ABSTRACT
Objective:To summarize the practices in measuring the gross α and gross β radioactivity in IAEA-2020-intercomparison samples, which could be expected to be beneficial to the similar analysis and research.Methods:With 241Am, Th, 90Sr/ 90Y, 40K and 137Cs solution as standard materials, the gross α and gross β radioactivity in water and aerosol samples were determined using thin source method. With 241Am, 40K powder as standard materials, the gross α and gross β radioactivity in water and fish samples were measured using thick source method combined with evaporation. Results:The result showed that the relative deviation and Z-score by using thin source method were 4.12%-31.6% and 0.14-1.71, respectively, and those from thick source combined with evaporation were 2.63%-32.5% and 0.11-0.93, respectively, with the acceptance rate being 100%. Conclusions:Generally, standard material shall be selected in the same types of radionuclides and energies as in samples. The thin source method is appropriate for emergency monitoring in the event of an accident. The thick source combined with evaporation should be perfered to the environmental monitoring or the analysis of unknown samples in laboratory. And then an intercomparison should be done with thin source method based on the radioactivity in samples. This work can provide a technical reference for similar measurements.
ABSTRACT
Objective To investigate the distribution of gross α and gross β levels of centralized drinking-water of township in Beijing from 2018 to 2019, so as to carry out better monitoring and evaluating the radioactivity in water. Methods A total of 215 underground drinking water samples were collected from 12 districts of Beijing, then monitored and evaluated according to the Determination of gross alpha activity in water-thick source method EJ/T 1075—1998 and Determination of gross beta activity in water-evaporation method EJ/T 900—1994. Results The gross α level of centralized drinking water of township in Beijing was 0.050 (0.052) Bq/L, ranging from 0.001 to 0.210 Bq/L, and the gross β level was 0.048 (0.038) Bq/L, ranging from 0.002 to 0.261 Bq/L from 2018 to 2019. Gross α and gross β levels of all samples did not exceed the guidance value recommended by standards for drinking water quality. There was no significant difference in the distribution of gross α and gross β levels of samples of all districts from 2018 to 2019(P > 0.05), there were significant differences in the distribution of gross α and gross β levels of samples from different district in the same period (P < 0.05). And the levels of Miyun, Huairou and Shunyi in Chaobai River system were higher than other districts. Conclusion The distribution of radioactive background of centralized drinking-water of township in Beijing was mastered, which was in the normal range.