RADIATION PROTECTION

Co-operation between China and Nuclear Energy Agency: review and prospects

LI Jinfeng, ZENG Chao, XIAO Lili, LI Xuefeng, REN Lixia, ZHANG Qinghua, WANG Lijiao

RADIATION PROTECTION. 2022, 42(6): 505-517.

Abstract ( 165 )

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Through a number of international and multilateral co-operation mechanisms on nuclear energy or nuclear safety, the Organisation for Economic Co-operation and Development/Nuclear Energy Agency (OECD/NEA), as one of important international organisations in nuclear field, forges common understanding among countries on a broad range of key civil nuclear technology and policy issues, promotes the development of advanced nuclear power technologies and provides suggestions for governments in the areas of energy and sustainable development of low-carbon economies. China has participated in NEA activities since 2002. China has engaged in formulating technical documents and development strategies, and improved the level of global governance in the nuclear field. This paper systematically reviewed the co-operation between China and NEA in the past 20 years, especially the important progress in the fields of nuclear safety, radioactive waste management, decommissioning and legacy management, radiological protection, nuclear law and the fourth generation nuclear systems, and provided suggestions for further strengthening international co-operation and enhancing China's international influence.

The research trends of linear non threshold hypothesis on cancer induced by ionizing radiation

LIU Xiaoming, WU Xiaoyan, MA Yuefeng, ZHANG Yanna, XUE Xiangming, GU Xiaona, ZHAN Jingming, LIU Zhanqi, BIAN Linxiu

RADIATION PROTECTION. 2022, 42(6): 518-524.

Abstract ( 130 )

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The linear non threshold (LNT) model for cancer induced by ionizing radiation is the Foundation and basis of nuclear and radiation protection supervision. However, in recent years, the validity of LNT risk model has been questioned more and more. It is considered that the LNT based regulatory system has brought excessive cost to the society. In this paper, the recent international literature on LNT is studied to explore the development trend and further research direction of LNT, so as to provide reference for the domestic work in related fields.

Applicability analysis of linear non threshold model for low dose radiation

ZHENG Guofeng, SHANG Yuyao, XU Haifeng

RADIATION PROTECTION. 2022, 42(6): 525-531.

Abstract ( 156 )

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For radiation protection purposes, it has been assume that the overall risk of radiation-induced cancer increases as a 1inear-nonthreshold function of the radiation dose. However, epidemiological evaluation cannot support and validate LNT model, and studies on biological effects of low dose radiation have found new results that are not conducive to the LNT model. The existing data do not exclude the existence of a threshold, and the dose-response relationship is known to vary, depending on the type of cancer, the dose, dose rate, and the LET of the radiation, the age, sex, and physiological state of the exposed individuals as well as other variables. On this basis, it is concluded that no alternative dose-response model for the carcinogenic effects of low-dose radiation is more plausible than the linear-non-threshold model, although other dose-response relationships cannot be excluded. Before the establishment of the new theory and new model, LNT model is still the most realistic attitude, and LNT is also the best methodology for radiation protection so far.

Evaluation on implementation of diagnostic standards for common occupational radiation diseases by occupational disease diagnosis

HE Ling, GAO Yiying, WANG Jie

RADIATION PROTECTION. 2022, 42(6): 532-539.

Abstract ( 107 )

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An online questionnaire was used to investigate the current status of the implementation of five commonly used diagnostic standards for occupational radiation diseases by occupational diagnostic physicians, in order to analyze the implementation effect of the standards and the ability of diagnostic physicians to implement the standards. The results showed that: (1) A total of 87 occupational disease diagnostic physicians were investigated, and the average working years were 15.4±11.9 years; (2) The mastery rate, training rate and application rate of the standard were 82.8%-88.5%, 73.6%-85.1% and 46%-70.1%, respectively; (3) The proportion of diagnostic physicians in standard training departments was 40%-67.1% in health departments, 0.6%-6.4% in environmental protection departments, 8.7%-51.5% in safety supervision departments, and 2.8%-23.6% in our own organization; (4) In diagnostic institutions, the standard system establishment rate was 51.7%-92%, and the standards funds supporting rate was 25.3%-51.7%; (5) The feasible rate of standards determined by diagnosticians was 88.5%-97.7%; (6) Diagnostic physicians’ recommendations on standard revision mainly focused on dose threshold and dose estimation; (7) Diagnostic physicians suggested that the relevant government departments should strengthen the training of occupational disease diagnostic standards and improve the understanding and implementation of the standard technical provisions. This study will provide technical basis for the evaluation and revision of the implementation effect of the five standards.

Follow-up evaluation of diagnostic criteria for common radiation diseases ——Radiological health supervisors

MA Ya, HOU Dianjun, MAO Xuesong, LIU Wei, WANG Xiankai

RADIATION PROTECTION. 2022, 42(6): 540-547.

Abstract ( 103 )

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According to WS/T 536—2017, “Health Standards Tracking and Evaluation Work Guide.”, 337 radiation health supervisors in 7 provinces of China were polled via questionnaires, regarding their knowledge, comprehension, and application of the current diagnostic criteria for 5 prevalent radiological diseases. Only 47.5 percent (160) of radiation health supervisors are familiar with all five diagnostic criteria for radiological diseases, and 18.4 percent (62) of them are only familiar with one of the criteria, indicating the need for improvement in knowledge, familiarity, understanding, and application of these criteria by radiation health supervisors. The standard “Diagnosis of Acute Radiation Diseases from Occupational External Exposure” has been trained or disseminated to 60% of the health supervisors, whereas the standard “Diagnosis of Occupational Radiation Cataract” has been disseminated only to 4% of the health supervisors. When completing health monitoring duties, about 60% of the respondents used the conventional diagnostic criteria, but citations typically occurred once a year. More than 92% of the supervisors who responded to the survey thought that the diagnostic criteria are in line with the requirements of the prevailing national laws, rules, and standards for occupational disease prevention and treatment. For each criterion, less than 20% of respondents said it wasn’t feasible. More than 50% of supervisory institutions lacks specialized management support funds for occupational disease diagnosis requirements. Only 198 (58.75%) of the respondents’ institutions engaged in specific supervision of diagnostic institutions’ quality management. Less than 20% of respondents to the subjective question survey gave their opinion on the survey. We should increase training and dissemination of diagnostic criteria for radiation health supervisory staff in order to enhance their capacity to implement the standards. Health supervision agencies should increase funding to strengthen special supervision of radiological diagnostic institutions and establish an effective feedback mechanism.

Method discription and simulation verification of a coded aperture gamma camera with different vertical and horizontal fields of view

LI Yan, LIU Liye, CAO Qinjian, ZHAO Yuan, XIA Sanqiang, DONG Jiajie

RADIATION PROTECTION. 2022, 42(6): 548-555.

Abstract ( 106 )

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The method of the imaging system based on the M-M coded method is discussed, and the model of the imaging system based on the M-M coding method is established through Monte Carlo software MCNP. Using radiation sources of different energies at different positions to irradiate coding collimators with different thicknesses, it is determined that the optimal thickness of the coded collimator is 10mm by analyzing and explaining the reconstructed image SNR obtained. Then the response of the imaging system based on the optimal parameters of coded mask to the single-point source, multi-point source and extended source was simulated. The reconstructed image SNR of the single-point source reached 40.36, and the imaging system also successfully reconstructed the shape of the extended source. There are no fluctuating sidelobes in the background of reconstructed images of point and extended source. The above results prove the excellent performance of the M-M coded method, and it has the potential to replace MURA or URA in special scenarios. This article can lay the foundation for the subsequent development of coded aperture gamma camera based on M-M coded method.

Study on the absolute activity measurement method of ¹²⁵I nuclide point source and volume source by HPGe spectrometer

ZHANG Lei

RADIATION PROTECTION. 2022, 42(6): 556-562.

Abstract ( 123 )

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This paper derived the ¹²⁵I activity calculation formula based on the coincidence summing characteristics of ¹²⁵I nuclide X-ray and γ ray. The formula only included the net counting rate of the full-energy peaks (27.3, 35.5, 31.2 keV), the net counting rate of the sum-peaks (58.5, 66.7 keV) and the net counting rate of the total spectrum. The point source, activated carbon cartridge source and liquid source were verified by Broad-energy and N-type germanium spectrometer. When the distance from point source to detector was less than 5cm, the relative deviation between the calculated results of the absolute activity and the reference values was within ±1.2%. The self-absorption effect of ¹²⁵I nuclide in activated carbon cartridge could be ignored, and the absolute activity calculation formula was not affected by the distribution form of ¹²⁵I nuclide. The relative deviation of front and rear measurements for activated carbon cartridge source was within ±1.4%. The relative deviation between the measurement results and reference values of liquid source with volume less than 40mL was within ±2.6%. The sample height should not be too high during the measurement of liquid source, so as to reduce the weakening effect of self-absorption on sum-peaks. The experimental results show that the absolute activity calculation formula derived in this paper can be used to accurately measure the activity of ¹²⁵I nuclide without relying on standard substances and nuclide parameters.

Research on fast searching method of radioactive sources based on parameter estimation and cross locating

XU Hang, AI Xianyun, GUAN Xian, QI Sheng, XIE Jianming, WANG Ying

RADIATION PROTECTION. 2022, 42(6): 563-570.

Abstract ( 88 )

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The rapid and accurate search of lost radioactive sources is the core technology for radioactive source locating by aerial measurement. In this paper, the advantage and disadvantages of two methods, parameter estimation and cross locating method, were analyzed. Monte Carlo simulation was used to obtain the dose rate distribution of ¹³⁷Cs point radioactive source and natural background in the model of air-ground interface. Based on the simulation data, The optimal sampling range of the parameter estimation method (the minimum distribution range of sampling points required for maximum positioning accuracy) and the optimal threshold of the cross locating method (the minimum dose rate when the positioning success rate is greater than 95%) were obtained respectively. Aiming at the problem that the parameter estimation method is time-consuming and the accuracy of cross location method is poor, based on the obtained optimal parameters, a combined location method is proposed. The method firstly uses the cross locating method to quickly approach the radiation source, and then uses the parameter estimation method for precise positioning, and tested with simulation and field experimental data. The results show that the accuracy of this combined location method is improved by 49.6% compared with the cross locating method; and the time consumption is reduced by 71.1% compared with the parameter estimation method.

Study on the testing device of diffusion sampling radon measuring instrument and preliminary application

ZHAO Ying, CHEN Zhi, HU Xudong, WANG Chengnan, XIAO Mengren, BAO Zhicheng

RADIATION PROTECTION. 2022, 42(6): 571-578.

Abstract ( 79 )

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The response ability and stability of radon detector are the key factors to ensure the effectiveness of seismic monitoring and prediction. As a new method of moniroing Seismic underground fluid, the response ability and stability of electrostatic collection diffusion radon detector are related to the applicability of continuous seismic monitoring. In order to meet the detection requirements of the diffusion sampling radon for seismic monitoring, this study designed a test equipment for diffusion sampling radon detector based on the high radon content well water sample of Jiujiang No.2 well, and tested the response ability and stability of a electrostatic collection diffusion sampling radon detector under high concentration. The results show that the concentration of radon in the test device can switch between 0-120 kBq/m³ and can be relatively stable for a long time under the target concentration. The response time of the radon detector at high concentration is 2 hours and the stability is less than 5% for 8 h. The test device consists of crossflow module, degassing module, drying bottle, test chamber, measuring standard, air pump, etc, which can be used to test the response ability and stability of seismic monitoring diffusion sampling radon meter.

Study on background value of soil natural radionuclides in Dandong area

ZHENG Cunde, LIU Qingkuan, DONG Guochao, SUN Yu

RADIATION PROTECTION. 2022, 42(6): 579-584.

Abstract ( 139 )

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In order to clarify the background value of soil radioactivity in Dandong area, representative soil in Dandong area was used as research object, and the specific activities of ²²⁶Ra, ²³²Th and ⁴⁰K in 0-10 cm soil layer were measured by RMS 4096-USB digital low background multichannel r spectrometer. Results were evaluated by Nemero comprehensive evaluation method. The results show that the average specific activities of ²²⁶Ra, ²³²Th and ⁴⁰K in 0-10 cm soil layer in Dandong area are 100.12 Bq·kg^-1, 11.84 Bq·kg^-1 and 688.65 Bq·kg^-1 respectively. And the Nemero comprehensive index is 3.17, 0.35, 1.07, which is at a high level in Liaoning province and at a normal level in the whole country.

Numerical analysis and study on the representativeness of sampling at uniformly mixed place of new and old ISO 2889 standards

SHEN Fu, ZHANG Zhen, HOU Jie, JIANG Jing, LIU Xinhua

RADIATION PROTECTION. 2022, 42(6): 585-592.

Abstract ( 597 )

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In order for the design of nuclear power emission facilities, the mixing uniformity which met the requirements of ISO 2889—1975 and “2∶8” principle was studied in this paper, by the method of modeling calculation in accordance with ISO 2889—2010 standards. The results show that only the basic flow characteristics as flow angel and velocity meet the requirements, but the mixing uniformity of emission representative radioiodine nuclide assessment in radioactive gas and aerosol could not meet the requirements. In order to ensure the reliability of the study, the results are verified by both simulation program and experiment. The results show that the Graphene calculation method used in this paper is in good agreement with compared program. Grapheneprogram has better results than compared program by comparing with the experimental results. The research methods and results of this paper can provide an important reference for the safe emission control of nuclear power and the implementation of relevant regulations.

Application of ArcGIS to regional population surveys and statistics at nuclear facility sites

CHEN Chunyan, ZOU Ke, WEN Fuping

RADIATION PROTECTION. 2022, 42(6): 593-597.

Abstract ( 81 )

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In this paper, the population data of administrative villages and natural villages within a radius of 5 km arounda nuclear facility site and the scope of its residential area were obtained through field investigation and visits. The demographic data of the towns within the radius of 80 km around the plant site were obtained by means of data collection. With the help of 91 Vetu Assistant software and ArcGIS software, a statistical analysis model of regional population data of nuclear facility sites was established, and the population distribution of nuclear facility sites was statistically analyzed.

Analysis of iodine-removing performance of venturi scrubber in containment filtration and discharge system

WANG Zhen, ZHANG Jirong, BAI Dongjin, MIAO Qiyuan, LI Yongguo, REN Hongzheng, WANG Jia, ZHANG Yuan, QIU Dangui, HOU Jianrong

RADIATION PROTECTION. 2022, 42(6): 598-602.

Abstract ( 118 )

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In this paper, the operation conditions of Venturi scrubbers in nuclear power plants is simulated with a CFD numerical simulation method. The influence of the change of air flow velocity and system pressure on the ejection volume was analyzed. Combined with the experiment method, the influence of the ejection capacity of the Venturi scrubber on iodine removal efficiency was discussed, and some guiding suggestions for the discharge conditions of the containment filtration and discharge system of a nuclear power plant were put forward. The results show that increasing air flow velocity can increase the injection amount, and the injection amount presents an approximate linear growth relationship. Meanwhile, the pressure difference between the inside and outside of the suction tube presents an approximate parabola law. The iodine removal efficiency of the system is consistent with the increasing trend of the injection amount in the initial stage, and then tends to be stable after the injection amount reaches a certain level. In order to ensure a high iodine removal efficiency, the exhaust air flow of the system should be kept above 3 300 m³/h. In the range of 0.1 to 0.5 MPa system pressure, the iodine removal efficiency can be maintained at a high level. The increase of pressure is helpful to the increase of ejection capacity, and the increase is more obvious in the high flow area.

Experimental study on the radon exhalation from the soil overburden of uranium tailing pond under prefabricated fractures

WANG Hong, HE Runcheng, LIU Yong, HONG Changshou, LI Xiangyang, LUO Mengke, WANG Jianmin

RADIATION PROTECTION. 2022, 42(6): 603-610.

Abstract ( 97 )

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Faced with the problem of radon exhalation from fractures in soil overburden layer of uranium tailing pond, a simulation experiment of radon exhalation from fractures in soil overburden layer of uranium tailing pond was carried out with a self-made test device, and the effects of different fracture parameters (depth, number and dip angle) on radon exhalation from overburden layer were studied. The results show that the radon exhalation is mainly affected by the pore-fracture migration path, and the radon exhalation rate has a positive linear correlation with the fracture depth. The shortest pore migration distance is shortened with the increase of fracture inclination angle, and the radon exhalation rate for slope angle of 60° increases by 0.164 Bq·m^-2·s^-1 than that of 45°. The pore-fracture path has an influence boundary on radon exhalation on tailing pond surface, and the increase of radon exhalation decreases greatly after the overlap of the fracture affected area. The shortest pore path proportion ζ is introduced, and there is a good correlation between ζ and radon precipitation J. The research results can provide a theoretical reference for radon control of tailing pond surface.

Development and application of automatic grasp and security linkage system for radioactive sources in urban radioactive waste repository in Sichuan province

TANG Hui, XU Bin, WANG Yan, DENG Xiaoqin, GU Hong

RADIATION PROTECTION. 2022, 42(6): 611-617.

Abstract ( 99 )

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In order to achieve automatic grasp and to improve the security leve of urban radioactive waste repository in Sichuan provincel, this study carried out the design and development of the automatic grasp system of radioactive sources in urban radioactive waste repository and the security linkage system of radioactive waste repository. By designing the loading and unloading system of radioactive sources and the automatic grasping software system, which are interlinked with the dose monitoring system, radio frequency system and vehicle channel monitoring system of the waste repository, the functions of automatic access and safety linkage management of radioactive sources in the radioactive waste repository are realized. It has achieved the effect of effectively reducing the dose of the staff and improving the safety level of the waste repository. Through this study, the feasibility of the automatic grasp system of radioactive sources and the safety linkage technology of the warehouse is verified, and a new idea is put forward for the storage and management of radioactive waste, and a strong support is provided for the further development of the application of nuclear technology.

Optimization of medical emergency treatment process at nuclear accident site based on operation level

ZHAO Hongjun, WANG Fang, LU Zhijuan, JIAO Ling

RADIATION PROTECTION. 2022, 42(6): 618-624.

Abstract ( 96 )

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By comparing the nuclear emergency standards at home and abroad, combining the medical emergency treatment experience during international major nuclear accident emergency and the experience of domestic nuclear emergency drills, the radiation protection, triage, decontamination, psychological intervention aspects during emergency response on nuclear accident site are analyzed. Suggestions on process optimization at the operational level are put forward to help improve the capability of professional nuclear emergency rescue teams.

Discussion on the development of simulation training system for nuclear emergency in the armed forces

YUAN Wei, WANG Gang, LI Miao, LI Xiao, CHEN Xianbo

RADIATION PROTECTION. 2022, 42(6): 625-629.

Abstract ( 169 )

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In this paper, the necessity and the pattern of developing the simulation training system of nuclear emergency under new situation are expounded in view of the current problems in the military nuclear emergency training. The main ideas, basic considerations, main objectives, overall structure and the functional design of the subsystem are introduced in detail. The purpose of this paper is to provide theoretical support and method guidance for improving the capacity of nuclear emergency response at all levels of the army.

Investigation on X-ray diagnostic equipment and examination frequency of medical institutions in Qingdao city

ZHANG Xiuyun, LIU Jie, LIU Zhenyou, CHE Zijing, CUI Xinjian

RADIATION PROTECTION. 2022, 42(6): 630-636.

Abstract ( 143 )

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Documenting the distribution of radiology diagnosis professional staff, equipment and frequency is an important health economics problem. The aim of this report is to provide a data base for the application of radio-diagnostic resources in Qingdao city. Totally 230 medical institutions (not include dental clinics) equipped with X-ray diagnostic equipment were surveyed by questionnaire, and the data were collected from April 1, 2020 to March 31, 2021. There are 61.7% X-ray radio-diagnosis professionals in Grade III hospitals, but only 5.5% professionals are working in not rated hospitals. The ratio of X-ray radio-diagnosis professional between male and female is 1.59∶1. Totally 921 X-ray diagnostic equipment in Qingdao city were used. DR (33.44%) and CT (22.69%) are the most common used X-ray equipment. 23 Grade III hospitals possess 40.28% of all X-ray diagnostic equipment, with average 16.13 in each one. The frequency of X-ray diagnostic medical examinations is 688.24 per 1000 population, and CT accounts for 52.65% of them. The professionals and equipment in Grade III hospitals are dominant than that in secondary and primary Grade hospitals and not rated hospitals. CT scanning should be paid more attention because it constitutes more than half of all X-ray diagnostic medical examinations.

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