In order to quickly screen for the presence of 14C in target water body and provide quantitative measurement results, a rapid and accurate analysis of 14C activity concentration in samples was achieved by optimizing the counting region of the liquid scintillation spectrum and improving counting efficiency with an internal calibration method under quenching effects, resulting in a lower detection limit of 1.8 Bq/L. This method was then applied to determine the 14C activity concentration in the samples from the deday pool of a nuclear medicine factory and the surrounding environmental water. The results showed that the activity concentrations of the three samples were below the lower detection limit, whereas those of the others were within 38-1 332 Bq/L. The accuracy of this direct analysis method was verified by using self-prepared samples with known activity concentrations, which showed a maximum deviation of 1.1% from the reference values.

This study investigated the gross radioactive background levels in paddy, vegetables, and cultivated soils around major agricultural production bases and key nuclear and radiation facilities in Guangdong Province. From 2018 to 2022, continuous sampling and follow-up monitoring were conducted on paddy, vegetables, and their respective soils. The collected data were statistically analyzed by area and city to explore the α/β ratio in soils across different locations. The gross α, gross β and 40K specific activities in paddy are (13.8±11.5) Bq/kg, (105±13) Bq/kg, (114±16) Bq/kg, respectively. The gross α, gross β and 40K specific activities in vegetables are (4.7±4.9) Bq/kg, (93±33) Bq/kg, (109±47) Bq/kg, respectively. The gross α specific activities of paddy soil and vegetable soil are (2.18±0.94)×103Bq/kg and (1.81±0.83)×103 Bq/kg, respectively. The gross β specific activities of paddy soil and vegetable soil are (1.09±0.49)×103Bq/kg and (0.91±0.39)×103 Bq/kg, respectively. These findings contribute to the enrichment of the background database for natural radioactivity surveys in China, providing essential data for environmental impact assessments post-operation of nuclear facilities, emergency responses to nuclear and radiation accidents, and food safety evaluations in Guangdong Province. The α/β ratio in soil obtained in this study can serve as an early warning indicator, where deviations from the established range may signal the presence of artificial radioactive contamination.

Radio frequency anti-theft devices employ radio frequency identification (RFID) technology to identify and track objects. An anti-theft system based on the identification of information legitimacy judgment realizes an anti-theft alarm function. In this study, we effectively evaluated the safety of a 13.56 MHz RF anti-theft device in terms of electromagnetic exposure of pedestrians using the RF module in the COMSOL Multiphysics software. To this end, we designed an electromagnetic environment model to study the public electromagnetic exposure of pedestrians when such an RF anti-theft device is used. In particular, four exposure scenarios were analyzed in which the antenna system of the RF antitheft device was operating at 100 mW and 1 W and a pedestrian was located at the center (location A) and 25 cm away in front of the center (location B) of the anti-theft device. The results showed that when the pedestrian was at location A, for the aforementioned antenna feed power of 100 mW and 1 W, the maximum electric field strength of the whole body tissue was 0.26 V/m and 0.84 V/m, and the maximum magnetic field strength was 0.05 A/m and 0.16 A/m, respectively. The maximum values of the specific absorption rate (SAR) were 1.55×10-5 W/kg and 1.5×10-4 W/kg, respectively. When the pedestrian was at location B, for the aforementioned antenna feeding power of 100 mW and 1 W, the maximum electric field strength of the whole body tissue was 0.1 V/m and 0.36 V/m, and the maximum magnetic field strength was 2.08×10-3 A/m and 6.56×10-3 A/m, respectively. In this case, the maximum SAR values were 2.29×10-6 W/kg and 2.92×10-5 W/kg, respectively. These values obtained from simulation are lower than the public electromagnetic exposure limit established by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). This indicates that pedestrians passing through the RF electromagnetic environment analyzed in this study are within a safe range of public electromagnetic exposure. Therefore, the proposed anti-theft device does not pose a threat to public health.