Physics-informed neural networks (PINNs) are vital for machine learning and exhibit significant advantages when handling complex physical problems. The PINN method can rapidly predict 220Rn progeny concentration and is very important for regulating and measuring this property. To construct a PINN model, training data are typically preprocessed; however, this approach changes the physical characteristics of the data, with the preprocessed data potentially no longer directly conforming to the original physical equations. As a result, the original physical equations cannot be directly employed in the PINN. Consequently, an effective method for transforming physical equations is crucial for accurately constraining PINNs to model the 220Rn progeny concentration prediction. This study presents an equation adaptation approach for neural networks, which is designed to improve prediction of 220Rn progeny concentration. Five neural network models based on three architectures are established: a classical network, a physics-informed network without equation adaptation, and a physics-informed network with equation adaptation. The transport equation of the 220Rn progeny concentration is transformed via equation adaption and integrated with the PINN model. The compatibility and robustness of the model with equation adaption is then analyzed. The results show that PINNs with equation adaption converge consistently with classical neural networks in terms of the training and validation loss and achieve the same level of prediction accuracy. This outcome indicates that the proposed method can be integrated into the neural network architecture. Moreover, the prediction performance of classical neural networks declines significantly when interference data are encountered, whereas the PINNs with equation adaption exhibit stable prediction accuracy. This performance demonstrates that the proposed method successfully harnesses the constraining power of physical equations, significantly enhancing the robustness of the resultant PINN models. Thus, the use of a physics-informed network with equation adaption can guarantee accurate prediction of 220Rn progeny concentration.

As a core component in high-energy physics experiments, the performance of the positron source target directly determines the positron yield and the overall operational stability of the system. This study presents a systematic design of a positron source target tailored for an electron (10 MeV, 10 kW) accelerator. Initially, Monte Carlo simulations using Geant4 were conducted to optimize the target thickness for maximizing positron production. Subsequently, a series of multi-layer water-cooled target models were established. Their temperature distributions under high-power electron beam bombardment were simulated using Finite Element Analysis (FEA) to determine the optimal number of target layers. The transient simulation results indicate that for the 6-layer target operating at 10 kW, the maximum surface temperature of the tungsten plates reaches 370 K, which is well within the safety limits. Furthermore, thermal stress analysis reveals that the maximum stress within the target is 22 MPa, ensuring a sufficient safety margin. The findings of this research confirm the feasibility of the proposed target design and provide valuable technical insights for the engineering development of high-power positron sources.

After tobacco smoking, radon exposure is the second most common cause of lung cancer. To accurately measure 220Rn and its progeny doses, a high-precision thoron chamber is required to calibrate the radiation detectors. However, traditional empirical regulation and analysis methods struggle to satisfy the accuracy requirements for state-parameter control. This study proposes a hybrid data-physics-driven approach to establish an efficient prediction method for 220Rn and its progeny concentrations, enabling the precise regulation of state parameters in a thoron chamber. First, a high-fidelity computational fluid dynamics model of the thoron chamber was developed and experimentally validated to generate a reliable database for neural-network training. Innovatively, the diffusion equations of 220Rn and its progeny, along with fluid mass conservation equations, were embedded as physical constraints into the neural-network architecture. The resulting neural-network model achieved rapid prediction of 220Rn/progeny concentrations and flow-field parameters. The predicted concentration distribution patterns and flow-field characteristics showed strong consistency with previous research, demonstrating prediction deviations within 1.8

The non-contact membrane distillation(MD)method developed by researchers at the University of South China marks a notable advancement over traditional direct contact membrane distillation approaches.Conventional MD methods encounter substantial limitations,such as shortened membrane lifespan due to continual contact with contaminants,low and inconsistent membrane flux,and inadequate mechanisms for real-time membrane damage monitoring.These challenges significantly reduce the operational efficiency and reliability of MD in practical applications,particularly in environments where stable,uninterrupted performance is critical.The non-contact MD method,however,minimizes the direct interaction between the membrane and feed solution,thereby markedly extending the membrane's functional lifespan and enhancing its flux stability,rendering it more suitable for long-term,large-scale deployment.This study aims to adapt the non-contact MD technique for on-site volume reduction and purification of radioactive wastewater generated by nuclear power plants,hospitals,and similar facilities.To meet the specific requirements of these applications,the researchers referenced established design frameworks for non-contact MD devices and incorporated heat pump waste heat recovery technology.This integration not only improves energy efficiency but also addresses the need for an economical and practical treatment system.By utilizing heat pump technology,energy consumption in the MD process is reduced by approximately 26％,with projected energy use maintained below 500 kW·h per ton of wastewater treated.Such energy efficiency is essential for large-scale application,enhancing both the economic feasibility and sustainability of radioactive wastewater treatment.A pilot-scale engineering prototype was designed,constructed,and rigorously evaluated to determine its performance metrics.Experimental results indicate that the prototype achieves a robust membrane flux of over 20 kg/(m2·h).Additionally,the prototype's wastewater treatment capacity is flexible,ranging from 16.58 kg/h to 75.15 kg/h based on operational settings.This adjustable treatment capacity allows operators to calibrate the processing rate in real time,aligning the system's functionality with varying demands and expanding its applicability across diverse use cases.The prototype demonstrated superior ion removal efficiency for wastewater treatment.Conductivity assessments revealed an ion removal efficiency of 99.7％,while retention rates for simulated radioactive contaminants such as strontium(Sr2+)and iodine(I-)surpassed 99.9％.These findings underscore the prototype's capability to treat radioactive wastewater effectively,ensuring that the treated effluent meets stringent environmental safety standards.In summary,the successful design and validation of this engineering prototype establish a robust technical foundation for the future development of compact,on-site radioactive wastewater treatment systems.Such systems have the potential to substantially mitigate the environmental impact of radioactive wastewater from nuclear and healthcare facilities,advancing safer,more sustainable waste management solutions.

Objective In order to develop a non-heating, fast, and efficient method for activated carbon regeneration, the deep depressurization method was proposed. Methods A validation experimental setup was designed to systematically study the impact of desorption methods, desorption duration, and desorption conditions on the desorption effectiveness of activated carbon adsorbed with radon and water. Continuous repetitive experiments and expanded experiments were conducted. Results The experimental research results indicate that the combination of continuous ventilation and deep depressurization is the most effective desorption method. Considering factors such as overall energy consumption and time, the optimal desorption time for activated carbon is 2 hours. Reducing the relative humidity of radon-laden air and elevating the desorption environmental temperature significantly enhances the desorption rate. Under environmental conditions featuring a temperature of 24-25 °C, a relative humidity ranging from 5% to 15%, and a flow rate of 0.3 L/min, 122.5 g of activated carbon can achieve a desorption rate of 85% after 2 hours of desorption. Moreover, the desorption results remain stable through 10 consecutive repetitions. Further experiments on a kilogram-scale activated carbon bed demonstrate that under conditions featuring a vacuum level higher than that corresponding to the environmental temperature's water evaporation point and an appropriate flow rate, the desorption rate of the activated carbon can reach the efficiency of a smaller carbon bed and is independent of the shape of the activated carbon bed. Conclusion The deep depressurization method for the regeneration of the activated carbon adsorbed with radon and water holds promise as a rapid and efficient online regeneration method.

The impact of the radiation dose produced by 222Rn/220Rn and its progeny on human health has garneredincreasing interest in the nuclear research field. The establishment of robust, regulatory, and competent 220Rnchambers is crucial for accurately measuring radioactivity levels. However, studying the uniformity of the 220Rnprogeny through experimental methods is challenging, because measuring the concentration of 220Rn and itsprogeny in multiple spatial locations simultaneously and in real time using experimental methods is difficult.Therefore, achieving precise control of the concentration of 220Rn and its progeny as well as the reliable samplingof the progeny pose significant challenges. To solve this problem, this study uses computational fluid dynamicsto obtain the flow-field data of the 220Rn chamber under different wind speeds and progeny-replenishment rates.Qualitative analysis of the concentration distribution of the progeny and quantitative analysis of the progenyconcentration and uniformity of the progeny concentration are conducted. The research findings indicatedthat the progeny-concentration level is primarily influenced by wind speed and the progeny-complement rate.Wind speed also plays a crucial role in determining progeny-concentration uniformity, whereas the progeny-complement rate has minimal impact on uniformity. To ensure the accuracy of 220Rn progeny-concentrationsampling, we propose a methodology for selecting an appropriate sampling area based on varying progenyconcentrations. This study holds immense importance for enhancing the regulation and measurement standardsof 220Rn and its progeny.

正电子湮没信号的精准采集与关联符合技术是寿命谱灵敏表征材料微观缺陷的基础.测量环境中放射性射线对正电子湮没信号采集的影响,制约着寿命谱方法在复杂辐射背景中应用,特别是在核结构材料中子辐照损伤研究中,中子活化诱发的放射性核素形成的γ射线本底,将影响正电子寿命谱仪的测量结果.为探究γ本底对正电子湮没寿命测量的影响规律,本文基于60Co、137Cs源设计了辐射背景仿真实验,结果显示:60Co源产生的双高能γ射线是影响寿命谱形状及湮没寿命的主要因素;通过对比高、低两种典型活度比(60Co/22Na为3.3和1.9)下的测量结果,并经活化反应堆压力容器钢样品放射性本底真实情况检验,结果发现:在低活度比下,辐射本底导致的偶然符合概率增大,寿命谱峰谷比显著变差;在高活度比下,除偶然符合外,信号错误符合概率急剧增加,谱形明显畸变且寿命值迅速减小.基于本文辐射背景放射源模拟方法及干扰γ的影响规律,可进一步探索正电子湮没寿命测量中γ本底排除的新技术和新方法.

Radon (Rn) is an important contributing factor to lung cancer. Activated carbon (AC) is currently the only Rn adsorbent for industrial applications. However, the effect of the key pore size of AC on Rn adsorption remains unclear, and enhancement of the Rn adsorption performance when using AC is still a challenge. In this work, grand canonical Monte Carlo (GCMC) simulations were performed to simulate the Rn adsorption ability of AC with different pore sizes. The adsorption selectivity of AC with pore sizes from 0.42 nm to 0.60 nm for Rn in the atmospheric environment was much greater than that for nitrogen and oxygen. The Rn adsorption performance was also investigated using KOH-modified activated carbon (KAC) with different pore sizes experimentally prepared using high-temperature roasting. The results showed that when the pore volume of KAC was significantly increased to approximately 0.55 nm, the Rn adsorption performance was obviously improved. Its adsorption coefficient reached 6.50 +/- 0.11 m3 kg- 1, which was 46.7 % higher than that of AC. After heating and regeneration in air, the Rn adsorption performance of KAC was basically unchanged. Combined with the comparative analysis using theoretical and experimental results, the relationship between the Rn adsorption performance of KAC and the pore volume at 0.55 nm is determined, and the accuracy of the GCMC calculation results was substantiated. This research provides a theoretical basis and an experimental method for improving the Rn adsorption performance of AC.

Environmental radon emanates from the exhalation and release of soil, rocks, and building materials. Environmental radon contamination tracing and radon pollution prevention and control require the measurement of the radon exhalation rate on media surfaces. Reliable measurements of the radon exhalation rate cannot be achieved without regular calibration of the measuring instrument with a high-performance reference device. In this study, a reference device for the calibration of radon exhalation rate measuring instruments was developed using a diffusion solid radon source with a high and stable radon emanation coefficient, an integrated diffusion component composed of a plasterboard and a high-density wooden board, an air pressure balance device, a radon accumulation chamber, and a support structure. The uniformity and stability of the reference device were evaluated using the activated carbon-γ spectrum and open-loop method, respectively, to measure the radon exhalation rate. The reference device achieved different radon exhalation rates by using different activities of diffusion solid radon sources. Nineteen measurement points were regularly selected on the radon exhalation surface of the reference device, and the uniformity of the radon exhalation rate exceeded 5%. The short-term stability of the reference device was better than 5% under different environmental conditions and was almost unaffected by the ambient air pressure, environmental temperature, and relative humidity.

Radon is a naturally occurring radioactive inert gas that poses a significant threat to the human health. Coconut shell activated carbon has been verified to be the best radon adsorbing material, but its radon adsorption capacity still cannot meet the requirement of industrial applications. Activated carbon modification using liquid nitrogen is an effective method for improving the radon adsorption capacity, but it is necessary to determine the conditions for large-scale production. In this study, the influence of environmental temperature, container geometry, and amount of activated carbon and liquid nitrogen on the modification effect are examined. The results show that the activated carbon has the best modification effect when the container is placed in a water bath at 50 °C. The container geometry and activated carbon mass have a minor influence on the modification effect. Further, the radon adsorption capacity is increased by 36% when 6.5 L of liquid nitrogen is added to 1 kg of activated carbon. The characterization results reveal that the chemical structure and elemental content of the activated carbon do not change after modification, but the number of micropores is significantly increased, especially the micropores with a size of 0.5-0.6 nm, which is related to the radon adsorption capacity of the modified activated carbon. Overall, the liquid-nitrogen-based modification is a simple, environment-friendly, and low-cost method to improve the radon adsorption capacity of activated carbon, which can be used in the large-scale production of highly efficient radon adsorbents.

Determining the distribution of muonic atoms is essential for μ -X ray imaging. In this study, the generation and de-excitation of muonic atoms in multi-elemental targets were simulated using the Monte Carlo software toolkit Geant4. An approach that reconstructs the production sites of muonic atoms from the μ -X ray momentum is proposed. The imaging results indicated a high simulated spatial resolution of 0.1 mm and a significant increase in the detection efficiency compared to that achieved by the 3-mm pinhole imaging technique. In addition, an analysis of the image quality index ( Q ) revealed that a superior image quality can be achieved for elements with high and medium atomic numbers. The proposed method has the potential to be further developed into an accurate and efficient technique for positioning the distribution of elements.

Nickel nanoparticles supported on AC (Ni/AC) composites, combining abundant micropores with open metal sites, are rationally designed for adsorbing Rn.

Conventional contact membrane distillation technology has some problems, such as membrane fouling and wetting, resulting in short membrane life, low permeate flux, and instability, which limit its industrial application. Here, a non-contact membrane distillation method is proposed for radioactive wastewater treatment. The effects of hot-side inlet temperature, hot-side flow rate, sweeping gas temperature, and cold-side flow rate on permeate flux are examined. The purification ability of this method for strontium ion in simulated radioactive wastewater and actual radioactive wastewater from uranium-containing hydrometallurgical purification plant was investigated. Under the optimized conditions, the permeate flux of non-contact membrane distillation unit reaches 24.87 kg/(m(2).h), the rejection rate of Sr2+ in simulated radioactive wastewater is more than 99.99%, and the decontamination factor can reach more than 4.5 x 10(6). The total alpha and beta activity concentrations in the radioactive wastewater are 21279.7 Bq/L and 17811.9 Bq/L, respectively, while the actual alpha and 13 activity concentrations of the distillate produced by the membrane distillation device are 0.205 Bq/L and 0.877 Bq/L, respectively. Overall, the proposed method has the advantages of long membrane service life, high and stable permeate flux, which can facilitate its large-scale industrial application in volume reduction and deep purification of radioactive wastewater.

To investigate the thermal evolution of vacancy-type defects and the relationship between the evolution of vacancy-type defects and the formation of fuzz structure on the surface of W-Ni-Fe heavy alloys irradiated with He ions, isochronal annealing treatments at temperatures from 100 degrees C to 10 0 0 degrees C were conducted on the irradiated 97W-2Ni-Fe alloy. The evolution of microdefects was characterized by positron annihilation spectroscopy (PAS). Thermal desorption spectroscopy (TDS), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were used to supplement the positron annihilation method. A large number of vacancy-type defects were produced in the 97W-2Ni-Fe alloy after irradiation at room temperature and isochronal annealing, and the main defect types of positron capture changed at three stages: RT-60 0 degrees C, 600-800 degrees C, and 800-1000 degrees C. SEM found that a large number of nanoscale protrusions appeared on the surface of samples annealed at 800 degrees C, and these nanoscale protrusions were seeds of fuzz structures. The formation of fuzz structure is closely related to the movement of vacancy-type defects by PAS, TDS, SEM, and other characterization methods. In addition, we found that the high density Ni and Fe in the matrix phase of the 97W-2Ni-Fe alloy as He capture points would accelerate the nucleation and growth of He bubbles and promote the growth of the fuzz structure.(c) 2022 Elsevier B.V. All rights reserved.

In this paper, activated carbon has been modified by water immersion and freeze–thaw cycles to further improve its radon adsorption capacity. Under freezing at − 80 °C and thawing at 50 °C, three cycles of modification were most effective, the radon adsorption coefficient was increased by 24%, and remained stable after five repeated radon adsorption–desorption cycles. The apparent morphology of the modified activated carbon changed significantly. The specific surface area of micropores increased significantly and was positively correlated with the radon adsorption capacity. The new application of this method can provide some references for the modification of material. Experimental flow process diagram. The activated carbon was modified by water immersion and freeze–thaw cycles under different experimental conditions, and the best modification process was determined by measuring the static adsorption coefficient. The activated carbon with better modification effect was characterized and tested to observe the morphological and structural changes. It was finally concluded that water immersion and freeze-thawing could effectively enhance the microporous volume, specific surface area and radon adsorption capacity of activated carbon.

To examine the response of diffusion-type detectors for thoron under wind speeds similar to natural air ventilation, a special design thoron chamber was developed with a dynamic circulating air-flow field forced by fans. Wind speeds of 0–0.52 m s−1 were adjusted by control of the fan rotation rate according to a linear model, with higher wind speeds contributing to more homogenous air flow status. Thoron concentrations, ranging between 3.2 × 103 and 3.7 × 104 Bq m−3, were easily available through different injection conditions and 220Rn gas sources with high and stable emanation coefficient. The stability and homogeneity of thoron concentrations was controlled within 5.0% and the concentrations in the direction of wind speed had minimal differences compared with the other direction. Higher wind speeds also improved the stability and homogeneity of thoron concentrations. The design and construction of the thoron chamber functioned well in controlling thoron concentration. The response of an AlphaGUARD monitor to thoron was examined in the thoron chamber under different wind speeds. The study revealed a monitor response to thoron (rates of thoron infiltration into the detection chamber of the monitor) respectively was from 0.044 to 0.065 under winds speeds from 0.05 to 0.51 m s−1. Reproducible and controlled expourse conditions can be provided for testing thoron monitors.

The source and vertical distribution of 137Cs,239+240Pu and 241Am activity concentrations in a soil core from Hunan Province, China were investigated. The maximum 137Cs and 239+240Pu activity concentrations were 15.45 ± 0.76 mBq/g and 0.819 ± 0.066 mBq/g, respectively. While the maximum 241Am activity concentration in samples obtained from the core was 0.341 ± 0.019 mBq/g. The 240Pu/239Pu atom ratio and the 137Cs/239+240Pu activity ratio were 0.183 ± 0.011 and 19.5 ± 1.8, respectively, and both were consistent with the characteristic value of global fallout. The integrated 241Am/239+240Pu activity ratio for global fallout was also re-estimated. The measured 241Am/239+240Pu activity ratio (average 0.43 ± 0.07) in the samples was very close to the estimated value (0.45), which suggested their 241Am also came from the global fallout. Regarding the vertical distribution of 137Cs, 239+240Pu and 241Am in these red soil samples, all these radionuclides had higher concentrations in upper layers of several centimeters of soil while they had slightly lower concentrations in lower soil layers down to 30 cm. Vertical distributions of 137Cs/239+240Pu and 241Am/239+240Pu activity ratios indicated the migration velocity was Am ≈ Pu > Cs. The intrinsic chemical properties of the radionuclides as well as soil type and properties (acidic, nutrient-deficient and low in organic matter and cation exchange capacity) might be reasons for the differences in their migration behaviors.

The unattached fraction (fp) and activity concentration ratio of radon progeny (${\boldsymbol C}_{{}{}^{\bf 218}\bf{Po}}:{\boldsymbol C}_{{}{}^{\bf 214}\bf{Pb}}:{\boldsymbol C}_{{}{}^{\bf 214}\bf{Bi}}$) are important for radon exposure dose evaluation. For getting these characteristic parameters in dwellings, a series of field measurement was carried out. For comparison, a semi-continuous measurement was carried out in an office room and outdoors. Results show that the average fp is 4.5% ± 2.2% and 3.8% ± 1.7% in city dwellings and in rural dwellings, respectively. The average activity concentration ratios are 1:0.94:0.70 for radon progeny and 1:0.07:0.06 for unattached radon progeny in city dwellings, while those in rural dwellings are 1:0.88:0.66 and 1:0.09:0.07. The average values of fp are 5.1% ± 0.9% and 5.4% ± 3.1% in the office room and in outdoors without significant difference. The average activity concentration ratios are 1:0.88:0.77 for radon progeny and 1:0.11:0.11 for unattached radon progeny in outdoors.

Objective::To test the basic dosimetry characteristics of a new high-resolution matrix and to perform a preliminary study on the three-dimensional (3D) dose verification of intensity-modulated treatment (IMRT).Methods::The dosimetry characteristics of the new matrix were investigated, including repeatability, dose-rate response, and dose linearity. Twenty cases of nasopharyngeal carcinoma (NPC) and 20 cases with lung cancer were randomly selected for IMRT plans, and the novel matrix was employed for 3D dose verification. The measured results were evaluated using the gamma passing rate (GPR) and dose volume histogram (DVH). The action limit (AL) and tolerance limit (TL) of the target volume and each organ at risk (OAR) were calculated with reference to the American Association of Physicists in Medicine (AAPM) TG218 report.Results::The matrix performed well for all dosimetry characteristic tests, with a deviation of <1%. The average GPRs of the body were (99.32 ± 0.32)%, (98.36 ± 0.59)%, and (96.27 ± 1.20)% for NPC, and (99.17 ± 0.74)%, (98.09 ± 1.33)%, and (95.83 ± 2.22)% for lung cancer at the gamma standards of 3%/3 mm, 3%/2 mm, and 2%/2 mm. The average GPRs difference between the head-neck and thorax-abdomen plans were <1% for the same gamma standard. For both the target volumes and OARs, the average GPRs were >90% under the relatively strict standard of 2%/2 mm. The DVH showed that the measurement results of D98 and D95 for the target volumes were slightly lower and D2 were higher than those of treatment planning system (TPS) ( P < 0.01). In addition, with the same standard, there may be significant differences in the values of AL and TL between different structures for target volumes and OARs, especially small-volume OARs such as the chiasma and optic nerve-L. Conclusions::The new matrix showed good dosimetry characteristics and can be effectively applied to the treatment planning dose verification of the head-neck and lung cancer. Further research is needed to establish how to analyze the GPR and DVH of the target volume and OARs, and to determine more precise dose verification standards combined with the parameters of AL and TL to better guide 3D dose verification in clinic.

膜蒸馏能对放射性废水进行深度净化,但传统直接接触式膜蒸馏技术存在膜通量小、能耗高等不足,工业应用有限.为了克服直接接触式膜蒸馏技术的缺点,发展非接触式膜蒸馏技术,必须建立废水的低温蒸发技术.基于自制的废水低温蒸发装置,采用实验测量和理论模拟的方法,研究了装置蒸发特性与能力.在相同条件下,自制低温蒸发装置性能的实验测量结果与理论计算结果一致;理论计算了该装置在操作范围内蒸发量的最大值为80.6kg/h,以及将低温蒸发装置尺寸放大为塔径1m、填料高度3m时,其最大蒸发量可达到1143 kg/h;该装置出气冷凝水电导率反映的离子去除效率达到89.5％.低温蒸发装置能为后续膜蒸馏装置提供稳定且充足的待处理湿空气,为非接触式膜蒸馏技术的发展奠定基础.