RADIATION PROTECTION

Research progress on radon migration and coverage control

ZHAO Yong, ZHANG Guifeng

RADIATION PROTECTION. 2024, 44(1): 1-9.

Abstract ( 96 )

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With the development of nuclear power, the demand for natural uranium has increased. It has become evident that large volume accumulation of tailing on the ground may cause radon pollution. Therefore it is of great significance on how to effectively reduce the amount of radon exhalation from uranium tailing. Generally, the covering method after ground accumulation is used to reduce the ground environmental hazards caused by uranium tailing. The process of radon migration mainly undergoes two stages of migration in the covered material and the covering material. As a result, studying radon migration law has become a key component in solving the problem. In this paper, foreign and domestic scholars' studies on the factors influencing radon exhalation, radon migration theory, coverage control method and effect, and coverage parameters are summarized and reviewed. The following results are obtained: At present, the exhalation mechanism and influencing factors of radon are presented as comprehensive analysis. But there is a need for further research on the multi-factor coupling mechanism and action process during radon exhalation. Natural and artificially synthesized materials are selected as covering materials, the Natural materials are currently commonly used, in which the addition of bentonite in red soil, sandy sub-clay, and red soil are the good material for radon reduction. However, more research is needed to find covering materials that are effective in controlling radon and have minimal impact on the ecological environment. This paper provides ideas for more effectively eliminating radon pollution from uranium tailing in the future.

Research on accounting boundary and method of greenhouse gas emission of nuclear power plants life cycle

WU Feifei, KANG Jing, WANG Yan, LIAN Bing, YANG Jie, YUE Qi

RADIATION PROTECTION. 2024, 44(1): 10-18.

Abstract ( 73 )

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Nuclear energy is an important source of low-carbon electricity, which is conducive to achieving the “dual carbon” goal. At the national level, a unified and standardized accounting method for greenhouse gas emissions by nuclear power industry has not been established. Relevant research on the accounting boundary and method are essential. Based on critical issues of greenhouse gas emissions accounting, we systematically analyzed the accounting boundary and methods of greenhouse gas emissions from nuclear power life cycle at home and abroad. In addition, we compared the greenhouse gas accounting standards and guidelines for enterprises in key industries. The accounting research framework was proposed for greenhouse gas emissions during the nuclear power life cycle. The future research prospects are proposed from three aspects, which include the establishment of a greenhouse gas emission accounting system, research on emission influencing factors and case studies at the decommissioning stage. The proposed research can provide a reference for establishing a unified and standardized statistical accounting system for greenhouse gas in the nuclear power industry in China.

Study on air kerma measurement and conversion coefficient from air kerma to dose equivalent for 250-500 kV X-ray narrow spectrum

QU Bingbing, ZHAO Rui, WU Jinjie, LU Pingzhou, LI Mengyu, LI Ting, MA Yingjie

RADIATION PROTECTION. 2024, 44(1): 19-26.

Abstract ( 108 )

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Accurate measurement of radiation dosimeter is an important guarantee for conducting radiation protection. According to the operational quantities in ICRU report, it is necessary to verify or calibrate it in the reference radiation field. Referring to the ISO 4037-1:2019, the narrow spectrum X-ray reference radiation quality in (250-500) kV was established, and the uniformity of the radiation field and the spectrum were studied. The spectrum and half value layer parameters of radiation quality were obtained by Monte Carlo simulation and experimental measurement, and were compared with the ISO recommended values. These results meet the requirements of the relevant specification, indicating that the new radiation quality is accurate and reliable. The A5 ionization chamber is used to measure the air kerma in the new radiation field. According to the conversion coefficient of the air kerma to dose equivalent calculated by the X-ray energy spectrum, the conversion of the air kerma to the ambient dose equivalent and the individual dose equivalent is realized, which provides the measurement conditions for the energy response evaluation of various radiation dose meters in the high-energy region, and ensures the accuracy and reliability of the measurement value.

Calculation of RBE weighted absorbed dose coefficients for an accidental inhalation of ²⁴¹Am

CHEN Qianlan, CHEN Baowei, XIA Yihua, LUO Zhiping , LIU Senlin

RADIATION PROTECTION. 2024, 44(1): 27-32.

Abstract ( 72 )

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When an acute high intake of radionuclide has occurred or is going to occur in the dose range close to deterministic effect (or tissue reaction), it is needed for a technical platform or tool used to quickly estimate the short-term absorbed dose in interested organs or tissues, in order to make decision for nuclear and radiation response actions and other response actions suggested by IAEA Safety Guide No.GSG-2, which can minimize large radiation dose to the people exposed and then protect the health of the people actually. Therefore this paper focuses on the followings: studying the designing principle and models’ parameters foundation of the International Commission on Radiological Protection (ICRP) Human Respiratory Tract Model (HRTM), Systemic Model, Human Alimentary Tract Model (HATM) and Wound Model; compiling the retention and excretion fraction m(t) calculation codes, after its verification, to calculate the target organ’s RBE weighted absorbed dose AD(30)_T for an urgent inhalation of ²⁴¹Am, and the correctness of the results are ensured by comparison of two persons’ results.

A performance study of a new personal neutron dosimeter based on SSNTD

JIAO Yan, CAO Qinjian, WEI Xiaofeng, XU Yuan, ZHAO Yuan, LIU Liye

RADIATION PROTECTION. 2024, 44(1): 33-41.

Abstract ( 84 )

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As a passive personal neutron dosimeter, CR-39 solid state nuclear track detector is convenient, cheap, insensitive to gamma and beta rays and has strong anti-interference ability, and better response to fast neutrons. A new personal neutron dosimeter has been developed combining with two measurement methods of CR-39 and albedo thermoluminescence dosimeter. Performance experiments are carried out on the CR-39 detector according to the international standard ISO 21909-1. The results show that the CR-39 solid state nuclear track detector has good repeatability, batch homogeneity, dose linearity, stability, response of reference radiation field and no photon-sensitivity. The detection threshold and uncertainty of dose measurement are presented in this paper. It provides an experimental data reference for the introduction of international standard.

Development of a dosimeter for H_p(0.07) monitoring

WEI Yingjing, WU Zhifang, FANG Dengfu, LIU Liye, FENG Mei, WEI Shiliang

RADIATION PROTECTION. 2024, 44(1): 42-49.

Abstract ( 70 )

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In view of the poor performance of dosimeters for low energy β rays monitoring in China, a ZF-P7 H_p(0.07) dosimeter was developed, based on LiF:Mg,Cu,P thermoluminescence detector and combined with simulation calculation, in order to solve the problem of accurate measurement of H_p(0.07) dose in β and γ mixed fields. The performance test results of ZF-P7 H_p(0.07) dosimeter are as follows: For the maximum energy of 225 keV-2.274 MeV of β rays, the energy response ranges is 0.67-0.95; For energies between 16 keV to 1 250 keV of X or γ rays, the energy response ranges is 0.66-1.45; Within the range of 100 μSv-1.2 Sv, the dose linearity is 0.91-1.10; Under the X radiation of 65 keV and angle range of 0° to ±60 °, the angle response of -60° to 60° is 0.99-1.09; Under the β radiation of ⁸⁵Kr, the angle response of -60° to 60° is 0.94-1.11. According to the measurement results, the performance of ZF-P7 dosimeter meets the requirements of EJ/T 1178—2005 and JJG 37—2014. Because the ZF-P7 dosimeter has excellent performance, especially the radiation response is good at X,γ,β mixed radiation filed, which can solve the problem of operators’ H_p (0.07) dose monitoring in the mixed radiation fields. It can be widely used in the H_p(0.07) dose monitoring for workers in the mixed radiation fields.

Application of an adaptive Wiener filter in noise reduction for gamma energy spectrum

ZHANG Jiawei, NIE Yajie, QI Zijian, ZHAO Yanhui

RADIATION PROTECTION. 2024, 44(1): 50-56.

Abstract ( 60 )

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A noise reduction algorithm based on the adaptive Wiener filter for portable gamma spectrum detectors was developed. Compared with traditional gamma spectrum noise reduction algorithm represented by the five-point third-order filtering and the centerofgravity method,the estimated variance value is used as a measure of local details to implement adaptive adjustment of the noise reduction algorithm. Verified by simulated signals and measured data, the noise reduction algorithm based on the adaptive Wiener filter has faster running speed and better noise reduction effect than the five-point third-order filtering and the center-of-gravity method while retaining the gamma energy spectrum characteristic information. With the advantage of no distortion, it has certain application potential in the energy spectrum noise reduction processing of portable gamma energy spectrum detectors.

Comparison and analysis of electromagnetic radiation monitoring instruments in anechoic chamber

NING Jian, LI Zhanyou, ZHOU Feng, YUAN Xiuhua

RADIATION PROTECTION. 2024, 44(1): 57-61.

Abstract ( 69 )

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In order to improve the comparability of the comparison results of monitoring instruments, it is necessary to select a place where the field strength is stable and is not affected by the external electromagnetic environment for comparison. This article analyzes and summarizes the experience and practices of conducting frequency-selective radio frequency electromagnetic radiation monitoring instrument comparison-measurement in a standard anechoic chamber, and finds out some problems that are difficult to detect in daily work.This paper also proposes suggestions for monitoring instrument verification during the monitoring period.Conducting comparisons in a stable and standard electromagnetic field environment could provide a new practice for electromagnetic environment monitoring instrument comparison.

Research on the effects of fast neutron irradiation on silicon photomultiplier tubes and CLYC detectors

CHEN Zhaoxi, SUN Shifeng, ZHANG Xiangming, ZHANG Ao

RADIATION PROTECTION. 2024, 44(1): 62-70.

Abstract ( 79 )

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In this experiment, the SiPM device and Cs₂LiYCl₆ (CLYC) scintillator detector were exposed to a 14 MeV fast neutron field, and the maximum cumulative irradiation fluence reached 1.53×10¹¹ cm^-2. The effects of neutron irradiation on the SiPM device parameters and effects on CLYC detector performance were studied. The focus was on the gain, dark count rate, dark current, breakdown voltage, quenching resistance and other parameters of SiPM before and after irradiation with different fluences, as well as the changes and causes for the detection performance of the CLYC detector. Among them, the dark count rate increased the highest with 3 orders of magnitude, the dark current increased by up to 2 orders of magnitude, and the energy resolution of the CLYC detector decreased by 1.4% after removing the background. After the irradiation experiment, the SiPM and CLYC detectors were annealed at room temperature to study the SiPM device parameters and detector performance recovery. The performance of SiPM and CLYC detectors gradually deteriorates as the neutron fluence increases. For SiPM, the main performance is the increase in dark count rate and dark current. For the CLYC detector, the main manifestation is the reduction of energy resolution. The annealing process helps mitigate the effects of neutron irradiation and restores some performance of SiPM and CLYC detectors.

Numerical simulation and analysis on intermittent discharge of liquid effluent from a coastal nuclear power plant

ZHANG Haiwen, JI Ping, ZHAO Yijun, CHEN Xiaoli, ZENG Li

RADIATION PROTECTION. 2024, 44(1): 71-79.

Abstract ( 75 )

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A numerical model for discharge of liquid effluent from a coastal nuclear power plant is established by using MIKE 21 Hydrodynamic model with transport module in an unstructured grid. Numerical simulations of transport and diffusion of liquid effluent with non-decaying nuclide are carried out with different scenarios of the intermittent discharge starting at the four typical tidal moments respectively, in addition to a comparison with continuous discharge under the condition of equal discharge concentration. The mean concentration distribution, impact areas of liquid effluent in the sea water and characteristic values of intake concentration in different scenarios are given. The comparative analysis indicate that the transport and diffusion process of liquid effluent from the coastal nuclear power plant is mainly affected by tidal current. The intermittent discharge starting at the moment of ebb strength has significant advantages in respect of environmental impact and intake concentration. The calculated results can provide technical support for the optimization of liquid effluent discharge mode and marine environmental impact assessment.

Study on the dominant ventilation method for radon reduction in uranium mine

LI Xianjie, ZHANG Zhe, HU Penghua, CHENG Gang, REN Jianjun, LIU Xiaochen

RADIATION PROTECTION. 2024, 44(1): 80-84.

Abstract ( 68 )

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Based on the radon exudation rule in the inlet and the using sections of the mine ventilation network, the calculation formula of air demand for radon reduction in uranium mines under different ventilation modes is derived from the basic equation of radon reduction ventilation in uranium mines. The evaluation indicators of dominant ventilation mode are derived from the effective air supply capacity of the inlet section. And the discrimination method of radon reduction ventilation mode in uranium mines is suggested.

Study on standard system for containment enclosures

LIU Fugui, LIU Lipo, DONG Fangfang, JIN Liqiang, PAN Jianjun, LI Xiaozhen, GUO Jianxin

RADIATION PROTECTION. 2024, 44(1): 85-92.

Abstract ( 77 )

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Containment enclosures are specialized facilities that meet specific requirements of seal and radiation protection. This paper comprehensively sorts out the current status of containment enclosure standards in China. This paper also analyzes the standard requirements of containment enclosures in terms of design, manufacture, installation & commissioning, operation & maintenance as well as decommissioning. Finally this paper establishes the structure diagram and gives standard specifications for containment enclosures, which lays a foundation for guiding the application and implementation of containment enclosures standards and the standards research and development work urgently needed in the next step.

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