The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) was established by the United Nations in 1955. Its main function is to make assessment and reports on the global exposure levels, effects, and risks of ionizing radiation exposure from scientific perspective. As one of its core tasks, 7 surveys and evaluations of occupational exposure has been organized by UNSCEAR, which statistically analyzed the global occupational exposure levels and trends over 40 years from 1975 to 2014. This article provides a detailed introduction to the latest task, including the process, content, methods of the survey, the current situation, and the global levels and trends of occupational exposure to man-made radiation sources.

The annual dose and collective dose during planned outage of China’s operational nuclear power units from 2018 to 2023 were compiled, summarized, and analyzed based on different reactor types. It was observed that the collective dose for HPR1000, AP1000, VVER, and CNP600 units remained relatively low. Moreover, the average collective dose during planned outage for CNP600, VVER, and AP1000 units also exhibited a low level. By comparing the collective doses at global reactor units with data from World Association of Nuclear Operators (WANO), it was determined that China’s single reactor unit collective dose is equivalent to that of the United States but surpasses France in terms of performance. Considering radiation protection practices across various reactor types in operation, it is necessary to further promote reasonable and feasible measures for reducing doses while comprehensively strengthening risk control in high-radiation areas. Additionally, continuous improvement in task-oriented occupational exposure management should be pursued to enhance international competitiveness of Chinese nuclear power units and facilitate the transformation into a leading force in the industry.

The short-term atmospheric dispersion factors under four different classification methods of atmospheric stability were calculated by using PAVAN program, and the dose at the boundary of exclusion area (500 m) and planning restricted area (5 km) under the postulated siting accident was calculated. The result shows that the value of the short-term atmospheric dispersion factor under the Richardson number method is the smallest, while the value under the ΔT/U method is the largest. The value of the maximum individual effective dose on the exclusion area boundary (2 hour after the accident) and value at the planning restricted area boundary during the postulated siting accident satisfied the requirement of GB 6249, and the value of the dose was also the smallest under the Richardson number method, the largest under the ΔT/U method. The maximum value is about 1.6 times the minimum value. For the environmental impact assessment, it should be paid more attention to the influence of different atmospheric stability classification method on the dose evaluation of postulated siting accident.

To achieve rapid assessment of public exposure from liquid effluent discharge from nuclear facilities under some scenarios with limited assessment parameters, this study developed a graded screening assessment model for public exposure due to multi-pathway liquid effluent discharge based on IAEA Safety Report Series No. 113. The model can perform a graded screening assessment process from conservative to realistic for public exposure due to radioactive effluent discharges to river, lake, coastal and sewage systems. A case study of liquid C-14 effluent release scenarios from the Hualong One nuclear reactor was established and the assessment results of different public exposure assessment models were compared. The results of the study demonstrate the robustness of the developed screening assessment model. This study provides an approach and methodology for assessing the environmental impacts of liquid effluents from nuclear facilities under multiple discharge pathways. The model can be applied to site selection assessment in the siting phase of nuclear facilities, rapid assessment of the environmental impact for nuclear technology application facilities as well as small and medium-sized nuclear reactors, and independent review of the environmental impact assessment conclusions for nuclear facilities by regulatory authorities.

By using two sample media, the detection efficiency of natural and artificial β nuclides with different mass thickness was simulated by experiment and Monte Carlo Method. The relationship between detection efficiency, count rate, detection efficiency correction factor, reciprocal of detection efficiency and mass thickness, as well as detection efficiency and energy were analyzed. The results show that ⁴⁰K is used as the standard source, the detection efficiency correction factor are needed to correct the detection efficiency. The measurement of β radioactivity of ²³⁴Th, ²¹⁰Pb, ²¹²Pb, ²²⁸Ra, ⁶⁰Co, ⁹⁹Tc, etc. should be modified by thin source method and detection efficiency correction factor. The reciprocal of detection efficiency is linear with the mass thickness, which can be used to scale the detection efficiency better. The detection efficiency is exponentially related to the average energy of beta rays. The β ray equivalence of KCl and CaSO₄ media is good and can meet the requirements of relevant standards.

Based on the basic data of ²¹⁰Pb activity concentration in surface air, this study analyzed the correlation between ²¹⁰Pb activity concentration in surface air and meteorological parameters such as sunshine, temperature, relative humidity, pressure, average total cloud cover and rainfal. This study used Fourier series to complete the change trend prediction of ²¹⁰Pb activity concentration in surface air. The results showed that the monthly mean activity concentration of ²¹⁰Pb in the surface air had a strong negative correlation with temperature, relative humidity, average total cloud cover and rainfall while showed a strong positive correlation with air pressure, confirming the possibility of using Fourier series to predict the activity concentration of ²¹⁰Pb in surface air. In the activity concentration harmonic spectrum of ²¹⁰Pb, except for the maximum harmonic wave with a period of 1 year, the harmonic wave with a period of 5 years is also significant, but the periodicity is not very significant compared with temperature, relative humidity, pressure, average total cloud cover and rainfall. The Fourier series prediction results show that the predicted value of ²¹⁰Pb activity concentration in the surface air is roughly consistent with the measured value, but not completely consistent. In the subsequent research, machine learning, neural network and other methods can be considered to improve the prediction accuracy.

In order to understand the long-term and short-term changing trend in time and space of electromagnetic environment, three studies were carried out by vehicle survey. Firstly, in 2022 and 2023, frequency selective monitoring of electromagnetic environment ranging from 30 MHz-6 GHz were conducted on four ring roads in Beijing, including the Second Ring Road, the Third Ring Road, the Fourth Ring Road, and the Fifth Ring Road, respectively, which collected 200,000 values. Through temporal and spatial variation analysis on different ring roads and base stations of different generation, it reveals that the general electric field rising from (1.34±0.85) V/m to (1.64±1.00) V/m, and all the values show that: the Third Ring Road > the Second Ring Road > the Fourth Ring Road > the Fifth Ring Road; also the electromagnetic field from 5G BS in 2023 exceeds that of 4G BS. In terms of spatial distribution, the total number of hotspots in 2023 is significantly higher than that in 2022, and the number of hotspots in the Fifth Ring Road is less than that in other ring roads. The electromagnetic environment level in the eastern and western parts of each ring road is relatively high. Secondly, in 2024, vehicle surveys of electromagnetic environment ranging from 0.1 MHz-6 GHz both in the daytime and nighttime were implemented on the Beijing Ring Roads, extracting spectral data and analyzing the proportion of major electromagnetic radiation sources,and found that the base station had the highest proportion. Third, in 2023 and 2024, the same 5G base station was continuously monitored for 24 hours, and it is found that the average hourly values in 2024 are basically higher than those in 2023, and due to the adjustment of the night working modes, the values in the 4-7 o’clock period change from the background value in 2023 to the normal working state in 2024.

In this paper, the monitoring results and variation trends of tritium in air around Ningde NPP from 2014 to 2022 were analyzed. The monitoring results of the baseline, the background survey results and other nuclear power plants in China were compared and analyzed, and the correlation with tritium emission of gaseous effluent from Ningde NPP were studied. The analysis results show that the measured values of tritium in air of the monitoring points around Ningde NPP range from <2.8 to 56 mBq/m³. The detection activity concentration of tritium in air around the NPP site generally have an increasing trend. The measurement value at Niulanggang, which is closest to the NPP site, is higher than other points and significantly higher than the background survey results, but still far below the clearance level stipulated by regulatory body. Tritium monitoring results at various locations over the years have a strong correlation with the tritium emission of the gaseous effluent of the nuclear power plant, indicating that the tritium level in air around the Ningde NPP may be affected by the tritium emission of the gaseous effluent of the nuclear power plant.

Compared with elemental iodine, organic compounds represented by methyl iodine are the most difficult radioactive iodine compounds to be delt with. In the application of removing radioactive methyl iodine, the application environment is the key factor that determines the adsorption material: such as high temperature, high humidity, nitrogen oxide and operation time. Through literature research, this paper summarizes the research status of removing gaseous radioactive methyl iodine by adsorption materials at different environment, with the aim to provide reference for the removal of gaseous radioactive methyl iodine with functional porous materials in the future.

With the development of nuclear technology and changes in nuclear safety situation, IAEA has issued an updated Generic Procedures for Medical Response During a Nuclear or Radiological Emergency (2024) to provide guidance to States on how to respond to such emergencies. The Generic Procedures (2024) made more detailed classification and response measures for the evolving emergency situation of malicious use of radioactive materials. The Generic Procedures (2024) also made certain thinking and preparation for new nuclear technologies on the basis of traditional nuclear facility accidents, and paid more attention to flexibility and adaptability in the organizational structure and resource allocation of emergency response. In addition, the 2024 version also fully absorbed the progress of emergency response technology and communication technology in recent years, optimized and improved the aspects of radiation monitoring, decontamination, communication, and dose estimation in emergency response. The Generic Procedures (2024) also took the lessons of Chernobyl accident and Fukushima accident into account to improve public psychological support and information communication and sharing. This paper comprehensively compares the similarities and differences between the 2024 version and the 2005 version, and highlights the improvements made by the new version, aiming to provide some reference for the revision of relevant guidelines and the development of nuclear or radiological emergency work.

This article analyzes the current status of decision-making strategies and related preparations for emergency termination of nuclear power plant accident in China. In comparison with the guidance and suggestions on work arrangements related to nuclear and radiation emergency termination in the International Atomic Energy Agency (IAEA) General Safety Guidelines GSG-11 “Arrangements for the Termination of Nuclear and Radiological Emergency”, combined with China’s national conditions and practical work experience, relevant suggestions for improving decision-making strategies for termination of nuclear power plant emergency are proposed, with the aim of providing reference for improving China’s nuclear emergency preparedness and response capabilities, and improving the preparation for the transition phase from accident emergency status to normal production and social life status.

This paper provides a concise overview of a radiation accident resulting from the unauthorized alteration of the usage of a medical portable X-ray transilluminator, which led to excessive radiation exposure to staffs. The accident is analyzed comprehensively, with the aim of offering insights from various perspectives including the sequence of events, analysis of the radiation source, the current status of Category Ⅲ radiation devices in our country, statistics on radiation accidents, and examination of the underlying causes.

Instantaneous accidents generally refer to instantaneous radioactive releases or extremely short time radioactive release scenarios. It is not appropriate to adopt the traditional point source dispersion model for continuous release to evaluate the habitability consequence of Main Control Room (MCR). This paper refers to the basic model of instantaneous plume release model and considers the actual design characteristics of nuclear power plants to form an atmospheric dispersion model for evaluating the habitability of MCR under instantaneous accident conditions. The model was utilized based on a typical instantaneous accident. The comparison results with traditional point source dispersion model show that the model formed in this paper can better characterize the release characteristics of such accidents, and the atmospheric dispersion results used for evaluating the habitability of MCR are closely related to the volume of instantaneous accident plume. Additional analysis conducted in this paper indicates that under the same released source terms, the larger the volume of released plume, the lower the radioactive impact on the MCR.

In this paper, the engineering applicability of epoxy resin/solidification agent is studied. The temperature change law of the solidification process of sealing material is explored and the temperature rise limit value is determined. The concrete HIC sealing process with the epoxy material was verified by engineering scale equipment. The results show that the operational performance, temperature rise amplitude and impact resistance of the epoxy resin/solidification agent meet the application conditions of HIC sealing engineering.

In order to study the influence of gamma-ray irradiation and thermal simultaneous action on the absorption property of buffer material, this study is based on the modified sodium bentonite which is from Gaomiaozi. The distribution coefficients of ¹³⁷Cs are measured separately in the modified sodium bentonite and the modified sodium bentonite undergoing gamma-ray irradiation and thermal simultaneous action by batch method. The experiment results show that gamma rays irradiation and thermal simultaneous action helps improve the ability to absorb ¹³⁷Cs on the sodium bentonite under the experimental conditions. Compared with the modified sodium bentonite, the increment is in the range of 38.5 % to 46.8 %. A pilot evaluation model for nuclide release, migration, and dose estimation of the HLW geological repository was established. GoldSim safety evaluation software was used to simulate the release rate in the near and far field and radiation effects on the biosphere of ¹³⁵Cs under the reference sites. The simulation results show that the ambient dose caused by ¹³⁵Cs can be reduced by increasing the thickness of bentonite after being irradiated by waste.

The demand for environment friendly non-Pb X-ray shielding materials in medical diagnosis is increasing. Therefore, novel shielding materials of TPV combined with WO₃ or Gd₂O₃ or Bi₂O₃ are successfully prepared by melt blending and characterized microscopically. Properties of the composite materials are characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). Results show that the functional particles are uniformly dispersed in the matrix without obvious agglomeration; the functional particles do not form any chemical bonds with the matrix; and the crystal structures of the functional particles also remain unchanged. Tests of mechanical properties show that TPV/WO₃ is the best, with a tensile strength of 4.65 MPa, a fracture elongation of 544.76%, and a Shore hardness of 73 HA at the doping ratio of 100∶100. The shielding experiment for 100 kV tube voltage X-ray shows that both Gd₂O₃ and WO₃ can meet the minimum lead equivalence requirement (0.25 mmPb), with WO₃ reaching the highest 0.33 mmPb. MCNP simulation is basically consistent with the experiment, and the data show that X-ray absorption ranges of Gd₂O₃ and WO₃ are located in the “weak absorption region” of Pb. In summary, this group of shielding materials exhibit good protective performance against 100 kV tube voltage X-ray and have potential applications in fields such as nuclear medicine and nuclear industry.

To analyze the Entrance surface air kerma (K_a,e) and its influencing factors for subjects undergoing posteroanterior (PA) chest digital radiography (DR), and to explore reasonable control measures, 22 DR machines from 19 representative monitoring points in medical institutions in Hangzhou were selected as the research cohort. The K_a,e of 1 055 patients undergoing chest DR (PA position) was measured using thermoluminescent dosimeters. The rank sum test method was used to analyze the differences in K_a,e among subjects of different age groups. The Kruskal-Wallis test method was used to analyze the differences in K_a,e between medical institutions of different levels and equipment from different manufacturers.The results showed that the K_a,e of subjects in the same age group who underwent photography in top tier hospitals were lower than those in other medical institutions (H=93.280, P<0.05); The K_a,e of subjects detected by imported DR machines was significantly lower than that of domestic DR machines (H=145.373, P<0.05); There were differences in K_a,e among subjects of different age groups (H=68.667, P<0.05); The DRL for subjects in Hangzhou undergoing chest DR for the age groups 2-5, 6-10, 11-15, and over 15 years was 140.74 μGy,148.52 μGy,169.52 μGy,216.89 μGy, respectively, and it is necessary to establish DRL for subjects of different age groups. Although the DRL of adult subjects undergoing chest DR (PA position) in Hangzhou is lower than the recommended value of the national standard, there is still room for further improvement.

To protect the skin of interventional therapy operators from radioactive damage, a bismuth oxide nano ointment has been developed. Various proportion of bismuth oxide cream were prepared, through rats model to assess the protetion effect against acute radiation skin injury induced by 40 Gy X-ray exposure. Then the mice exposed to 4 Gy γ-ray TBI induced the hemopoietic system stress, and the prevention effects of the various proportion bismuth oxide creams were analyzed by WBC counts, PLT counts and bone marrow nucleated cells counts. And the radionuclide ¹²⁵I was administrated i.v.to the mice and SPECT scan was performed. The shield efficiency of internal exposure was accessed between the bismuth oxide cream group and vehicle. The prevention of the bismuth oxide cream was observed by application on the skin of rats prior to the 40 Gy X-ray exposure. Various proportion bismuth oxide cream presented significant prevention effects on the hemopoietic system stress induced by 4 Gy gamma-ray TBI. The bismuth oxide cream applied on the skin of mouse effectively blocked the gamma photon generated by ¹²⁵I.