Table of Content

20 March 2015 Volume 35 Issue 2

  

Study on simulated radionuclide strontium mineralized by bacteria

Xiao Xiangzhu, Zhu Wenkun, Zhang Youkui, Mu Tao, Duan Tao, Nie Xiaoqin, Luo Xuegang

RADIATION PROTECTION. 2015, 35(2):  65-70. 

Abstract ( 11 )   PDF (1355KB) ( 0 )  

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Sr²⁺ was transformed into insoluble state to provide a reference method for dealing with radionuclide strontium. Bacillus pasteurii was cultivated with medium containing urea. Enzyme of urease was produced and urea was discomposed to CO₃^2-, which could put soluble Sr²⁺ into insoluble carbonate. The particle size and morphology of the solidifying product was characterized by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and scanning electronic microscope (SEM). Factors such as pH, temperature, inoculum concentration, incubation time, concentration of Sr²⁺ and urea on solidifying rate of Sr²⁺ was studied. It showed that the solidifying product was composed of aggregative globular SrCO₃ crystals in unequal size. The bacillus played an important role in the precipitating process. Cultivating 48 h at 30 ℃, the solidifying rate reached a peak as about 98.5% when the concentration of Sr²⁺ and urea, inoculum concentration and pH was 0.02 mol/L, 20 g/L, 6.0% and pH 8.0 respectively.

Parameter sensitivity study in the thermal analysis of the geological disposal repository of high-level waste in China

Lu Tao, Li Chang, Yang Qiuyu, Wang Xuhong, Li Tingjun, Zhang Wei

RADIATION PROTECTION. 2015, 35(2):  71-77. 

Abstract ( 10 )   PDF (1560KB) ( 0 )  

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A simplified thermal model of geological disposal repository of high-level waste (HLW) in China is generated by the numerical code FLAC3D. Sixteen key parameters having impact on the temperature field of geological disposal repository, including thermal, geometric and time parameters, are carefully selected. Peak temperature of inner surface of the bentonite, which is related to the temperature criterion for thermal design calculation of the geological disposal repository of HLW, is treated as the object temperature in the parameter sensitivity analysis. In the analysis, sensitivity degree is classified as three categories: high, medium and low. The research reveals that: 1) the following four parameters are of high sensitivity degree: conductivity of the bentonite; thickness of the bentonite; conductivity of the host rock; interim storage time of HLW. 2) thickness of heat spreader and backfill material are of intermediate sensitivity degree. 3) The rest ten parameters are of low sensitivity degree: thermal conductivity and specific heat of vitrified HLW, overpack, heat spread, backfill material, and specific heat of bentonite and host rock. Some conclusions are drawn from the analysis: in the design of geological disposal repository of HLW, accurate conductivity of bentonite and host rock should be obtained, the test results must be carefully treated to ensure the appropriate input in the design calculation; the thickness of bentonite may be reduced under the circumstances that the bentonite performs well in the engineered barrier system; more than 20 years of the interim storage time of HLW in China is estimated based on the simplified thermal model.

Transfer and concentration to marine aquatic biota for ¹⁴C released from nuclear power plants

Yang Duanjie, Li Wei, Xiong Xiaowei, Xu Haifeng

RADIATION PROTECTION. 2015, 35(2):  78-81. 

Abstract ( 8 )   PDF (1075KB) ( 0 )  

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The predominant radionuclide is ¹⁴C in the public dose assessment by liquid release pathway in Chinese coastal nuclear power plants. So, it is very critical to properly evaluate ¹⁴C concentration in aquatic biota. In this paper, based on carbon content in seawater and aquatic biota, concentration factors of ¹⁴C in aquatic biota were recommended that can be used in Chinese coastal nuclear power plants.

Radiation field study on high frequency and high voltage electron irradiation accelerator machine room

Yu Guobing, Chen Zhi, Gu Xianbao, Du Qin, Chen Le, Li Yuxiong

RADIATION PROTECTION. 2015, 35(2):  82-86. 

Abstract ( 7 )   PDF (1702KB) ( 0 )  

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By using MCNP simulation and measurement, the source terms and the influence factors to its field strength was researched for the machine hall of high frequency and high voltage electron irradiation
accelerator. The results show that the source terms in machine hall mainly come from the scattering irradiation after electrons shooting the target in radiation room. The radiation field intensity in the machine hall is determined by the sizes of the pipe hole between the machine hall and radiation room, and the thicknesses of shielding material in the pipe hole.

Study on liver proteomics of rats accumulated ¹³⁷Cs γ ray irradiation

Zuo Yahui, Dang Xuhong, Yuan Yayi, Wang Chao, Zhang Zhongxin, Liu Jiangong, Zhang Ruifeng, Duan Zhikai

RADIATION PROTECTION. 2015, 35(2):  87-92. 

Abstract ( 11 )   PDF (1420KB) ( 0 )  

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This study was designed to investigate the changes of proteomics in liver of Sprague-Dawley(SD)rats after accumulated irradiation by ¹³⁷Cs γ ray. Isobaric tags for relative and absolute quantitation (iTRAQ) was used to analyze the different protein expression in liver of irradiated rats. Thirty mature SD rats were randomly divided into three groups: 0.2 Gy group, 2 Gy group and healthy control group. Rats were irradiated at dose rate of 0.336 mGy/min for 10 days and 20 days continuously. Gene Ontology and protein-protein interaction network analysis were conducted using softwares. The results demonstrated that 2 220 protein spots were identified. 122 proteins were differentially expressed both in two groups compared with control, of which 52 were up-regulated and 70 down-regulated. Based on the information of GO categories,these differentially expressed proteins mainly located in the cytoplasm and membrane,involving in the function of protein binding and catalytic activity. Analysis with the PAJEK software demonstrated that those 16 differentially expressed proteins could form a complicated interaction network where SF3B1, ATP6V1C1 might be key nodes.

Research on nuclide natural background correction and detection sensitivity of continuous monitoring of alpha aerosols

Huang Xianguo, Xia Wenyou, Tu Jun, Su Rongbo, Lu Chuanxia, Wu Zhongyi

RADIATION PROTECTION. 2015, 35(2):  93-96. 

Abstract ( 6 )   PDF (1389KB) ( 0 )  

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This research addresses problems in conducting continuous monitoring of α aerosols at decommissioning sites.According to the theoretical analysis and experiment results, the method of nuclide natural background compensation was used, realized the spectrum forword trailing compensating of natural background.The compensating efficiency is greater than 90%.An α aerosols continuous monitoring system was set up using natural background correction technology and the differentiated particle size sampling technology. The detection sensitivity for Pu aerosols in 25 minute is 0.02 Bq·m^-3 when the concentration of radon thorium progeny is 100 Bq·m^-3.

Discussion on volume reduction treatment of disused drying agents from heavy water vapor recovery system

Guo Xiliang, Xiong Kouhong, Yang Weibing, Gao Chao, Xiong Xiaowei, Jia Meilan, Li Houwen, An Hongxiang

RADIATION PROTECTION. 2015, 35(2):  97-103. 

Abstract ( 9 )   PDF (2005KB) ( 0 )  

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Based on the minimization principle of radioactive waste management, two treatment methods ware discussed for disused drying agents from heavy water vapor recovery system, detritiation and mixed solidification. The detritiation solution can be applied when the drying agents are rendered, to be compliance with clearance levels. Otherwise mixed solidification should be used. Preliminary test results show that high temperature heating and microwave treatment are applicable for detritiation; the mixed solidification of drying agents and boroned concentrate is feasible.

Design and construction of a multi-pass test stand for filtration performance evaluation of nuclear-grade water filter element

Shen Dapeng, Qiu Dangui, Shi Yingxia, Liu Qun, Hou Jianrong, Kong Haixia, Wang Ruiyun, Liu Xianli

RADIATION PROTECTION. 2015, 35(2):  104-111. 

Abstract ( 7 )   PDF (1542KB) ( 0 )  

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The design and the selection of main equipment and instruments of the multi-pass test stand in evaluating filtration performance of a nuclear-grade water filter element were discribed. Some conclusions were obtained through performance tests: the maximum water flux of 4.0 m³/h for the standard filter element, and the maximum fracture strength of 0.4 MPa both meets the test requirements; particle distribution of the test system is uniform and stable, which basically meet the deviation of within ±15% between the given particle size number of each sampling interval and the average value; for the contamination impouring test, the weight contamination degree of each sample and the average value is controlled within ±5%, and the deviation between the average value and theoretical value is less than ±10%, and the deviation between the average impouring flow rate and the predetermined impouring flow rate is within ≤5%.

Research status on activated carbon absorption of radioactive noble gases and their influencing factors

Li Yongguo, Liang Fei, Zhang Yuan, Hou Jianrong, Chen Jianli, Liu Yu, Hu Bo, Zhang Jirong, Qiao Taifei, Zhang Qun

RADIATION PROTECTION. 2015, 35(2):  112-116. 

Abstract ( 7 )   PDF (1614KB) ( 0 )  

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The gaseous radioactive waste processing systems in different types of reactor nuclear power plant were investigated. Influencing factors with the activated carbon absorption of noble gases and the feasibility of activated carbon performance test were then discussed. Dynamic absorption coefficient increases with the rise of system pressure and decreases with the rise of temperature and relative humidity. The influence of flow rate in a certain range, ratio of length and diameter, noble gas, CO₂, Freon, methane concentration are neglectable. The sampling method may be used in performance test of carbon delay system.

Environment monitoring and evaluation to a mobile roof type X-ray flaw detection room

Li Qing, Ma Junjian, Liu Wei, Chen Qingfeng, Gao Xinguo, Zhao Lingxi, Zhang Jing, Ding Shigang

RADIATION PROTECTION. 2015, 35(2):  117-122. 

Abstract ( 8 )   PDF (1317KB) ( 0 )  

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A 451P Ion Chamber Survey Meter was used to monitor the surrounding radiation environment of a mobile roof type X-ray flaw detection room while the industrial X-ray flaw detection machine running in the detection room. The results show that the monitoring values on both sides of the exposure chamber door exceed the standard values, while the remaining monitoring sites values (0.15—0.37 μGy/h) can meet the limit requirement of 2.5 μGy/h. The shield of the exposure chamber door was calculated accordingly with improvement suggestions proposed then. The monitoring values of the door after rectification meet the limit requirement. Estimation was also made to the potential annual effective doses for the workers and the public.

Evaluation of soil natural radioactive level in Maoniuping REE deposit

Zhang Cong, Shi Zeming, Kan Zezhong, Yang Weihe, Zhang Junji, Wei Fei

RADIATION PROTECTION. 2015, 35(2):  123-128. 

Abstract ( 8 )   PDF (1939KB) ( 0 )  

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The natural radioactivities of radionuclides in the soil of Maoniuping REE deposit were measured using gamma ray spectroscopy with its internal and external exposure index, γ exposure rate and γ external exposure effective dose calculated accordingly and then compared with that of the Baiyun Obo rare earth mining area and Xiazhuang uranium ore field in Guangdong. Results show that the main value of γ exposure rate (177.16 Gy/h) is higher than the national reference value (81.50 nGy/h), international reference value (80.00 nGy/h), Baiyun Obo rare earth mining area reference value (120.00 nGy/h) and Xiazhuang uranium ore field reference value (124.00 nGy/h)in Guangdong as well. The natural radioactivity level of study area still lies within normal range because its internal and external exposure index, γ exposure rate and gamma external exposure effective dose are within the national referenced range. Rare earth mining contributes to the higher soil natural radioactivity level of the study area; Large area exposed in Triassic crown west granite rock mass in the study area also leads to a higher natural radioactivity level of soil than Baiyun Obo rare earth mining area and Xiazhuang uranium ore field in Guangdong.