Table of Content

20 September 2024 Volume 44 Issue 5

  

Research on the calculation method of full-energy peak efficiency of point source and volume source by hybrid Monte Carlo method

ZHANG Lei

RADIATION PROTECTION. 2024, 44(5):  445-453. 

Abstract ( 26 )   PDF (3409KB) ( 13 )  

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Based on the integral expression of the efficiency of the high purity germanium detector, the full-energy peak linear attenuation coefficients are calculated theoretically. Combined with the different tracks of gamma photons in the detector, the Monte Carlo method is used instead of the numerical integration to obtain the expected value of the full-energy peak efficiency. Firstly, the full-energy peak efficiencies of N-type and P-type high purity germanium spectrometers at the axial position of 5 cm from the point source to the detector are simulated and verified. The deviations between the simulation results and the experimental results are within ± 5.24%, which prove the accuracy of the method for calculating the full-energy peak efficiency of point source. On the basis of the point source efficiency simulation, the full-energy peak efficiency of volume source is simulated by the efficiency transfer method. The method is verified by the standard sources of four different media, namely resin, silica, coffee ash and aerosol filter in the laboratory. Except for the relative large deviations at low energy regions of the P-type detector, the calculation deviations of the other energy detection efficiencies are less than ±6.67%. Compared with the whole-process Monte Carlo simulation method, this method does not require professional modeling programs and expensive commercial software, and can calculate the full-energy peak efficiencies of point sources and volume sources through simple programming, which has great practical significance for quantitative analysis of radioactivity under emergency conditions.

Design and performance test of secondary standard ionization chamber for β radiation personal dose equivalent H_p(3)

LI Yin, WANG Chuan, YI Hengguan, LIU Xinhao, WANG Zhen, DUAN Jiayu

RADIATION PROTECTION. 2024, 44(5):  454-460. 

Abstract ( 17 )   PDF (2675KB) ( 5 )  

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In this paper, a secondary standard ionization chamber for β radiation personal dose equivalent H_p(3) is developed. Different from the extrapolation structure design of the primary standard extrapolation ionization chamber, the secondary standard ionization chamber adopts the structure of a flat plate ionization chamber with a phantom, and takes into account high measurement accuracy (relative inherent error <2.0%) while greatly simplifying the complexity of the test process. The radiation performance test results show that relative inherent error within the individual dose equivalent rate of beta radiation H_p(3) from 5 mSv/h to 170 mSv/h does not exceed ±1.5%; with regard to beta radiation H_p(3), for measurement range of at least 5 orders within the personal dose equivalent rate of 0.5 mSv/h-1.5 Sv/h, the relative inherent error does not exceed ±4.0%; the relative deviation of the response under the incident angle of β radiation ±60° does not exceed ±5%; measurement repeatability of the ionization chamber is 0.6%; relative expanded uncertainty of the measurement with flattening filter at 30 cm for the ⁹⁰Sr/⁹⁰Y source is U_rel=3.9% (k=2). In addition, it was found experimentally that the H_p(3) ionization chamber has a relatively high response to low-energy contamination photons.

Correction of crosstalk influence in the sample measurement of total α/β used by ultra low background flow gas proportional counter

XU Hailiang, CHEN Cheng, WANG Liang, ZHU Zhu, GUO Xuying, WANG Qian, SU Kunpu

RADIATION PROTECTION. 2024, 44(5):  461-468. 

Abstract ( 23 )   PDF (3036KB) ( 14 )  

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The ultra-low background flow gas proportional counter is the ideal detector for total α/β sample measurement, but itself has strong crosstalk phenomenon, which affects the accuracy of sample measurement. This paper systematically studies the flow type proportional counter under the same mass thickness, different ²⁴¹Am and ⁴⁰K mass fractions α→β, β→α Cross channel influence. This paper established a binary equation for total α/β channel correction and compared it with the cover correction method and with the self-made 25 groups α/β simulate powder samples for measurement and channel correction. The results show that: The impact of α→β crosstalk is significant; The change with α counting rate is not constant; The influence of the β→α channel correction factor is relatively small, with an average value of 0.001. The accuracy of the measurement results is poor by using the cover correction method to correct the simulated powder β sample, with absolute relative deviation ranging from 1.4% to 45.0%. The binary equation correction method is used to correct the simulated powder β sample. The accuracy of the measurement results is relatively high, with an absolute value of relative deviation ranging from 0 to 5.5%.

A combined rapid analytical method for strontium-89, strontium-90, iron-55, iron-59 and nickel-63 in liquid effluent of nuclear power plant

FANG Chunming, JIANG Dong, GUO Xiaocui, MO Nian

RADIATION PROTECTION. 2024, 44(5):  469-475. 

Abstract ( 17 )   PDF (3396KB) ( 6 )  

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Strontium-89, strontium-90, iron-55, iron-59 and nickel-63 are the major radionuclides concerned in liquid effluent of nuclear power plant. In this study, a method for rapid analysis of strontium-89, strontium-90, iron-55, iron-59 and nickel-63 in liquid effluent by four-stage resin column was established. The cation in the sample was enriched by cation exchange resin; and then strontium was separated and purified by strontium resin; iron was separated and purified by TRU resin; nickel was separated and purified by nickel resin. The chemical recovery rate was determined by ICP-OES; radioactive counting rate was determined by LSC; and then the activity concentration of each nuclide in the sample was calculated. Under typical conditions, the amount of sample is 1.0 L, and the measurement time is 30 min, the minimum detectable activity can reach 0.07 Bq/L for strontium-89, 0.05 Bq/L for strontium-90, 0.34 Bq/L for iron-55, 0.11 Bq/L for iron-59, and 0.16 Bq/L for nickel-63.

Numerical simulation study on salt deposition in huge salt water cooling towers

YANG Jie, LI Lujun, LIANG Ziqi, SONG Xiaojun

RADIATION PROTECTION. 2024, 44(5):  476-482. 

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A three-dimensional numerical simulation model for salt water cooling tower was established to study the characteristics of drifts and salt deposition in nuclear power project. In the model, site meteorological data, design parameters of cooling tower, general layout and environmental characteristics are considered. The results show that when the natural wind direction is parallel to the tower row, two hot air streams are superimposed on each other as one, which is beneficial to reducing the influence of drifts and salt deposition in the environment. The drifts with particle size greater than 550 μm can not escape from the outlet of cooling towers. For normal operation of 2 nuclear power units at the same site, the salt deposition will not cause damage to plants.

Comparison of analysis and measurement results for a 250 MeV medical proton therapy facility shielding

JIANG Wenhua, TU Yu, XUE Huiyuan, LI Yadong, ZHANG Jie

RADIATION PROTECTION. 2024, 44(5):  483-489. 

Abstract ( 15 )   PDF (5007KB) ( 7 )  

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Proton energy in the range of 70-250 MeV are used for tumor therapy. The neutron spectrum, which has wide energy range and large angle distribution difference, generated in target object bombarded by protons which may escape or expected to be stopped in the target is the main source term for the shielding design of proton therapy system. In this paper, the point kernel model is adopted to estimate the ambient neutron dose equivalent rate outside the Probeam proton therapy system tunnel. Estimation results are compared with the measured results to verify the effectiveness of the shielding construction.

Calculation efficiency optimization of point kernel integration method based on adaptive source term split up

ZHAO Yuan, LONG Zeyu, LI Hua, SONG Peitao, WEI Jiafu, LIU Liye, CHEN Ling

RADIATION PROTECTION. 2024, 44(5):  490-498. 

Abstract ( 14 )   PDF (3999KB) ( 8 )  

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The point kernel integration method has the problem that it takes a long time to calculate complex scene with multiple source terms or the situation that the radiation field needs to be dynamically updated. To solve this problem, this study employs the point kernel integration program CIRPDose to simulate and calculate the variation law of errors resulting from the split up of source terms (a total of five types, including cylindrical source and cuboid source, etc.) in relation to the distance between the calculated point and the source, and proposes an efficiency optimization method for the point kernel integration based on adaptive source term split up. After integrating the method into the CIRPDose program, the method was tested through customized examples. The test results show that the calculation time of radiation field for each type of source term under the adaptive split up method is reduced by 96.77%, as opposed to the conventional fixed number split up method. Moreover, the maximum average deviation in the calculated results is only 3.19%, which verifies the reliability and effectiveness of the proposed method. The research presented in this paper can provide technical support for the rapid calculation of 3D gamma radiation fields in nuclear facilities.

Development and experimental research of fast ion loss detection system in HL-3 device

XU Jia, ZHANG Jie, HAN Yuxiao, TANG Changjian, ZHANG Yipo

RADIATION PROTECTION. 2024, 44(5):  499-509. 

Abstract ( 15 )   PDF (16951KB) ( 3 )  

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Fast ion losses in tokamak plasma can reduce the heating efficiency. Fast ion loss detector (FILD) can simultaneously measure the loss rate, energy, and pitch angle of fast ions, making it one of the important means for monitoring and studying the phenomenon of fast ion losses. Based on the discharge parameters of the Chinese HL-3 device, the installation position of the probe is confirmed by simulating the motion trajectory of 80 keV deuterium ions in the HL-3 device with different initial pitch angles at first. Secondly, the collimator size is confirmed by simulating the motion trajectory of deuterium ions under different incident energy, magnetic field strength, and incident angles. Thirdly, by simulating the transverse and longitudinal maximum movement distance of deuterium ions on the silver-doped zinc sulfide ZnS(Ag) scintillator screen after passing through the collimator with designed size, the size of the scintillator screen is confirmed. Finally, the designed fast ion loss detector (FILD) based on the silver-doped zinc sulfide ZnS(Ag) scintillator screen is installed in the HL-3 device for experimental research. The research results show that the fast ion loss detector (FILD) can successfully measure the fast ion loss signal and monitor the fast ion loss induced by the toroidal Alfvén eigenmodes (TAE) mode.

Hydrochemical control of primary circuit during the implementation of hydrogenation passivation process for HPR1000

YE Wei, MIN Chun, DENG Yi, ZHENG Dechao, LIU Xiaojun, ZHAO Hongjie, MA Laishan

RADIATION PROTECTION. 2024, 44(5):  510-517. 

Abstract ( 18 )   PDF (5801KB) ( 12 )  

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In order to meet the hydrochemical control requirements of primary circuit hydrogenation passivation process during HFT, the water quality control methods adopted in chemical platform, thermal shutdown platform and primary heating and cooling stages of HPR1000 unit are briefly described, and the implementation results are analyzed. The control results show that the water quality indexes of the HPR1000 unit are controlled within the expected range during the implementation of hydrogenation passivation.

Molecular dynamics simulation of Primary Knock-on Atom energy on Fe irradiation damage

ZHANG Wenli, LIU Chengwei, WEI Shaochong, ZOU Yang, LIU Shengyong, SHI Jingcan,CHEN Guoxing

RADIATION PROTECTION. 2024, 44(5):  518-523. 

Abstract ( 13 )   PDF (2979KB) ( 1 )  

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In the high-energy irradiation environment, the structural materials of nuclear power plant could produce internal defects, which will affect the service performance. In this paper, molecular dynamics method is used to simulate the cascade collision process of Fe in irradiation environment and the effect of PKA (Primary Knock-on Atom) energy on irradiation damage defects. The results show that the cascade collision process of Fe is divided into three stages, the number of Frenkel defect pairs first reaches the peak and then recombines, resulting in a rapid decrease in the number of defect pairs and finally a tend to be stable. With the increase of PKA energy, the higher the number of Frenkel defect pairs in peak and stable states, the higher the defect recombination ratio. Meanwhile, with the increase of PKA energy, the larger the cluster size of interstitial clusters and vacancy clusters, the more the number of corresponding clusters. Therefore, the radiation damage process of Fe can be used to predict the radiation damage of materials under high-energy radiation environment and provide theoretical guidance for the service life of materials.

Design and performance analysis of an elliptic iodine adsorber

QIU Jilin, LI Yi, YU Jie, TIAN Lintao, ZHANG Yuan, WANG Jia, HAN Ming, ZHANG Zhiquan, SHEN Dapeng, WANG Ruiyun

RADIATION PROTECTION. 2024, 44(5):  524-529. 

Abstract ( 13 )   PDF (4807KB) ( 3 )  

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In order to meet the needs of iodine adsorber in the ventilation system of nuclear facilities with confined space or small air flow rate, an elliptical iodine adsorber was designed. The internal flow field simulation analysis and overall performance test of the iodine adsorber were carried out. The experimental results show that the internal air flow distribution in the iodine adsorber is uniform, the structural design is reasonable, the volume is small, the weight is light, and the connection with the system is convenient and fast. Under the flow rate of 300 m³/h , the resistance is less than 300 Pa, the mechanical leakage rate is less than 0.01%, and the adsorption efficiency of the adsorber of radioactive methyl iodine is more than 99.99%. It generally meets the purification and treatment requirements of specified application of nuclear facility, and the engineering application is realized.

Discussion on the clothing decay time and clothing decay room's spatial distribution of the ¹³¹I treatment area

ZHANG Hansheng, YANG Suyun, WANG Mengting, HU Manman

RADIATION PROTECTION. 2024, 44(5):  530-536. 

Abstract ( 20 )   PDF (1145KB) ( 8 )  

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In order to analyze the time required for the decaying of the surface contamination level of the clothing used by the patients who received ¹³¹I treatment to the clearance level, and to write the Python code to discuss the minimum area and optimal layout of the clothing decay room needed in the ¹³¹I treatment site in the department of nuclear medicine at different scales. 50 quilts used by patients with differentiated thyroid cancer treated in the Department of Nuclear Medicine of a Grade 3A Hospital in Taiyuan City, Shanxi Province from August to September 2023 were selected and the surface contamination level of the quilt was measured at the same time period every day. Python code was written to discuss the minimum space area and optimal layout of clothing decay under different parameters. The surface contamination decay constant of clothes used by patients treated with ¹³¹I was 0.097 0±0.242 1. Two hours after discharge, the surface contamination level of the clothing ranges from 0.42 to 8.67 (2.23±1.64) Bq/cm². The time required for the clothing to decay to the clearance level ranges from 0 to 24.57 (8.67±6.35) days. A set of Python code for calculating the minimum area of clothing decay room under different conditions is compiled, and the layout of the clothing decay room is divided into three types according to the number of storage shelves. Taking our institute in Grade 3A Hospital as an example, at least 7.5 m2 clothing decay room is needed. In clinical practice, by running Python code and defining relevant parameters, we can give reference to the area planning of clothing decay room, and provide some reference for the problems such as insufficient decay room and insufficient space in clinical work. The code is also applicable to the area planning and calculation of radioactive waste decay room or storage room.

Effects of transglutaminase 2 on radiosensitivity of human glioblastoma cell line U251

LAN Ruilong, WU Bing, WANG Zeng

RADIATION PROTECTION. 2024, 44(5):  537-545. 

Abstract ( 10 )   PDF (8215KB) ( 0 )  

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To investigate the effect of transglutaminase 2 (TG2) on radiosensitivity of glioblastoma, bioinformatic analysis was adopted to analyze the relationship between TG2 expression and the prognosis of glioma patients and TG2 level in GBM radioresistant cell line U251; TG2-overexpression cells (U251-TG2) or control cells (U251-EV) were obtained by transient transfection; cell growth curve was drawn by CCK8 method, and cell migration ability was measured by transwell; colony formation ability, ROS level and γ-H2AX foci were measured after X-ray treatment; Beclin-1, LC3 and mTOR phosphorylation levels were detected by Western blot. The results showed that glioma patients with high TG2 expression had worse progression-free interval and overall survival, and TG2 expression in radioresistant U251 was significantly higher than that in wild type U251; the cell proliferation and migration ability of U251-TG2 were higher than that of U251-EV; after X-ray treatment, compared with U251-EV, U251-TG2 showed higher colony-forming ratio, lower ROS level and γ-H2AX foci number; the levels of Beclin-1 and LC3-II/I in U251-TG2 were higher than those in U251-EV; mTOR phosphorylation level in U251-TG2 was lower than that in U251-EV. The results indicated that TG2 could promote autophagy by inhibiting mTOR phosphorylation, and then decrease the radiosensitivity of U251 cells.

The impact of total β discharge limits on Lu-177 nuclide therapy and recommendations for future optimization

ZHANG Qi, GE Yuwen

RADIATION PROTECTION. 2024, 44(5):  546-553. 

Abstract ( 20 )   PDF (1094KB) ( 8 )  

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The current national standards in China stipulate that radioactive wastewater from medical institutions must be stored in a decay tank for some time. The wastewater can only be discharged when the total β-radioactivity level at the outlet of the decay tank is reduced to below 10 Bq/L (daily average). Lu-177, a β-nuclide accompanied by low-energy γ-rays, has broad application prospects in the treatment of neuroendocrine tumors. When medical institutions use Lu-177 for nuclide therapy, a portion of Lu-177 enters the decay tank through patient excreta and other means. The Lu-177-containing wastewater needs to be temporarily stored in the decay tank until the total β-radioactivity level is reduced to be below the discharge limit. This paper derives theoretical formulas for calculating the total activity of Lu-177 in the decay tank when the hospital is operating at full capacity under both inpatient and outpatient treatment modalities. Furthermore, it provides the minimum temporary storage time for wastewater and the required capacity of the decay tank that medical institutions should construct. The paper also reviews the regulations for the total β discharge limit in different historical periods in China and discusses the rationality and potential optimization paths for the current wastewater total β discharge limit.

Establishment of nursing quality evaluation index system in radionuclide treatment ward

LIU Liu, HOU Bei, ZHU Yanan, GAO Yan, LIANG Yingfeng, GUO Shanshan

RADIATION PROTECTION. 2024, 44(5):  554-561. 

Abstract ( 13 )   PDF (1084KB) ( 4 )  

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By establishing an evaluation index of nursing quality in radionuclide wards, in order to scientifically evaluate the nursing quality of patients in radionuclide wards. The evaluation index system of nursing quality in radionuclide treatment wards was established, through literature search, semi-structured interview, Delphi method and analytic hierarchy process based on Donabedian three-dimensional quality evaluation model of structure-process-result. Under the guidance of evidence-based nursing practice, a radionuclide treatment ward and nursing quality evaluation index pool were constructed by integrating the results of literature search and semi-structured interview, and the index contents were determined after two rounds of expert letter consultation. In our research, twenty experts were included. The effective recovery rates of the questionnaire were 90% and 100%. The expert authority coefficients were 0.945 and 0.950, respectively. Kendall concordance coefficients were 0.128 and 0.550 (P<0.05), respectively. The revised results after 2 rounds of expert consultation were summarized, 3 indexes were deleted, 7 indexes were modified, and 9 indexes were added. Finally, the nursing quality evaluation index system of radionuclide treatment ward was established, including 3 first-level indexes, 13 second-level indexes, and 58 third-level indexes. The average value of importance assigned to all indexes was > 4.00, and the coefficient of variation was < 0.33. It shows that each index has high reliability. The evaluation index system of nursing quality in radionuclide wards established in this study has guiding significance for nursing work of patients, and quality evaluation of patients treated with radionuclide, and provides a reference for the quality evaluation of nursing work in radionuclide treatment wards.

CFD study on aerosol distribution characteristics of radioactive powder material scattering accident

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

RADIATION PROTECTION. 2024, 44(5):  562-572. 

Abstract ( 14 )   PDF (12799KB) ( 1 )  

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Based on CFD method, this paper studied the indoor air flow and particle movement after the radioactive powder material scattering accident in a closed workshop, and analyzed the influence of particle size, scattering speed and scattering height. The results show that the particle movement is mainly affected by the gas circulation inside the confined space. Most of the particles are deposited on the ground or attached to the wall and captured, and a small part of the particles will be floating and suspended indoors in the later period and move with the airflow. There is little difference in aerosol motion and distribution caused by different scattering velocities. Particles with small particle size are more likely to be separated from the mainstream area and form scattered dust under the influence of the drag force of the surrounding gas. Therefore, the smaller the particle size is, the larger the deposition range caused by the spraying lag is.