Table of Content

20 October 2023 Volume 43 Issue 5

  

Ariticles

Evaluation of Shielding Scheme for Gamma Irradiation Facilities

Tao Youzhi, Zhao Hong

RADIATION PROTECTION BULLETIN. 2023, 43(5):  1-10. 

Abstract ( 38 )   PDF (6615KB) ( 19 )  

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Based on 《Radiation protection and safety regulations for Gamma irradiation facilities》, a detailed quantitative calculation and analysis were carried out for the different radiation paths of the typical gamma irradiation facilities in the source up-state, in order to verify the reliability of the shield design. Radiation dose rates of different radiation paths were compared, and the optimization of the shield calculation and design suggestions were put forward. The results show that: ① the design scheme of the typical gamma irradiation facilities meets the requirements of radiation shielding; ② During the shielding calculation, the contribution of sky back scattering dose rate outside the shielding is greater than that of direct radiation, and the contribution of scattered radiation dose rate at the entrance of the labyrinth is greater than that of direct radiation; ③ Considering the large work load at gamma irradiation facilities, and follow the optimization principle of radiation protection: in the shielding design process the contribution of a scattering radiation dose rate should be considered; and if necessary, some local thickening should be added; for the scattering design the scattering number should be more than 5 times; the roof area is not recommended for long term personnel residencet.

A Study on the Effects of Dose, Layer Thickness,and Radiation Quality on the Low Contrast Detectability of CT Images

Zhao Xipeng, Wang Jiaying, Xiong Qiang, Tong Linquan

RADIATION PROTECTION BULLETIN. 2023, 43(5):  11-17. 

Abstract ( 30 )   PDF (21615KB) ( 14 )  

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On the premise of keeping other parameters or conditions unchanged, the effects of scanning dose, layer thickness, and tube voltage on the low contrast detectability of CT images were studied. This study will provide data support for testing and standard revision of standardized CT equipment quality control. The results of this study suggests that when detecting the low contrast detectability of CT equipment, the CTDI_w should be as close as possible to 50 mGy, and the minimum should not be less than 40 mGy; 10 mm layer thickness should be selected, and the minimum should not be less than 5 mm; The voltage of a single tube is not significant for the detection results, and clinical commonly used tube voltages above 100 kV can be selected.

Reconstruction of 3D Radiation Field Based on Geostatistical Spatial Interpolation

Long Zeyu, Song Peitao, Feng Qingliang, Li Hua, Wei Jiafu, Liu Ruiwen, Niu Jinbo

RADIATION PROTECTION BULLETIN. 2023, 43(5):  18-24. 

Abstract ( 23 )   PDF (3549KB) ( 23 )  

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In this paper, according to the spatial auto-correlation characteristics of radiation field, the general Kriging method in geo-statistical spatial interpolation combined with logarithmic transformation is used to reconstruct the radiation field under the condition of unknown radioactive source. The method is tested through two measured radiation field data sets. The results show that when the Exponential model or Spherical model is selected for semi-variance fitting and the measuring points are selected randomly, the mean deviation of the of the reconstructed result ranges from 21.51% to 74.01%, which proves that the method is effective and feasible in practical application. In addition, the relationship between the distribution of measuring points and the accuracy of reconstructed radiation field is preliminarily analyzed and studied, and the selection scheme that the distribution of measuring points should be as uniform as possible is determined.

Management

Status and Recommendations on the Documentation of Environmental Impact Assessment for Nuclear Technology Application Facilities in Guangdong Province

Dai Jiacheng, Xia Keying, Ren Rong, Liang Sihua, Yue Yu

RADIATION PROTECTION BULLETIN. 2023, 43(5):  25-28. 

Abstract ( 25 )   PDF (600KB) ( 18 )  

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This paper introduces the current status of document preparation for environmental impact assessment for nuclear technology application facilities in Guangdong Province. The major issues at present are analyzed. Recommendations on how to improve technical standards and normative documents, to enhance the supervision and management of the environmental impact assessment preparation agency are put forward. All of which will help to improve the quality of the documents′ preparation and lessen the workload associated with getting them approved by the relevant authorities responsible for environmental protection.

Experiences

Robustness Analysis and Application of Methods for Estimating the Background Value and Anomaly Threshold of Radon Concentration in Urban Soil Based on Different Survey Scales

Ma Tingting, Que Zesheng

RADIATION PROTECTION BULLETIN. 2023, 43(5):  29-34. 

Abstract ( 19 )   PDF (3623KB) ( 21 )  

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The background value and anomaly threshold of soil radon concentration in the investigation area were calculated by using four methods which include: traditional statistical method, distribution form test method, exploratory data analysis method and median absolute dispersion method. The robustness of the four methods was analyzed. Finally the soil radon concentration level in the investigation area was calculated. The results showed that the soil radon samples in the whole investigation area obeyed an approximate lognormal distribution. The median absolute dispersion method had good robustness in measuring the background value and anomaly threshold of soil radon concentration. The background value of soil radon concentration in the whole region was 9 132 Bq/m³, and the anomaly threshold was 13 497 Bq/m³.

Analysis and Discussion on International Intercomparison of Simulated Aerosol Filter γ-Spectrometry

Li Bin, Xu Zheting, He-Yu Zhenghan, Wang Xingang, Gong Chuande

RADIATION PROTECTION BULLETIN. 2023, 43(5):  35-39. 

Abstract ( 27 )   PDF (3280KB) ( 19 )  

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Employing self-made radioactive reference source and LabSOCS (Laboratory Sourceless Calibration Software), the radioactivity of ¹³⁴Cs and ¹³⁷Cs of three simulated aerosol filters for IAEA intercomparison were determined by γ-spectrometry in 2019. The relative deviations between the measured results and the IAEA reference values were less than 4%. The coincidence summing correction factors for the five full-energy-peaks with high emission probability of ¹³⁴Cs were from 0.729 to 0.829. Ignoring coincidence summing correction in near geometry configuration may result in a deviation of more than 20%. The detection efficiency was significantly affected by the distance between the sample and the detector. This study can be applied for aerosol filter measurement of airborne effluent from nuclear power plants.

Reports

Research and Development of Online Radiation Monitoring System for Emergency Command Center of Nuclear Power Plants

An Shifeng, Yang Jingping, Sun Bo, Xu Yaoyao

RADIATION PROTECTION BULLETIN. 2023, 43(5):  40-43. 

Abstract ( 21 )   PDF (7467KB) ( 16 )  

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The emergency command center is the pivot of command, management and coordination for emergency response of nuclear power plant operators. Radiation monitoring in the relevant area is an important means to judge whether the emergency command center is habitable. The online real-time monitoring of relevant radiation monitoring data is realized by integrating the γ dose rate monitoring system, personal dose management system, and air pollution monitoring equipment operation measurement data in the preset area. The alarm setting value can be set to provide early warning information for the activation of radiation protection measures during the emergency period. At the same time, the statistical analysis of the stored monitoring data can provide a reference for the formulation of radiation protection measures under the emergency state.