RADIATION PROTECTION

Protection of public exposure in nuclear and radiological emergency exposure situation

Li Bing, Yang Duanjie, Wu Deqiang

RADIATION PROTECTION. 2017, 37(2): 81-86.

Abstract ( 51 )

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Following the new recommendations of the ICRP Publication 103, IAEA has superseded the International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources (IAEA Safety Series No. 115, 1996) with the Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards (IAEA Safety Standards Series No. GSR Part3, 2014). Major revisions have been made for the protection of public exposure in nuclear and radiological emergency situations in the new IAEA safety standard. Issues concerning the application of IAEA GSR Part3 are discussed.

Development of energy compensated high pressure ionization chamber as standard dosimeter for metrological verification

Gao Fei, Xiao Xuefu, Ni Ning, Hou Jinbing, Song Mingzhe

RADIATION PROTECTION. 2017, 37(2): 87-93.

Abstract ( 35 )

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In the ionizing radiation metrology work, the measurement results of the standard dosimeters are transferred to working metrological instruments through verification in order to achieve a unified unit and accurate and reliable quantity value. Due to low environmental gamma ray dose rate, the common PTW-UNIDOS series standard dosimeter can not meet the requirements for verification. An energy compensated high pressure ionization chamber was developed for this feature. The response characteristics of high pressure ionization chamber for X ray, gamma ray and cosmic ray were simulated using Monte Carlo method. Test results showed that the response deviation within the energy range of 87 keV—1.25 MeV for the ¹³⁷Cs gamma ray was less than 6% when the dose rate was about 30 μGy/h, the deviation in cosmic rays and ¹³⁷Cs gamma ray response was less than 10%, relative intrinsic error was -3% in the dose rate range of 0.5 μGy/h—1 mGy/h, the repeatability was 0.7% when the dose rate was 0.5 μGy/h, and the uncertainty of the calibration factor was 4% (k=2). The energy compensated high pressure ionization chamber can be used as a standard dosimeter in calibration and verification at environmental levels.

Monte Carlo simulation on optimal design of neutron shielding for Am-Be source

Wu He, Zhang Feng, Li Yafen, Han Zhongyue, Gu Mingxiang

RADIATION PROTECTION. 2017, 37(2): 94-99.

Abstract ( 103 )

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Hydrogen-rich material is currently used as shielding material in the conventional container of ²⁴¹Am-Be neutron source, which causes the protective bucket large size, low efficiency and difficult to transport to well logging field. In this work, two different shielding materials are determined. And Monte Carlo simulation method is employed to optimize the thickness and combination mode of that filling material. Results show that the optimal volume and weight of protective tank is 0.187 m³ and 430 kg, respectively. Particularly, 13 centimeters thick tungsten is select as the inner shielding layer and 18 cm thick boron polyethylene is chosen for thermal neutron-absorbent as the outer layer, and the radiation levels of concerned location is evaluated using MCNP code. It can be conclude that the dose rate of the outside is less than 0.025 mSv·h^-1, which meet the requirement of relevant standards.

Estimation of air contamination in EPR reactor building

Ren Xueming, Li Xiaoning

RADIATION PROTECTION. 2017, 37(2): 100-107.

Abstract ( 48 )

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The method for estimating the air contamination conditions in EPR reactor building during power operation and shutdown is described, and a model for estimation of the H-3 activity concentration is established. Air contamination levels in the equipment room and the work room of reactor building during the power operation and shutdown are evaluated. The results show that H-3 is the main contributor for air contamination in reactor building during the shutdown with a concentration in air of about 0.07 DAC, which could cause a collective dose of about 56 man·mSv in a typical outage

Evacuation time estimation (ETE) in case of an emergency at Fuqing nuclear power plant

Li Wenting, Hou Jie, Gao Jianwei, Wang Ruiying, Lin Quanyi, Yang Ling

RADIATION PROTECTION. 2017, 37(2): 108-115.

Abstract ( 62 )

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A system of virtue reality simulation on emergency evacuation around nuclear power plant is described. We simulated the evacuation process under different scenarios through modeling the influences of population distribution, human behavior, traffic infrastructure and weather condition of the Fuqing nuclear power plant. Major influencing factors on evacuation time were analyzed using the evacuation simulation system. The results indicated that congested roads play an important role in emergency evacuation time under typical accident scenarios. Meanwhile, the increasing fraction of private car usage would also increase the evacuation time.

Method for measuring the activity of ¹⁵²Eu, ¹³³Ba and ⁶⁰Co with γ ray cascade by HPGe spectrometer

Du Yunwu

RADIATION PROTECTION. 2017, 37(2): 116-120.

Abstract ( 62 )

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A practical method for measurement of cascade gamma radiation nuclide by HPGe gamma spectrometer is given. A certain thickness water absorption layer is placed between the detector and the sample, which can reduce the detection efficiency and reduce the effect of the cascade gamma coincidence effect. Experiments showed that the detection efficiency and activity relative deviation of ¹³³Ba, ⁶⁰Co and ¹⁵²Eu radionuclide in TC-45 samples are followed by exponential decay with the increase of the water absorption layer thickness. When the thickness is increased to 70 mm, the relative deviation of measurement is less than 4%.

Preliminary study on outfall design and environmental impact assessment of liquid effluents in inland nuclear power plants

Qin Chunli, Zhang Ailing, Shangguan Zhihong, Zhang Kun

RADIATION PROTECTION. 2017, 37(2): 121-125.

Abstract ( 53 )

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The outfall engineering of inland nuclear power plants (NPPs) in United States is summarized. In accordance with Regulation GB 6249—2011 (Regulations for environmental radiation protection of nuclear power plant), considering high standards for tritium discharge to receiving water in China, the outfall design of liquid effluents from China inland NPP and its environmental impact simulation are summarized. Recommendations on the diffuser system in China inland NPPs are given.

Inter-comparison among analytical laboratories for measurements of radionuclides in soil and water samples

Li Zhou, Li Pengxiang, Zhang Jing, Gao Zequan, Wang Ruijun, Bao Li, Jiang Kai, Song Qinnan, Yang Yuxuan, Li Yuan

RADIATION PROTECTION. 2017, 37(2): 126-130.

Abstract ( 34 )

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Inter-comparison among analytical laboratories for measurements of radionuclides in soil and water samples is described in this article. Inter-comparison media included spiked soil, real soil, and spiked water. Determination of ⁹⁰Sr, ⁶⁰Co, ¹³⁴Cs, and ¹³⁷Cs for spiked soil, ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K, ⁹⁰Sr, and ¹³⁷Cs for real soil, and ³H, ⁹⁰Sr, ⁶⁰Co, ¹³⁴Cs, and ¹³⁷Cs for spiked water were carried out. Eleven laboratories participated in this inter-comparison, and the result of inter-comparison was fine. Key problems found during the inter-comparison are summarized and some suggestions are put forward for future inter-comparison activities.

Estimation and validation of radiation dose to patients subjected to high-pitch and standard-pitch CCTA using Monte Carlo software

Liu Xiao, Zeng Yongming, Yu Rengqiang, Wang Jie, Sun Jingkun

RADIATION PROTECTION. 2017, 37(2): 131-137.

Abstract ( 72 )

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The distribution characteristics of radiation dose of Coronary Computed Tomography Angiography (CCTA) with high-pitch and standard-pitch is studied using Monte Carlo simulation. The data from 61 patients subjected to high-pitch CCTA using the dual source CT scanner were collected and divided into 3 groups according to the BMI classification for Asians recommended by WHO: normal group (12 cases), overweight group (41 cases) and obese group (8 cases). Organ dose and effective dose (E) of the three groups with high-pitch and standard-pitch CCTA were calculated using Monte Carlo software. In high-pitch mode, the effective dose values calculated by Monte Carlo software were compared with the direct data readings from the CT equipment. The results showed that the organ dose of high-pitch CCTA calculated by the Monte Carlo software was about 70% lower than that of standard-pitch CCTA on the dual source spiral CT. The most significant reductions in organ doses were found for heart and thymus, which have decreased by about 80%. For all the 3 groups, the effective doses of high-pitch CCTA were significantly lower than those of the standard-pitch CCTA (p<0.05), and the most obvious reduction in E was found in patients of the normal group subjected to the high-pitch CCTA. In high-pitch mode, deviation in E between the Monte Carlo simulation and the reading of the CT device was less than 50%. This suggested that, as a new clinical calculation method for radiation dose, Monte Carlo simulation can be used for prediction or retrospective analysis of the distribution of organ dose and E in CCTA. It is also indicated that the chest organ dose and effective dose can be significantly reduced with the high-pitch CCTA, and this will subsequently decrease the radiation risk, especially for the subjects of smaller BMI (such as children). This study has a potential for practical applications in development of low dose CT technology.

Study on toxicity of low dose γ radiation to Qinghai Vibrio Q67

Zhao Weichao, Hu Nan, Ding Dexin, Long Dingxin, He Shuya, Li Le, Hu Miao, Feng Yongfu

RADIATION PROTECTION. 2017, 37(2): 138-144.

Abstract ( 45 )

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The effects of low dose and ultra-low dose γ radiation on luminous intensity and optical density (OD₆₀₀) of Qinghai Vibrio Q67 were studied using biological irradiator and simulated uranium irradiation chamber as γ radiation source. The results showed that the luminous intensity inhibition rates of Qinghai Vibrio Q67 were no significant difference when the cumulative radiation dose varied within a certain range at a dose rate of 5.5 cGy/min. Once over the dose threshold value in this range, there was a positive correlation between the luminous intensity inhibition rate and the cumulative radiation dose. Moreover, Qinhai Vibrio Q67 irradiating with 320 mGy cumulative radiation dose at three different irradiated dose of 5.5, 14 and 51 cGy/min, it was found that its luminous intensity inhibition rate increased on the condition of low dose rate and long time γ ray radiation. Qinhai Vibrio Q67 irradiated with γ rays at ultra low dose rate for long time the inhibition rate of the OD₆₀₀ value reached the maximum at 24 h, and then reduced gradually. The hormesis of Qinghai Vibrio Q67 occurred with γ dose rates both at 30 and at 120 μGy/h. It was feasible to establish biological early warning method by calculating the inhibition rate of luminous intensity and OD₆₀₀ values of Qinghai Vibrio Q67 in low dose and ultra-low dose γ irradiation.

Controlled synthesis of amidoxime polymer materials and its absorption of Uranium

Gong Ziyue, Chi Fangting, Wei Guilin, Zhang Shuo, An Peng

RADIATION PROTECTION. 2017, 37(2): 145-152.

Abstract ( 47 )

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The divinylbenzene (DVB) and vinylbenzyl chloride (VBC) were used as raw materials, then the Atom Transfer Radical Polymerization (ATRP) method was used to graft acrylonitrile, finally, polyacrylonitrile powder reacted with aqueous hydrochloric acid hydroxylamine to prepare amidoxime ploymer materials. Using fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) techniques, the chemical compositions and microstructure of the absorbent were analyzed. The effects of pH values of initial uranyl ion and different ratios of absorbent to uranyl ion on the absorption were studied. The results showed that the best absorption efficiency occurred when the ratio of absorbent to uranyl ion was 2∶1. The absorption capacity can reach to 24.2 mg/g when the pH value was 4 at this ratio. Furthermore, the kinetic data can be well fitted with the second-order absorption kinetic model.

Progress of patient size-specific dose estimation in CT examinations

Liang Baohui, Chen Zhi, Xu Xie

RADIATION PROTECTION. 2017, 37(2): 153-160.

Abstract ( 54 )

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American Association of Physicists in Medicine (AAPM) have published Reports 204 and 220 about size-specific dose estimation (SSDE) in CT examinations in 2011 and 2014, respectively. Antero-posterior dimension (APD) and lateral dimension (LD) have been used to represent the size of patient in Report 204, while Report 220 has used water-equivalent diameter to estimate the SSDE. In recent years, many papers on thorough SSDE studies have been published. In this review, we introduced the main contents of the two Reports, followed by an overview of the applications of SSDE in CT radiation protection, such as establishment of diagnostic reference levels of CT examinations, evaluation of image quality of CT, estimation of organ dose and effective dose of the patients, which can be adopted in the research and applications of SSDE in China.

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