Natural radioactivity levels in some vegetable crops under greenhouse conditions.

Estimating any radioactivity released into the environment is critical for public health protection, particularly if the radioactivity can enter the food chain. In the present work, the activity concentration of natural radionuclides in the soil, water, plants, and fruits of four vegetable crops, namely cucumber, sweet pepper, hot pepper, and tomato, growing under greenhouse conditions has been measured using a High Purity Germanium (HPGe) Detector. The measured activity concentrations for 226Ra, 232Th, and 40K in the studied soil samples ranged from 4.7 to 6.8, 3.4 to 6.1, and 63.9 to 112.4 Bq kg-1, respectively, while in plants, they ranged from Not Detected (ND) to 15.2, ND to 3.4, and 495.1 to 1467.4 Bq kg-1, respectively. The measured activity concentrations for 40K in the studied fruit samples ranged from 967.1 to 1459.1 Bq kg-1, while 226Ra and 232Th were not detected. The Transfer Factor (TF) of 226Ra, 232Th, and 40K from soil to plants and fruits has been evaluated, and the results from soil to plants varied from ND to 2.5, ND to 0.8, and 6.0 to 19.2, while the results for 40K in fruits varied from 8.7 to 18.4, while 226Ra and 232Th were not detected.

Uncertainty of LiF thermoluminescence at low dose levels: Experimental results.

The LiF:Mg,Ti (TLD-100) thermoluminescence (TL) detectors are widely used in many dosimetric applications, particularly in personal dosimetry area. In the present study, the uncertainty of TLD-100 measurements at the low dose levels has been assessed for different TL readout analysis methods. The criteria used to evaluate the minimum measurable dose (MMD) have been also investigated. It has been found that between-sample variations and the precision of the TL measurements were the significant uncertainty components. However, the precision of the measurement is critically dependent on the TL readout analysis and background (BG) subtraction methods. The estimation of the MMD based on the 3σBG approach may lead to inaccurate measurements. On the other hand, a new criterion for evaluating the MMD based on the signal-to-noise ratio and can be evaluated from the glow-curve deconvolution analysis has been established. It has been shown that the implementation of this criterion ensures acceptable levels for both the precision and trueness of TL measurements.