RADIATION PROTECTION

Research status and prospects of microdose experimental measurement technology based on SOI

YAN Xuewen, LI Hua, LI Deyuan, LI Hui, NIU Mengqing, QIAO Pei

RADIATION PROTECTION. 2022, 42(1): 1-10.

Abstract ( 220 )

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The characteristics and research status of the tissue equivalent proportional counter (TEPC) and the microdosimeter based on silicon-on-insulator (SOI) technology were analyzed. Based on the present technique, the performance of TEPC and SOI was compared, and the shortages of TEPC in the experimental measurement of microdose were pointed out. Several physical structures of the fifth generation SOI microdosimeter were explained in detail. Moreover, the research status for neutron, proton and heavy ion microdose and tissue equivalence were also analyzed. The problems of SOI microdose measurement technology were pointed out, and its development prospects were outlined.

Research progress on influencing factors of radon exhalation in granite

LONG Shuqin, XIE Yanshi, TAN Kaixuan, ZHANG Minghua, SHAN Jian, WANG Sheng

RADIATION PROTECTION. 2022, 42(1): 11-17.

Abstract ( 258 )

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With the deepening awareness of radon hazards, granite is a natural radiation source to which people are more often exposed in production and daily life. Granite's radon exhalation characteristics and its radiation impact on human settlements have been widely attention. In this paper, a literature review has been made for radon exhalation in granite from two aspects ofprimary properties and secondary changes of rocks. It is found that the radon exhalation of granite is relevant to the primary properties of rock chemical composition, rock mineral composition, and rock genetic type, as well as secondary factors caused by weathering and alteration such as the distribution of radionuclides, the size of mineral granules and rock micro-cracks. Researches show that there is a linear correlation between both uranium activity and radium activity and radon exhalation rate in granite, but this will be affected by the types of uranium-occurring minerals, the specific impact of mineral composition needs further study, which may be related to its structural background or material source. The effect of secondary changes on radon exhalation in granite is mainly manifested in weathering and alteration that cause radionuclides to migrate to the granule surface and rock fractures that are favorable for radon exhalation. Secondly, the granule size decreases and the specific surface area increases, and the internal surface area and pores of the rock also increase. These changes makes uranium and radium enrich and escape, which ultimately promotes the radon exhalation from the rock. Both the primary properties and secondary changes of rock play an important role in the radon exhalation in granite. Uranium and radium activity can be used as a predictor of the potential for radon exhalation rate in granite, while the mineral composition and the secondary changes of granite are important potential factors for the study of radon exhalation in granite. Therefore, it is necessary to systematically study and quantitatively describe chemical composition, mineral composition and these secondary changes, and establish a reasonable and effective rock radon exhalation model in the future, so as to more comprehensively grasp the rules of radon exhalation in the rocks, and provide a theoretical basis for radon exhalation in underground engineering and human settlements.

Study on the uranium existing form in groundwater of a uranium mining area along the Gan-Hang tectonic belt

WANG Zhe, ZHU Jianlin, ZHANG Huaisheng, ZHANG Chunyan, LI Dong

RADIATION PROTECTION. 2022, 42(1): 19-23.

Abstract ( 148 )

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To study the influence of hydrochemical properties of groundwater on the existing forms of uranium in uranium mining areas based on the analysis of chemical composition of groundwater, the mathematical statistics software SPSS 18.0 and the numerical simulation software PHREEQC with LLNL database were used to simulate and explore the groundwater hydrochemical characteristics and the existing forms of Uranium in groundwater throughout a uranium mining area along the Gan-Hang Tectonic belt. The results show that the hydrochemical types are mainly HCO₃-Na and HCO₃-Na·Ca, Uranium was positively correlated with Ca²⁺ and Mg²⁺, and moderately correlated with SO₄^2-. Aqueous Uranium in groundwater is mainly hexavalent, accounting for almost 100%. The existing forms of Uranium are mainly UO₂(CO₃)₂^2-, UO₂(CO₃)₃^4-, UO₂CO₃, UO₂(OH)₂, UO₂(OH)₃^- and UO₂OH⁺. Among them, UO₂(CO₃)₂^2- accounts for the absolute majority, followed by UO₂(CO₃)₃^4-, UO₂CO₃ and UO₂(OH)₂, and the total is mainly of a uranyl carbonate form, which corresponds to the acid-base property of groundwater in the studied area.

Determining the atmospheric diffusion parameters in a site using numerical simulation and tracer test

YANG Zongzhen, BAO Xinjie, TAO Naigui, ZHANG Xiaofeng

RADIATION PROTECTION. 2022, 42(1): 25-33.

Abstract ( 158 )

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A Weather Research and Forecasting Model (WRF) and atmospheric diffusion model (CALPUFF) have been used to numerically simulate and analyze the atmospheric diffusion parameters in coastal area of a site. Compared with the results of atmospheric tracer test, whether from value range or from distribution of diffusion factor, CALPUFF diffusion model can better reflect the local atmospheric diffusion characteristics. Compared with P-G diffusion parameters, atmospheric diffusion parameters obtained from CALPUFF model are more consistent with the general law of atmospheric diffusion. In consideration of the actual underlying surface and flow field characteristics of the site, the diffusion parameters determined by the CALPUFF numerical model which are larger than the P-G diffusion parameters and smaller than the IAEA diffusion, can more truly reflect the diffusion capacity of pollutants in the area.

Study on the leakage value of primary to secondary side of steam generator in a nuclear power plant

HE Gening, ZHOU Meiling, LAI Jianyong, LI Donghui, WU Ge, HU Yu

RADIATION PROTECTION. 2022, 42(1): 35-40.

Abstract ( 126 )

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It is of great significance to determine reasonable leakage value from primary side to secondary side of steam generator, in order to ensure safe and stable operation and to formulate the operation strategy of nuclear power plant. The leakage value is divided into three categories: the leakage value for radiation protection design, the leakage control value for nuclear power plant operation control, and the leakage protection threshold value for ensuring the integrity of steam generator heat transfer tube. The basis of various values are discussed. A comprehensive investigation and analysis on the leakage value of primary side to secondary side of steam generator in nuclear power plants from both at home and abroad has been completed. Combined with the research situation, suggestions on the value and leakage control of primary side to secondary side of steam generator in nuclear power plants in China are given.

Shielding design of radiation resistant composite material based on Monte Carlo method

BAI Hongwei, LI Da, GUO Xun, XUE Yunfei, JIN Ke

RADIATION PROTECTION. 2022, 42(1): 41-47.

Abstract ( 233 )

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Mixed low-energy neutron and γ-ray radiations may exist in the working environment of the spent fuel reprocessing plants, which threatens the health of staff. In this work, Monte Carlo simulations based on Geant4 software is applied to assist the design of composite materials, i.e., tungsten/boron fibers in the polymer substrate containing boron and bismuth, for shielding such mixed radiations by simulating the effects of various material parameters. The results show that this tungsten-boron composite material has an excellent shielding effect for both neutron and γ-ray radiations. It can be proved that the vertical arrangement of fibers has better shielding effect than parallel arrangement, since the distribution of transmission beam became more uniform when the fibers were arranged vertically. Moreover, the shielding effectiveness of this material can be further enhanced by adding bismuth into the polymer substrate. These findings can be expected to provide guidance not only for radiation protection suits, but also other relevant protective gears used in the radiation environment, such as reprocessing plants.

Methods and performance of radon reduction techniques in underground facilities

WEN Weiwei, XU Rongzheng, WU Youpeng, CHENG Jinxing, WANG Qiongbo, LI Shuai, LIU Fengguo

RADIATION PROTECTION. 2022, 42(1): 48-53.

Abstract ( 295 )

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In order to scientifically select radon reduction methods for underground facilities, typical radon reduction methods have been sorted out, and the capabilities of each radon reduction method has been evaluated through actual measurements as well as performance tests. The test results show that ventilation is a common technique to reduce radon concentration in underground facilities. With one hour ventilation at 2 m³/s for a 12 000 m³ space, about one third of radon concentration in the underground air can be reduced; While adsorption technique can reduce radon locally in areas where people are concentrated, which can reduce the radon concentration by about 55% in 80 m³ of space after working two hours; And the the sealing technique can significantly reduce radon in areas with high radon exhalation rates, with using of polyimide resin radon prevention materials, the radon resistance efficiency can be increased to more than 99.5%. Therefore, each radon reduction technique has its scope of application, advantages as well as disadvantages, and should be optimized according to the actual situation of underground facility.

Discussion on NORM exposure and management mechanism of radioactive waste

WEI Fangxin, WANG Chunli, ZHANG Yu, ZHU Zhaowen, LEI Qiang, XU Chunyan

RADIATION PROTECTION. 2022, 42(1): 54-62.

Abstract ( 168 )

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The natural radioactive level raised by development and utilization of minerals associated with radioactivity is received wide attention from all over the world. The present situation and occurred problems in the field of NORM waste management are analyzed and presented in this paper. The systematic causes for the problems are considered to be unclear responsibility, lack of financing guarantee system and poor foundation for waste disposal technology. Suggestions for strengthening the functions of regulatory body, establishing national NORM inventory list, promoting research on risk assessment and developing waste disposal demonstration project etc., are proposed for the purpose of promoting safe and proper disposal of NORM waste in China.

Preliminary study on incineration ash of uncompleted combustion by microwave treatment

WANG Peng, GAO Chao, CHU Haoran, CUI Han, ZHANG Yu, RUAN Jiasheng, XU Wei, ZHENG Bowen, LI Xiaohai

RADIATION PROTECTION. 2022, 42(1): 63-69.

Abstract ( 114 )

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Due to changes in process, equipment and feeding, there exists incomplete combustion phenomenon in the incineration ash, which does not meet the requirements of subsequent treatment and brings trouble in safety. By using microwave ashing furnace to heat the incomplete combustion ash and relatively completed combustion ash, a series of tests and characterizations of weight loss, weight loss rate and composition of incineration ash were carried out before and after heating. The feasibility and principle of microwave heating for incineration ash were studied, and the process conditions of microwave treatment were preliminarily explored. The results show that it was feasible for incineration ash by microwave heating, which could achieve the same effect as the traditional muffle furnace. The performance of microwave treatment of incineration ash was related to heating power, heating time and treatment capacity. The heating power and heating time determined the efficiency of microwave treatment of incineration ash, and the processing capacity determined the ability of microwave treatment of incineration ash. The treatment efficiency was preliminarily explored. For incineration ash with particle size under 1 mm, the treatment efficiency was roughly the same when the power was enough.

Development and preliminary test of a novel plane-parallel ionization chamber

SUN Mingyan, ZHANG Weihua, TONG Teng, LI Daowu, ZHANG Yi, HUANG Xianchao, LV Ning

RADIATION PROTECTION. 2022, 42(1): 71-78.

Abstract ( 239 )

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A plane-parallel ionization chamber for position and dose detection of proton beam is developed. The ionization chamber structure is optimized by simulating the electric field distribution, equivalent water thickness, and lateral scattering of proton beams of different energies after passing through the ionization chamber using the FEM-based Ansys simulation software and Geant4 Monte Carlo toolkit. A YXLON 450 kV X-ray tube, 6 MeV pulse accelerator and Peking University tandem accelerator were used to conduct preliminary tests on the ionization chamber. The ionization chamber operated stably, and the information of 2-D distribution of rays and the collection of dose information were accurate and the performance was good.

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