RADIATION PROTECTION

Electromagnetic exposure safety assessment of electrostatic discharge through numerical simulation

SONG Yanxia

RADIATION PROTECTION. 2023, 43(4): 289-299.

Abstract ( 99 )

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Based on the numerical calculation method on electromagnetic dosimetry and according to the typical electrostatic discharge (ESD) current waveform specified by IEC (International Electro technical Commission), the first harmonic component with the strongest energy and the full harmonic components in the frequency domain after Fourier transform were used as electromagnetic radiation sources, the electromagnetic effect of human biological tissue when the human body is located at different positions of the exposure source is simulated and analyzed, and the numerical simulation results were compared with those recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The results showed that the electric field intensity (E), magnetic field intensity (H) and specific absorptivity (SAR) decreased with the distance from the exposure source, and the distribution of electric field lines became more uniform with the increasing distance; The electric field intensity attenuates rapidly after entering the head, and the brain has a certain shielding effect on the space electromagnetic field; The SAR peak values and distributions in coronal and sagittal planes are almost the same at different positions in the human head, and the SAR peak values in sagittal and coronal planes are 15.7 times of those in axial planes; The peak of head SAR at different positions appeared at the skull, and the SAR in the brain was the smallest and distributed symmetrically with respect to x and y; Under the condition of multi frequency exposure, the whole-body SAR value of the exposure source located at 1m (position A) on the right side of the human body exceeded the basic limit of ICNIRP, while the whole-body SAR value of the exposure source located at 5 m (position B) on the right side of the human body and beyond did not exceeded the basic limit of ICNIRP. The human body should be located 5 m away from the exposure source to reduce the exposure risk. The research results can provide a numerical reference for human ESD electromagnetic exposure protection, and can provide a theoretical basis for the formulation of ESD electromagnetic exposure related standards.

Study on statistical method of effluent emissions from nuclear power plant

DANG Yuqin, WANG Wenhai, ZHENG Guofeng, ZHU Kun

RADIATION PROTECTION. 2023, 43(4): 300-310.

Abstract ( 160 )

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The statistics of radioactive effluent emissions from operating nuclear power plants is an important work. However, it is found in practice that the activity concentrations of many radionuclides in the effluents from nuclear power plants are not high, and the analysis results are often lower than the detection limit in the effluent emissions statistics. In this context, it is a challenge to make deep research on how the monitoring data can be processed to bring emissions statistics closer to actual emissions. In this paper, the monitoring data of effluents from Qinshan nuclear power base in recent years are collected; their numerical distribution characteristics are analyzed and studied; the statistical method and strategy of effluent emissions based on radionuclide detection rate are put forward; and the recommended value of the value coefficient of the detection limit of effluent is given. By comparing with the statistical results of traditional methods and by analyzing the differences, it is considered that the statistical method and strategy based on radionuclide detection rate is realistic and feasible, and the statistical results are closer to the actual emission situation, which is worthy of further research.

Application of vehicle-mounted frequency-selection measurement in urban electromagnetic environment monitoring

TANG Hui, GAO Peng, SU Kunpu, TANG Yanbo, XU Bin, GU Hong, LI Yuandong, MIAO Erkang

RADIATION PROTECTION. 2023, 43(4): 311-317.

Abstract ( 106 )

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Objective: To measure the level of urban electromagnetic environment more efficiently and accurately and master the composition of electromagnetic environment. Methods: The DZER100 vehicle-mounted fast frequency selection measurement system was developed jointly with Chengdu Dot Matrix Technology Co., LTD. The full-band scanning time of the system was 300 ms under the condition of 30 MHz-6 GHz frequency band and 100 kHz resolution. With a driving speed of 60 km/h and a distance of 5 m between measuring points, the total field intensity, spectrum and electromagnetic environment of specific frequency band of each measuring point can be effectively obtained. Results: 14 393 effective point data were obtained for 5.3 km² area. Through automatic analysis of system data, the average electric field intensity of the whole area was about 1.23 V/m, and the ratio of 0 V/m-2 V/m reached 87.411%. The average value of standard ratio was 1.41%, and only 0.24% of the sites accounted for more than 20%. Through the spectrum visualization analysis function, the spectrum composition of the focus point and the contribution of the focus frequency band can be quickly grasped. Conclusion: The vehicle-mounted frequency selection measurement (30 MHz-6 GHz) can realize the simultaneous measurement of the total field intensity and spectrum of each point, which effectively solves the remaining pain points caused by the use of non-frequency monitoring instruments. The obtained data amount is far more than that of the traditional grid measurement method, and the data are more representative, which can reflect the electromagnetic environment in the region more comprehensively. The vehicle-mounted frequency selection measurement can meet various requirements such as the measurement and evaluation of the overall level of regional electromagnetic environment and the analysis of the composition of the electromagnetic environment source terms, and provide more detailed and accurate basic data for the management of electromagnetic environment through visualized data.

Evaluation of ¹³⁷Cs radioactivity level and the induced resident external exposure dose in soils surrounding a nuclear facility

LI Lifan, WEN Fuping, HU Xiang, LI Huiping

RADIATION PROTECTION. 2023, 43(4): 318-324.

Abstract ( 108 )

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¹³⁷Cs is an artificial radionuclide that has been paid special attention in environmental monitoring of nuclear facilities. In this paper, the ¹³⁷Cs radioactivity level in soils around a nuclear facility was statistically analyzed, and was compared with similar nuclear facilities from 2012 to 2021. The background deduction method was established for the external radiation dose caused by ¹³⁷Cs in soils, and the resident external radiation dose caused by ¹³⁷Cs in soils around the nuclear facility was estimated. The results showed that the activity concentration of ¹³⁷Cs in soil samples around the nuclear facility decreased first and then increased from 2012 to 2021, and the average activity concentration of 1.81 Bq/kg in recent ten years was slightly higher than that of similar nuclear facilities. From the point of view of monitoring locations, four of the six locations with the highest average ¹³⁷Cs activity concentration are distributed within a 2 km radius of the nuclear facility. The annual effective dose caused by ¹³⁷Cs from soil samples around the nuclear facility was 1.24 μSv, which was only 0.5% of the target annual dose for the public specified for the nuclear facility.

Study on the application of uncertainty analysis technology in safety assessment of an environmental protection supporting project

LIU Xingwei, WANG Xuhong, LV Tao, LI Xingyu, LI Chang, KANG Baowei, WANG Xin, XIA Jiaguo

RADIATION PROTECTION. 2023, 43(4): 325-335.

Abstract ( 70 )

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In order to solve the uncertainty problem (caused by cognitive level and long time scale) of safety assessment results for radioactive waste disposal, this study, based on an environmental protection supporting project, first carried out deterministic model safety assessment, and then generated 1 000 samples based on probability theory method and Latin hypercube sampling technology to carry out uncertainty analysis and sensitivity analysis. The results show that the calculation results of near-field release rate of deterministic model are high, that of geosphere is fit, and that of Mo-93 and Ni-59 is good, and that of I-129 is low in biosphere. The results of sensitivity analysis show that the parameters related to concrete materials (such as effective diffusion coefficient of concrete, distribution coefficient of nuclide in concrete, thickness of concrete barrier), leaching rate of waste, initial activity and distribution coefficient of nuclide in geosphere are the main influencing parameters of model release rate peak value, which can be treated as the key parameters for subsequent engineering design and field investigation.

Preliminary study on combustion release behavior of tributyl-phosphate/kerosene in nuclear fuel cycle

LIAN Yiren, SUN Hongchao, YANG Hao, SONG Xiaopeng, ZHUANG Dajie, SUN Shutang, WANG Changwu, CHEN Lei, YANG Xinjing, SUN Qian, XU Xiaoxiao, WANG Pengyi, LI Guoqiang, ZHANG Jiangang

RADIATION PROTECTION. 2023, 43(4): 336-342.

Abstract ( 82 )

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The combustion of tributyl-phosphate/kerosene is a typical fire accident in nuclear fuel cycle facilities, and it is an important research content of nuclear fuel cycle safety that cannot be ignored. In this paper, a preliminary study on the solvent fire accidents (combustion area 77.9-2 921.0 mm²) was carried out. The combustion rate of the solvent, the release components of gases, the release of aerosols and their particle size distribution were analyzed by basic experiments. And the differences between experimental results with the published foreign data were analyzed.

Research on neutron shielding performance and the secondary γ dose simulation of tungsten boride material

CHI Xiaomiao, HAN Yi, LIU Liye, CHEN Faguo, LI Guodong, SHEN Huaya, YANG Mingming, SUN Yansong

RADIATION PROTECTION. 2023, 43(4): 343-352.

Abstract ( 139 )

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In order to neutron absorption and secondary γ ray shielding performance. In this paper, the Geant4 program is used to simulate and analyze the incident neutrons with material thickness from 0 to 2 cm and energy from thermal neutron to 20 MeV. The results show that: (1) W-B series compounds mainly act on the absorption and shielding of neutron energy from thermal neutrons to 10^-2 MeV; When the thickness is constant, the neutron absorption performance of W₂B₅ is the best; When the mass is constant, WB₄ has the best neutron absorption performance. (2) From the neutron macroscopic cross section and material density of different materials, compared with traditional neutron absorbing materials, W-B series compounds have more significant advantages in low-energy neutron absorption. Taking thermal neutrons as an example, the neutron macroscopic l cross section of W₂B₅ material is about 8.67 times that of B203 material and 40.59 times that of PB202 shielding material.(3) the contribution of the secondary γ dose to the total dose decrease with the increase of the incident neutron energyand the contribution of the secondary γ dose to the total dose increase with the increase of the thickness of the shielding material. study provides a reference for the realization of the optimal design of neutron shielding devices for clarifying the application advantages and application scenarios of W-B series compounds, and has practical engineering guidance value.

Design of nuclear emergency assessment and decision support system for spent fuel reprocessing plant

YANG Yapeng, ZHANG Jiangang, FENG Zongyang, JIA Linsheng, LIANG Boning, WANG Ning, XU Xiaoxiao

RADIATION PROTECTION. 2023, 43(4): 353-359.

Abstract ( 88 )

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A nuclear emergency assessment system should be established to deal with the potential accidents such as criticality, radioactive material leakage, fire and explosion which could occur in spent fuel reprocessing plant. This paper introduces the design of a real-time three-dimensional visualization system for nuclear emergency assessment and decision support for five typical accidents in spent fuel reprocessing plant. The system is capable of diagnosising emergency conditions on real-time based on dynamic process monitoring data, calculating the source terms released into the plant and environment, carrying out emergency response process management based on emergency plan, and implementing protection action analysis for protecting staff and the public. The system can realize the dynamic display of emergency evaluation results and response process based on three-dimensional visualization technology. The system was developed for the emergency assessment and decision support of the spent fuel reprocessing plant, and will improve the emergency preparedness and response capacity.

Practice and consideration on clearance of very low level radioactive contaminated material

XU Kan, XIONG Kouhong, YAN Xiaojun, GUO Xiliang, XU Chunyan, GAO Chao

RADIATION PROTECTION. 2023, 43(4): 360-365.

Abstract ( 96 )

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Based on the analysis of clearance practice of very low level radioactive contaminated material in recent years and the analysis of the latest description of IAEA on the applicability of clearance concept, some considerations on the clearance management of radioactive contaminated material arising from domestic NPPs are put forward.

Evaluation of the application value of chromosome aberration and micro-nucleus analysis in occupational health surveillance of radiation workers

HAN Lin, ZHAO Fengling, LIU Yulong, LYU Yumin

RADIATION PROTECTION. 2023, 43(4): 366-371.

Abstract ( 92 )

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Application of chromosome aberration and micro-nucleus in peripheral blood lymphocyte as radio-sensitive biological indicators to biodosimetry was widely recognized by the international academia. Nevertheless some problems on the application value of the indicators are still worth discussing in occupational health surveillance of radiation workers. In this paper, based on the formation mechanism of chromosome aberration and micro-nucleus, the signification and practical value of the two indicators were explored in occupational medical examination of radiation workers, in order to provide discussion and a reference for the counterparts.

Carcinogenic effect of tritium water on mice or rats: A systematic review and Meta analysis

XU Kai, LI Mei, WANG Chunping, LU Haili, SHAN Wenping, QIN Xiujun

RADIATION PROTECTION. 2023, 43(4): 372-383.

Abstract ( 83 )

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A systematic review and meta-analysis were used to explore the relationship between exposure to tritium water (HTO) and carcinogenic effect in rats or mice. Database such as PubMed, Embase, The Cochrane Library, Web of Science, CNKI, China Biomedical Literature Database, Wanfang, and VIP were searched with computer. Literature regarding carcinogenicity of rats exposed to tritium water was searched for experimental studies that met the inclusion criteria, with time frame from the establishment of the aformentioned databases to February 15th 2021. Literature was managed by using Endnote 9.2. Toxicological data reliability evaluation tool ToxRTool was used to evaluate the quality of the literature. A total of 10 experimental studies were included. Among them, 4 articles reported the malignant transformation experiment in vitro and 7 articles reported the experiment in vivo. For the in Vitro cases, the cell Surviving Fraction decreased exponentially with the increase of radiation dose. The equation was lnSF = 0.047-0.270 D (P<0.001), R²=0.850. Taking the radiation dose of cells as the independent variable and the malignant transformation fraction (foci/dishes) as the dependent variable, the fitting equation was y=0.205+0.195x (P<0.001), R²=0.853; Meta-analysis of dose-response relationship showed that the risk of malignant transformation of cells increased rapidly at first and then increased slowly with the increase of radiation dose. For the in Vivo cases, the increase of the activity of intraperitoneal injection resulted in a decrease of median or average survival time. Tritium water (HTO) has a definite carcinogenic effect on both cells and animals and leads to the decline of life quality. However, the carcinogenic effect of very low dose tritium water exposure needs further study.

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