RADIATION PROTECTION

Main challenges for the application of the ICRP recommendations: Recent and future developments

Thierry Schneider

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

Abstract ( 98 )

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Following the publication of the general recommendations of the International Commission on Radiological Protection (ICRP) in 2007, several developments have been made to address the challenges associated with the implementation of these recommendations into practice. Notably, the introduction of the three types of exposure situations (i.e. planned, existing and emergency exposure situations) for managing the radiological protection has led to further investigate their application in several domains such as industrial activities involving naturally occurring radioactive materials and emergency and recovery situations following a nuclear accident. This paper highlights the main issues addressed in some recent publications and on-going with a focus on the development related to the ethical foundations of the radiological protection system, the application of the radiological protection system for managing existing exposure situations and the integration of the environmental radiological protection in the ICRP system of protection. Finally, the aims of the new Task Groups set up in 2022 related to the application of the radiological protection system are presented.

ICRU Report 95: Operational quantities and consequences for dosimetry

Hans Menzel, Thomas Otto

RADIATION PROTECTION. 2023, 43(1): 11-16.

Abstract ( 174 )

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The International Commission on Radiological Protection (ICRP) introduced so-called protection quantities. The most used protection quantity, the effective dose E, serves to set exposure limits and is used in operational radiation protection to implement the optimization principle.Effective dose, however, is not a measurable quantity. That is the reason why the International Commission on Radiation Units and Measurements (ICRU) introduced measurable (operational) quantities for dosimetry of external radiation to provide acceptable estimates of effective dose.Presently used operational quantities were defined in the 1980s, when nuclear industry was the predominant concern of occupational radiation protection. In other radiation fields, in particular for high-energy radiations, shortcomings of today’s operational quantities became evident: the effective dose can be either over- or underestimated.Based on a comprehensive study, ICRU and ICRP have now introduced new operational quantities for the dosimetry of external radiation to overcome these shortcomings. The new definition of operational quantities is more closely related to the definition of protection quantities including the effective dose, in particular by using the same anthropomorphic phantom. The proposed operational quantities simplify the system of radiation protection quantities—by reducing the difference in the definitions of protection and operational quantities—and provide in general an improved estimate of effective dose. The consequences of introducing new operational quantities on practical dosimetry are discussed in the paper.

Solubility of typical PGMs in HLLW glass and influence of PGMs on the properties of HLLW glass

LU Jiawei, LIN Peng, LI Lili, ZHAO Xing, WANG Yi, WENG Hanqin, LIN Mingzhang

RADIATION PROTECTION. 2023, 43(1): 17-30.

Abstract ( 99 )

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This paper mainly summarized the chemical behaviors (the content and the existing form) of precious metals (PGMs) in high-level liquid radioactive waste (HLLW) and the solubility, the existing form and the granularity of PGMs in HLLW glass. At the same time, the influence of PGMs on the properties of HLLW glass (rheology, viscosity, thermal conductivity and resistance) was summarized. The results were expected to provide a research basis for the solubility, the chemical behavior and sediment mechanism of typical PGMs in HLLW glass. Besides, The results were hopeful to provide a theoretical basis for studying the influence of typical PGMs on the properties of HLLW glass.

Counting rate correcting method of gamma spectrum based on Digital Multichannel Analyzer

CHEN Chen, WU Huan

RADIATION PROTECTION. 2023, 43(1): 31-37.

Abstract ( 102 )

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Affected by the dead-time, the Digital Multichannel Analyzer (DMCA) which receives gamma spectrum will occur counting rate loss. This effect will bring some errors to γ spectrum analysis. Therefore it is necessary to correct the gamma spectrum with counting rate loss. Based on the dead-time model of Digital Multichannel Analyzer, Lambert W function is used to establish the closed form solution of real counting rate relative to the measured counting rate. Then the definition of counting rate limit of DMCA and the theoretical calculation of the optimal threshold of the dead time of the fast channel are proposed, and the pulse signal detected by fast channel is used as the basis of counting rate correction. Based on this basis, a method for correcting the counting rate of gamma spectrum is proposed. Experimental results show that this method can correct the counting rate loss effectively;Within the range of counting rate less than 1.8 Mcps of DMCA [using LaBr₃(Ce) detector], the relative inherent error of the net counting rate at the corrected characteristic peak is less than 9%, and the linear correlation coefficient between the net counting rate at the characteristic peak and the doserate was above 0.995, which broadens the application range of Digital Multichannel Analyzer.

Design and development of a variable angular resolution gamma camera based on LaBr₃(Ce) crystal-coupled SiPM array

SHI Boxuan, LI Yan, CAO Qinjian, ZHAO Yuan, XIA Sanqiang, WANG Chongyang, LIU Liye

RADIATION PROTECTION. 2023, 43(1): 38-46.

Abstract ( 93 )

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Coded aperture imaging technology is widely used in nuclear safety, nuclear facility decontamination and decommissioning measurement as well as nuclear medicine due to its advantages of high detection efficiency, high signal-to-noise ratio, good angular resolution, and stable and reliable imaging quality. Aiming at the problems of the fixed imaging field of view and angular resolution of the traditional coded aperture gamma imaging system, a gamma imaging system with variable angular resolution is proposed by changing the distance between the coded collimator and the detector. The imaging system is mainly composed of coded collimator, position sensitive detector (PSD), data acquisition card and image reconstruction system. The coded collimator of the imaging system adopts the Modified Uniformly Redundant Array (MURA) coded method. In order to ensure the detection ability of higher energy rays, the material of the coding collimator adopts tungsten copper alloy with 90% tungsten content. The PSD is composed of LaBr₃(Ce) crystal coupled SiPM array, and the reconstruction algorithm adopts the direct convolution algorithm which is fast and efficient. The test results show that the average energy resolution of the PSD is 4.96% (662 keV). The radiation imaging system can accurately locate Am-241, Cs-137, and Co-60 clearly, and can successfully distinguish the positions of two Cs-137 point sources by changing the distance between the coded collimator and the detector.

Assessment of uncertainty in collecting radioactive soil samples by sampling and analytical quality control (SAX)

BAO Li, CHEN Ling, REN Xiaona, WANG Ruijun

RADIATION PROTECTION. 2023, 43(1): 47-54.

Abstract ( 73 )

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Sampling uncertainty is one of an important part of the uncertainty in radiation environmental monitoring results. Because of the difficulty of quantifying sampling uncertainty, at present, the uncertainty of monitoring results of radiation environment only includes the analysis process, without considering the sampling process. Sampling design using SAX method and data analysis using robust variance analysis method can quantify the uncertainty of sampling process. A batch of actual monitoring data are analyzed by the SAX method, and the sampling uncertainty is obtained. And the uncertainty of monitoring results is studied carefully. It is considered that SAX method can be used to guide the monitoring of radiation environment, so as to optimize the monitoring strategy and to improve the monitoring quality.

Application study of radioactive decay corrections to the analysis of gaseous effluents monitoring samples from nuclear power plant

YIN Wangming, YOU Chengmao, MEI Xiangjie, ZHOU Kebo

RADIATION PROTECTION. 2023, 43(1): 55-63.

Abstract ( 89 )

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In the analysis of radioactive samples, radionuclides decay correction methods could be classified into three different stages(types): correction for decay during the counting period, correction for decay prior to the starting time of counting, and the correction for decay during the sampling duration. Based on the law of radioactive decay, the principles of three different types of decay correction methods are explained. Aiming at the gaseous effluents monitoring and samples analysis in nuclear power plants, for the short half-life radionuclides of noble gases & iodines, the necessity of decay corrections which were applied to the specific activity results is analyzed and the decay correction factors of three different types are calculated. For gamma-ray spectrometry, experimental results reveal that the Minimum Detectable Concentration(MDC) of radionuclide is directly related to the decay corrections. The application scheme of decay corrections for gaseous effluents monitoring samples analysis in nuclear power plants is introduced and studied. For the short half-life radionuclides of noble gases & iodines, the monitoring analytical data deviation was reduced by the implementation of the reasonable conservative corrections scheme, and the conservativeness of statistical emissions could be ensured too.

Study on the influencing factors of pulmonary effective dose conversion coefficient of inhaled radon progeny

MA Tianci, XIANG Dong, CHENG Weiya, TAN Zhiyu, CHEN Liangping

RADIATION PROTECTION. 2023, 43(1): 64-71.

Abstract ( 62 )

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Based on the respiratory tract biodynamic model in ICRP 66 report, this paper established the clearance model of human respiratory tract by using Simulink simulation tool in MATLAB software. The variation of pulmonary effective dose conversion coefficient (mSv/WLM) under different parameters was calculated by using the clearance model. The results showed that the particle size of inhaled radon progeny had the greatest influence on the lung effective dose conversion coefficient. The lung effective dose conversion coefficient could change more than 10 times when the particle size range was between 0.7 nm and 10,000 nm. The second factor is respiration rate, which directly determines the number of radon daughter particles inhaled. The lung effective dose conversion coefficient of a male under heavy working state is 4.2 times that of a male under sleep state. The effect of unbound state fraction on dose conversion coefficient will change with the size of inhaled radon daughters. When the unbound state fraction changes from 0 to 0.08, the lung effective dose conversion coefficient can increase by 79% at most. In contrast, absorbed blood rate only affects the pulmonary effective dose conversion coefficient by less than 4%.

Brief description of changes in screening coefficients in the revision of IAEA Safety Report Series No.19 (SRS 19)

CHEN Jiachen, WANG Yan, LIAN Bing, YANG Jie, YUE Qi, WU Feifei, MENG Binchi

RADIATION PROTECTION. 2023, 43(1): 72-76.

Abstract ( 74 )

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The paper introduces the IAEA Safety Report Series No. 19 (SRS 19) and the revised version of SRS 19; expounds the necessity of revision and summarizes the changes of screening coefficient of the three kinds of discharge pathways, namely surface water discharge, air discharge and sewage pipeline system discharge. The paper also provides reference for prospective assessment of public exposure and environmental impact caused by radioactive material discharge.

Monte Carlo continuation calculation method based on complex intermediate surfaces

YU Hong, LV Huanwen

RADIATION PROTECTION. 2023, 43(1): 77-82.

Abstract ( 69 )

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In order to improve computational efficiency of large and complex problems, a Monte Carlo Continuation Calculation method is proposed for structures with multiple spatial surfaces and complex curved surfaces. In this method, the external boundary of the structure is used as the source for the continuation calculation, and the sum of the calculation results of the source writing process and the continuation calculation process is taken as the final result. In terms of efficiency improvement, the method can avoid repeated calculation of the same structure in the process of direct calculation by means of one source writing process and several continuation calculation processes, which greatly improves the computational efficiency. A typical reactor structure calculation model is established by MCNP, and the continuation calculation results of four structural schemes are compared with those of direct calculation method. The results show that the calculation of the continuation method is consistent with those of the direct method, and the efficiency of the continuation calculation method is about three times higher than that of the direct calculation method. Therefore, the Monte Carlo continuation Calculation method proposed in this study can achieve significant efficiency improvement for large and complex problems involving a large number of repeated calculations.

Effects of substance P on cell cycle and apoptosis of irradiated skin fibroblasts

LIU Xiaoming, DANG Xuhong, ZHANG Ruifeng, LI Xiaozhen, YUAN Yayi, LIU Hongyan, CHAI Dongliang, REN Yue, ZHANG Zhongxin, ZUO Yahui

RADIATION PROTECTION. 2023, 43(1): 83-89.

Abstract ( 77 )

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To explore the effects of substance P on cell cycle and apoptosis of irradiated skin fibroblasts, Human Foreskin Fibroblasts (HFF-1) in logarithmic growth phase were divided into five experimental groups: 0 Gy group, 12 Gy group, 18 Gy group, 12 Gy+SP group and 18 Gy+SP group. The experimental groups were irradiated with electron beam at doses of 12 Gy and 18 Gy, while the 12 Gy+SP group and 18 Gy+SP group were treated with 10^-7 mol/L SP one hour before irradiation. After 48 hours of irradiation, cell cycle and apoptosis were detected by flow cytometry. The expression of apoptosis-related genes Bcl-2 and Bax in cells of each experimental group was quantitatively detected by real-time quantitative PCR. Cell cycle detection showed that the percentage of cells in G₂ phase in 12 Gy and 18 Gy experimental groups was significantly higher than that in 0 Gy group. And, compared with the 18 Gy experimental group, the percentage of cells in G₂ phase in the 18 Gy+SP experimental group was significantly lower than that in the 18 Gy group. Apoptosis detection showed that compared with 0 Gy experimental group, the apoptosis rate of 12 Gy and 18 Gy irradiation group increased significantly, while the apoptosis rate of substance P intervention group (12 Gy+SP, 18 Gy+SP) was significantly lower than that of radiation group (12 Gy, 18 Gy). Real-time fluorescence quantitative PCR detection of Bcl-2 and Bax expression showed that compared with 0 Gy experimental group, Bax gene expression was significantly increased and Bcl-2 gene expression was significantly decreased in 12 Gy and 18 Gy irradiated groups. And, the expression of Bcl-2 gene in substance P intervention group (12 Gy+SP and 18 Gy+SP) was significantly higher than that in radiation group (12 Gy and 18 Gy), but there was no significant difference in Bax gene expression. The above results suggest that electron irradiation can induce apoptosis and cell G₂ phase arrest of human skin fibroblasts. Substance P can inhibit the apoptosis and G₂ phase arrest of human skin fibroblasts damaged by radiation.

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