RADIATION PROTECTION

Expert consensus on radiation biodosimetry by semi-automatic analysis of dicentric chromosome

Nuclear Emergency Medicine Branch of Chinese Nuclear Society, Chinese Society of Radiological Medicine and Protection of Chinese Medical Association, Radiological Health Professional Committee of Chinese Preventive Medicine Association, Nuclear and Radiation Emergency Response Branch of China Society of Radiation Protection

RADIATION PROTECTION. 2024, 44(3): 199-209.

Abstract ( 90 )

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Over the past ten years, semi-automatic analysis of dicentric chromosome (dic) has been widely used for estimating radiation biological dose internationally due to its technical maturity. However, there are still no relevant technical specifications and standards in China, although both technical reports published by the IAEA and technical standards published by the International Organization for Standardization have recommended this method for dose estimation. The present technical consensus of biological dose estimation was established from the aspects of the dic semi-automatic analysis principle, main technical content, factor analysis, and application examples, based on more than 30 years of practical experience for dic manual and semi-automatic analysis at home and abroad. Compared with the existing national standard GB/T 28236, it could significantly improve the efficiency of biological dose estimation, and could also reduce the requirements for technical proficiency of professionals, thus could be better promoted and applied. Similar to manual analysis, dic semi-automatic analysis could be used to estimate and reconstruct the exposed dose under different radiation exposure scenarios including acute uniform, local, extensional irradiation, and delayed sampling. Considering the inefficiency of current domestic dose estimation which cannot meet the needs of clinical classification and diagnosis for large-scale nuclear and radiation accidents that have a large number of exposed people, the promotion and application of dic semi-automatic analysis might solve these bottleneck problems and provide technical support for further development of relevant national standard.

International status of the development of transportable small modular nuclear reactors and transportation safety

SUN Hongchao, LI Guoqiang, WANG Pengyi, MENG Dongyuan, WANG Changwu, WANG Zhipeng, ZHUANG Dajie, SUN Shutang, ZHANG Jiangang

RADIATION PROTECTION. 2024, 44(3): 210-216.

Abstract ( 79 )

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The transportable nuclear power reactors (TNPPs), as a kind of small modular reactors (SMR, generally below 30 MW), can produce electricity for remote and small local communities. TNPPs can be transported by land or other means of transportation, and can operate on the transport vehicle or after unload from the transport vehicle. Thanks to meeting diverse energy needs, TNPPs have been attracting the attention of all countries. In this paper, the development status of TNPPs was introduced, and the features of different types of TNPPs, the problems and challenges to TNPPs development were summarized. The problems arising in the transport safety of TNPPs and countermeasures were mainly discussed.

Status and enlightenment of eye lens dose monitoring for radioactive workers in foreign nuclear facilities

XUE Xiangming, WU Xiaoyan, YANG Xue, Gu Xiaona, ZHAN Jingming

RADIATION PROTECTION. 2024, 44(3): 217-223.

Abstract ( 74 )

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International community has revised the eye lens dose limit for more than 10 years, during which several countries have integrated the new eye lens dose limit into their national law. Data from abroad show that the eye lens dose of some job in nuclear facilities may be high. Some countries have put forward specific monitoring programs, but relevant domestic information is lacking. On the basis of sorting out the dose levels of eye lens among occupational populations in foreign nuclear facilities, this article reviews the monitoring objects, requirements for monitoring dose levels, and monitoring methods proposed by foreign institutions, in order to provide reference for the revision of eye lens dose limits and related work in China’s nuclear facilities.

Research on regional environmental electromagnetic radiation monitoring technology

WANG Guan, MIAO Erkang, XU Hui, GAO Peng

RADIATION PROTECTION. 2024, 44(3): 224-232.

Abstract ( 84 )

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With the continuous improvement of information technology in society, complex and changeable electromagnetic wave signals fill the whole space. How to obtain electromagnetic environment monitoring data accurately and effectively has become the key to scientific assessment of regional environmental electromagnetic radiation level. Based on the characteristics of environmental electromagnetic radiation and the existing standards and monitoring practices as well as the work of the international organization, regional environmental electromagnetic radiation monitoring by means of vehicle-borne survey and grid monitoring are discussed. This study not only provides guidance for further improving the existing work of electromagnetic environment monitoring, but also provides a technical reference for improving the regulation efficiency of Chinese electromagnetic environment.

Investigation and risk assessment of soil radioactivity levels at a rare earth refining factory and surrending area

ZHU Xiaojiao, XIAO Bifu, GU Hong, LV Yingfu, LIU Pei, ZHOU Wei, LI Yuandong, TANG Hui

RADIATION PROTECTION. 2024, 44(3): 233-239.

Abstract ( 70 )

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In order to find out the range and harm of radioactive contamination in soil of a rare earth refining factory and its surrounding soil, the mass activity concentrations of ²³⁸U, ²³²Th and ²²⁶Ra in soil of a rare earth refining factory and its surrounding soil were investigated. The radionuclide contamination of soil in the study area was evaluated by geological accumulation index method, single factor pollution index method and Nemerow comprehensive pollution index method. The health risk assessment model of US EPA was used for risk calculation. The results showed that the mass activity concentration ranges of ²³⁸U, ²³²Th and ²²⁶Ra were 20.9-92.6 Bq/kg, 25.1-565.5 Bq/kg, 17.3-83.1 Bq/kg, respectively. The geological accumulation index method showed that the two sampling points downstream of the outlet and west side of the plant were mono-nuclide pollution. The single factor pollution index method and Nemerow comprehensive pollution index method showed that the comprehensive pollution of soil at each site reached mild pollution. Health risk assessment showed that the maximum risk values caused by ²³⁸U, ²³²Th and ²²⁶Ra were all less than 10^-6, and all were within the acceptable range. The main exposure routes were ingestion routes, and the greatest risk came from ²³²Th. The investigation shows that the health risk of ²³⁸U, ²³²Th and ²²⁶Ra in a rare earth refining factory and its surrounding soil is within the acceptable range.

Analysis on tritium discharged at Tianwan Nuclear Power Station VVER reactor

GUO Yinglai, WANG Hu, CHEN Yunfeng, HUI Miaomiao, LIU Hanhan, WU Chunyuan

RADIATION PROTECTION. 2024, 44(3): 240-243.

Abstract ( 71 )

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This article analyzes gaseous tritium discharge and liquid tritium discharge since the operation of TNPS Unit 1&2 (VVER). It was found that the tritium discharge and normalized discharge meet the standard's requirements. After the 18-month fuel cycle, the annual emission of gaseous tritium did not change significantly, but the annual discharge of liquid tritium increased. Liquid tritium discharge is the main way at TNPS Unit 1&2, and the proportion of liquid tritium discharge is greater than 90% of total tritium discharge. In each fuel cycle, the monthly discharge of liquid tritium changes periodically, while the monthly emission of gaseous tritium does not change significantly.

The correlation analysis on tritium in the air and rainwater around Tianwan Nuclear Power Plant

GUO Yinglai, WANG Hu,CHEN Yunfeng, LIU Hanhan,WU Chunyuan, HUI Miaomiao

RADIATION PROTECTION. 2024, 44(3): 244-247.

Abstract ( 70 )

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Based on the environmental monitoring data of tritium in air and rainwater around Tianwan nuclear power station (TNPS) over the years, the correlation is analyzed with the distance, season and gaseous tritium emission from the sampling station. It is found that the activity concentration of tritium in air and rainwater around the nuclear power station is negatively correlated with the distance from the nuclear power station, and is positively correlated with gaseous tritium emission. The monitoring statistical results in the third quarter are the lowest.

Study on the formation mechanism and preparation of ^110mAg colloid in the primary circuit of PWR nuclear power plant

SUN Yun, XIAO Yan, LI Fuhai, LIN Genxian, LIU Canshuai, SONG Lijun

RADIATION PROTECTION. 2024, 44(3): 248-256.

Abstract ( 59 )

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Under the condition of the simulating water quality of the primary circuit of PWR, colloidal silver nanoparticles were prepared by using lithium borate solution as the medium and hydrazine to reduce silver nitrate. The effects of reducing agent, boric acid, concentration of Ag⁺, temperature and irradiation conditions on the properties of colloidal silver were investigated. The results showed that boric acid and reducing agent hydrazine can effectively stabilize the colloidal particles. When the molar ratio of hydrazine to silver is 1.0-2.0, the reduction rate of Ag⁺ is the highest and the colloid is the most stable. The higher the concentration of silver ions, the more negative charges on the surface of colloidal particles, therefore there will be less particle aggregation, and the colloidal stability will be enhanced. Under high temperature and high pressure water environment, it is easier to form colloidal particles with larger particle size. While the irradiation dose ranges from 0.9 kGy to 7.2 kGy, colloidal silver can be formed with or without hydrazine.

Sensitivity analysis of assessment parameters for dose calculations due to atmospheric tritium discharge

YANG Jie, YUE Qi, GU Zhijie, LIAN Bing, WANG Yan

RADIATION PROTECTION. 2024, 44(3): 257-264.

Abstract ( 48 )

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Currently, specific activity model is used to assess the dose due to atmospheric tritium release, and the uncertainty of the selected model parameters will cause variability of the dose assessment results. Considering the differences in environmental parameters of different sites, the key parameters in the atmospheric tritium dose assessment model that are affected by the site were analyzed for sensitivity and uncertainty of the dose assessment results. The results show that the humidity of the ambient air at the site has the greatest influence on the dose evaluation results of atmospheric tritium. As the humidity of the site rises, the ingestion internal dose due to atmospheric tritium discharge decreases, and the uncertainty of the dose calculation results also decreases. It was also shown that at low humidity site, the focus should be on the measurement and selection of empirical constants for the proportion of HTO retained in the soil. At high humidity plant site, the focus should be on the measurement and selection of the crop water equivalent factor and the concentration ratios for HTO intake. Thus, the uncertainty of the dose assessment results should be minimized.

TCAD simulation and irradiation effect study on low gain avalanche detector

ZHANG Xiangming, SUN Shifeng, ZHANG Ao

RADIATION PROTECTION. 2024, 44(3): 265-274.

Abstract ( 56 )

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The Low Gain Avalanche Detector (LGAD) is a new type of fast timing detector designed to overcome the slow response and poor irradiation resistance of conventional silicon detectors under heavy hadron radiation. This study aims to analyze the variation of LGAD related electrical parameters under different temperature and neutron flux irradiation, including leakage current, dark count rate, transient signal, gain, etc. The physical model of LGAD is constructed by using Technology Computer Aided Design (TCAD) tool, and a new “three-trap body damage model” is introduced to study it. The results show that LGAD has better performance at low temperature. After irradiation, the leakage current increases, the dark count rate increases, the transient collection signal deteriorates and the gain decreases. The defects caused by irradiation affect the space effective charge and internal electric field of the LGAD, which can be reduced by increasing the voltage and decreasing the temperature. The effect of different temperature and irradiation on the performance of the detector obtained by this study has some guiding significance for the follow-up research and radiation hardening design of the detector.

Study on the measurement method of radon emanation coefficient in uranium mine tailing and the main influencing factors

DENG Hao, ZHANG Qingxian, JIN Yifan, GU Yi

RADIATION PROTECTION. 2024, 44(3): 275-281.

Abstract ( 57 )

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During the mining process of radioactive minerals and their associated radioactive minerals, the crushing of rocks alters the original physical structure of the ores, leading to changes in the radon emanation coefficient and its migration characteristics. This causes environmental issues such as excessive radon emissions from tailing. Determining the radon emanation coefficient of tailing and studying the main factors affecting the emanation coefficient are of great significance for the protection and management of radon in tailing. This paper focuses on the radon emanation coefficient of uranium mine tailing, establishes a measurement device for the emanation coefficient, and uses the device to measure the emanation coefficient of samples under different particle sizes and temperature conditions. Based on experimental data, relationships and empirical formulas between emanation coefficient and temperature and particle size were established. The experimental results show that within the particle size range of 5 to 30 mesh, the emanation coefficient is in a power-law relationship with the sample size, thus increasing as the sample size decreases; there is a positive correlation between the emanation coefficient and temperature, with a certain linear relationship within the temperature range of 20-40 °C. The empirical formulas derived in this paper can be used for simulating radon concentration in uranium mine tailing, providing basic data for the management of radon in tailing.

Experimental study on the microbial remediation technology of uranium tailings based on biological reduction

SUN Juan, AN Yifu, LIAN Guoxi, GAO Yang

RADIATION PROTECTION. 2024, 44(3): 282-289.

Abstract ( 41 )

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In this study, the factors of initial pH value, temperature, the added amount of bacterial liquid and the solid-liquid ratio on the remediation effect were explored by an experiment on the microbial remediation of uranium tailings, the uranium occurrence morphology and microbial community structure changes in the tailings before and after remediation were compared. The result shows that the SRB (sulfate-reducing bacteria) screened from the uranium tailings can reduce uranium concentration at seepage effectively; The effect of uranium tailings remediation was positively correlated with initial pH value, temperature, and added amount of liquid, but not significantly correlated with solid-liquid ratio; Under the adverse conditions of pH=3 or temperature at 15 ℃, the uranium concentration was reduced to 0.04 mg/L and 0.019 mg/L, the remediation efficiency could reach 96.9% and 93.6%, indicating good remediation efficiency. The residual uranium content increased by 14.6%-18.7%, the abundance of functional bacteria increased by 2.9%-12.2%, the mass proportion of insoluble uranium and the number and activity of reduction microorganisms increased significantly. The result shows that the remediation was stable. The result further verified that the microbial remediation technology of uranium tailings contamination is feasible.

Study on the irradiation resistance of hollow fiber membrane materials for membrane distillation

YANG Wenwen, GAO Ge, WANG Chenxiao, CHENG Weiya

RADIATION PROTECTION. 2024, 44(3): 290-297.

Abstract ( 54 )

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Theeffect of γ ray on the properties of polypropylene (PP), polytetrafluoroethylene (PTFE) and polyvinylidene difluoride (PVDF) hollow fiber membrane materials was studied. The dose rate of 5.1 kGy/h and the doses of 0.5, 1, 5, 10, 30, 50, and 60 kGy were used to irradiate three kinds of membrane materials respectively. The relevant performance characterization parameters of the samples before and after irradiation were tested and compared. The results showed that after irradiation treatment, the thickness, maximum pore size, water permeability pressure and gas flux of the three membrane materials basically have not been changed, while the mechanical properties and hydrophobicity have been changed significantly. With the increase of irradiation dose, the fracture strength, elongation and fracture pressure of PP and PTFE membranes showed a downward trend, while the fracture strength, elongation and fracture pressure of PVDF showed an increasing trend first and then decreasing; When the irradiation dose of the three kinds of membrane materials is 50 and 60 kGy, the water contact angle of some membrane wires will drop significantly, and even hydrophilicity will occur. This shows that 0-60 kGy γ irradiation dose was not enough to change the pore structure of the membrane, but could destroy the surface properties of the membrane and form hydrophilic groups and unsaturated bonds. Through comparison, it is determined that the most suitable material for membrane distillation before irradiation is polyvinylidene fluoride; At the same time, among the three materials, the most radiation resistant material is polyvinylidene fluoride, followed by polypropylene, the most sensitive to radiation is polytetrafluoroethylene.

Landfill disposal of very low level soil waste containing ⁶⁰Co

XU Bin, BI Chaowen, WANG Yan, ZHU Jie, GU Hong, LIU Pei, LI Yuandong, TANG Hui

RADIATION PROTECTION. 2024, 44(3): 298-303.

Abstract ( 47 )

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Based on the source term analysis of ⁶⁰Co containing very low level radioactive soil waste which was temporarily stored in urban radioactive waste repositories in Sichuan Province, a landfill disposal plan was determined through research on radioactive waste disposal sites in Sichuan Province and a design of landfill units was put forward. According to the landfill disposal plan, this batch of very low level soil waste containing ⁶⁰Co was landfilled, and the radiation dose to the workers during the landfill process was estimated. After calculation, the total personal dose to the workers during this landfill operation is 103.07 μSv, that meets relevant dose control requirements.

Study on the protective effect of hesperidin and hesperetin on radiation-induced cardiovascular injury in mice

HU Weixiang, ZHAO Hongling, ZHANG Yu, MA Lanfang, ZHOU Pingkun, GUAN Hua

RADIATION PROTECTION. 2024, 44(3): 304-314.

Abstract ( 45 )

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This study investigates the protective effects of hesperidin and hesperetin on radiation-induced cardiovascular injury in C57BL/6J mice. The mice were randomly divided into eight groups: a blank control group (NC group), an irradiated control group (IR group), a hesperidin low-dose group (L group, 200 mg/kg), a hesperidin medium-dose group (M group, 400 mg/kg), a hesperidin high-dose group (H group, 800 mg/kg), a hesperetin low-dose group (L group, 50 mg/kg), a hesperetin medium-dose group (M group, 100 mg/kg), and a hesperetin high-dose group (H group, 200 mg/kg). Two hours before irradiation, the blank control group and the irradiated control group were given an equal amount of solvent by gavage method. Except for the blank control group, all groups of mice were exposed to a single dose of 2 Gy of ⁶⁰Co γ-ray irradiation. At 24 h and 48 h after irradiation, indices related to immunity, antioxidant capacity, and DNA damage in the mice were measured. The results showed that compared with the irradiated group, the liver index of the mice given hesperidin and hesperetin was significantly reduced, without a clear dose-effect relationship, indicating that hesperidin and hesperetin may have a certain protective effect on the organs of irradiated mice. The levels of pro-inflammatory factors such as IL-1β and IL-6 in the serum of mice given hesperidin and hesperetin were significantly decreased and showed a dose-effect relationship, with the high-dose groups being more prominent. The administration of hesperidin and hesperetin significantly reduced the content of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in the aorta of the mice, indicating that both treatments have significant antioxidant effects. The administration of hesperidin and hesperetin reduced the number of γ-H2AX foci in the aortic tissue after irradiation in a dose-dependent manner, indicating that both treatments can alleviate the DNA damage in the mouse aorta after irradiation. The results of this study suggest that hesperidin and hesperetin have a certain protective effect against radiation-induced vascular damage in mice, and the possibility of their development as health supplements requires further exploration.

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