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    20 September 2022 Volume 42 Issue 5
      
    Several basic concepts must be clarified scientifically and rigorously in the field of nuclear science and technology and radiological protection
    ZHENG Junzheng
    RADIATION PROTECTION. 2022, 42(5):  381-394. 
    Abstract ( 70 )   PDF (3565KB) ( 70 )  
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    Nuclear science and technology has been widely used in various fields and industries, which is oneof the most outstanding scientific and technological achievements since the 20th century. Faced with a wide range of aspects and influences, it is necessary to effectively prevent and control the possible radioactive risks, which will inevitably attract great attention from all walks of life and the general public. Therefore, it is very important to adhere to scientific rigorous spirit, to interpret the basic concepts accurately and to disseminate the knowledge of nuclear science and technology and related radiological protection.This article lists 8 fairly common vague questions for analysis and comment, in order to call for scientific and rigorous clarification of relevant basic concepts, so as to promote the development of nuclear science and technology and its wide application. The 8 questions to be reviewed are:①The Ionizing Radiation and the Non-ionizing Radiation are completely different types of radiation. ②The core connotation of the Radiological Protection, the Radiological Hygiene, and the Health Physics is all about the study of protection against ionizing radiation. ③The medical application of nuclear technology is not equal to Nuclear Medicine, and Radiodiagnosis and Radiotherapy can not be called “Nuclear Medicine”. ④The Radiology and the Radiation Medicine are completely different branch of disciplines. ⑤It is very important to distinguish different concepts of the Absorbed Dose, the Dose Equivalent, the Equivalent Dose and the Effective Dose. ⑥Attention must be paid to the correct use of whole body Effective Doses for radiological protection evaluation. ⑦The special name for Dose Equivalent, Equivalent Dose and Effective Dose is “Sievert”,which should be used in Chinese“希沃特”in stead of“西弗”. ⑧The term “frequency” for epidemiological investigation and research must not use the Chinese character“频度”, which is used in Japanese .
    Calculation and analysis of gamma-ray exposure buildup factor for common double-layer materials
    LI Hua, WEI Ziyang, ZHAO Yuan, LIU Liye, LI Hui, WEI Jiafu
    RADIATION PROTECTION. 2022, 42(5):  395-401. 
    Abstract ( 52 )   PDF (4258KB) ( 40 )  
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    Based on Geant4, a calculation program for the buildup factors of the double-layer materials was developed and the exposure buildup factor database of double-layer combination for some common materials (water, iron, lead and concrete) at nuclear facility site were calculated and established. Meanwhile, some calculation results are compared with corresponding simulation data of empirical formula with good reliability and the main reasons for their difference are analyzed. The results show that the buildup factor data of the double-layer materials calculated by Geant4 are relatively in good agreement with simulation results of the empirical formula. And most of the deviations among them are within 10%, which verifies the reliability of the calculation results of the buildup factors for the double-layer materials by Geant4. The work of this paper can provide underlying data basis for the related simulation of radiation protection field.
    A preliminary study on technical requirements for the design of environmental radiation monitoring program of marine nuclear power platform
    HUANG Yanjun, SHANGGUAN Zhihong, XU Yueping, ZHANG Xiaofeng
    RADIATION PROTECTION. 2022, 42(5):  402-410. 
    Abstract ( 37 )   PDF (2032KB) ( 33 )  
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    The marine nuclear power platform is a nuclear facility that combined with the technologies of nuclear power and the marine engineering, and is promoted in China in recent years. However, the related environmental ration regulatory requirements and the environmental protection design are insufficient since it is an innovative technology in the world, for instance in the aspect of the effluent monitoring and the environmental radiation monitoring, which is urgently needed and needs to be studied and established. In this paper, a preliminary design of the effluent monitoring system and the environmental radiation monitoring system were discussed, based on the characteristics of the construction and operation of the marine nuclear power platform and the related current regulations for nuclear power facilities in China. The study gives a useful reference for the design of the monitoring system and the following supervision of the radiation environment of the marine nuclear power platform.
    Research on the influence of Reynolds number on the uniformity of gas mixing in chimney by CFD method
    ZHENG Jinge, CHENG Weiya, GUO Haocheng, LIU Weifu, WANG Chenxiao, HAO Guizhen, ZHAO Yulun, CHEN Ling
    RADIATION PROTECTION. 2022, 42(5):  411-417. 
    Abstract ( 29 )   PDF (4548KB) ( 9 )  
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    In order to study the gas mixing uniformity in the ventilation duct under various flow status, we established a simulation model by using computational fluid dynamics method. The Reynolds number covers the range of 800 to 70 000. The simulation results showed that: the change of Reynolds number has an important influence on the velocity distribution; When the height is less than 8 times hydraulic diameter, the velocity distribution will become more uniform when the monitoring surface is raised. In the region of more than 8 times hydraulic diameter, increasing the degree of turbulence can improve the uniformity of velocity distribution. However, when the flow state reaches full turbulence, it is not beneficial to increase the Reynolds number. For the tracer gases, they could reach a sufficient mixing in each monitoring surface. When the Reynolds number is lower than 29 000, the mixing uniformity of the tracer gas on each surface will slightly decrease as the Reynolds number increases. But when the Reynolds number exceeds 29 000, the uniformity of mixing is no longer significant. Comparing the simulation results with the test results, the simulation results of wind speed and tracer gas concentration are in good agreement with the test measurements.
    The monitoring and assessment of atmospheric 14C specific activities around Ningde NPP
    LIN Minggui
    RADIATION PROTECTION. 2022, 42(5):  418-424. 
    Abstract ( 30 )   PDF (4132KB) ( 25 )  
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    The monitoring of atmospheric 14C around nuclear power plant is an important content of the supervisory monitoring of radiation environment. In this paper, the sampling and monitoring methods of 14C in the ambient air around Ningde NPP were presented. The variations and trends of the monitoring results from 2013 to 2021 were analyzed, and were comparatively studied with the baseline and other reported values around NPPs. Meanwhile, the correlation study with the gaseous effluent emission from Ningde NPP were analyzed. It was shown that the average specific activity of atmospheric 14C at each monitoring point of Ningde NPP ranges from 0.229 to 0.230 Bq/g(C), and the results of the Niulanggang monitoring point closest to the plant site may be affected by the discharge of the NPP. Furthermore, the seasonal variation of 14C specific activity was analyzed. It was shown that, except for the Niulanggang monitoring point, the specific activity of 14C was higher during July to September.
    The development of calculation code CPGale for radioactive effluent source term of pressurized water reactor nuclear power plant
    LV Weifeng, CHEN Mingliang, LIU Jie, XIONG Jun, JIANG Zhenyu
    RADIATION PROTECTION. 2022, 42(5):  425-432. 
    Abstract ( 17 )   PDF (1899KB) ( 9 )  
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    Following the analysis on the generation and discharge mechanism of radioactive gaseous and liquid effluents during normal operation of pressurized water reactor nuclear power plant, the calculation model is improved and the calculation code CPGale with good man-machine interface is developed. The CPGale code is validated by operation data of in-service nuclear power plant in China. The validation result shows that the radioactive gaseous and liquid effluent source term calculated by CPGale code has an appropriate conservation compared with the operation data of in service nuclear power plant. The CPGale code can fulfill the requirements of nuclear power plant design and can be used in engineering applications.
    Effects on pollutant dispersion over complex terrain on CALPUFF model
    SHI Xuefeng, GUO Dongpeng, WANG Ran, LI Yunpeng, YAO Rentai
    RADIATION PROTECTION. 2022, 42(5):  433-441. 
    Abstract ( 23 )   PDF (9495KB) ( 15 )  
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    In this paper, the WRF/CALPUFF model is used to simulate a tracer experiment at Taohuajiang Inland Nuclear Power Plant in Hunan Province, and the plume dispersion of SF6 in complex terrain is studied. The simulated results are compared with field experiment results. The results show that the dispersion of SF6 approximates a Gaussian distribution with the distance from the sample points to the release point, and the maximum value of SF6 dispersion factor appears at 1.2 km from the release point. Terrain is an important factor affecting the dispersion trajectory of SF6. In addition, the statistical parameters are used to analyze the feasibility of model. The value of FAC2 and FAC5 is 30.1% and 57.7%, respectively. These values show that the simulated dispersion factor are better in agreement with the observed dispersion factor. In conclusion, the CALPUFF model can simulate the dispersion of pollutants over complex terrain.
    Aircrew radiation dose assessment based on Monte Carlo simulation
    WU Renyao, GENG Changran, TIAN Feng, LIU Huan, TANG Xiaobin
    RADIATION PROTECTION. 2022, 42(5):  442-449. 
    Abstract ( 37 )   PDF (6558KB) ( 21 )  
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    Based on the Monte Carlo method, the radiation dose of aviation crew was studied by using mesh polygon based radiation computational phantom and digital aircraft model. The air route from Kunming to Beijing was selected as an example, the effective dose rate of aviation radiation received by air crew during flight on this route was calculated, the influence of human parameters on the effective dose rate was analyzed, and the variation of effective dose rate received by air crew when the flight route parameters were changed was explored. The results show that the effective dose rate of the crew on the route from Kunming to Beijing is 2.114 μSv/h, the difference of effective dose rate between radiation computational phantom based on Chinese reference physiological characteristics and Caucasian parameter body model is 25.3%. Among the route parameters, the altitude of the route is the most important influencing factor, the effective dose rate of aviation radiation at a flight altitude of 14 km is 1.8 times that at a flight altitude of 10 km. When the latitude of the airline increases, the effective dose rate of aviation radiation received by the aircrew will also significantly increase. This work will provide a certain degree of reference and guidance for radiation dose assessment of aviation crew.
    A preliminary study on packaging and shielding schemes for reactor pressure vessel decommissioning
    CHEN Xingzi, WANG Xuhong, LV Tao, KANG Baowei, WANG Xin, XIA Jiaguo
    RADIATION PROTECTION. 2022, 42(5):  450-453. 
    Abstract ( 18 )   PDF (1143KB) ( 7 )  
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    In order to ensure the safe decommissioning of reactor pressure vessel (RPV), this paper takes Qinshan Phase I RPV as the reference object, stimulates and designs packaging and radiation shielding schemes under the decommissioning plans of keeping RPV intact and dismattling RPV. This paper further compares and analyzes two schemes by estimating the operability, convenience and economy. The results show that the plan of dismantling RPV is more optimal, which could better support decommissioning of nuclear power plant.
    Improvement of leak test method for the cover for exhaust and drain hole of ENUN 24P spent fuel transport container
    LIU Yiqing, ZHAO Xiaodong, ZHENG Yu, ZHAO Jingchang, ZHONG Maihao
    RADIATION PROTECTION. 2022, 42(5):  454-459. 
    Abstract ( 17 )   PDF (3378KB) ( 7 )  
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    The cover for exhaust and drain hole on the inner cover of the spent fuel transport container is part of the container’s containment boundary, which uses a double O-type metal seal. After the container is loaded with spent fuel assembly, the cover for exhaust and drain hole should be tested by helium leakage test. During the commissioning of the ENUN 24P spent fuel transport container, the leak test tool provided by the manufacturer was found to be difficult to centering the hole cover and sealing surface, complicate to operate, easy to damage the sealing surface, increased exposure risk of the operator, and the detection method did not consider the natural background value. In view of the above issues, background measurement and an improved detection tool was developed and validated through testing and verification, which can effectively speed up the leakage detection and simplify the operation. The operating personal dose was also reduced. The improved detection tool can be applied to the leakage detection of the cover for exhaust and drain hole of NAC-STC spent fuel transport container which is used domestically.
    Study on operational intervention level for HPR1000
    LIU Yun, LONG Liang, XING Ji, CUI Hao, HUANG Shuming, XUE Na, QIU Lin
    RADIATION PROTECTION. 2022, 42(5):  460-466. 
    Abstract ( 24 )   PDF (3990KB) ( 12 )  
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    The development of operational intervention level (OIL) is important in emergency preparedness for nuclear power plants. In order to meet the requirement of international nuclear emergency management, the OILs for HPR1000 are calculated and studied based on the latest OIL derivation methodology of the International Atomic Energy Agency (IAEA). The level two probabilistic safety analysis (PSA) severe accident source terms of HPR1000 are used, and the applicability of OIL default values of IAEA are analyzed. The results showed that the values of OIL2γ dose rate of HPR1000 within the first 10 days after the reactor shutdown are as low as 60 μSv/h, which is 3/5 of the default value of IAEA. Other OILs of HPR1000 are within the range of the default values of IAEA. The setting value of OIL2γ less than 60 μSv/h within the first 10 days after reactor is recommended, the setting value of OIL4γ dose rate should be 1-4 μSv/h according to the natural radioactive background at the site and the nature of the characteristics of monitoring instrument, and the other OILs should be set as the default values of IAEA.
    Study on emergency management of near surface disposal facilities for radioactive waste
    CUI Hao, CHEN Peng, YANG Duanjie, LI Bing
    RADIATION PROTECTION. 2022, 42(5):  467-472. 
    Abstract ( 22 )   PDF (1034KB) ( 11 )  
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    Near surface disposal facilities for radioactive waste are some kind of radioactive waste disposal facilities. According to the Nuclear Safety Law of the People’s Republic of China, radioactive accidents in such facilities belong to the category of nuclear accidents. Considering that such accidents have the characteristics of radiation accidents, it is recommended that the on-site emergency plan be prepared with reference to the emergency plan for nuclear accidents of nuclear facilities, in which the emergency system is managed according to nuclear accidents of nuclear facilities, such as emergency organization system, emergency reporting system, emergency facilities, etc. However, the principle of classification of radiation accidents is recommended in the accidents emergency classification of near surface disposal facilities for radioactive waste.
    Experience and practice of emergency management system at Fuqing nuclear power plant
    JIN Li, GU Jian, HUANG Hong
    RADIATION PROTECTION. 2022, 42(5):  473-480. 
    Abstract ( 25 )   PDF (2877KB) ( 14 )  
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    Based on the current situation and challenges on the capacity building of nuclear emergency management, and in line with the idea “one benchmark, two main lines, taking one part leading the whole, whole, and full participation”, the nuclear emergency management system has been established by FQ NPP. Its capacity building activities could provide experience for peer professionals to improve mutually.
    Analysis on nuclear emergency management and technical support systems in Russia
    SUN Zhigang
    RADIATION PROTECTION. 2022, 42(5):  481-490. 
    Abstract ( 30 )   PDF (10700KB) ( 195 )  
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    With the steady development of nuclear power, Russia has gradually established a complete, fully functional and highly efficient national nuclear emergency response system which is well integrated with national emergency management system in Russia. The vertical management model in Russia could provide good reference for the emergency management in China. This paper describes the nuclear emergency management system in Russia, and conducts a preliminary analysis on technical support systems of nuclear emergency. Finally, the inspiration and reference for the establishment and development of nuclear emergency response technology in China are analyzed from several aspects of emergency management system, including pre-warning and monitoring system, information and resource sharing as well as capacity building of technological system.
    Analysis of transboundary emergency of the 5 MWe graphite reactor in Yongbyon
    YU Hong, LIU Ting, CHENG Shisi, LI Lan
    RADIATION PROTECTION. 2022, 42(5):  491-494. 
    Abstract ( 20 )   PDF (2836KB) ( 10 )  
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    There is a 5 MWe graphite reactor in operation in Yongbyon, North Korea. In case of a nuclear accident, China could have to take emergency response actions as a result of possible radioactive materials released into environment due to the accident, which requires China to make appropriate emergency preparedness. Transboundary emergency of the 5 MWe graphite reactor in Yongbyon is analyzed from two aspects based on limited information: international planning zone and distance, and transboundary emergency practices of Chernobyl nuclear accident. The analysis result shows that it is unlikely that China's territory is within emergency planning zones and distances of the 5 MWe graphite reactor in Yongbyon. China's emergency preparedness for transnational emergency due to its nuclear accident should focuse on local food and trade restrictions.
    Relationship between two standard positions of mammography and breast compression thickness and average glandular dose in breast cancer screening
    LI Lingling, QIAN Yinfeng, WANG Tao, LI Li
    RADIATION PROTECTION. 2022, 42(5):  495-500. 
    Abstract ( 37 )   PDF (2657KB) ( 19 )  
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    In order to optimize the application of mammography in breast cancer screening, we retrospectively analyzed 132 patients with 139 lesions who underwent mammography and breast color doppler ultrasonography in our hospital, and obtained pathological results(CC), medial lateral oblique view (MLO), breast compression thickness, breast density and the average glandular dose (AGD) received by the subjects, and the detection of lesions in two positions.The results showed that: (1) Both breast compression thickness and breast density were independent influencing factors of AGD, and were positively correlated; and the influence of breast compression thickness on AGD was greater than that of breast density. (2) The exposure parameters tube voltage and tube current tended to increase with the increase of breast compression thickness, resulting in the increase of AGD. (3) No specific pattern was found in the compression thickness and AGD of CC and MLO in the same breast, but the mean ± standard deviation at CC position was (2.49±0.84) which is greater than that of MLO position (2.27±0.81), and MLO was more prone to display lesions than CC. MLO combined with breast color Doppler ultrasound examination has great advantages, which not only ensures the need for diagnosis, but also reduces the AGD value of the subject. Moreover, the greater the thickness of breast compression and the density of the subject, the more the AGD decreases.