ABSTRACT
Objective To summarize and analyze the difficulties and key points in the measurement of gross α and gross β radioactivity in water based on the results of national measurement capability comparison assessment, and provide the basis and reference for the future work and the development of new local standards. Methods The research team participated in the comparison assessment for measurement of the gross radioactivity in water samples organized by National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention. According to the comparison assessment results and the content in the national standard GB/T 5750.13—2023 (published draft), the steps of spike recovery involved during the measurement were analyzed and discussed. Two different formulas used for spike recovery calculation were analyzed for their impact on the final measurement results. Results When the spike recovery F(derived) derived from the formulas was used for result calculation, the spike recovery ranged as follows: gross α: 63.00%−84.60%, and gross β: 95.0%−99.1%; 3/6 of the comparison results were determined as excellent and 3/6 as pass as a whole (among them, 4 were excellent and 2 were pass for both single gross α assessment items and single gross β assessment items). When the spike recovery F from the GB/T 5750.13—2023 (published draft) was used for result calculation, the spike recovery ranged as follows: gross α: 39.69%−71.57%, and gross β: 90.25%−98.21%; 5/6 of the comparison results were determined as fail and 1/6 as pass (among them, 5 were fail and 1 was pass for single gross α assessment items; 5 were excellent and 1 was pass for single gross β assessment items). When two different formulas were used for spike recovery calculation, there was a significant difference in gross α radioactivity measurement (t = 4.27, P = 0.03 < 0.05), but there was no significant difference in gross β radioactivity measurement (t = 0.667, P = 0.524 > 0.05). Conclusion In the measurement of gross α and gross β radioactivity in water, appropriate reference to the spike recovery has a great influence on the measurement results. Therefore, quality control should be strengthened to further ensure the accuracy of measurement.
ABSTRACT
Objective To summarize and improve the related technical issues by analyzing the nationwide interlaboratory comparison of gross α and gross β radioactivity measurement over the years. Methods According to the requirements of interlaboratory comparison and the national standards, the gross α and gross β radioactivity in water were measured, and the results were analyzed to identify the influencing factors. Results From 2018 to 2022, our laboratory participated in five nationwide interlaboratory comparisons of gross α and gross β radioactivity measurement. The Z-test values for gross α and gross β measurement ranged from −0.24 to 1.8 and −1.4 to 0.35, respectively. The relative deviations ranged from −4% to 32% and −18% to 6%, respectively. All comparisons were within the acceptable ranges. Conclusion The analysis of comparisons showed that the results were within the acceptable ranges. The relative deviations between the measurement and the reference values have decreased over the years. The summary and improvement of related technologies have improved the measurement accuracy.
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Objective To study gross α and gross β radioactivity in environmental samples in Wuxi, China, and perfect the radioactivity data, and to discover possible radioactive contamination in time. Methods The BH1227 low-background α and β measuring instrument was used to determine gross α and gross β radioactivity in sedimentary dust, aerosol, drinking water, and food samples in Wuxi. Results Among environmental samples collected in Wuxi, 2014—2019, the mean gross α and gross β radioactivity levels were 0.01～5.98 Bq/kg and 9.47～547.86 Bq/kg in food samples, respectively, 1.2～22 mBq/L and 0.1～141 mBq/L in water samples, respectively, 39～44790 mBq/m3 and 743.1～101500 mBq/m3 in sedimentary dust samples, respectively, and 50～1125 μBq/m3 and 38～9510 μBq/m3 in aerosol samples, respectively. Conclusion We should strengthen radioactivity monitoring of environmental samples in Wuxi through increasing the scope and frequency of monitoring, to perfect baseline radioactivity data of Wuxi.
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Objective To ascertain the gross α/β levels in drinking water in Inner Mongolia and to estimate the annual effective dose to the local residents from radionuclides in drinking water.Methods A total of 768 water samples were collected from 101 counties distributed over 12 cities of Inner Mongolia.Low background α/β measuring instrument was used to measure the radioactivity level;On this basis,use EPA Federal Guidance Report 11 universal method to estimate the annual effective dose to the local residents via intake of radionuclides from drinking water.Results The gross α radioactivity range was 0.016-1.003 Bq/L for tap water,O.016-0.975 Bq/L for factory water,0.017-1.544 Bq/L for river water,0.120-0.672 Bq/L for lake water,0.016-0.492 Bq/L for reservoir water,0.016-1.139 Bq/L for well water,0.032-3.156 Bq/L for spring water,respectively.The gross β radioactivity range was 0.030-0.828 Bq/L for tap water,0.031-0.571 Bq/L for factory water,0.066-0.873 Bq/L for river water,0.169-2.268 Bq/L for lake water,0.046-0.519 Bq/L for reservoir water,0.071-0.526 Bq/L for well water,0.087-1.063 Bq/L for spring water,respectively.Conclusions In Inner Mongolia,the gross α/β mean value in tap water is less than the World Health Organization-recommended value and the average annual effective dose from tap water is also less than the WHO-recommended value O.1 mSv/a.The gross α/β radioactivity from the other water samples is also within the range of the nationwide average.
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Objective To measure the total β radioactive background level in the urine of normal adults,and to establish the method which can be universally used and satisfy the needs of rapid screening of samples in large batch.Methods A total of 83 urine samples from healthy adults were prepared by evaporation.And the gross β activity in urine was detected by using low background measuring instrument.Results The optimal experimental conditions were in place.The sampled volume was 200 ml,and the samples were turned to nitric acid salinization,ashed at 300℃ for 2 h,and the measured time was 1000 min.To get a more stable result,the urine residues were put aside for 24 h before measurement.The radioactivity in urine of healthy adults was between 9.40-55.92 Bq/L,and showed no correlation with age and sex.Conclusions When the radioactivity in urine is detected under the conditions mentioned above,the sample preparation process is simple and quickly,which can satisfy the needs of large batch sample screening.