Objective To construct a rapid prediction system to improve the accuracy and efficiency of evaluation of the consequences of nuclear accidents at a field scale. Methods Base on a diagnostic wind field model and Lagrangian particle diffusion, we established a rapid prediction method for wind field and pollutant dispersion around complex underlying surfaces within a field scale, in a way of visual discrimination of buildings and vegetation distribution. With data simulation and the use of a real urban field example, the simulated results were compared with wind tunnel test measurements and computational fluid dynamics results to study the influence of complex underlying surfaces on wind field and pollutant transport in the region. Results The rapid prediction system could clearly simulate the high-resolution wind field and pollutant concentration distribution of the region in about five minutes. It could interface with geographic information software and couple with a mesoscale weather prediction model. In terms of accuracy, the system performed well in wind field simulation, with the fractional deviations of wind speed and wind direction being 0.33 and −0.08, respectively. Concentration field simulation was greatly affected by the wind field, and the ratios of simulated concentrations to observed concentrations were between 0.05 and 3.4, except for a few low concentration points. Conclusion The rapid prediction system can effectively simulate the distribution characteristics of the flow field and improve calculation efficiency when ensuring calculation accuracy, which provides an important reference for emergency response to nuclear accidents.

Objective To analyze the dose distribution of induced radiation in fixed proton beam therapy room and the influence of shielding materials, and to provide a basis for radiation protection and shielding material selection in proton therapy. Methods FLUKA was used to simulate the dose distribution of induced radiation in fixed proton beam therapy room, the dose over time, and the influence of different concrete materials. Results The dose of induced radiation was mainly concentrated around the target, and the dose rapidly decreased to 1/5-1/10 of the value at the time of stopping irradiation after cooling for 3-5 min. The induced radiation in concrete formed a slightly higher dose area at the end of the main beam near the inner side of the shield. The content of Fe, O, and H in concrete had significant effects on induced radiation (P < 0.01), and the dose was negatively correlated with the content of Fe. Conclusion The patients after proton therapy as well as the induced radiation in air and shielding materials are the main sources of external radiation dose for workers, and waiting for a period of time is the most effective way to protect the staff. Without considering the difficulty in construction and based on the analysis of shielding materials in protection against external irradiation and their influence on induced radiation, heavy concrete with a relatively high level of Fe is the best choice of the shielding material for proton therapy room.

Objective To develop a portable nuclear radiation detector with low-energy γ-nuclide recognition capability for rapid measurement of the dose levels in low-energy radiation fields and identification of nuclides. Methods A digital multi-channel circuit was developed for a detector based on the room temperature semiconductor cadmium zinc telluride, nuclide recognition was achieved using an intelligent nuclide recognition algorithm, and the energy response function G(E) was used to calculate the real-time ambient dose equivalent rate H*(10). Results The portable spectrometer had a minimum detectable energy of 20 keV, and the typical energy resolution for low-energy X-rays was > 4.10% at 59.5 keV and 20℃, enabling accurate identification of ²⁴¹Am nuclide. Conclusion The device has a good measurement performance for low-energy γ/X rays, effectively addressing the limitations of existing devices for monitoring low-energy radiation fields, and provide reliable technical methods for monitoring and emergency response in spent fuel reprocessing plants or nuclear material production plants.

Objective To improve the analysis of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Co in aerosol samples by the national key radiation environment laboratories. Methods Intercomparison of analysis results of ¹³⁴Cs, ¹³⁷Cs, and ⁶⁰Co in standard aerosol samples was performed among the national key radiation environment laboratories according to Gamma spectrometry method of analyzing radionuclides in biological samples (GB/T 16145-1995 ), and the intercomparison results were evaluated by the standard deviation. Results Six laboratories were involved in the intercomparison. For ¹³⁴Cs, 50% of the laboratories showed a relative deviation less than 10%, and 50% showed a relative deviation of 10%-20%. For ¹³⁷Cs, 33.3% of the laboratories showed a relative deviation less than 10%, and 76.7% showed a relative deviation of 10%-20%. For ⁶⁰Cs, all laboratories showed a relative deviation less than 10%. The overall intercomparison results were acceptable. Conclusion The laboratories in this intercomparison show generally good results.

Objective To evaluate the migration of plutonium aerosol caused by α recoil. Methods In this paper, the recoil deposition and Brownian motion of plutonium-containing nanoaerosols were simulated by Monte Carlo method. The recoil angle and the vertical first landing time of Brownian motion in the process of settling were sampled, and then the lateral displacements of Brownian motion were sampled to determine the final settling position of aerosol. Results For aerosols with particle sizes of 10-50 nm, the maximum migration distance of a single recoil settling was 1.39 μm. Brownian motion increased the migration capacity. Although there was a high likelihood that aerosols settled within 100 μm, there remained a slight probability of long-term suspension in the air. Conclusion The α recoil is one of the mechanisms of plutonium aerosol migration. An important mechanism for long-distance migration of nanoaerosols is that Brownian motion after recoil may cause them to suspend for a long time.

Radionuclide-contaminated wounds are common in medical response to nuclear emergencies, which have different manifestations in different types of accidents. Medical treatment is the key part of the response. Based on the drill experience gained from medical response to nuclear emergencies, the authors summarize the research advances in radionuclide-contaminated wounds in recent years, mainly involving the biokinetic characteristics, medical response, surgical debridement, and prevention and treatment of internal contamination of radionuclide-contaminated wounds; the authors summarize the key points of technical operations and provide suggestions on improvements in the drills. The authors believe that medical treatment of radionuclide-contaminated wounds requires highly compatible integration of the practical skills from clinical medicine and radiological knowledge; emergency response, surgical debridement, and prevention and treatment of internal contamination all together constitute an integrated rescue and treatment strategy with internal logic correlations. However, targeted improvements are needed to achieve desired effects in the drills.

Objective To investigate the gross alpha and gross beta radioactivity levels in drinking water around Shidao Bay Nuclear Power Plant before its operation. Methods Ten sampling sites were set up within 30 km of Shidao Bay Nuclear Power Plant. From 2018 to 2021, samples were collected during the dry season and wet season each year and were tested in a laboratory according to Standard examination methods for drinking water—radiological parameters (GB/T 5750.13—2006). Results From 2018 to 2021, the gross alpha radioactivity in drinking water within 30 km of Shidao Bay Nuclear Power Plant was within the range of about 0.004-0.420 Bq/L, which does not exceed the guided gross alpha radioactivity specified in the National Standard; from 2018 to 2021, the gross beta radioactivity level was about 0.008-1.050 Bq/L. In 2018, the gross beta radioactivity at the sampling site 4.7 km from the Nuclear Power Plant exceeded the guided level specified in the National Standards for Drinking Water Quality (GB 5749—2006), but it fell within the guided level in a repeat laboratory test after deducting the effect of ⁴⁰K on the gross beta radioactivity. Conclusion After deducting the effect of ⁴⁰K on the gross beta radioactivity, the gross alpha and gross beta radioactivity levels in drinking water within 30 km of Shidao Bay Nuclear Power Plant are within the guided levels specified in the National Standards.

Objective To determine the current situation of radiological health management in medical institutions in Nanyang, China, to analyze existing problems and propose improvement measures, and to improve the management level of radiological diagnosis and treatment practice in medical institutions. Methods According to the work plan of the Occupational Disease Prevention and Control Project in Henan Province, China, 66 medical institutions engaged in radiological diagnosis and treatment at different levels were selected for a questionnaire survey, in combination with on-site inspections, inquiries, and access to relevant materials. Results Of 66 medical institutions, 65 institutions held radiological diagnosis and treatment licenses, with a license holding rate of 98.5%. There were 17 “new construction, reconstruction, and expansion” projects, with an evaluation rate of 94.1%. In this survey, a total of 391 radiological diagnosis and treatment equipment were involved, and 387 units of equipment were tested for status, with a detection rate of 99.0% and a qualification rate of 94.8% (367/387); 55 units of equipment were tested for stability, with a detection rate of 14.1%; the workplace protection detection rate was 99.0%, and the qualification rate was 100%; 66 medical institutions had 1809 radiation workers, with an occupational health examination rate of 97.8%; 1262 people were trained, with a training rate of 95.7%; 1773 people were monitored for individual dose, with a monitoring rate of 98.0%. Conclusion Medical institutions should further strengthen management in licensing change, construction project evaluation, and equipment stability monitoring to improve the level of radiological health management.

Objective To primarily investigate the indoor radon concentrations in the urban and rural dwellings in Yinchuan, China, and to estimate the effective dose. Methods A total of 67 dwellings, which included 49 urban households and 18 rural households in Yinchuan, were selected to cumulatively measure the indoor radon concentrations for more than 3 months using solid state nuclear track detection. Results The arithmetic mean, geometric mean, median, and range of indoor radon concentrations in urban and rural areas in Yinchuan were 64 Bq/m³, 59 Bq/m³, 57 Bq/m³, and 25-172 Bq/m³, respectively. Surveillance sites with an indoor radon concentration higher than 100 Bq/m³ accounted for 7.5%. Indoor radon concentrations in rural areas were higher than those in urban areas. Indoor radon concentrations were highest in winter and lowest in summer. The effective dose of indoor radon exposure among residents in Yinchuan was 1.86 mSv/a. Conclusion The results of indoor radon concentrations measured in this investigation in Yinchuan are significantly higher than those measured in the 1990s. The annual effective dose is higher than the mean levels in the world and China.

Objective To analyze the results of acceptance testing of 60 extraoral dental X-ray equipment in Beijing, China from 2021 to 2022, and understand the main types and performance parameters of newly installed extraoral dental X-ray machines in the clinical market of Beijing, as well as the level of installation and trial run of the whole machine by various manufacturers, and to summarize the problems found in acceptance testing for improving equipment testing. Methods Field acceptance testing and evaluation were carried out according to the Specification for Testing of Quality Control in Medical X-Ray Diagnostic Equipment (WS 76—2020). Results The overall qualified rate of 60 extraoral dental X-ray equipment was 98.33%. Under the same condition of the same tube voltage for one dental equipment, the maximum deviation of the tube voltage indicated by the two modes (panorama and skull) is 5.5%, and the maximum difference of the half-value layer of the useful beam is 1.22 mm Al. There is also a certain difference between the exposure time indicating deviation from the panorama and the skull, with a maximum difference of 75.51%. Conclusion Strengthening ex-factory quality control, installing, and debugging of equipment can basically guarantee the performance of newly installed equipment. In the testing process, it is critical to ensure the effective point of measurement of the dose detector located on the central axis of the primary beam.