RADIATION PROTECTION

Calculation of internal exposure dose coefficients for Chinese adult reference phantom

YAN Shuchang, QIU Rui, WU Zhen, LUO Xiyu, ZHANG Hui, LI Junli

RADIATION PROTECTION. 2024, 44(4): 323-335.

Abstract ( 79 )

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In the fields of nuclear science and technology, nuclear energy and nuclear medicine, accurate assessment of internal exposure dose received by relevant public, professionals, and patients is an important guarantee for personnel health and safety during work, nuclear accidents, and radiation therapy. Referencing the ICRP biokinetic model and radionuclide information, the internal dose coefficient is obtained by calculating the Specific Absorbed Fraction (SAF). The correctness of the calculation method is verified using the ICRP reference human phantom. Finally, based on Chinese adult reference human phantom, a database of internal radiation dose coefficients for Chinese adult reference human is calculated. The database obtained includes the Specific Absorbed Fraction (SAF) of α, β, and γ rays for Chinese adult reference human, the committed equivalent dose coefficients for sensitive organs (tissues) of Chinese adult reference human, and the committed effective dose coefficients for Chinese adult reference human. The calculated results were compared and analyzed with the internal dose conversion coefficients provided by GB 18871—2002. It was found that using the internal radiation dose conversion coefficient database of Chinese adult reference human can more accurately assess the internal dose caused by the intake of radioactive nuclides by Chinese adults.

Study on radiation field measurement technique by utilizing total station positioning

ZHAO Yuan, LIU Liye, LI Hua, LIU Xuegang, CHENG Jinfeng, WANG Xiaolong, LONG Zeyu, LI Hui, CHEN Ling

RADIATION PROTECTION. 2024, 44(4): 336-342.

Abstract ( 61 )

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During the maintenance or decommisioning of nuclear facilities, it is often necessary to measure the radiation dose rate field on site. Traditional dose rate meters do not support spatial coordinate measurement and require additional coordinate measurement tools. Additionally, dose rate measurement and coordinate measurement are not synchronized, which limits measurement efficiency. A measurement method based on total station positioning was proposed, which can simultaneously measure dose rates and corresponding spatial coordinates with a positioning accuracy of mm level. A prototype measurement system was developed. The prototype was used to conduct testing experiments on a cement solidified radioactive waste container, and the outcomes were compared against Monte Carlo calculations. The discrepancy between the measured and simulated values conforms to a normal distribution, with an average deviation of 12.8% and a standard deviation of 9.37%. The relative deviation of approximately 96% of the measurement points is within the range of [-30%, 5%], reflecting high measurement accuracy. Radiation field assessments were also conducted in two other intricate settings within a nuclear facility structure. The interpolation of radiation fields at discrete measurement points was performed using the logarithmic transformation ordinary Kriging method. When measurement points were appropriately chosen, the average relative deviation in the three-dimensional radiation field reconstruction results could be maintained at approximately 50%. The results indicate that the radiation field measurement system based on total station can reconstruct the 3D radiation field on site, and the accuracy can meet the application requirements.

Performance verification of wide range neutron fluence rate measurement by fission ionization chambers for nuclear measurement

WANG Chunchi, XIAO Wei, LIU Jiaqi, SHI Yunhao, HU Chan, QIU Shunli, GE Mengtuan, ZHOU Yulin, DONG Jincheng

RADIATION PROTECTION. 2024, 44(4): 343-348.

Abstract ( 35 )

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This article analyzes the working principle of the fission ionization chamber and various working modes of wide range measurement. Based on its characteristics of multiple working modes, the measurement technology of wide range neutron fluence rate is studied, and the test method in reactor is discussed. Performance verification was conducted on the fission chamber pulse mode and mean square pressure mode in the reactor. The test results showed that the detector has an ultra wide range, and the maximum linearity between the detector output and neutron fluence rate in pulse counting mode is 1.16%. The maximum linearity in mean square pressure working mode is 2.06%, and the upper limit of neutron flux measurement can reach the level of 10¹⁰ cm^-2·s^-1, which complies with the wide range usage requirements of the intermediate range channel of the AP series external nuclear measurement system, and can be widely used in nuclear power and marine external nuclear measurement and monitoring systems.

Discussion on key technologies of portable on-line monitoring equipment for low-level radioactive waste water in NPPs

ZHOU Jianwang, YOU Chengmao, MEI Xiangjie, ZHOU Kebo, ZHANG Sujie, YIN Wangming

RADIATION PROTECTION. 2024, 44(4): 349-355.

Abstract ( 52 )

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Based on the situation and demand of a NPP, the features of LLRW are summarized. The technical requirements for portable online radioactive monitoring equipment are specified. The most important requirement is to meet the low detection limit (minimum detectable activity concentration, MDAC≤8 Bq/L) and portability of the equipment (total weight of the equipment should be≤50 kg). Key technologies such as measurement mode, detector selection and calibration method are then discussed. The measurement mode is generally sampling mode. The detector is generally large volume NaI crystal. The calibration methods are usually standard liquid source method and representative point method. Finally, the current online monitoring equipment for LLRW is investigated. It is found that the weights of all the existing equipment are more than 200 kg, which is far from the requirement of NPPs. Therefore, it is necessary to develop new on-line monitoring equipment with low MDAC and excellent portability. Three research directions are suggested, which are the application of new detector types, the development of new detector structure, and the development of new measurement methods. In order to improve the detection efficiency, a new detector structure based on annular NaI crystal is proposed. The weight of the new equipment and the MDAC is discussed preliminarily. It is expected to meet the requirements of NPPs.

Preliminary analysis on area ambient electromagnetic fields in part of Beijing by vehicle survey

XU Hui, TONG Jing, LI Fei, WANG Guan, LI Miao, KANG Xiaohan

RADIATION PROTECTION. 2024, 44(4): 356-366.

Abstract ( 67 )

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The electromagnetic fields ranging from 0.1 MHz to 6 GHz were measured by vehicle survey within the area of 800 km² in Beijing, in order to promote the monitoring and evaluation of area ambient electromagnetic quality. The vehicle survey gathered 900,000 values including global electric fields of total frequency bands, Radio Frequency and long, medium, and short waves, as well as selective electric fields of total base stations and 5G base stations. Mass data were analyzed by SPSS and ArcGIS to understand general ambient electromagnetic quality level, spatial and temporal distribution pattern, electromagnetic fields characteristics of various functional regions, electromagnetic source contribution and trace to the Electromagnetic sources for hot points. The analysis reveals that the electric field of total frequency band of this area is(1.08±0.59) V/m,84.00% of all points values are less than 1.5 V/m, and the total value of RF and the long-medium-short waves accounted for 68.2% and 31.8% of the total value of the total frequency band respectively, while the electric field of the base station is 0.63 V/m, accounting for 76.70% of the total radio frequency value, which means the most contributed source of electromagnetic radiation in the region is base stations. The spatial distribution of the total value of the full frequency band and radio frequency band basically have the same trend, which is significantly positively correlated with the population density and the distribution of base stations, while the electric field strength of long-medium-short waves in the ambient is mainly influenced by the relative radiated facilities within small ranges. The intensity of the full-day electric field strength of the base stations in residential area is generally above industrial zone which shows that the distribution of the base stations of the residential area is relatively dense. From 7: 00—18: 00 working hours, the electric field strength of 5G base stations in industrial area is greater than that of residential area. And during the rest time period, the electric field strength of 5G base stations in residential area is greater than that of industrial zones. Analysis of hot-spot map can position concentrated areas of electromagnetic radiation facilities such as mobile base stations of multiple operators, and trace back to the long-medium-short wave electromagnetic radiation sources and surrounding affected areas through spectrum analysis.

Investigation on radon concentration in Chengdu metro

XU Lipeng, CHEN Li, WANG Xianliang, LI Jie, PENG Yi, LIU Min, LI Chunyang, YANG Qiang, GU Yi, LI Jianying

RADIATION PROTECTION. 2024, 44(4): 367-373.

Abstract ( 61 )

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To understand the radon concentration levels in the Chengdu metro environment, instantaneous methods and cumulative methods were used to conduct an investigation to the radon concentration levels at 31 subway stations. The results showed that the radon concentration of 279 measuring points in Chengdu metro as measured instantaneously ranged from 9.1 to 39.0 Bq/m³, with an average of (19.7±7.8) Bq/m³. The radon concentration of 124 measuring points at the subway stations as measured cumulatively twice ranged from 9.7 to 32.5 Bq/m³, with an average of (18.4±4.3) Bq/m³. The radon concentration level was significantly lower than the standard reference value. It was found that the radon concentrations inside the subway cars were lower than that at the subway stations on the corresponding line, with a positive correlation reaching 0.84 (P<0.05), and the radon concentrations at the upper security inspection points were lower than that at the lower platforms of the corresponding line, with a positive correlation reaching 0.81 (P<0.05). The radon concentrations in the open ticket halls were lower than that in the control rooms in the enclosed area on the same floor of the corresponding line. Analysis revealed that ventilation is effective in reducing the level of radon concentration in the subway. The annual effective dose of radon and its progeny in the ambient air of the Chengdu metro to the subway staff and passengers is estimated to be 0.15 mSv and 0.05 mSv respectively.

Acceptability analysis of public radiotion risk for HPR1000

WANG Mengxi, LIU Xinjian, LIN Hongtao, XUE Na, QIU Lin, ZHAO Bo

RADIATION PROTECTION. 2024, 44(4): 374-382.

Abstract ( 31 )

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After the Fukushima nuclear accident, more and more attention has been paid to the public radiation risk assessment of NPPs. With the “going out” initiative of China’s independently developed GEN-III technology HPR1000, Argentine Atomic Energy Commission and other foreign regulatory agencies have clearly requested to carry out level-3 PSA for NPPs. Public radiation risk assessment has been an important indicator to judge whether the plant safe or not. Combined with the level-2 PSA source terms, demographic, meteorological and topographic data, using the self-developed accident consequence assessment code based on the CALPUFF model, personnel exposure dose and radiation risk at different distances from the NPP site are quantitatively simulated. The results show that the public radiation risk after serious accidents is lower than 10^-8/a, which meets the relevant requirements of criteria in Argentina, the United States and the United Kingdom, etc. This paper provides technical support for the safety review of HPR1000 technology, and promotes the safe and effective global deployment of HPR1000. Meanwhile, suggestions have been made for regulatory authorities to formulate quantitative risk acceptance criteria.

Numerical simulation of the effect of cooling tower plume on the air flow and diffusion around a nuclear power plant

PEI Juan, LI Ruojie, ZHANG Junfang, ZHAO Dan, WANG Xue, PU Xiang

RADIATION PROTECTION. 2024, 44(4): 383-390.

Abstract ( 40 )

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In this paper, a nuclear power plant is taken as the research object. The computational fluid dynamics (CFD) method is used to study the influence of natural ventilation cooling tower on the flow and pollutant diffusion around the nuclear power plant, and the results are compared with the wind tunnel experiment results to verify the validity of the model. The results show that on the leeward side of the cooling tower, the wind speed in the near wake region (including the re-circulation zone) decreases significantly, and the turbulence intensity increases significantly. When the cooling tower is located in the downwind direction of the stack, the plume emission has a great influence on the pollutant diffusion of the stack. The pollutant is naturally sucked through the cooling tower, and the secondary emission phenomenon occurs. When there is plume emission, the ground axis diffusion factor is less than that without thermal plume emission before 1 000 m.

Numerical analysis of the effect of mesh scale on the tidal characteristics of coastal areas simulated by 3D hydrodynamic model

LIU Jiaonan, HAN Lijuan, QIAO Jianhao, HAO Ruixia

RADIATION PROTECTION. 2024, 44(4): 391-402.

Abstract ( 25 )

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In this paper, a three-dimensional hydrodynamic model of Sanmen Bay is constructed. Different mesh scales are set up after comparing and analyzing the calculation results with the measured data, and the tidal current characteristics of three sections and four typical points are analyzed. The results show that: when the study water is a bay with many harbor branches and complex topography, the relative deviation of the numerical simulation value will increase with the mesh scale. When the mesh scale increases to a certain value, the relative deviation will stabilize due to the accumulation of multiple errors. The topography is a key factor affecting the calculation of tidal currents. The tidal range and current velocity values in the inter-tidal waters with drastic topographic changes and small water depths are relatively large, while in the flat areas with large water depths, they are almost unaffected by the mesh scale. The current direction has a low sensitivity to the mesh scale and has no obvious relationship with the mesh scale. The horizontal vortex viscosity coefficient is positively correlated with the mesh area and the mesh area has a greater effect on the current velocity deformation rate S_ij at the larger places. Comprehensive analysis shows that, in the calculation of tidal currents, it is necessary to encrypt the mesh in the shore with complicated topography, inter-tidal zone with small water depth and islands, and to determine the appropriate mesh scale by considering the factors of calculation time, stable convergence of the model calculation and the accuracy of the calculated values, so as to make the calculation results meet the requirements of accuracy.

Analysis of the effect of residual heat removal system on the surrounding area during oxygenation in HPR1000 reactor

LI Ming, SHI Shengchun, PANG Zongzhu, LIU Yu, JIANG Yanman

RADIATION PROTECTION. 2024, 44(4): 403-409.

Abstract ( 33 )

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The radiation level of residual heat removal system will change significantly during reactor shutdown, and will reach the shutdown peak during oxygenation, which will affect the surrounding area. In this paper, the surrounding area radiation level of the HPR1000 residual heat removal system is calculated and compared with the measured maximum value. The influence on the radiation level in the surrounding area of residual heat removal system is analyzed comprehensively, and the corresponding optimization suggestions are put forward.

Discussion on radiation protection for PWR second-loop steam supply for industrial application

ZHUANG Yaping, LIU Weili, FANG Yuan, WU Fang, MIAO Zhengqiang

RADIATION PROTECTION. 2024, 44(4): 410-415.

Abstract ( 28 )

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Nuclear power reactor units have the ability to provide large-scale, stable industrial steam. Laboratory measurements show that, under the condition of no leakage in the heat transfer tube of the steam generator, the concentration of radionuclides in the condensed water of the second-loop steam is not different from that in the environmental water sample except for tritium. Based on the drinking water standard, this article proposes to control the target value of radionuclide management for industrial application of second-loop steam at 3.0 Bq/kg; A high-sensitivity radiation monitor was set up on the steam generator drainage pipeline and technical renovation on the main steam pipeline N-16 radiation monitoring channel was carried out, with the aim to provide timely, effective, and reliable monitoring of steam generator heat transfer tube leakage. It is interlocked with the control valve of the external steam supply pipeline at the factory boundary to prevent radionuclides from leakaging outside the factory area through the steam supply pipeline during operation and accident conditions.

Consideration and suggestions on improving China’s nuclear emergency training and exercise in the new era

LIU Yulong, WANG Youyou, HOU Yuhan, BIAN Huahui, LIU Chang

RADIATION PROTECTION. 2024, 44(4): 416-422.

Abstract ( 44 )

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The Chinese government attaches great importance to nuclear emergency training and exercises. As an important component of nuclear emergency management system, this article takes nuclear emergency training and exercises as the starting point, useing the national “Shendun” series of nuclear emergency joint exercises as case analysis, Based on the key points of nuclear emergency core capacity building, this article proposes ideas and suggestions on improving China’s nuclear emergency training and exercise in the new era.

Analysis of key technical points and difficulties in the process of emergency response to radiation accidents

ZHANG Yan, QIAO Qingdang, YANG Duanjie

RADIATION PROTECTION. 2024, 44(4): 423-429.

Abstract ( 66 )

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The response process to radiation accidents includes several important action steps. This article analyzes the technical key points of each main step in the process of radiation accident emergency response, combines with practical experience, and provides countermeasures and suggestions for the existing difficulties. This analysis could provide reference for further improvement of radiation accident emergency response in the future.

A brief introduction to the fire accident research facilities for nuclear fuel cycle safety at CIRP

SUN Hongchao, LIAN Yiren, LI Guoqiang, CHEN Lei, MENG Dongyuan, SUN Shutang, ZHUANG Dajie, ZHANG Jiangang

RADIATION PROTECTION. 2024, 44(4): 430-436.

Abstract ( 31 )

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Fire accident is a typical postulated accident in nuclear fuel cycle facilities, and is the focus of international nuclear fuel cycle safety research. A series of fire research facilities were constructed in China Institute for Radiation Protection (CIRP). The small-scale facility consists of a 200 L cylindrical combustion chamber, and is mainly used for testing the basic parameters of combustibles. The middle-scale and large-scale facilities consist of 20 m³ and 120 m³ rectangular combustion chambers respectively, both of them are mainly used to carry out tests for combustion rate, temperature distribution, radioactive gas and aerosol release share, nuclide release share and filtration efficiency of HEPA. This paper briefly introduces the characteristics of the three experimental facilities, and the research capabilities of each facility were summarized. Further research plans were put forward.

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