To address the inefficiency of demolition robots at nuclear contamination sites due to frequent retreats to safe zones for attachment replacement, this study develops and experimentally evaluates a six-wheeled mobile platform for attachment-replacement support near the work area. Structurally, the prototype adopts a well-established passive rocker-bogie suspension architecture combined with six-wheel independent drive. The focus of this work is not to claim a new suspension topology, but to evaluate its engineering feasibility and drive-load margins for a heavy-duty nuclear support platform through multibody simulation and onboard-sensor measurements. A constrained multibody model was implemented in ADAMS/Simulink to represent rocker joints, wheel revolute joints, actuator limits, and wheel–ground contact. A full-scale prototype was tested on representative nuclear-facility terrain conditions, including a 20° slope and a 250 mm vertical step. The results show that the prototype completed both tests while the measured motor torques remained within the allowable drive range. The positive and negative torque signs observed on the left and right sides are explained by mirrored motor installation and coordinate definitions rather than by a special torque-distribution mechanism. This study provides a structural selection and experimental performance reference for mobile operation support in radiation environments.

To improve the safety of road transportation of Spent Nuclear Fuel (SNF), this paper proposes a novel approach for risk identification and chaotic synchronous control in SNF road transportation systems. Firstly, a dynamic risk evolution model for the road transportation of SNF is developed by analyzing the nonlinear interactions among vehicles, environmental conditions, and human factors using complex network analysis and nonlinear dynamics. Secondly, an enhanced K-shell decomposition method is applied to identify key risk nodes and assess the relative importance of different risk factors, providing a basis for targeted risk control. Finally, a chaotic synchronization control strategy based on Lyapunov stability is proposed to suppress risk divergence and restore system stability. Three targeted control schemes are evaluated by varying the control gain coefficients across the 'Vehicle-Environment-Human' dimensions. Simulation results indicate that the strategy prioritizing environmental and human risk control yields the fastest convergence, significantly outperforming vehicle-centric approaches. The results show that prioritizing both environmental and human-factor control is most effective for suppressing chaotic divergence. This provides a solid quantitative basis for the strategic shift from passive defense to active environmental warning, thereby significantly optimizing the dynamic risk management of the SNF transportation system.

In the assembly process of nuclear fuel assemblies, fuel rods are assembled through rod pulling, and grid springs inevitable leave pre-damage on the surface of the fuel rods. In this study, the pre-damage is simulated by scratch, and the effect of pre-damage on the high temperature steam oxidation behavior of Cr-coated Zr-4 alloy is investigated. The Cr coating is deposited on the surface of Zr-4 alloy by multi-arc ion plating. The pre-damage to Cr coating is simulated by the scratch with different normal loads of 25 N and 50 N. The results indicate that the Cr coating suffers more severe pre-damage and more Zr-4 alloy is exposed under larger normal load. Due to the pre-damage caused by scratches on the initial structure of Cr coating, the thickness of the generated Cr2O3 in the pre-damage area is greater than that in the area without pre-damage. In some case, the thickness difference of the generated Cr2O3 has exceeded twice. After oxidation for 30 and 60 min, ZrO2 with a thickness of several tens or even over a hundred micrometers is generated below and around the pre-damaged area. Therefore, it can be concluded that pre-damage has a significant negative impact on the high temperature steam oxidation resistance of Cr-coated Zr-4 alloy.

The safe operation of nuclear facilities and the demand for real-time radiation monitoring have continued to increase. Active Pixel Sensor based nuclear radiation imaging technology has attracted significant attention due to its low power consumption and high integration capability. However, in high-radiation environments, APS devices are susceptible to interference from high-energy particle impacts, generating random high-amplitude noise that severely degrades video quality and reduces dose rate measurement accuracy. To address this issue, this paper proposes a real-time radiation noise suppression and dose detection method that combines timedomain minimum-value substitution with spatial median filtering with two-dimensional wavelet decomposition, implemented on a parallel FPGA architecture. The proposed method fully exploits the multi-stage pipelining and parallel processing capabilities of FPGAs to efficiently suppress radiation-induced noise in APS image streams and extract residual dose information at multiple scales. Experiments conducted using a 60Co gamma-ray source on both a video test chart and a real-world scenario demonstrate that the method improves the peak signal-to-noise ratio by an average of approximately 11 dB after denoising, significantly outperforming Gaussian and low-pass filtering, and achieving comparable results to deep learning approaches such as DnCNN and Vision Transformer. Moreover, the hardware implementation does not require power-hungry GPUs, ensuring real-time performance for embedded applications. Further wavelet decomposition and pixel value fitting analyses confirm excellent linear correlation for dose rate estimation, with the Daubechies wavelet diagonal component achieving an R2 as high as 0.99624. Overall, the proposed approach offers a low-power, high-efficiency engineering solution for real-time APS video denoising and dose detection in nuclear environments, providing a solid technical foundation for building FPGA-based intelligent nuclear radiation monitoring expert systems.

As nuclear energy expands, nuclear emergency response systems increasingly exhibit strong human–machine–environment (H–M–E) coupling, long-duration operations, and multi-department coordination, in which minor disturbances can be amplified by feedback loops into cascading failures and loss of situational control. To address the inability of conventional static and linear methods to represent dynamic risk evolution and chaotic uncertainty, this study proposes an integrated “risk network–chaotic evolution–synchronization control” framework. Based on 12-year-old on-site comprehensive drill reports from a Chinese nuclear power base, we construct a directed H–M–E risk network in a semi-quantitative, qualitative–quantitative manner and identify critical nodes using a composite betweenness–PageRank risk metric. We further abstract the system into a three-dimensional nonlinear coupled dynamical model; phase portraits, Lyapunov exponents, and bifurcation analysis confirm threshold effects, period-doubling routes, and chaotic attractors, revealing nonlinear amplification under strong coupling. Finally, an adaptive chaotic synchronization controller driven by network coupling strength is designed. Simulations show all strategies suppress chaos and achieve synchronization, while the machine-dominated strategy offers the best speed–energy trade-off for emergency resource allocation.

This paper investigates the radiation effects of alpha particle on Complementary Metal-Oxide-Semiconductor (CMOS) Active Pixel Sensors (APS). By analyzing the variation patterns of dark signals in CMOS APS after 72 h of alpha particle irradiation and 120 h of room-temperature annealing, the study explores the mechanisms of alpha particle induced radiation damage and the corresponding annealing effects. Experimental results show that under the same irradiation conditions, the number of damaged pixels is positively correlated with the alpha particle fluence. The dark image of CMOS APS is highly sensitive to alpha particle, with the number of dark signals in the effective pixel area increasing in proportion to the total fluence. As irradiation time or cumulative dose increases, the pedestal pixel values rise continuously, and the number of dark signals in high-value regions also grows. The annealing experiment results indicate that room-temperature annealing has a certain recovery effect on APS radiation damage, suggesting that the charged-particle radiation damage caused by alpha particle is not necessarily permanent. The findings of this study reveal clear patterns in the radiation damage and annealing effects of CMOS APS, which can help mitigate and compensate for signal degradation caused by radiation damage, thereby improving detection accuracy.

In this study, the mechanism and characteristics of the response α particles and the damage caused by them in CMOS active pixel (APS) sensors were investigated. A detection and compensation algorithm for dead pixels caused by α particle ionizing radiation was proposed, and the effects of dead-pixel compensation algorithms were compared and analyzed under different parameter conditions. The experimental results show that α particle response signal has highest accuracy at 9 dB gain, with an obvious "target-ring" distribution. With increasing cumulative dose, the CMOS APS pedestal tends to saturation while dead pixels continue increasing. Though some pixel damage recovers through natural annealing, the dead-to-noise ratio increases with irradiation time, reaching 32.54% after 72 h. A hierarchical clustering dead-pixel detection method is proposed, categorizing pixels into two types: those within and outside the response event. A classification compensation strategy combining mean and majority filtering is proposed. This compensation algorithm can address dead-pixel interference without affecting α particle radiation response data. When iterated multiple times and with integrationtime exceeding 6.31 ms, the number of dead pixels can be effectively reduced.

Aluminum based boron carbide (B4C/Al) composites have received a lot of attention as the preferred neutron absorbing material. In this study, B4C/6061Al neutron absorbing composites (NACs) are fabricated by laser directed energy deposition (LDED) and three different heat treatments are applied to the deposited NACs. The influence of heat treatment on the microstructure, tensile property, and corrosion resistance of B4C/6061Al NACs is investigated. The results indicate that heat treatment has a significant impact on the microstructure of Al grains in the NACs. Heat treatment leads to an increase in the proportion of low angle grain boundaries (LAGBs), orientation concentration, and local dislocation density, while the mean size of Al grains decreases. At the same time, it also causes compressive stress inside the Al grains and B4C grains. Among them, the tensile strength of B4C/6061Al NACs is enhanced after T73 heat treatment. The fracture mechanism of the NACs is a mixed mode of ductile fracture of 6061Al matrix and brittle fracture of B4C. After heat treatment, the corrosion potential of the NACs increased and the corrosion current density decreased, indicating that heat treatment improved the corrosion resistance of B4C/6061Al NACs. The research results in this study demonstrate that the B4C/6061Al NACs exhibit the best comprehensive performance after T73 heat treatment.

To reduce pulse pile-up and improve ionizing particle discrimination efficiency, we use a CMOS active pixel sensor to analyze ionizing particle optical responses and propose morphology-based discrimination. By comparing the characteristics of response events of different ionizing particles, the regulatory mechanisms influenced by gain and integration time are elucidated, and the discrimination effectiveness is verified. Results show alpha events differ significantly from beta and gamma events in pixel count, mean pixel value, rectangularity, convexity, and compactness. beta and gamma events are similar in pixel count, rectangularity, and convexity, but differ in mean pixel value or compactness. Using pixel count, alpha events were identified with over 99% accuracy. beta and gamma events were discriminated by mean pixel value with over 82% accuracy. The results provide a new method and basis for ionizing particle identification in mixed radiation fields. It supports nuclear particle discrimination and noise mitigation, providing new approaches and theoretical guidance.

The AlCrFeMoTi high-entropy alloy exhibits promising application potential as a corrosion-resistant structural material in advanced nuclear energy systems, particularly in lead–bismuth fast reactors. In this present study, first-principles calculation based on the density functional theory was employed to investigate the phase and electronic structure of AlCrFeMoTi HEA. The Gibbs free energy calculation results and XRD experimental results both indicate that the BCC phase is more stable for AlCrFeMoTi HEA. The atom distribution model was constructed according to the site preference of atoms occupying sublattices. The results indicate that alloying atoms have an obvious site preference. For example, Fe, Mo, and Cr atoms always prefer the 1a sublattice, while Al and Ti atoms tend to favor the 1b sublattice. And the atom site preference is temperature-sensitive. At 973 K, the site occupancy configuration is (Al5Cr16Fe26Mo17Ti0)1a(Al21Cr9Fe0Mo9Ti25)1b. Based on the steady-state phase structure, the band structure, density of states, and charge density were calculated. The electronic structure results show that metal bonds are formed between alloying elements in AlCrFeMoTi HEA, exhibiting strong metallic properties.

B4C/Al Neutron absorbing composites with 30 wt% B4C were fabricated by laser directed energy deposition (LDED) and vacuum sintering (VS). The 10B areal density (10BAD), microstructure, and corrosion properties of the composites fabricated by the two technologies were comparatively investigated. The 10BAD of B4C/Al composite fabricated by LDED was 1.1 times that fabricated by VS, indicating better neutron absorption performance. SEM observation revealed the formation of AlB2 and Al4C3 precipitates in the B4C/Al composite fabricated by LDED. Electrochemical corrosion and boric acid (H3BO3) immersion corrosion show that the main corrosion form of the B4C/Al composite fabricated by LDED and VS was pitting corrosion, while the B4C/Al composite fabricated by LDED had higher resistance to H3BO3 corrosion. The main reason is that the generated AlB2 and Al4C3 precipitates provide cathodic protection for the Al matrix.

This study proposes a novel TC4-Gd2O3 neutron absorbing composite, which employs TC4 as the matrix and 10 wt% Gd2O3 as the neutron absorber. The effect of sintering time on the phase, microstructure, density, compressive property, and corrosion resistance of the vacuum sintered TC4-10Gd2O3 composites was investigated. The Ti in the composite exists as alpha-Ti and beta-Ti, with alpha-Ti dominating. The extension of sintering time promotes the generation and growth of secondary alpha-Ti and beta grains. And the density of the composite increases with the prolongation of sintering time. The compressive strength of the composite fabricated by sintering time of 2 h is highest, reaching 901.03 MPa. Pitting is the main form of corrosion of TC4-10Gd2O3 composites in H3BO3 solution. The interface between Gd2O3 particles and Ti becomes the most prone location for pitting. The main corrosion products include Al(OH)3, GdAlO3, Ti2O3, and Ti3O5. The research results in this study indicate that the optimal sintering time for the TC4-10Gd2O3 neutron absorbing composite is 2 h at 1000 degrees C.

Multi-target inspection path planning (MTIPP) of mobile robot (MR) represents a significant area of research in the context of environmental monitoring and routine inspection of nuclear power plants (NPPs). Given the challenges posed by complex radioactive indoor environments, characterized by the presence of numerous radioactive sources and dense obstacles, a bi-level multi-objective programming framework is proposed to model the MTIPP problem. To navigate this model effectively, a novel bi-level hybrid algorithm named ACO-GA-A* that integrates improved ant colony optimization (IACO), genetic algorithm (GA) with modified A* algorithm is developed. In the upper level, ACO with a GA-based non-uniform initial pheromone distribution, an adaptive heuristic function and an elite strategy for pheromone update is employed to determine the optimal traversal sequence of inspection targets. In the lower level, a modified A* algorithm, which considers multiple constraints including path length, risk degree and energy consumption, is utilized to plan pairwise paths between targets, thereby generating cost graphs. Comparative simulation experiments are conducted in various complexity radioactive scenarios. The results indicate that the modified A* can plan pairwise paths with lower total costs in shorter time compared to traditional A*, ACO, and GA. Furthermore, the ACO-GA-A* demonstrates better sensitivity, reliability, and convergence characteristics compared to some other bi-level hybrid algorithms. Subsequent real-world experimentation corroborates the effectiveness and feasibility of both the bi-level programming framework for MTIPP and the proposed ACO-GA-A* algorithm

Marine nuclear power plants (MNPPs) represent items of forward-looking high-end engineering equipment combining nuclear power and ocean engineering, with unique advantages and broad application prospects. When a nuclear accident occurs, it causes considerable economic losses and casualties. The traditional accident analysis of nuclear power plants only considers the failure of a single system or component, without considering the coupling between the system and the operator, the environment, and other factors. In this study, the cause mechanism of nuclear accidents in MNPPs is analyzed from the perspective of a social technology system. The causal analysis model is constructed by using the internal core causal analysis (e.g., technical control) and external stimulation causal analysis (e.g., social intervention) of accidents, after which the mechanism of the coupled evolution of each influencing factor is analyzed. A Bayesian network inference model is used to quantify the coupling relationship between the factors that affect the deterioration of nuclear accidents. The results show that the main influencing factors are pump failure, valve failure, insufficient response time, poor psychological state, unfavorable sea conditions, unfavorable offshore operating environments, communication failure, inappropriate organizational procedures, inadequate research and design institutions, inadequate regulatory agencies, and inadequate policies. These 12 factors have a high degree of causality and are the main factors influencing the deterioration of the small break loss of coolant accident (SBLOCA). In addition, the causal chain that is most likely to influence the development of SBLOCA into a severe accident is obtained. This provides a theoretical basis for preventing the occurrence of marine nuclear power accidents.

Reflood of nuclear fuel assemblies is the top priority accident management strategy for nuclear power plants in the event of a loss of coolant accident, during which the cladding tubes inevitably undergo reflood oxidation. This study aims to investigate the single-sided reflood oxidation behavior of Cr-coated Zr-Sn-Nb alloy cladding tubes at 1000 degrees C-1200 degrees C. High-temperature steam oxidation and in-situ quenching were employed to simulate the reflood oxidation process of nuclear fuel assembly cladding tubes in the early stages of severe accidents. The microstructure, cross-sectional layer thickness evolution, oxidation kinetics, and hydrogen absorption of Crcoated Zr-Sn-Nb alloy cladding tubes during single-sided reflood oxidation process were investigated. The results showed that after single-sided reflood oxidation, microcracks appeared on the surface of the cladding tubes. As the oxidation temperature increases and the oxidation time prolongs, the surface oxidation products gradually evolve from porous flocculent structures to strip-shaped or elliptical bubble structures and worm aggregated structures. A multi-layer layered structure of Cr2O3 layer/Cr coating/Cr-Zr diffusion layer/alpha-Zr(O) was formed on the cross-section of the cladding tube after single-sided reflood oxidation. The thickness of the Cr2O3 layer and residual Cr coating does not increase or decrease monotonically with the extension of oxidation time after reflood oxidation at 1200 degrees C. The kinetics of single-sided reflood oxidation follows a parabolic law, and the oxidation constant increases by about an order of magnitude as the oxidation temperature increases by 100 degrees C. As the oxidation temperature increases and oxidation time prolongs, the hydrogen absorption of the cladding tube gradually increases. After single-sided reflood oxidation, the hydrides in the Zr-Sn-Nb alloy cladding tube are mainly delta-ZrH1.5.

Radioactive strontium (Sr) from reprocessed high-level waste (HLW) poses a significant environmental hazard due to its long half-life and high radiotoxicity. Effective immobilization of Sr is crucial for the safe disposal of nuclear waste, and ceramic materials like pyrochlore have shown promise due to their high thermal stability and resistance to leaching. This study investigates the application of La2Ce2O7 fluorite oxide ceramic as a host material for immobilizing radioactive Sr from reprocessed HLW. A simulated waste-form, La1.5Sr0.5Ce2O7 (LSCO50), is synthesized via the sol-gel method and systematically evaluated for thermal stability, leaching resistance, and Sr segregation behavior. The LSCO50 waste-form shows minimal weight loss (4.6 %) from 26 to 1200 degrees C, and low Sr2+ leaching rates (1.41 x 10-7g cm-2 d-1 after 42 days at 90 degrees C). Density functional theory (DFT) calculations reveal segregation energies around 0.487 eV, supporting its suitability for HLW immobilization.

Ti6Al4V-10 wt%Gd2O3 (TC4-10Gd2O3) composites were fabricated by vacuum sintering. And the influence of sintering temperature on the microstructure, mechanical and corrosion properties of the fabricated composites was investigated. The results indicate that Ti in the fabricated composites appears in aggregated or thin strip form, with alpha phase and beta phase coexist. As the sintering temperature increases, the density, hardness, compressive strength, and strain of the composites also increase. It was found that pitting was the main corrosion form of the fabricated TC4-10Gd2O3 composite, And pitting corrosion mostly occurs at the interface between agglomerated Ti and Gd2O3. In low concentration H3BO3 solution, the main corrosion product of Ti in the composites was Ti2O3, while in high concentration H3BO3 solution, the main corrosion product was Ti3O5.

The safe immobilization of radiotoxic strontium (Sr) in high-level radioactive waste (HLW) remains a major challenge due to its tendency to segregate and leach under aqueous conditions. In this study, a surface vanadium (V) engineering strategy is proposed to enhance the chemical stability of Sr2Fe1.5Mo0.5O6-delta (SFM) ceramics. Vdoped samples (SFMV), synthesized via a sol-gel method with 0.05 mol V partially substituting Mo, show improved resistance to Sr migration. DFT calculations reveal that V modification increases the Sr migration barrier from 0.14 eV (in SFM) to 0.34 eV (in SFMV) and induces the formation of strong Fe-O-V, and Mo-O-V effectively suppressing Sr surface segregation. Additionally, the formation of SrMoO4 phases may act as Sr sinks, further enhancing stability. Leaching tests show that the Sr release from SFMV drops from 7.43 x 10-4 to 2.89 x 10-6 g & sdot;cm-2 & sdot;d-1 over 42 days, representing a 64 % reduction compared to pristine SFM. This work provides a promising strategy for designing durable ceramic hosts for Sr-containing HLW.

Aluminum matrix boron carbide (B4C/Al) composites with moderate strength but excellent ductility are fabricated by laser-directed energy deposition (LDED) with different laser powers. The microstructural features underlying the outstanding mechanical properties of such fabricated composites have been fully explored. The mechanism of the excellent ductility without notably sacrificing strength is attributed to dislocation formation, grain refinement, and precipitation effect, which could therefore advance the state-of-art in the field of B4C/Al composites. The influence of laser power on the microstructure, mechanical, and corrosion properties is also investigated. The composite fabricated by the laser power of 1200 W has the best corrosion resistance. It is found that pitting is the primary type of corrosion of the LDED B4C/Al composites in H3BO3 solution, and it is most likely to occur at the interface between Al and B4C particles. These findings highlight that the LDED process can fabricate high-performance corrosion-resistant composites.