the analysis of radiation environment and damage forms. In order to simplify the calculation, the principles and indexes of damage estimation are determined according to the radiation damage process of three typical materials: polymer materials, high-energy explosives, and metal materials. The results show that the pure nuclear radiation environment has no obvious effect on the properties of three typical materials. It lays a theoretical foundation for radiation hardening of devices.

Data-Retention-Voltage-Based Analysis of Systematic Variations in SRAM SEU Hardness: A Possible Solution to Synergistic Effects of TID

Single-event upset (SEU) hardness varies across dies, wafers, and lots—even just after fabrication and further across time. Mechanisms of postfabrication variations include total ionizing dose (TID) effects, which are caused by long-term radiation exposure. This synergistic effect of TID on SEU hardness is a particular concern in integrated circuits used in space and nuclear radiation environments. This article shows that an electrical parameter called the data-retention voltage is useful in dealing with such TID effects on the SEU hardness of static random access memories (SRAMs), which are known to be particularly radiation-sensitive. Experiments showed that TID-induced variations in SRAM SEU hardness, i.e., variations in SEU cross sections, were predicted by measuring the data-retention voltage. In addition, these variations were canceled out by adjusting the power supply voltage according to its interesting relationship to the data-retention voltage. Results suggest that it might be possible in flight to predict and cancel out SEU hardness variations caused by TID and other synergistic effects.

Influence of total absorbed dose of Co-60 γ-radiation on the properties of h-MoO3 thin films

Optoelectronic and photonic devices are confronted with challenges imposed by extreme environmental conditions encountered in applications such as space satellite, nuclear radiation environment, etc. High energy radiations may alter the physical characteristics of these devices. In this context, studying the effect of gamma (γ-) radiation on relevant semiconductor thin films for devices is of paramount importance to ensure its optimum performances. In this research, the effect of high energy γ-radiation (with doses 50 kGy, 150 kGy and 250 kGy) on the properties of hexagonal molybdenum trioxide (h-MoO3) thin films was thoroughly investigated. The enhanced crystallinity of the as-synthesized thin films was observed due to the reduction of defects and disorders. Interestingly, the identified hexagonal phase of the pristine film remained identical after high dose irradiation. Field Emission Scanning Electron Microscopy (FESEM) revealed no significant changes in surface morphologies of the films after irradiation. Fourier transforms infrared (FTIR) spectra confirmed the hexagonal structure of MoO3 films evidently before and after irradiation, although the peak intensities and wavenumbers were found to vary slightly. With increasingγ-irradiation the band gap was shown to reduce from 2.92 to 2.84 eV as measured byUV–Vis-NIR diffuse reflectance spectrophotometer. The γ-irradiation has displayed a significant improvement in the degree of crystallinity and reduced the optical band gap without transforming the hexagonal phase of pristine nanocrystalline h-MoO3 film.

An innovative device to transport electron gun automatically in nuclear power plant

ABSTRACT The electron gun, as the equipment to generate and control nuclear reactions, has been widely used in nuclear power plants of the traveling wave reactor. To avoid the damage of radiation to maintenance personnel and improve the safety and security of nuclear reaction, it was necessary to realize the automatic transportation of electron gun. However, the working conditions of the automotic devices in a nuclear radiation environment were harsh and complex, which required the high operational reliability. Combining with the features and working environment, an innovative engineering design process based on quality function deployment (QFD) and function-behavior-structure (FBS) model was proposed for designing the transport device in the nuclear industry. With the guidance of this process, firstly, the problems and technical characteristics of the transport device were analyzed by the QFD method to obtain basic functions. Then, the FBS model was used to assist the designer to express knowledge and expand the search space of the schemes of control, structure, and material. Finally, the overall design scheme of the automatic transport device was obtained by adjusting these preliminary schemes. The design provided a solution to the possible interference phenomenon in automatic transportation and achieved the maximum reliability and safety.

Manufacturing Long Optical Fiber With Specialty Coatings for Distributed Sensing

Long optical fibers with specialty coatings enable truly distributed fiber optic sensing applications for measuring both physical and chemical parameters in inaccessible or harsh environments. We report an innovative magnetron sputtering deposition process to continuously manufacture up to 1000-m long optical fiber encapsulated with specialty coatings for distributed sensing. Coating materials can be metals, non-metals, metal alloys, oxides, nitrides, or any materials, which can be deposited via magnetron sputtering process. Multiple coatings of different materials can be deposited on optical fiber without interrupting the deposition process. We employed this process to fabricate 60-m-long optical fiber with titanium and palladium coatings for distributed hydrogen sensing. Acting as numerous point hydrogen sensors, the optical fiber was used to detect hydrogen leaks and determine leak locations simultaneously along the entire fiber length. The experimental sensing results demonstrate the capability of the manufacturing process for fabricating long optical fibers with specialty coatings for chemical sensing or other critical applications in extremely high-temperature environments, nuclear radiation environments, or high vacuum environments, where traditional metal coatings or polymer coatings are undesirable.