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1.
Chinese Journal of Radiological Medicine and Protection ; (12): 112-117, 2023.
Artigo em Chinês | WPRIM | ID: wpr-993060

RESUMO

Objective:To measure the influencing factors associated with the analysis of 226Ra gamma spectra in order to obtain more acurate and precise measuring result on a basis of further optimizing the gamma spectrometry method for 226Ra activity. Methods:A laboratory-based HPGe gamma spectrometer was used to carry out the studies on tracking measurement of sample sealing time, measurement of background fluctuation with lead shielding, analytical method, and selection of characteristic gamma ray energy peak of its daughter nuclides in 226Ra measurement. Results:After the sample was sealed for 12 d, the decay products of 226Ra- 222Rn basically reached equilibrium. The day and night fluctuations of 222Rn in the shielded lead room were obvious but had no obvious regularity. The way of filling nitrogen into the shielded lead room could reduce or avoid the influence of background fluctuations. For 31 soil samples measured after 23 days of sealing, the result of using the efficiency curve method showed that the 226Ra result calculated from the 351.9 keV energy peak were generally higher than the 609.3 keV energy peak, and the higher ratio ranged from 8.0% to 20.7%. The result of relative comparison method showed that the deviation ratio of the two peaks ranged from -4.1 % to 10.3 %. Conclusions:It is recommended to consider the uncertainty attributed from decay equilibrium about 4 % of measured at 12 d after the sample is sealed. When filling nitrogen through the shielded lead chamber to avoid background fluctuations, attention must be paid to the matching relationship between the volume of the lead chamber and the nitrogen filling flow. When the efficiency curve method is used to analyze the activity of 226Ra, the 214Bi ( 609.3 keV ) energy peak has the effect of cascade coincidence addition, so 214Bi(609.3 keV) energy peak should be avoided. When the relative comparison method is used to analyze the activity of 226Ra, both two energy peaks of 214Pb ( 351.9 keV ) and 214Bi ( 609.3 keV ) can be used.

2.
Chinese Journal of Radiological Health ; (6): 93-97, 2023.
Artigo em Chinês | WPRIM | ID: wpr-973111

RESUMO

@#<b>Objective</b> To correct the counting loss of <sup>37</sup>Ar below the activity threshold during the measurement of the absolute activity of the inert radioactive gas <sup>37</sup>Ar using the proportional counter filled with gas. <b>Methods</b> Monte Carlo simulation with Geant4 was performed to establish a proportional counter model and output the energy deposition spectrum of <sup>37</sup>Ar, which were used to simulate and analyze the causes and correction of counting loss. <b>Results</b> The photon detection efficiency was only 38.7% at 60 kPa. The counting loss was mainly caused by the wall effect produced by the photons, which could be reduced by increasing the gas pressure and corrected by extrapolation. The influence of wall effect at 100 kPa was 4.4%, and the deviation between simulation and experiment was < 0.6%. <b>Conclusion</b> A factor could be calculated by Geant4 simulation for the correction of counting loss, thus achieving the accurate measurement of <sup>37</sup>Ar activity by proportional counter.

3.
Chinese Journal of Radiological Health ; (6): 387-391, 2022.
Artigo em Chinês | WPRIM | ID: wpr-965696

RESUMO

Objective@#To explore the effect of change in occupational internal dose coefficients on estimation of the in- ternal exposure dose of radiation workers.@*Methods@#Forty-one radionuclides were selected as the research objects, and their new and old occupational internal dose coefficients were summarized. The change in internal dose coefficients was analyzed by calculating the ratios of dose coefficients and using the frequency distribution of ratios.@*Results@#The occupational in- ternal dose coefficients of the 41 radionuclides analyzed had all changed, with ratios ranging from 0.1 to 4.5, and the maxim- um difference reaching 10 times (when the ratio was equal to 0.1).@*Conclusion@#It is recommended to revise the national standards concerning occupational internal dose coefficients in time and update the occupational internal dose coefficients, so as to better monitor the occupational health of radiation workers.

4.
Chinese Journal of Radiological Health ; (6): 548-552, 2022.
Artigo em Chinês | WPRIM | ID: wpr-965676

RESUMO

@#<b>Objective</b> To discuss the selection of dose estimation methods for internal exposure to tritium, their applicable working scenarios, and accurate dose estimation. <b>Methods</b> We compared the process and formula of two methods of urine tritium concentration monitoring in estimating the committed effective dose, explained the limitations of the atmospheric tritium concentration monitoring method, and compared the three methods from the aspects of the application scope and measurement methods. <b>Results</b> The atmospheric tritium concentration monitoring and urine tritium concentration monitoring methods provided opposite results of the magnitude of the committed effective doses for persons 3 and 10. The mean of the absolute values of the percentages by which <i>E</i>(<i>τ</i>)<sub>1 </sub>values were higher than <i>E</i>(<i>τ</i>)<sub>3 </sub>values was 29.6%, and that of <i>E</i>(<i>τ</i>)<sub>2</sub> higher than <i>E</i>(<i>τ</i>)<sub>3 </sub>was 72.4%. The consistency between the reference man-based tritium dose estimation method and the atmospheric tritium concentration monitoring method was better. The atmospheric tritium concentration monitoring method tended to underestimate the committed effective dose of tritium. <b>Conclusion</b> We suggest urine tritium concentration monitoring for estimating the committed effective dose, rather than atmospheric tritium concentration monitoring. The use of the reference man-based tritium dose estimation method or urine tritium activity concentration integration method should be based on individual metabolic conditions, working environment, and intake time, and urine sampling should be on time and repeated for monitoring..

5.
Chinese Journal of Radiological Health ; (6): 6-12, 2022.
Artigo em Chinês | WPRIM | ID: wpr-973569

RESUMO

Objective To optimize the Marinelli beaker with the simulation of Laboratory Sourceless Object Calibration Software (LabSOCS), to investigate the detection efficiency of HPGe detector in measuring noble gas, and to provide a reference for the measurement and optimization of noble gas effluent from nuclear power plants. Methods LabSOCS was used to establish a Marinelli beaker model to investigate the relationship of gamma ray detection efficiency of noble gas with gas components, gas density, size and volume of the Marinelli beaker, and the shape of source container. Results The gas components had little effect on the detection efficiency of the noble gas in the Marinelli beaker. The gas density had a relatively great effect on the detection efficiency of low-energy gamma ray. The Marinelli beaker of appropriate height and radius enabled the HPGe detector to get better measurement results. For the BE5030 HPGe detector, the highest detection efficiency of the Marinelli beakers of different volumes were observed at the location where the radius/height ratio was 0.7, and the optimal values of height and radius were given for the Marinelli beakers of different volumes. Conclusion Choosing Marinelli beaker of the appropriate size can improve the detection efficiency of noble gas in the effluent from nuclear power plants.

6.
Chinese Journal of Radiological Health ; (6): 564-567, 2021.
Artigo em Chinês | WPRIM | ID: wpr-974652

RESUMO

Objective The effect of sieved particle size and equilibration time of soil samples on the measurement of radionuclides was studied to improve the accuracy of the specific activity of radionuclides in soil samples measured by gamma spectrometer. Methods The collected soil samples were dried and divided into four parts. After sieved with width of the mesh 2.0 mm, 1.0 mm, 0.5 mm and 0.25 mm respectively, they were filled into sample containers and sealed. The activity concentrations of 226Ra, 210Pb, 228Ra, 40K and 137Cs in different sieved soil samples were then measured at the sealed interval of 0, 4, 8, 12, 16, 21, 25 and 29 days by HPGe gamma-ray spectrometry respectively. Results The coefficients of variation ofthe specific activities of 226Ra, 210Pb, and 228Ra in soil samples measured at different equilibration intervals range from 0.9% to 4.3%. The coefficients of variation of the specific activities of 226Ra, 210Pb, 228Ra, 40K and 137Cs in soil samples with different sieved particle sizes range from 3.7% to 14.1%. Conclusion When the specific activities of radionuclides are determined by gamma-ray spectrometer, the effect of the sieved particle size on the measurement result must be considered, and its impact is higher than the equilibration time. This study is very useful for improving the accuracy of the determination of radionuclides in soil sample using gamma-ray spectrometer.

7.
Chinese Journal of Radiological Health ; (6): 34-37, 2021.
Artigo em Chinês | WPRIM | ID: wpr-973715

RESUMO

Objective To apply InSpector 1000 portable γ spectrometer and its corresponding supporting software to the monitoring of thyroid 131I activity of radiation workers, and to estimate the internal radiation dose of medical staff in nuclear medicine department. Methods The spectrometer was calibrated and taken to participate in the 2018 thyroid radioactive iodine intercomparison program initiated by Lawrence Livermore National Laboratory in the United States to ensure the accuracy of the measurement; the spectrometer was used to measure 131I activity ofthe radiation workers of the nuclear medicine departments of two grade-A tertiary hospitals in Beijing and Jinan to verify the feasibility of the method. Results The InSpector 1000 portable γ spectrometer was qualified for international intercomparison. Measurement results from the grade-A tertiary hospital in Beijing showed that the thyroid 131I activity of each of 10 radiation workers was below the detection limit (33.30 Bq). Measurement results from the grade-A tertiary hospital in Jinan showed that the thyroid 131I activities of the 4 radiation workers were 64.05 Bq, 160.77 Bq, 416.67 Bq, below the detection limit (35.18 Bq) respectively, and of 3 of the 4 subjects 131I was detected in the thyroid, and their corresponding thyroid accumulative organ doses were 0.70 μSv, 1.77 μSv, and 4.58 μSv, respectively. Conclusion InSpector 1000 portable γ spectrometer has a strong feasibility for thyroid 131I monitoring of radiation workers in nuclear medicine. The spectrometer has a good application prospect in the field of radiation monitoring, and can play an important role in the field of radiation protection and nuclear emergency detection.

8.
Chinese Journal of Radiological Medicine and Protection ; (12): 758-764, 2020.
Artigo em Chinês | WPRIM | ID: wpr-868523

RESUMO

Objective:To improve the radionuclide measurement technology by γ-spectrometry throuth a review of the intercomparisons between China and Japan results over the past 20 years.Methods:Before the beginning of each intercomparison, one of participating laboratories was agreed to be responsible for preparing the samples for the intercomparison. By intercomparison of the measurement results arnong the laboratories some potential problems during the sample pre-trement or analysis were found and solved.Results:The intercomparisons had been carried out for 11 times over the past 20 years. Totally 290 measured and analyzed results had been obtained from 20 samples of six categories. The proportion 95.5% of measurement results were in agreement with each other within the deviation range.Conclusions:The measuring and analytical capability of the laboratories involved were tested. The intercomparisons also provide long-term quality assurance measures for the radionuclide measurement and analysis in each laboratory.

9.
Chinese Journal of Radiological Medicine and Protection ; (12): 790-794, 2019.
Artigo em Chinês | WPRIM | ID: wpr-796648

RESUMO

Objective@#To standardize the operation and data processing in radiological health institutions in China, in order to promote the assessment of γ-spectrometry, improve the measurement and analysis capabilities of each laboratory, and accordingly improve accuracy of environment sample measuring.@*Methods@#By collecting the values of 232Th, 40K and 137Cs contents in soil samples from 2015 to 2017, the assessment results of γ-spectrometry laboratores were summarized and analyzed.@*Results@#The technical institutions from 25 provinces were involved in the assessment until 2017, including disease control and prevention centers, entry-exit inspection and quarantine agencies, research institutes, universities and companies. The number of participants was increased from 40 to 48, and the qualified rate exceeded 90%, and the excellent rate was no less than 11% each year. The percentage of relative deviation less than 10% between the measuring result of 232Th, 40K and 137Cs contents and the reference value was larger than 80% in 2017. The accuracy became better. However, the number of institutions with U and Z score less than 1 was increased from 11 to 25, suggesting that the precision of measuring result has also been greatly improved.@*Conclusions@#Radiological health institutions in China have good measurement and analysis capabilities with regard to γ-spectrometry, which can meet the needs of environmental sample measurement and in-food radionuclide risk monitoring in an emergency of nuclear and radiation. But a few institutions′ measuring results were largely different from the reference values, as a consequence, it is important to strengthen their ability of measurement and analysis.

10.
Chinese Journal of Radiological Medicine and Protection ; (12): 790-794, 2019.
Artigo em Chinês | WPRIM | ID: wpr-791399

RESUMO

Objective To standardize the operation and data processing in radiological health institutions in China, in order to promote the assessment of γ-spectrometry, improve the measurement and analysis capabilities of each laboratory, and accordingly improve accuracy of environment sample measuring. Methods By collecting the values of 232 Th, 40 K and 137 Cs contents in soil samples from 2015 to 2017, the assessment results of γ-spectrometry laboratores were summarized and analyzed. Results The technical institutions from 25 provinces were involved in the assessment until 2017, including disease control and prevention centers, entry-exit inspection and quarantine agencies, research institutes, universities and companies. The number of participants was increased from 40 to 48, and the qualified rate exceeded 90%, and the excellent rate was no less than 11% each year. The percentage of relative deviation less than 10% between the measuring result of 232 Th, 40 K and 137 Cs contents and the reference value was larger than 80% in 2017. The accuracy became better. However, the number of institutions with U and Z score less than 1 was increased from 11 to 25, suggesting that the precision of measuring result has also been greatly improved. Conclusions Radiological health institutions in China have good measurement and analysis capabilities with regard to γ-spectrometry, which can meet the needs of environmental sample measurement and in-food radionuclide risk monitoring in an emergency of nuclear and radiation. But a few institutions′ measuring results were largely different from the reference values, as a consequence, it is important to strengthen their ability of measurement and analysis.

11.
Chinese Journal of Radiological Medicine and Protection ; (12): 552-556, 2018.
Artigo em Chinês | WPRIM | ID: wpr-806878

RESUMO

Studies about the radioactivity level in whole diet of Chinese residents were presented in this paper. Related method and result were analyzed and compared between different countries. A summary and an outlook of this field were put forward in the end. This study estimated the radioactivity level in whole diet of Chinese residents and those in other countries. It also provided information for food safety and radiation protection of the public.

12.
Chinese Journal of Radiological Medicine and Protection ; (12): 774-778, 2018.
Artigo em Chinês | WPRIM | ID: wpr-708131

RESUMO

Objective To study the variation in net count rates of natural radionuclides in background of gamma-ray spectrometer,so as to provide a scientific basis for reducing the effect of background fluctuations on sample measurement.Methods The unscheduled background spectrum obtained using two high-purity gamma-ray spectrometers during 2013-2017 were collected,and then the net count rates of 210pb,234Th,212Pb,214pb,208Tl,214Bi,228Ac and 40K were calculated and analyzed by aid of statistical method.Results There was a significant difference in the net count rates of 210Pb,234Th,212Pb,214Pb,208Tl,214Bi,228Ac and 40K in the background spectrum of gamma-ray spectrometer,and the net count rates of 214Pb,214Bi and 40K was significantly higher than those of 210Pb,234Th,212pb,208Tl and 228Ac.There were no significant differences in the net count rates of these eight natural radionuclides from 2013 to 2017,respectively (P > O.05).However,the coefficients of variation in the net count rates for 214pb and 214Bi were both greater than 50%.Conclusions When the activity concentration of natural radionuclides is determined in a sample by gamma-ray spectrometer,it is critical to subtract the background spectrum obtained recently to ensure the accuracy of the measurement,especially for the low activity concentration of natural radionuclide to be measured.

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